WO2019153218A1 - Environmentally friendly non-destructive fiber-reinforced composite material recovering method - Google Patents

Environmentally friendly non-destructive fiber-reinforced composite material recovering method Download PDF

Info

Publication number
WO2019153218A1
WO2019153218A1 PCT/CN2018/075923 CN2018075923W WO2019153218A1 WO 2019153218 A1 WO2019153218 A1 WO 2019153218A1 CN 2018075923 W CN2018075923 W CN 2018075923W WO 2019153218 A1 WO2019153218 A1 WO 2019153218A1
Authority
WO
WIPO (PCT)
Prior art keywords
carbon fiber
recovered
catalyst
composite material
reinforced resin
Prior art date
Application number
PCT/CN2018/075923
Other languages
French (fr)
Chinese (zh)
Inventor
朱继华
苏玫妮
陈丕钰
Original Assignee
深圳大学
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by 深圳大学 filed Critical 深圳大学
Priority to PCT/CN2018/075923 priority Critical patent/WO2019153218A1/en
Priority to CN201880000077.5A priority patent/CN108323169B/en
Publication of WO2019153218A1 publication Critical patent/WO2019153218A1/en

Links

Images

Classifications

    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J11/00—Recovery or working-up of waste materials
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J11/00—Recovery or working-up of waste materials
    • C08J11/04—Recovery or working-up of waste materials of polymers
    • C08J11/10—Recovery or working-up of waste materials of polymers by chemically breaking down the molecular chains of polymers or breaking of crosslinks, e.g. devulcanisation
    • C08J11/16—Recovery or working-up of waste materials of polymers by chemically breaking down the molecular chains of polymers or breaking of crosslinks, e.g. devulcanisation by treatment with inorganic material
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J2363/00—Characterised by the use of epoxy resins; Derivatives of epoxy resins
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
    • Y02W30/00—Technologies for solid waste management
    • Y02W30/50—Reuse, recycling or recovery technologies
    • Y02W30/62—Plastics recycling; Rubber recycling

Definitions

  • This invention relates to the recovery and reuse of fiber reinforced composite materials.
  • Fiber reinforced resin matrix composites are reinforced resin-based composites of all high performance fibers and their products.
  • the types include, but are not limited to, various types of profiles, panels, cloths, meshes, grids, and the like, as well as various products made from fiber reinforced resin-based composite materials, including but not limited to composite automotive bodies and components. , composite fan blades, composite aircraft fuselage and components, various composite materials for applications and building structures.
  • the resin matrix includes various types of resin materials including, but not limited to, various thermoplastic epoxy resins, thermosetting epoxy resins, and the like.
  • the curing agent for the epoxy resin includes various types of curing agents well known in the art, including, but not limited to, amine curing agents and acid anhydride curing agents.
  • CFRP Carbon Fiber Reinforced Plastic
  • CFRP is taken as an example, and specifically refers to a composite material made of carbon fiber as a reinforcement and a resin (mainly organic epoxy) as a matrix.
  • CFRP is widely used in aerospace, medical equipment, industrial manufacturing, sporting goods, automobile manufacturing and construction industries due to its excellent corrosion resistance, light weight, high strength and toughness. It is estimated that by 2020, worldwide consumption of CFRP will reach 130,000 tons, most of which will be used in the industrial sector. However, such large-scale CFRP consumption has brought about serious waste disposal problems. For example, the first aircraft using carbon fiber reinforced composites as a structural material is about to be retired, and large-scale aircraft retiring tides will arrive around 2026. At that time, only Airbus Co., Ltd. has about 6,400 aircraft going to the end of its life, and each Airbus A350 uses up to 53% of the total weight of CFRP composites, about 20 tons.
  • the existing methods for recovering carbon fibers from fiber reinforced composite materials mainly include: (1) physical recovery method.
  • the CFRP waste is mechanically pulverized into fine-sized particles, and then the particles are separated to obtain a fiber-rich and resin-rich product, respectively.
  • the waste containing organic matter or completely organic matter is obtained by incineration or the like. The energy obtained can be converted into available thermal or electrical energy.
  • (3) Thermal decomposition recovery method The CFRP waste is placed under high temperature conditions to decompose the resin macromolecular polymer in CFRP into small molecular compounds, and then the carbon fibers are separated.
  • Atmospheric pressure chemical solvent decomposition recovery method By the synergistic action of the chemical solvent and the high-temperature heat, the C-N or C-O linkage chemical bond in the resin polymer is broken, the polymer is dissolved in the solution, and the carbon fiber is released from the resin, thereby achieving the purpose of recovery.
  • Other recycling methods Such as supercritical / sub-supercritical method, electric recycling method.
  • the existing method for recovering carbon fiber recovered from fiber reinforced composite waste has the following defects: (1) complicated process, difficult operation, and even requiring toxic auxiliary agents; (2) high equipment requirements, often requiring fiber The composite material (waste) is pretreated by cutting and pulverizing, resulting in shorter fibers and low economic value. (3) The initial equipment investment is large and industrialization is difficult.
  • the main object of the present invention is to provide a method for recovering fibers in a fiber-reinforced resin-based composite material (waste), wherein the fiber recovery method provided by the invention has the advantages of simple process steps, low difficulty, high recovery rate, low cost and The fiber damage is small and so on.
  • Another object of the present invention is to provide a method for recovering fibers in a fiber-reinforced resin-based composite material (waste), wherein the fiber recovery method provided by the present invention can not only recover fibers but also simultaneously recover resin materials, thereby further It is of great environmental value and important social significance to maximize the recycling and reuse of fiber-reinforced resin-based composite waste.
  • Another object of the present invention is to provide a method for recovering fibers in a fiber-reinforced resin-based composite material (waste), wherein the fiber-recovering method provided by the present invention has low toxicity and low requirements on production equipment.
  • the reaction conditions are mild.
  • the fiber recovery method provided by the present invention does not require shearing and/or crushing of the fiber-reinforced composite material, and therefore, materials of any size can be recovered. At the same time, it is not necessary to shear and/or crush the fiber reinforced composite material, and the length of the recovered fiber material is hardly damaged, and the economic value of the recovered fiber material is higher.
  • Another object of the present invention is to provide a composition for recovering fibers in a fiber-reinforced resin-based composite material (waste).
  • a method for recovering fibers in the fiber-reinforced resin-based composite material (waste) of the present invention capable of achieving the aforementioned objects and other objects and advantages includes the following steps:
  • the present invention further provides an electrolyte for recovering fibers in a fiber-reinforced resin-based composite material (waste), comprising:
  • Figure 1 shows a schematic diagram of the structure of a common carbon fiber electrochemical recovery system.
  • FIG. 2 is a cross-sectional view of a carbon fiber reinforced resin-based composite material, which is shown in which a carbon fiber reinforced resin-based composite material sheet is alternately laminated with a carbon fiber cloth and an epoxy resin layer by layer.
  • Figure 3 shows the voltage values of the carbon fiber reinforced resin-based composite sheet during the carbon fiber recovery process.
  • Figure 4 shows an SEM image of a black precipitate in an electrolyte under high current recovery conditions, which shows that the carbon fibers in the carbon fiber reinforced resin-based composite sheet are deteriorated and peeled off under a large current condition.
  • Figure 5 shows an energy spectrum detection analysis image of a black precipitate in an electrolyte under a large current recovery condition, which shows that the main component of the black precipitate in the electrolyte is carbon.
  • Figure 6 shows the length of carbon fiber recovered from a carbon fiber reinforced resin matrix composite at a current of 40 mA.
  • Figure 7 shows the amount of carbon fiber recovered from the same carbon fiber reinforced resin matrix composite sheet under different current conditions.
  • Figure 8 shows the degumming rate of carbon fibers recovered from carbon fiber reinforced resin matrix composites under different current conditions.
  • Figure 9 shows the tensile strength of the monofilament of the carbon fiber recovered from the carbon fiber reinforced resin matrix composite under different current conditions.
  • Figure 10 shows SEM images of carbon fibers recovered from carbon fiber reinforced resin matrix composites under different current conditions.
  • Figure 11 shows an SEM image of carbon fibers recovered from a carbon fiber reinforced resin matrix composite under different current conditions at a low NaCl concentration.
  • Figure 12 shows the voltage of the carbon fiber reinforced resin matrix composite in the electrolyte at different reaction times under different amounts of catalyst (KOH) conditions.
  • Figure 13 shows the voltage of the carbon fiber reinforced resin matrix composite in the electrolyte at different reaction times without any catalyst conditions.
  • Figure 14 shows the amount of carbon fiber recovered from the carbon fiber reinforced resin-based composite material under different amounts of catalyst (KOH).
  • Figure 15 shows the tensile strength of the monofilament of the carbon fiber recovered from the carbon fiber reinforced resin-based composite material under different amounts of catalyst (KOH).
  • Figure 16 shows the interfacial shear strength of carbon fibers recovered from carbon fiber reinforced resin-based composites under varying amounts of catalyst (KOH).
  • Figure 17 shows the interfacial destruction of carbon fibers recovered from carbon fiber reinforced resin matrix composites under varying amounts of catalyst (KOH).
  • Figure 18 shows an SEM (Scanning Electron Microscope) image of carbon fibers recovered from a carbon fiber reinforced resin-based composite material under different amounts of catalyst (KOH) at a current intensity of 20 mA and 40 mA.
  • KOH catalyst
  • Figure 19 shows an SEM image of carbon fibers recovered from a carbon fiber reinforced resin-based composite material at a current intensity of 20 mA when the amount of the catalyst (KOH) is high.
  • Fig. 20 is a view showing an AFM (atomic force microscope) image of carbon fibers recovered from a carbon fiber reinforced resin-based composite material under different amounts of catalyst (KOH) and current intensity.
  • AFM atomic force microscope
  • Fig. 21A shows an XRD (X-ray diffraction) image of a carbon fiber recovered from a carbon fiber reinforced resin-based composite material under a current concentration of 20 mA under different NaCl conditions.
  • Fig. 21B shows an XRD image of carbon fiber recovered from a carbon fiber reinforced resin-based composite material under a current concentration of 40 mA under different NaCl conditions.
  • Fig. 22A shows an XRD image of a carbon fiber recovered from a carbon fiber reinforced resin-based composite material under a different amount of catalyst (KOH) at a current intensity of 20 mA.
  • Fig. 22B shows an XRD image of a carbon fiber recovered from a carbon fiber reinforced resin-based composite material under a different amount of catalyst (KOH) at a current intensity of 40 mA.
  • Figure 23A shows an XPS (X-ray photoelectron spectroscopy) image of carbon fiber precursor (VCF).
  • Figure 23B shows a high resolution narrow spectrum image of C1s of carbon fiber precursor (VCF).
  • Fig. 24A shows an XPS image of carbon fibers recovered from a carbon fiber reinforced resin-based composite material under a low-dose catalyst (KOH) at a current intensity of 20 mA.
  • Figure 24B shows a high-resolution narrow-spectrum image of C1s of carbon fibers recovered from carbon fiber-reinforced resin-based composites at a current intensity of 20 mA under low-dose catalyst (KOH) conditions.
  • Figure 25A shows an XPS image of a carbon fiber recovered from a carbon fiber reinforced resin-based composite material at a current intensity of 20 mA and a medium dose catalyst (KOH).
  • Figure 25B shows a C1s high resolution narrow-spectrum image of a carbon fiber recovered from a carbon fiber reinforced resin-based composite material at a current intensity of 20 mA and a medium dose catalyst (KOH).
  • Fig. 26A shows an XPS image of carbon fiber recovered from a carbon fiber reinforced resin-based composite material under a high-dose catalyst (KOH) at a current intensity of 20 mA.
  • Fig. 26B shows a C1s high resolution narrow-spectrum image of carbon fiber recovered from a carbon fiber reinforced resin-based composite material under a high-dose catalyst (KOH) at a current intensity of 20 mA.
  • KOH high-dose catalyst
  • Fig. 27A shows an XPS image of carbon fibers recovered from a carbon fiber reinforced resin-based composite material at a current intensity of 20 mA, a low concentration of NaCl, and a medium dose catalyst (KOH).
  • Fig. 27B shows a C1s high resolution narrow-spectrum image of carbon fiber recovered from a carbon fiber reinforced resin-based composite material under a current intensity of 20 mA, a low concentration of NaCl, and a medium dose catalyst (KOH).
  • Fig. 28A shows an XPS image of carbon fibers recovered from a carbon fiber reinforced resin-based composite material at a current intensity of 20 mA, a high concentration of NaCl, and a medium dose catalyst (KOH).
  • Fig. 28B shows a C1s high resolution narrow-spectrum image of carbon fiber recovered from a carbon fiber reinforced resin-based composite material under a current intensity of 20 mA, a high concentration of NaCl, and a medium dose catalyst (KOH).
  • Figure 29A shows an XPS image of a carbon fiber recovered from a carbon fiber reinforced resin-based composite material under a medium dose catalyst (KOH) at a current intensity of 40 mA.
  • KOH medium dose catalyst
  • Figure 29B shows a C1s high resolution narrow-spectrum image of a carbon fiber recovered from a carbon fiber reinforced resin-based composite material at a current intensity of 40 mA and a medium dose catalyst (KOH).
  • Fig. 30A shows the surface functional group content of the carbon fiber recovered from the carbon fiber reinforced resin-based composite material at a current intensity of 20 mA under different doses of catalyst (KOH).
  • Fig. 30B shows the surface functional group content of the carbon fiber recovered from the carbon fiber reinforced resin-based composite material at a current intensity of 20 mA under different NaCl conditions.
  • Fig. 30C shows the surface functional group content of the carbon fiber recovered from the carbon fiber reinforced resin-based composite material under the same dose catalyst (KOH) at a current intensity of 20 mA and 40 mA.
  • Figure 31 shows the currents of 20 mA and 40 mA, the temperature of the carbon fiber reinforced resin matrix composite in the electrolyte at different temperatures and different reaction times.
  • Figure 32 shows the 20 mA and 40 mA current intensities, carbon fiber recovery at different temperatures.
  • Figure 33 shows the tensile strength of the monofilament of the recovered carbon fiber at different current conditions for 20 mA and 40 mA current intensities.
  • Figure 34 shows the 20 mA and 40 mA current intensities, and the interfacial shear strength of the recovered carbon fibers at different temperatures.
  • Figure 35 shows the 20 mA and 40 mA current intensities, and the interface damage of the carbon fibers recovered from the carbon fiber reinforced resin matrix composite at different temperatures.
  • Figure 36 shows SEM images of carbon fibers recovered from carbon fiber reinforced resin matrix composites at 20 mA and 40 mA current intensities at different temperatures.
  • Figure 37 shows AFM (atomic force microscope) images of carbon fibers recovered from carbon fiber reinforced resin matrix composites at 20 mA and 40 mA current intensities at different temperatures.
  • Figure 38 shows the XRD (X-ray diffraction) image of the carbon fiber recovered from the carbon fiber reinforced resin-based composite material at a current intensity of 20 mA under different temperature conditions.
  • Figure 39 shows the XRD image of the carbon fiber recovered from the carbon fiber reinforced resin-based composite material at a current intensity of 40 mA under different temperature conditions.
  • Fig. 40A shows an XPS image of carbon fiber recovered from a carbon fiber reinforced resin-based composite material at a current intensity of 20 mA at a temperature of 40 °C.
  • Fig. 40B shows a C1s high resolution narrow-spectrum image of carbon fiber recovered from a carbon fiber reinforced resin-based composite material at a current intensity of 20 mA at a temperature of 40 °C.
  • Fig. 41A shows an XPS image of carbon fiber recovered from a carbon fiber reinforced resin-based composite material at a current intensity of 20 mA at a temperature of 60 °C.
  • Fig. 41B shows a C1s high resolution narrow-spectrum image of carbon fiber recovered from a carbon fiber reinforced resin-based composite material at a current intensity of 20 mA at a temperature of 60 °C.
  • Fig. 42A shows an XPS image of carbon fiber recovered from a carbon fiber reinforced resin-based composite material at a current intensity of 20 mA at a temperature of 75 °C.
  • Fig. 42B shows a C1s high resolution narrow-spectrum image of carbon fiber recovered from a carbon fiber reinforced resin-based composite material at a current intensity of 20 mA at a temperature of 75 °C.
  • Figure 43 shows the surface functional group content of the carbon fiber recovered from the carbon fiber reinforced resin-based composite material at a current intensity of 20 mA at a temperature of 75 °C.
  • Figure 44 illustrates a method of recovering carbon fibers from a carbon fiber reinforced resin-based composite material in accordance with a preferred embodiment of the present invention.
  • the fiber includes various types of fiber materials including, but not limited to, glass fiber, carbon fiber, silicon carbide fiber, PBO, etc., preferably carbon fiber, silicon carbide fiber, wherein the fiber reinforced resin matrix composite material recovers fiber
  • the electrolyte means containing NaCl, water, and a catalyst, which is used for recovering carbon fiber from the carbon fiber reinforced resin-based composite material.
  • the NaCl concentration is x1 (0.5%), x2 (1%), x3 (2%), and x4 (3%) of water mass, respectively.
  • the current magnitude is measured by mA, such as 20mA, 40mA, 62.5mA, 78.1mA, 104.2mA, and 156.3mA.
  • the calculation method and value of the corresponding current density are shown in 3.1 of Example 3.
  • the grouping and experimental parameters of specific carbon fiber reinforced resin matrix composites are shown in Table 3.1.
  • the number of carbon fiber reinforced resin matrix composites is determined by the magnitude of the applied current and the concentration of NaCl solution, for example, the number "I20S x1 ", and the first half “I20” indicates that the nominal current of the carbon fiber reinforced resin matrix composite is 20 mA; the second half The part “S x1 " indicates the concentration of the NaCl solution x1 (0.5%) of the sample (carbon fiber reinforced resin-based composite sheet).
  • the (electrochemical) recovery system for recovering carbon fibers from carbon fiber reinforced resin-based composite materials includes a DC power source to provide a unidirectional operating current for the system; a cathode anode, a carbon fiber reinforced resin-based composite material sheet.
  • (Recycled sample) is connected as an anode to the positive electrode of the power supply, consuming degraded epoxy resin, and the stainless steel piece is connected as a cathode to the negative electrode of the power source;
  • the electrolyte contains NaCl, water (solvent) and catalyst; the data log (Datalog), and the recovered sample and
  • the stainless steel sheets are connected in parallel to monitor sample voltage changes.
  • the carbon fiber reinforced resin-based composite sheet is placed in parallel with the stainless steel sheet, and the distance between the two is fixed at 50 mm.
  • the carbon fiber reinforced resin-based composite material is formed by alternately stacking carbon fiber cloth and epoxy resin layer by layer.
  • the voltage monitoring of the carbon fiber reinforced resin matrix composite shows that the smaller the current, the smaller the voltage value and the more stable the carbon fiber reinforced resin matrix composite material group during electrochemical recovery.
  • the carbon fiber recovered from the carbon fiber reinforced resin-based composite material has a good length at a current of 40 mA.
  • the difference in the removal rate of carbon fibers recovered from the carbon fiber reinforced resin-based composite material is not significant under the conditions of 20 mA current and 40 mA current.
  • the tensile strength of the monofilament of the carbon fiber recovered from the carbon fiber reinforced resin-based composite material is significantly deteriorated under a large current (62.5 mA).
  • the carbon fiber recovered from the carbon fiber reinforced resin-based composite material is significantly deteriorated under a large current condition.
  • the carbon fibers recovered from the carbon fiber reinforced resin-based composite material are significantly deteriorated under a low NaCl concentration.
  • the catalyst KOH has a function of stabilizing the voltage of the carbon fiber reinforced resin-based composite material.
  • the increase in the dose of the catalyst KOH will exacerbate the oxidative etching of the recovered carbon fiber surface and improve the interfacial shear performance; the too low or too high NaCl concentration will reduce the recovered carbon fiber.
  • the interfacial shear performance; excessive current is not only conducive to improving the shear properties of the recovered carbon fiber interface, but also reduces the tensile strength of the recovered carbon fiber.
  • the high-dose catalyst will increase the surface oxidation degree of the carbon fiber recovered; the high NaCl concentration electrolyte will reduce the oxidation degree of the carbon fiber surface; the larger the current, the recovery The higher the degree of oxidation of the obtained carbon fiber, the more severe the corrosion of chlorine.
  • the surface functional group content of the carbon fiber recovered from the carbon fiber reinforced resin-based composite material increases with an increase in temperature under a current of 20 mA.
  • the carbon fiber reinforced resin matrix composite material also referred to as a fiber reinforced resin matrix composite material to be recycled, comprises curing, pasting or fabricating with various organic cementing materials (such as epoxy resin), and adopting various inorganic cementing materials.
  • a fiber reinforced resin-based composite material that is cured, pasted, or fabricated (such as a cementitious cementitious material).
  • the method of pretreating the fiber-reinforced resin-based composite material to be recycled includes, but is not limited to, cleaning, cutting, and grinding the fiber-reinforced resin-based composite material to be recycled by a method well known in the art.
  • Various pretreatment or recovery methods disclosed in current fiber material recovery or aging techniques include, but are not limited to, solution immersion, chemical decomposition, heating, pressurization, ultrasonic strengthening of the carbon fiber reinforced resin-based composite material to be recovered. , microwave enhancement, and a combination of various methods.
  • the heating temperature is 0 to 800 degrees Celsius, and the heating time is 0.5 to 200 hours.
  • the pressure of the pressurization is 0.5 to 20 atm, and the pressurization time is 0.5 to 200 hours.
  • the carbon fiber reinforced resin-based composite material to be recovered may be heated and pressurized in a liquid, and the liquid is characterized in that the resin is caused to expand and decompose.
  • the carbon fiber reinforced resin matrix composite sheet (or CFRP sample) has a size of 30 mm 245 mm and a thickness of 2 mm.
  • the CFRP sample is divided into three regions along its length: one region is the test region, the region used to recover carbon fibers, and the length is 100 mm; the second region is the protected region, which is insulated and waterproof. In order to ensure that the area of the test area is consistent during the experiment, the length is 80mm; the third area is the electrical connection region, which is used to connect the stainless steel plate joints to ensure the circuit connectivity and the length is 65mm.
  • the carbon fiber reinforced resin matrix composite material sheet (CFRP) sample used in this experiment was formed by alternately stacking carbon fiber cloth and epoxy resin layer by layer.
  • the epoxy resin mass content was 31.5%, and each layer of carbon fiber cloth was longitudinal and horizontal carbon fiber. Interwoven (see Figure 2).
  • the carbon fiber in the carbon fiber reinforced resin matrix composite sheet is T700 type carbon fiber (produced by Toray Co., Japan), and the epoxy resin is LAM-125/226 type epoxy resin.
  • the detailed chemical composition is shown in Table 1.1.
  • the frequency of the frequency is 1h/time and the power frequency is 50HZ.
  • the STA409PC model integrated thermal analyzer manufactured by NETZSCH of Germany was selected.
  • the maximum rise temperature of the sample was set to 800 ° C, the heating rate was 10 ° C, and the nitrogen flow rate was 100.
  • the thermogravimetric analysis three samples were tested for each sample, and the results were averaged.
  • the thermal cracking temperature range of the epoxy resin is about 300 ° C ⁇ 600 ° C, which is the optimum thermal cracking temperature of the LAM-125/226 epoxy resin used in this experiment, and the epoxy resin is completely cracked at 600 ° C.
  • the carbon fiber monofilament tensile strength test was carried out using a nano UTM 150 model nano-stretcher manufactured by Agilent, USA; the test system was UTM-Bionix Standard Toecomp Quasistatic.
  • the test parameters were set as follows: application load 750 ⁇ N, tensile rate 0.2 ⁇ m/s, load resolution 50 nN, displacement resolution ⁇ 0.1 nm, tensile resolution 35 nm, actuator maximum displacement 1 mm.
  • the test temperature is 20 ° C ⁇ 30 ° C, the air humidity is 40%.
  • the carbon fiber monofilament Before the carbon fiber monofilament tensile test, the carbon fiber monofilament should be fixed on the photo paper of 15mm 20mm in size, and the middle of the photo paper is a circular hole with a diameter of 6mm. The carbon fiber monofilament is adhered to the horizontal diameter of the round hole by using the paste glue. On the fiber, the fiber should not be too tight or too loose.
  • the sample After the sample is prepared, it is placed in laboratory conditions for one day, and the glue is allowed to dry naturally.
  • the sample can be loaded into the nano-tensile fixture, then the edges of the photo paper are cut and the test begins.
  • the carbon fiber monofilament test length is 61 mm, the number of samples to be tested per sample is 20, and the carbon fiber monofilament strength result is 20 sample intensity average.
  • the tensile strength formula of the monofilament is as follows:
  • the diameter of the carbon fiber monofilament was measured using a laser caliper manufactured by Changchun Industrial Optoelectronic Technology Co., Ltd. The sample is placed on the sample holder, and the diffraction dark line spacing of the monofilament is measured by the diffraction principle.
  • the exact diameter of the monofilament can be calculated by formula conversion, and the formula is as follows:
  • the HM410 composite interface feature evaluation device manufactured by Japan Toyon Co., Ltd. was used for the droplet embedding test.
  • the test parameters were set as follows: the test speed was 0.12 mm/min, and the microscope magnification was 2 times.
  • the diameter of the test resin sphere should be selected from 40 ⁇ m to 80 ⁇ m.
  • the number of resin balls tested in each sample was 5, and the interfacial shear strength results were averaged.
  • the interface shear strength formula is as follows:
  • the surface morphology of the recovered carbon fiber was observed and analyzed by using the FINA company's Quanta TM 250FEG model scanning electron microscope. Select high vacuum mode, the working distance is about 10mm, and the test acceleration voltage is 20KV. In order to obtain a clearer and more accurate surface topography, it is necessary to increase the conductivity of the carbon fiber, so the sample is subjected to gold spray treatment in an ion sputtering apparatus before being tested.
  • the ICON-PT-PKG model scanning probe microscope produced by Bruker Company of USA was used to test the recovered carbon fiber to obtain two-dimensional and three-dimensional images of the surface topography and undulation.
  • the sample scanning range of this experiment was 4 ⁇ m, and the tapping mode was adopted, and the scanning rate was 1.0 Hz.
  • the length of the carbon fiber monofilament should not be less than 20 mm.
  • N y the number of steps in the Y axis
  • the ULVAC-PHI VPII model photoelectron spectrometer was used to perform the full-spectrum scanning of the recovered carbon fiber in the range of 0eV ⁇ 800eV to obtain the surface element information, and then the C1s were scanned with high resolution, and the results were performed by XPSPeak4.1 software. Gaussian function and Lorentz function fitting, analysis of the type and content of functional groups. When testing, it is necessary to ensure that the carbon fiber is placed flat on the test bench.
  • the X-ray source of the monochromator is an Al target, and the test elements include: C, O, Cl, N, Si, Ca, and 90° is selected as the incident angle.
  • the inventors designed six different constant current densities and four different sodium salt concentrations to recover carbon fibers, wherein the NaCl solution was prepared from deionized water and sodium chloride.
  • the concentrations were 0.5 (%), 1.0 (%), 2.0 (%), and 3.0 (%), respectively.
  • the constant current magnitudes were 20 mA, 40 mA, 62.5 mA, 78.1 mA, 104.2 mA, and 156.3 mA, respectively.
  • the specific sample grouping and experimental parameters are shown in Table 3.1. The sample number is determined by the magnitude of the applied current intensity and the concentration of the NaCl solution.
  • the entire electrochemical recovery process will last for 18 days under laboratory conditions, during which time the solution volume will remain constant.
  • the recovered carbon fiber will be washed first with a washing liquid (such as alcohol) in an ultrasonic cleaner, and then washed three times with a washing liquid (such as deionized water), and the cleaning time per one time is 5 minutes.
  • a washing liquid such as alcohol
  • a washing liquid such as deionized water
  • the recovered carbon fiber picture given here is the carbon fiber wire recovered from the I40S2.0 sample.
  • the length of the recovered carbon fiber filament was almost non-destructive compared to the test length (100 mm).
  • the electrolyte solution is clarified, and as the electrochemical recovery reaction proceeds, the color of the solution gradually becomes darker. From the color change of the solution, it can be roughly divided into two categories, one type: small current group (I20, I40 and I62.5), the solution first turns from clarification to pale yellow, then turns into dark yellow. Class 2: Large current groups (I78.1, I104.2, and I156.3), the solution turns brown from clarification and then slowly turns black. Under the same concentration of NaCl, the darker the sample electrolyte is, the darker the sample electrolyte is; the higher the NaCl concentration is, the more yellow the sample electrolyte is.
  • small current group I20, I40 and I62.5
  • Class 2 Large current groups (I78.1, I104.2, and I156.3)
  • the carbon fiber recovery amount increases first and then decreases with the increase of current.
  • the carbon fiber recovery of the I40 series sample is the largest; when the current exceeds 40 mA, the carbon fiber recovery amount decreases; when the current continues to increase beyond 62.5 mA, Soft carbon fiber will not be recovered.
  • the recovery of carbon fiber increased first and then decreased with the increase of NaCl concentration.
  • the recovery of S 0.5 series samples was between 80mg and 100mg.
  • the highest recovery of S 2.0 series samples was from 230mg to 430mg.
  • the S 0.5 series sample recovery is several times; the I40S 2.0 recovery is even more than 4 times that of the I40S 0.5 ; the S 3.0 series is lower than the S 2.0 series, but higher than the S 1.0 .
  • Increasing the electrolyte NaCl concentration increases the amount of carbon fiber recovered. However, when the concentration reaches 3.0, the degradation of the epoxy resin is rather reduced.
  • the gel removal rate of the recovered carbon fiber decreases with the increase of current.
  • the carbon fiber removal rate is slightly decreased, and the I62.5 series carbon fiber removal rate is slightly decreased. Very low, between 63.3% and 68.5%.
  • the carbon removal rate of the recovered carbon fiber increases first and then decreases with the increase of NaCl concentration. Similar to the recovery amount, the S 2.0 series carbon fiber has the highest gel removal rate, but the difference between the S 1.0 and S 3.0 series is small, S The debonding rate of 0.5 series carbon fiber is very low, ranging from 63.3% to 68.3%.
  • the tensile strength results of the recovered carbon fiber monofilaments are shown in Table 3.2, in which the carbon fiber precursor (VCF) is the same as the carbon fiber model in CFRP.
  • the diameter is 7 ⁇ m, except for I62.5S 0.5 , the diameter of the recovered carbon fiber is slightly decreased. The reason may be that the epoxy resin on the surface of the recovered carbon fiber is degraded, exposed to the electrochemical oxidation etching in the electrolyte, the surface epoxy sizing agent is eroded, and the degradation and flaking are started, and even the carbon fiber matrix may be oxidized and peeled off.
  • the reason for the increase in diameter of I62.5S 0.5 should be excessive epoxy coating on the surface.
  • the tensile strength (tensile strength) of all recovered carbon fibers showed different degrees of decline compared with VCF (4641 MPa). The relationship between specific tensile strength and parameters is shown in Fig. 9.
  • the tensile strength of the recovered carbon fiber first rises and then decreases.
  • the tensile strength of carbon fiber reaches the minimum and maximum values at the concentrations of 0.5% and 2.0%, respectively.
  • the high NaCl concentration is more conducive to maintaining the tensile strength of the recovered carbon fiber.
  • the tensile strength of the recovered carbon fiber decreases with the increase of current.
  • the tensile strength of carbon fiber in I20 group and I40 group is very close.
  • the tensile strength of carbon fiber in I62.5 group is lower, only 51.41%-55.2% of carbon fiber precursor.
  • the tensile strength of the recovered carbon fiber is essentially related to the degree of damage suffered by the recycling process. In the high current action or low NaCl concentration environment, more oxygen is generated on the CFRP surface, and the oxidation and aerodynamic etching of the carbon fiber are more effective. Strong, leading to degradation of carbon fiber surface, defects, formation of tensile strength, long-term effects of large currents may even disturb the carbon fiber graphite block structure, resulting in greater damage.
  • the NaCl concentration is 0.5% to 3.0%, the tensile strength of the recovered carbon fiber is ideal, and the optimum NaCl concentration is 2.0%. However, considering the control difficulty and cost of actual production, the NaCl concentration is controlled at 1.25% to 2.5%, and the desired tensile strength can be obtained.
  • the tensile strength of the carbon fiber monofilament obtained by the three current groups is the maximum, which is 3768MPa, 3693MPa, and 2562MPa, respectively, which is equivalent to 81.19% of VCF. , 79.57% and 55.2%.
  • the best samples of recycled carbon fiber were I20S 2.0 (81.19%) and I40S 2.0 (79.57%), and the difference between the two was not obvious. Accordingly, when the current intensity is between 20 mA and 40 mA, the tensile strength of the recovered carbon fiber is ideal, as shown in FIG.
  • the SEM test method can be used to see the surface morphology of the carbon fiber and visually evaluate the quality of the recovered carbon fiber.
  • the carbon fiber removal rate of the S 1.0 , S 2.0 and S 3.0 series is very close, while the S 0.5 series has a much lower gel removal rate.
  • the carbon fiber recovered from the S 2.0 series is selected for SEM test, as shown in Fig. 10.
  • the surface of the carbon fiber precursor is smooth and clean, and there are no physical defects such as crack gaps and pits.
  • the surface of the I20S 2.0 is very clean, no epoxy particles are visible, and crack crack defects are not seen.
  • the NaCl concentration is 1.0 (%), 2.0 (%), and 3.0 (%) of the water mass, and the recovered amount (yield) of the carbon fiber recovered by the detection, the gel removal rate, the tensile strength of the carbon fiber monofilament, and the carbon fiber monofilament
  • the interfacial shear strength and the like are used to determine the quality of the recovered carbon fiber and the optimum amount of catalyst.
  • the sample number is determined by the applied current intensity, NaCl concentration and A concentration, such as the sample number “I20S 1.0 A 0.5g/L ”.
  • the first part “I20” means the current intensity applied by the sample is 20mA
  • the second part “S 1.0 ” It means that the NaCl concentration in the electrolyte is 1.0 by mass of deionized water
  • the third part “A 0.5g/L” means that the concentration of the catalyst KOH in the electrolyte is 0.5 g/L.
  • Table 4.1 Detailed sample grouping and experimental parameters are shown in Table 4.1 below.
  • the voltage of the sample to which the catalyst KOH was added was more stable, and the voltage value was generally lowered by about 0.5 V.
  • the sample voltage in Figure 12 can be roughly divided into two groups according to the size: the voltage range of group A40 is 3V ⁇ 3.6V, the voltage decreases first and then increases with the increase of NaCl concentration, the voltage is the lowest when the concentration is 2.0, and the difference of NaCl concentration The voltage difference between the samples is obvious; in the same NaCl concentration environment, the sample voltage difference between different catalyst KOH concentrations is very small.
  • the b-group I20 sample voltage range is approximately between 2.75V and 2.9V, so the sample voltage is very stable during the recovery cycle and the voltage difference is very small.
  • CB indicates that the failure mode is the peeling failure of the interface between carbon fiber and epoxy resin
  • the carbon fiber recovery amount is closely related to the catalyst KOH concentration. As the catalyst KOH concentration increases, the carbon fiber recovery amount first rises and then decreases. When the catalyst KOH concentration exceeds 1.0 g/L, the catalyst concentration increases. On the contrary, the amount of carbon fiber recovered was reduced, and the amount of carbon fiber recovered from the catalyst sample of KOH 1.0g/L was the largest. At the catalyst KOH concentration of 1.5g/L, the difference in the recovery amount of each parameter sample becomes smaller and the distribution is more concentrated. It seems that the decomposition of the epoxy resin is inhibited, indicating that the high concentration of the catalyst KOH is not conducive to carbon fiber recovery.
  • the optimum value of the catalyst KOH concentration was 1.0 g/L in terms of carbon fiber recovery. It can be seen from Fig. 14 that the recovery of carbon fiber increases first and then decreases with the increase of NaCl concentration, and the recovery of S 2.0 series is the highest, followed by S 3.0 and S 0.5 . The total carbon fiber recovery of I40 group is higher than I20, I40S 2.0 A The recovery of 1.0g/L samples reached a maximum of 1217mg, which was much higher than other parameter samples.
  • the diameter of the recovered carbon fiber is slightly reduced because during the recovery process, when the carbon fiber is released from the epoxy resin, it is subjected to electrochemical oxidation etching, and the surface sizing agent It is first eroded and the carbon fiber matrix may also be oxidized and peeled off.
  • the carbon fiber recovered from the A 1.5g/L series has the smallest diameter; the diameter of the carbon fiber recovered from the I40 group is slightly smaller than that in the I20 group; indicating that the high catalyst KOH concentration environment and the application of a large current cause the carbon fiber to be more oxidized.
  • the degree of deterioration and peeling is deeper. It is found from Table 3.5 that the residual value of the tensile strength of the recovered carbon fiber is not high, and the more intuitive relationship between the tensile strength of the carbon fiber and each parameter is as shown in FIG.
  • the tensile strength of the recovered carbon fiber decreases with the increase of the catalyst KOH concentration, indicating that the catalyst KOH has certain mechanical damage to the carbon fiber during the recovery process, and the higher the catalyst KOH concentration, the carbon fiber. The more serious the deterioration.
  • the tensile strength of the carbon fiber obtained by the recovery of the I40 current group sample is lower than that of the I20 group, indicating that the deterioration of the carbon fiber is more serious under the action of the large current, and the influence of the deterioration of the small current is lower, which is more favorable for maintaining the mechanical properties.
  • the tensile strength of the carbon fiber recovered from the S 1.0 and S 3.0 series samples is very low, and the carbon fiber of the S 2.0 series is recovered.
  • the tensile strength decreased by approximately 9%.
  • the strength of the carbon fibers recovered in the I20 group is smaller than that in the I40 group.
  • the A40 carbon fiber has a concentration of 1.0g/L and 1.5g/L, the tensile strength of the monofilament is very close, especially I40S 2.0 .
  • the interfacial adhesion capability of carbon fiber to epoxy resin is one of the key parameters for evaluating the quality of recycled carbon fiber.
  • the interfacial shear strength of the recovered carbon fibers was measured by a droplet embedding experiment, reflecting the bonding properties of carbon fibers and epoxy resins. It can be seen from Table 3.5 that the sample epoxy droplet diameter ranged from 42.18 ⁇ m to 51.07 ⁇ m, which is included in the reasonable diameter test range of 40 ⁇ m to 80 ⁇ m, and the test data is valid.
  • the interfacial shear strength of the carbon fiber precursor is 31 MPa
  • the failure mode is DB
  • the recovered carbon fiber interface strength varies greatly with the parameters.
  • the visually recovered carbon fiber interfacial shear strength (IFSS) is shown in Fig. 16.
  • the shear strength of the carbon fiber interface increases first and then decreases.
  • the KOH concentration of the catalyst is 1.0g/L
  • the interfacial shear strength reaches a maximum.
  • the A 0.5g/L series carbon fiber has the lowest shear strength, which is about 5% to 7% lower than the carbon fiber strand; the A 1.0g/L and A 1.5g/L series shear strength values are better than the carbon fiber precursor.
  • I20S 2.0 A 1.0g/L interface shear strength is up to 37.43MPa, which is 20.74% higher than carbon fiber precursor, while I20S 1.0 A 1.5g/L with lower shear strength is 105.68% of original yarn.
  • the shear strength of all samples was lower than that of the carbon fiber precursor, and the shear strength of the A 1.5g/L series carbon fiber was the lowest, while the shear strength of the sample I40I20S 2.0 A 1.5g/L was only 79.69% of the original silk value. .
  • the failure mode of the experimental sample of the droplet embedding test can be roughly divided into two types, namely, epoxy resin layer peeling damage (DB) and carbon fiber and epoxy resin interface layer peeling damage (CB).
  • DB epoxy resin layer peeling damage
  • CB epoxy resin interface layer peeling damage
  • I40S 2.0 A 1.5g/L is another typical failure mode, namely, carbon fiber and epoxy resin interface peeling damage (CB).
  • This interface failure mode is not ideal, carbon fiber.
  • the bond with the resin is poor, the interface becomes a weak layer and the shear strength is only 24.7 MPa.
  • the epoxy resin is completely peeled off from the interface and hardly remains on the surface of the carbon fiber.
  • a regular longitudinal groove can be seen on the surface of the carbon fiber, but no damage such as crack pits is found.
  • the failure mode of the sample has a great correlation with the catalyst KOH concentration and current, and the NaCl concentration has little effect on the failure mode. Therefore, only the interface damage pictures of the I20S 2.0 and I40S 2.0 series samples are listed here.
  • the catalyst KOH concentration is 0.5g/L
  • the failure mode of the sample is CB
  • the failure mode of the sample is DB
  • the A concentration continues to increase to 1.5g
  • the DB destruction mode occurred in the I20 group samples
  • the CB failure mode occurred in the I40 group samples.
  • I40S 2.0 A 0.5g/L can find a less obvious longitudinal groove structure, indicating that under this condition, the surface of the carbon fiber is slightly oxidized, and the carbon fiber body is not damaged, so the tensile strength of the carbon fiber is compared with the sample without the catalyst KOH added. Only a slight decline. With the increase of KOH concentration of the catalyst, the carbon fibers by oxidation etching, OH - ion intercalation and the like becomes severe, the carbon fiber surface is no longer smooth light circle, see clearer longitudinal groove structure shown in Figure 18 (c) ⁇ (f). The damage of the I40 group was more serious. The surface of the I40S 2.0 A 1.0g/L and I40S 2.0 A 1.5g/L carbon fiber could even see the presence of cracks, so the highest multiple (20000) scan of the two samples was performed. , as shown in Figure 19.
  • FIG. 19(a) the carbon fiber is etched away from a small portion of the skin, and the cross section becomes smaller, forming a distinct longitudinal groove structure; when the tensile strength test of the monofilament is performed, the cross section of the etched portion becomes weak. The layer forms stress concentration and causes fracture damage.
  • Figure 19(b) the surface of the carbon fiber has been smoothed by oxidation, forming pits and crack defects. When the tensile strength test of the monofilament is performed, it becomes a weak link, and the stress is concentrated around the pit. The crack tears the carbon fiber, causing greater stress concentration until the stress limit state is reached, and the carbon fiber breaks and breaks.
  • the surface topography of the recovered carbon fiber is an important factor affecting the interfacial properties of the carbon fiber, affecting the mechanical bite force of the interface and the wettability of the epoxy resin.
  • the surface morphology of the recovered carbon fibers was observed by a probe microscope and roughly characterized by roughness Ra and AFM images. The test results are shown in Table 4.3 and Figure 30 below. It should be pointed out that under the same current, the difference in carbon fiber AFM images obtained by different NaCl concentrations is very small, so only the recovered carbon fiber AFM images of the S 2.0 series are listed here. As can be seen from the table, the carbon fiber precursor has an Ra value of 201 nm. The difference in NaCl concentration has little effect on the Ra value of the recovered carbon fiber. Therefore, in the following AFM analysis, the I20S 2.0 and I40S 2.0 series are taken as an example.
  • the surface of the carbon fiber precursor is smooth and flat, free from cracks and the like, and is a regular longitudinal groove structure, and the width of the groove is large, and the size is about 0.3 ⁇ m. .
  • the A concentration is 0.5g/L
  • Fig. 30(c) and Fig. 30(d) it can be seen that there are two epoxy particles on the right side of the carbon fiber surface because of the epoxy resin under this condition. The degradation rate is relatively flat.
  • the epoxy resin is completely removed (occasionally there will be a very small amount of attached particles); the carbon fiber is not exposed to the electrolyte for a long time, so the electrochemical oxidation etching is not serious, carbon fiber remained significant longitudinal groove structure, but increasing the width of the longitudinal groove; OH - ions are adsorbed active carbon atom, a slight intercalation, resulting in carbon fibers with a very small amount of the skin surface projections expansion; therefore The calculated roughness is slightly lower than that of the carbon fiber precursor, and the Ra value is 195 nm, resulting in a slight decrease in the interfacial shear strength of the carbon fiber.
  • a concentration is increased to 1.0g/L, as shown in Fig.
  • the degradation rate of the epoxy resin is accelerated, the epoxy resin on the surface of the carbon fiber is completely removed, and the carbon fiber is quickly exposed to a higher temperature.
  • the more severe electrochemical oxidation etching makes the original longitudinal groove structure width smaller, and the calculated roughness is improved, and the Ra value is 219 nm.
  • These small width grooves not only increase the carbon fiber and the resin.
  • the mechanical bite is used together, and the specific surface area is greatly increased to improve the wettability of carbon fiber and epoxy resin. Therefore, the interfacial shear strength of I20S 2.0 A 1.0g/L is 37.43 MPa, which is 120.74% of the carbon fiber raw yarn value.
  • the OH - concentration in the electrolyte increases, the oxidation of the carbon fiber and the intercalation of OH - ions
  • the degree of reaction is enhanced, causing the expansion of the epidermis, from which the longitudinal small-width groove of the carbon fiber surface and a large number of convex structures are seen.
  • the size of these convex structures is in the range of several tens of nanometers to several hundred nanometers, and the carbon fiber is increased.
  • the specific surface area and mechanical bite interaction with the resin interface, the calculated Ra value is 213 nm, therefore, the interfacial shear strength of the carbon fiber is higher than the carbon fiber precursor, which is 33.06 MPa.
  • the AFM morphology of the sample carbon fiber of the I40 group is similar to that of the I20 group.
  • the specific surface area and mechanical bite of the interface decreased to different extents.
  • the corresponding carbon fiber interface shear strength can only reach 87.11%, 90.57% and 79.69% of the carbon fiber precursor.
  • the XPS scanning full spectrum and the C1s high resolution narrow spectrum of the recovered carbon fiber are shown in Fig. 21.
  • the left column is the scanning full spectrum of the sample, and the right column is the corresponding C1s high resolution narrow spectrum and its peak fitting map. From the scanning full spectrum, there are five main peaks in the figure, namely two main peaks: C (284.6eV) and O (532.0eV); three secondary peaks: Si (99.5eV), Cl (199.8eV) And N (399.5 eV).
  • the basic elements on the surface of carbon fiber are carbon, oxygen, nitrogen and silicon. The small amount of chlorine detected is likely to be introduced during production or transportation.
  • the carbon content and oxygen content of the carbon fiber precursor were 75.2% and 18.3%, respectively, and the oxygen to carbon ratio was 0.2434.
  • the carbon content of the recovered carbon fiber surface decreased slightly, and the lowest carbon content of I20S 3.0 A 1.0g/L was 71.2%.
  • the oxygen content increased greatly.
  • the recovered carbon fiber except I20S 2.0 A 0.5g/ Except for L the remaining oxygen content is above 20.3%.
  • the thus calculated carbon fiber oxygen to carbon ratio is higher than that of the original carbon fiber precursor, and the oxygen to carbon ratio of I20S 2.0 A 1.0g/L and I20S 2.0 A 1.5g/L is 0.3187 and 0.3192, respectively.
  • the increase of surface oxygen content can improve the surface activity of carbon fiber.
  • the increase of surface activity of carbon fiber can improve the interfacial shear strength.
  • the increase of carbon-oxygen ratio on the surface of carbon fiber can significantly improve the bonding performance between carbon fiber and resin.
  • Most of the recovered carbon fibers had higher interfacial shear strength than carbon fiber strands, while the shear strengths of the I20S 2.0 A 1.0 g/L and I20S 2.0 A 1.5 g/L samples were similar and highest in all samples.
  • I20S 2.0 A 0.5g / L has the highest nitrogen content of 3.1%, followed by I40S 2.0 A 1.0g / L and I20S 1.0 A 1.0g / L , respectively 2.9 % and 2.3%, I20S 3.0 A 1.0g/L nitrogen content is 0.8%, I20S 2.0 A 1.0g/L and I20S 2.0 A 1.5g/L nitrogen content is zero, from the sample tensile strength value results It can be seen that the higher the nitrogen content, the lower the tensile strength of the sample.
  • I20S 1.0 A 1.0g/L I20S 2.0 A 1.0g/L and I20S 3.0 A 1.0g/L groups
  • the NaCl concentration increased from 1.0 (%) to 3.0 (%)
  • the oxygen-carbon ratio increased first and then decreased.
  • the oxygen-carbon ratio of I20S 1.0 A 1.0g/L and I20S 3.0 A 1.0g/L is close to 0.2781 and 0.2795 respectively, and the chlorine content is first decreased and then increased.
  • I20S 3.0 A 1.0g/L chlorine content The surge rate to 4.3%, the nitrogen element decreased from 2.3% to 0 and then rose to 2.8.
  • the silicon element showed an increasing trend, indicating that 2.0 NaCl is the optimum concentration.
  • the too low or too high NaCl concentration can not achieve a better carbon fiber interface.
  • Shear properties also increase the chlorine content of the carbon fiber surface, especially at high NaCl concentrations. Comparing I20S 2.0 A 1.0g/L and I40S 2.0 A 1.0g/L, it can be found that the high current effect will result in lower oxygen to carbon ratio and silicon content, higher chlorine content and nitrogen content on the surface, and higher surface current effect. It is beneficial to improve the shear properties of carbon fiber interface and even reduce the tensile strength.
  • the C1s peak fitting is shown in the right column of Figure 21.
  • the surface functional group content of the carbon fiber obtained is shown in Table 4.5 below.
  • the surface contains less oxygen functional groups, low activity and hydrophobicity, and the increase of carbon-oxygen functional groups can improve its hydrophilicity, increase the wettability, and further contain oxygen such as COOR.
  • the reactive functional group can increase the reaction between the carbon fiber and the resin, form a strong chemical bond, and improve the interfacial bonding performance. It can be seen from Table 3.10 that the C1s peak functional groups on the surface of carbon fibers are classified into three types: carbon-carbon functional groups, carbon-oxygen functional groups, and carbon-chlorine functional groups.
  • the total content of C-C bonds in the graphite and amorphous carbon fiber precursors is 69.3, and the content of various carbon-oxygen bonds is 30.7%.
  • the total content of C-C bonds in the recovered carbon fibers shows a different degree of decline, carbon-oxygen bonds.
  • the increased content indicates that the surface of the recovered carbon fiber has undergone a certain degree of oxidation, especially the C-C bond of I40S 2.0 A 1.0g/L is only 53.3%, however, excessive oxidation will penetrate into the surface of the carbon fiber, causing connection with the carboxyl group.
  • the carbon layer becomes weak and reduces the tensile strength; the carbon fiber precursor has a C-C bond content of 0, indicating that the chlorine element is only adsorbed on the surface of the carbon fiber, not in the form of a chemical bond, and most of the recovered carbon fiber contains a certain amount.
  • the C ⁇ Cl bond indicates the chlorine gas generated during the recovery process. In addition to degrading the epoxy resin, it also acts on the carbon fiber to form a chemical bond, which has the effect of corrosion degradation.
  • the C-C bond content of I20S 2.0 A 0.5g/L and I20S 2.0 A 1.0g/L is basically the same as that of carbon fiber precursor, I20S 2.0 A 1.5g/L C-C
  • the bond content was reduced by 11.4% due to the more intense oxidation reaction on the surface of the carbon fiber, which formed more carbon-oxygen bonds, indicating that the high concentration of the catalyst KOH will cause the carbon fiber to oxidize more;
  • I20S 2.0 A 0.5g/L and I20S 2.0 A 1.5g/L C-Cl bond content is 6.3% and 6%, respectively, while I20S 2.0 A 1.0g/L C-Cl bond content is 0, indicating 1g/L catalyst KOH concentration, carbon fiber The chlorine corrosion received is the slightest.
  • I40S 2.0 A 1.0g / L is C ⁇ C bond content than I20S 2.0 A 1.0g / L much lower, and I40S 2.0 A 1.0g / L C ⁇ Cl bond content of 6.8%
  • the content of C ⁇ Cl bond of I20S 2.0 A 1.0g/L is 0, indicating that the larger the working current is, the higher the degree of oxidation of the recovered carbon fiber is, and the more severe the chlorine corrosion is.
  • the electrolytic solution contains 0.5 g/L to 1.5 g/L of catalyst A, wherein the catalyst A is a soluble base, It may be, but is not limited to, KOH.
  • KOH a soluble base
  • the KOH concentration was 1.0 g/L
  • the carbon fiber recovery amount and the interfacial shear strength were the highest, and the tensile strength was ideal, indicating that the optimum KOH concentration was about 1.0 g/L.
  • the KOH concentration is controlled at 0.75 g/L to 1.25 g/L, an ideal recovery effect can be obtained.
  • the chemical reaction process for the recovery of carbon fibers by electrochemical methods should also have suitable reaction conditions.
  • the foregoing tests are all carried out at room temperature, but a higher reaction temperature is expected to increase the recovery rate and the quality of the recovered fibrous material. Therefore, the present invention determines the appropriate temperature of the electrochemical recovery method of the present invention by the following experimental results.
  • the first part “I20” means the current applied by the sample is 20mA.
  • S 2.0 means that the NaCl concentration in the electrolytic solution is 2.0
  • the third portion "A 1.0 g/L” means that the concentration of the catalyst KOH added to the electrolytic solution is 1.0 g/L.
  • the fourth part “40” means that the temperature of the electrolyte is maintained at 40 ° C during the experiment. Detailed experimental grouping and experimental parameters are shown in Table 5.1.
  • the experiment was divided into two phases, each of which was recycled for 9 days for a total of 18 days.
  • the power was turned off, the carbon fiber on the sample was removed, and the power was continued for recovery experiments.
  • the carbon fibers are removed for washing and drying.
  • the carbon fiber recovered in the two stages showed no significant difference in macroscopic morphology, and was very clean and shiny, indicating that the carbon fiber was slightly damaged by oxidative damage. It should be pointed out that the recovered carbon fiber is neatly stripped when removed from the sample, and the ultrasonic cleaning process causes it to roll into a dense mass.
  • the voltage distribution range of all samples is 2.5V to 3.1V, and the sample voltage is basically stable throughout the recovery period, and the fluctuation range is small, and it can be inferred that the sample does not deteriorate seriously.
  • the sample voltage of the I20 group is close to the I40 group at a temperature of 40 °C, and higher than the I40 group at 60 °C and 75 °C, indicating that the current has a large influence on the sample voltage. It should be noted that in the I20 or I40 current group, the voltages of the 60°C and 75°C samples are quite close, and the difference is about 0.1V. The voltage difference between the 40°C and 60°C and 75°C samples is large and poor.
  • the value is approximately 0.2V to 0.5V. It shows that the resistance between samples is almost close at 60 °C and 75 °C, and the resistance of sample under 40 °C is different from that of 60 °C and 75 °C.
  • the voltage of the first stage is basically the same as that of the second stage. The short-cut power cut and the recovered carbon fiber have a very weak effect on the sample and do not hinder the subsequent electrochemical recovery process.
  • the data in Table 5.2 is the result of two stages of electrochemical recovery. That is, the carbon fiber obtained in the two stages was first tested three times by TGA, and the results showed that there was basically no difference in the removal rate of the carbon fiber in the two stages, so the removal rate was taken as the average of six experiments; the carbon fiber recovery in the two stages was also the same. Not large, in order to facilitate comparative analysis, the carbon fiber recovery amount is taken as the sum of two stages; I20S 2.0 A 1.0g/L 25 is I20S 2.0 A 1.0g/L (laboratory normal temperature condition), which is listed in the table for comparative analysis. .
  • the carbon fiber recovery amount here is the sum of the first and second stages of the recovery process.
  • the carbon fiber recovery amount is positively correlated with the temperature, and the carbon fiber recovery amount is increasing with the increase of temperature.
  • the carbon fiber recovery rate is slightly slower; at 40 ° C ⁇ 60
  • the growth rate of carbon fiber recovery is accelerated; in the temperature range of 60 °C to 75 °C, the growth rate of carbon fiber recovery is slowed down.
  • the temperature rises to 75 ° C the recovery of I20S 2.0 A 1.0g / L 75 reaches 2287mg, and the recovery of I40S 2.0 A 1.0g / L 75 reaches 2353mg, which is 3.05 times and 1.93 times respectively at 25 °C.
  • the temperature can be further increased, and the amount of carbon fiber recovered can be continuously increased. It shows that the temperature plays a key role in the degradation process of epoxy resin, and the increase of reaction temperature can greatly improve the degradation efficiency of epoxy resin. The effect of the difference in applied current can be clearly seen in the carbon fiber recovery.
  • the carbon fiber recovery of I40S 2.0 A 1.0g/L is always greater than I20S 2.0 A 1.0g/L , and the recovery at 25°C is I20S 2.0 A 1.0g. /L is 1.6 times more.
  • the thermal cracking temperature of epoxy resin in carbon fiber composites is about 300 ° C ⁇ 600 ° C under nitrogen or air atmosphere, and the highest temperature of this experiment is 75 ° C, far lower than the thermal decomposition of epoxy resin.
  • the temperature therefore, the large increase in the amount of carbon fiber recovered cannot be attributed to the thermal decomposition of the resin caused by temperature.
  • Increasing the temperature can increase the recovery of carbon fiber, which may be related to the synergy between temperature and catalyst KOH. Increasing the temperature increases the reaction performance of the catalyst KOH, and the presence of the catalyst KOH is equivalent to increasing the temperature to a certain extent.
  • the carbon fiber diameters of the first and second stages are not substantially reduced, indicating that the 9-day recovery cycle significantly reduces the effects of electrochemical oxidation etching, OH - ion intercalation, and alkali corrosion on the carbon fibers. Comparing the tensile strength of the recovered carbon fiber obtained in the two stages, it can be found that the difference in the strength of the carbon fiber under the same parameter does not exceed 1%, and the difference in the stage is very small, and the recovery from the two stages is also known from the previous results. The carbon fiber removal rate and recovery amount are basically close to each other.
  • the above carbon fiber performance test and analysis only lists the first stage data, which represents the entire electrochemical recovery cycle results of the experiments in this chapter. The relationship between the intuitive carbon fiber tensile strength and temperature is shown in Figure 33.
  • the tensile strength of the recovered carbon fiber increases with increasing temperature, and the tensile strength increases most from 25 ° C to 40 ° C; stretching in the range of 40 ° C to 60 ° C
  • the growth rate of strength slows down; when the temperature rises from 60 °C to 75 °C, the growth rate of tensile strength is almost close to zero.
  • the tensile strength of the carbon fiber recovered by I20S 2.0 A 1.0g/L 75 and I40S 2.0 A 1.0g/L 75 is 4077MPa and 4169MPa, respectively, which is 87.85% and 89.83% of the carbon fiber raw yarn value, which is higher than the mechanical recovery method (50%).
  • the shear strength of the carbon fiber interface tends to decrease first and then increase with the increase of temperature.
  • the shear strength of I20S 2.0 A 1.0g/L and I40S 2.0 A 1.0g/L decreases from the original 37.43MPa and 28.08MPa to 25.42MPa and 24.61MPa, and the decrease rate reaches 32.09%.
  • 12.36% the reason should be that after the recovery cycle is shortened from 18 days to 9 days, the surface oxidation etching and OH - ion intercalation reaction of carbon fiber are reduced, resulting in insufficient surface longitudinal groove structure and reduced skin protrusion and roughness reduction.
  • the shear strength of carbon fiber increases continuously.
  • the shear strength of I20S 2.0 A 1.0g/L 60°C and I40S 2.0 A 1.0g/L 60°C is 33.59MPa and 29.84, respectively.
  • MPa which is 108.35% and 96.26% of the carbon fiber precursor value, and the failure mode from both Fig. 35(c) and Fig.
  • 35(d) is DB
  • the damage occurs in the epoxy layer
  • I20S 2.0 A 1.0g/ L 60 ° C fracture section also adhered to the slender needle-like resin
  • I40S 2.0 A 1.0g / L 60 ° C sample surface is also wrapped with a smooth layer of resin, indicating that the temperature increase, the carbon fiber surface oxidized etching degree, the interface stick
  • the joint force is improved and the shear strength is increased.
  • the shear strengths of I20S 2.0 A 1.0g / L and I40S 2.0 A 1.0g / L were 33.72MPa and 35.79MPa, respectively, which were 108.77% and 115.45% of the carbon fiber precursor.
  • the stripping mode of both samples is DB.
  • the destruction interface of the epoxy layer is prismatic and concave, which increases the surface area of damage, especially I40S 2.0 A 1.0g. /L exhibits a tendency to break apart, and a strong force during breakage causes the inside of the droplet to rupture.
  • the intensity becomes larger and the damage mode is more desirable.
  • the I20 and I40 series have a small difference in shear strength and the current effect is weak.
  • the above situation indicates that shortening the recovery cycle will reduce the surface effect of the carbon fiber on the oxidative etching, thereby reducing the shear strength of the carbon fiber interface, and reducing the shear strength difference caused by the difference in applied current; the temperature increase can improve the surface roughness of the carbon fiber and Wettability, increase the shear strength of carbon fiber interface, and improve the interface mode of carbon fiber to epoxy resin interface.
  • the above situation indicates that the carbon fiber is less affected by electrochemical oxidation etching, OH - ion intercalation reaction and alkali corrosion during the 9-day recovery period due to the shorter sample exposed to the electrolyte, and the carbon fiber body is damaged. Very small, so the tensile strength of the recovered carbon fiber is improved; the higher the temperature, the less residual epoxy resin on the surface of the recovered carbon fiber, although the recycled carbon fiber has very little epoxy resin content under all temperature gradients. .
  • the roughness of I20S 2.0 A 1.0g / L 40 ° C and I40S 2.0 A 1.0g / L 40 ° C is 190nm and 195nm, respectively, lower than the 201nm of carbon fiber precursor, from Figure 37 (a) ⁇ (d Can be seen, I20S 2.0 A 1.0g / L 40 ° C carbon fiber surface is relatively flat, no longitudinal groove structure, only very fine pockmark, between a few nanometers to tens of nanometers, mechanical occlusion effect is very small, in the shear When the test is destroyed, the epoxy resin and carbon fiber can be easily separated, and the shear strength is not high; the surface structure of I40S 2.0 A 1.0g/L 40°C is relatively better, and the shallow groove structure with shallow depth can be seen.
  • the surface microstructure of the recovered carbon fiber shows that the temperature increase can enhance the etching and OH - ion intercalation reaction on the surface of the carbon fiber, resulting in deepening of the groove on the surface of the carbon fiber, increasing the nano-scale convex structure and improving the interfacial adhesion performance.
  • the interfacial shear strength of carbon fibers is increased.
  • the recovered carbon fiber scanning full spectrum and C1s high resolution narrow spectrum as shown in Figures 40A to 42B, the left column is the scanning full spectrum, and the right column is the corresponding C1s narrow spectrum and its peak fitting map. It can be seen from the scanning full spectrum that there are mainly five peaks in the figure, two main peaks: C (284.6 eV) and O (532.0 eV); three secondary peaks: Si (99.5 eV), Cl (199.8 eV) And N (399.5 eV).
  • the basic elements on the surface of carbon fiber are carbon, oxygen, nitrogen and silicon, and the small amount of chlorine detected may be introduced during production or transportation.
  • the content of specific elements on the surface of the recovered carbon fiber is shown in Table 5.4.
  • the carbon fiber recovered at different temperatures has a small decrease in the content of C on the surface of the carbon fiber compared with the carbon fiber precursor. This is due to the oxidation of the carbon fiber surface active carbon particles to a small amount; There is a certain degree of increase.
  • the carbon fiber precursor is only 0.2434, while the oxygen and carbon ratios of I20S 2.0 A 1.0g/L 60 and I20S 2.0 A 1.0g/L 75 are 0.2890 and 0.2898, respectively. The two are relatively close.
  • the carbon-oxygen ratio of I20S 2.0 A 1.0g/L 40 is 0.2961, which indicates that the carbon fiber undergoes a certain degree of oxidation during the recovery process, introduces more oxygen, and its surface activity increases.
  • I20S 2.0 A The oxidation degree of 1.0g/L 40 will be higher; the carbon fiber oxygen-carbon ratio obtained in this chapter is lower than that of Chapter 2 I20S 2.0 A 1.0g/L at 25 °C (oxygen-carbon ratio is 0.3187), which is due to The 9-day recovery period is short, and the exposure time of carbon fiber in the electrolyte is very short; the content of Cl element in the recovered carbon fiber increases, which should be related to the adsorption of chloride ions in the electrolyte; compared with the carbon fiber precursor, N element and Si element content Decreased to some extent, especially N element.
  • the C1s peak fitting is shown in the right column of Figure 4.12.
  • the C-Cl bond content of the recovered carbon fiber and carbon fiber precursor is 0, indicating that all temperature gradients (including 25) are recovered under the I20S 2.0 A 1.0g/L parameter.
  • the carbon fibers are substantially free of corrosion by chlorine.
  • the content of oxygen-containing functional groups at 75 ° C is the least, the content of oxygen-containing functional groups at 60 ° C is slightly more, and the content of oxygen-containing functional groups at 40 ° C is the highest, indicating that the higher the temperature, the carbon fiber
  • the electrolyzer used may be various decanting cells, electrolytic cells, and the like which are well known in the art.
  • the above electrolysis device as a recovery container is provided with a chemical solution in which a pre-designed recyclant and a catalyst are mixed, which can effectively invade the resin matrix material which has been solidified in the carbon fiber reinforced resin-based composite material to be recovered, and destroy the chemical bond thereof. Promotes expansion and decomposition of the resin.
  • the chemical solution includes, but is not limited to, water, liquid ethanol, liquid ethylene glycol, various acidic solutions (including but not limited to H 2 SiO 3 (metasilicate), HCN (hydrocyanic acid), H 2 CO 3 (carbonic acid), HF (hydrofluoric acid), CH 3 COOH (also known as C 2 H 4 O 2 acetic acid, also known as acetic acid), H 2 S (hydrogen sulfuric acid), HClO (hypochlorous acid), HNO 2 (nitrous acid ), all organic acids, H 2 SO 3 (sulfurous acid), etc., various alkaline solutions (including but not limited to potassium hydroxide solution, sodium hydroxide solution, etc.), various chloride ion solutions (including but It is not limited to sodium chloride solution, zinc chloride solution, etc.).
  • the above chemical liquid is characterized by being a mixed solution of the above various solutions, and the concentration of each solution is 0.001% to 99.9%,
  • the fiber material in the fiber-reinforced resin-based composite material to be recycled is connected to the anode of the power source in a well-known manner during the energization to ensure stable operation of the circuit during the recovery process.
  • the method of joining the fibrous material to the anode of the power source includes, but is not limited to, dissolving the resin, grinding away the resin, etc. to expose the internal fibrous material to facilitate electrical connection.
  • the cathode material during energization is a well known conductive material including, but not limited to, steel, iron, various metals, various forms of graphite materials.
  • the current density is characterized by cooperating with the above chemical solution, which can promote expansion and decomposition of the resin material in the carbon fiber reinforced resin matrix composite material to be recovered, without affecting various types of carbon fiber recovery. Mechanical properties, electrical conductivity, adhesion to resin materials and reworkability, while not affecting the recycling function of recycled resin materials.
  • the current density is designed according to the surface area of the fiber-reinforced resin matrix composite to be recovered exposed to the chemical solution, and ranges from 3333.3 to 15000 mA/m 2 , preferably from 3500 to 10000 mA/m 2 , more preferably 5000. ⁇ 7500mA/m 2 .
  • the energization time is characterized in that, in combination with the above chemical solution and current, the resin material in the carbon fiber reinforced resin matrix composite material to be recovered can be expanded and decomposed without affecting the recovery of the carbon fiber.
  • the energization time is from 0.5 to 200 hours, preferably from 2 to 120 hours, more preferably from 4 to 48 hours.
  • various resin aging methods well known in the art can be used to speed up the recovery, such as ultraviolet ray strengthening, ultrasonic strengthening, and microwave strengthening.
  • the reaction temperature is from 25 ° C to 75 ° C, preferably from 25 ° C to 30 ° C or from 55 ° C to 75 ° C. It should be noted that continuing to increase the temperature can increase the recovery speed and quality, but at the same time increase the requirements of the reaction device and increase the production cost.
  • the pressure in the recovery container is adjusted to a predetermined size, which, together with the above chemical solution, current and temperature, causes the resin material in the carbon fiber reinforced resin matrix composite to be recovered to expand and decompose without affecting
  • the various mechanical properties, electrical conductivity, adhesion to resin materials and reworkability of carbon fiber are recovered without affecting the recycling function of the recycled resin material.
  • the pressure range is from 0.5 to 20 atm and the pressurization time is from 0.5 to 200 hours.
  • the distance between the anode and the cathode material has an effect on the recovery effect, the recovery rate, and the recovery cost, and is preferably from 1 mm to 1000 mm, and more preferably from 20 mm to 60 mm.
  • the carbon fiber and the resin material are taken out and stored separately, and then put into production.
  • the method of removal is a variety of well known methods including, but not limited to, ultrasound, drying, heating, and the like, as well as combinations of various methods.
  • the length of the recovered carbon fiber is an important factor in its reuse value.
  • the carbon fiber recovered is straightened, and the length of the carbon fiber is about 80 mm to 100 mm.
  • the length of the sample recovery part of the experimental design is 100 mm. Considering the length loss of the carbon fiber obtained by the shear recovery, It is known that there is substantially no loss in the length of the carbon fiber during the electrochemical recovery process, indicating that the damage caused by the electrochemical oxidation of the carbon fiber is very slight throughout the recovery process.

Abstract

An environmentally friendly non-destructive fiber-reinforced composite material recovering method, comprising the following steps: (A) placing a fiber-reinforced resin-based composite material in an electrolyte, wherein the electrolyte contains a soluble hydrochloride salt having a weight percentage of 0.5%-3%; (B) energizing the fiber-reinforced resin-based composite material placed in the electrolyte, wherein the fiber-reinforced resin-based composite material is connected to a positive electrode of a power source, and controls the current density to be 3333.3-15000 mA/m2, wherein the current density is calculated according to the size of the surface area of the fiber-reinforced resin-based composite material to be recovered that is exposed to the chemical solution; and (C) reacting by energizing for 0.5-200 hours, and extracting the produced fiber recovery product from the electrolyte. The reaction temperature of the environmentally friendly non-destructive fiber-reinforced composite material recovering method is 25°C-75°C, the electrolyte further contains 0.5 g/L-1.5 g/L of a catalyst A, and the catalyst A is a soluble base.

Description

环保无损的纤维增强复合材料回收方法Environmentally friendly non-destructive fiber reinforced composite material recycling method 技术领域Technical field
本发明涉及纤维增强复合材料的回收和再利用。This invention relates to the recovery and reuse of fiber reinforced composite materials.
背景技术Background technique
纤维增强树脂基复合材料是所有高性能纤维及其制品增强的树脂基复合材料。其型式包括但不局限于各种型材、板、布、网格、栅格等各种型式，以及采用纤维增强树脂基复合材料制造的各种产品，包括但不局限于复合材料汽车车身与部件、复合材料风机叶片、复合材料飞机机身与部件、应用与建筑结构的各种复合材料等。所述树脂基体包括各种类型的树脂材料，包括但不局限于各种热塑性环氧树脂、热固性环氧树脂等。所述环氧树脂的固化剂包括本学科所熟知的各种类型固化剂，包括且不局限于胺类固化剂和酸酐类固化剂。Fiber reinforced resin matrix composites are reinforced resin-based composites of all high performance fibers and their products. The types include, but are not limited to, various types of profiles, panels, cloths, meshes, grids, and the like, as well as various products made from fiber reinforced resin-based composite materials, including but not limited to composite automotive bodies and components. , composite fan blades, composite aircraft fuselage and components, various composite materials for applications and building structures. The resin matrix includes various types of resin materials including, but not limited to, various thermoplastic epoxy resins, thermosetting epoxy resins, and the like. The curing agent for the epoxy resin includes various types of curing agents well known in the art, including, but not limited to, amine curing agents and acid anhydride curing agents.
以碳纤维增强树脂基复合材料(Carbon Fiber Reinforced Plastic,CFRP)为例，其具体指的是以碳纤维作为增强体，树脂(主要是有机环氧)为基体制作而成的复合材料。CFRP由于其腐蚀抵抗性能优良、质量轻和强度高与韧性强等优异力学性能，广泛应用于航空航天、医疗设备、工业制造、体育用品、汽车制造和建筑等行业领域。据估计，到2020年，世界范围内的CFRP消耗量将达到13万吨，其中大部分将被应用于工业领域。然而如此大规模的CFRP消费量，带来了严重的废弃物处理问题。例如，首架使用碳纤维增强复合材料作为结构材料的飞机即将退役，而大规模的飞机退役潮将会在2026年左右到达。届时，仅仅是空中客车有限公司就有大概6400架飞机走向寿命终结，而每架空客A350使用的CFRP复合材料高达总重量的53％，大约为20多吨。Carbon Fiber Reinforced Plastic (CFRP) is taken as an example, and specifically refers to a composite material made of carbon fiber as a reinforcement and a resin (mainly organic epoxy) as a matrix. CFRP is widely used in aerospace, medical equipment, industrial manufacturing, sporting goods, automobile manufacturing and construction industries due to its excellent corrosion resistance, light weight, high strength and toughness. It is estimated that by 2020, worldwide consumption of CFRP will reach 130,000 tons, most of which will be used in the industrial sector. However, such large-scale CFRP consumption has brought about serious waste disposal problems. For example, the first aircraft using carbon fiber reinforced composites as a structural material is about to be retired, and large-scale aircraft retiring tides will arrive around 2026. At that time, only Airbus Co., Ltd. has about 6,400 aircraft going to the end of its life, and each Airbus A350 uses up to 53% of the total weight of CFRP composites, about 20 tons.
然而，碳纤维增强复合材料废弃物在自然环境下不易降解。当前主要的处理方法是直接填埋或焚烧。直接填埋会占用大量宝贵的用地，而且会给环境带来长期影响。焚烧则会产生大量有毒气体，污染环境。与此同时，高性能纤维增强复合材料在寿命终结期后，仍具有相对良好的性能和较高经济价值。简单废弃也会造成资源的浪费。However, carbon fiber reinforced composite waste is not easily degraded in the natural environment. The current main treatment method is direct landfill or incineration. Direct landfills can take up a lot of valuable land and have a long-term impact on the environment. Incineration produces a large amount of toxic gases that pollute the environment. At the same time, high-performance fiber reinforced composites still have relatively good performance and high economic value after the end of life. Simple discarding can also result in wasted resources.
针对自纤维增强复合材料(废弃物)中回收碳纤维的研究，国内外均有大量科研机构和学者参与。现有自纤维增强复合材料(废弃物)中回收碳纤维的方法主要有：(1)物理回收法。通过机械将CFRP废弃物粉碎成细小尺寸颗粒，然后将颗粒进行分离，分别得到富含纤维和富含树脂的产品。(2)能量回收法。将含有有机物或完全为有机物的废弃物通 过焚烧等获得能量。所得的能量可以转化为可利用的热能或电能。(3)热分解回收法。将CFRP废弃物置于高温条件下，使CFRP中的树脂大分子聚合物断链降解为小分子化合物，然后再将碳纤维分离出来。(4)常压化学溶剂分解回收法。通过化学溶剂和高温热的协同作用，使树脂聚合物中的C-N或C-O链接化学键断开，聚合物溶解在溶液中，碳纤维从树脂中释放出来，从而达到回收目的。(5)其它回收方法。如超临界/亚超临界法、电回收法等。现有自纤维增强复合材料废弃物中回收得到的碳纤维的方法具有以下缺陷：(1)工艺复杂，操作难度大，甚至需要毒性较大的辅剂；(2)设备要求高，往往需要对纤维复合材料(废弃物)进行剪裁和粉碎等预处理，导致回收得到的纤维较短，经济价值低；(3)初期设备投入较大，产业化困难。A large number of research institutions and scholars have participated in the research on the recovery of carbon fiber from fiber reinforced composite materials (waste). The existing methods for recovering carbon fibers from fiber reinforced composite materials (waste) mainly include: (1) physical recovery method. The CFRP waste is mechanically pulverized into fine-sized particles, and then the particles are separated to obtain a fiber-rich and resin-rich product, respectively. (2) Energy recovery method. The waste containing organic matter or completely organic matter is obtained by incineration or the like. The energy obtained can be converted into available thermal or electrical energy. (3) Thermal decomposition recovery method. The CFRP waste is placed under high temperature conditions to decompose the resin macromolecular polymer in CFRP into small molecular compounds, and then the carbon fibers are separated. (4) Atmospheric pressure chemical solvent decomposition recovery method. By the synergistic action of the chemical solvent and the high-temperature heat, the C-N or C-O linkage chemical bond in the resin polymer is broken, the polymer is dissolved in the solution, and the carbon fiber is released from the resin, thereby achieving the purpose of recovery. (5) Other recycling methods. Such as supercritical / sub-supercritical method, electric recycling method. The existing method for recovering carbon fiber recovered from fiber reinforced composite waste has the following defects: (1) complicated process, difficult operation, and even requiring toxic auxiliary agents; (2) high equipment requirements, often requiring fiber The composite material (waste) is pretreated by cutting and pulverizing, resulting in shorter fibers and low economic value. (3) The initial equipment investment is large and industrialization is difficult.
因此，研究出一种技术可行、操作简便和经济效益高，同时兼顾环境保护的高性能碳纤维增强复合材料回收与再利用方法具备重要经济和社会意义。Therefore, it is of great economic and social significance to develop a high-performance carbon fiber reinforced composite material recycling and recycling method that is technically feasible, easy to operate, and economically efficient, while taking into consideration environmental protection.
发明内容Summary of the invention
本发明的主要目的在于其提供一种纤维增强树脂基复合材料(废弃物)中回收纤维的方法，其中本发明提供的该纤维回收方法具有工艺步骤简单、难度低、回收率高、成本低和纤维损伤小等优点。The main object of the present invention is to provide a method for recovering fibers in a fiber-reinforced resin-based composite material (waste), wherein the fiber recovery method provided by the invention has the advantages of simple process steps, low difficulty, high recovery rate, low cost and The fiber damage is small and so on.
本发明的另一目的在于其提供一种纤维增强树脂基复合材料(废弃物)中回收纤维的方法，其中本发明提供的该纤维回收方法不仅能够回收纤维，还能够同时回收树脂材料，从而更大限度地使纤维增强树脂基复合材料废弃物得到回收和再利用，具有重大环保价值和重要社会意义。Another object of the present invention is to provide a method for recovering fibers in a fiber-reinforced resin-based composite material (waste), wherein the fiber recovery method provided by the present invention can not only recover fibers but also simultaneously recover resin materials, thereby further It is of great environmental value and important social significance to maximize the recycling and reuse of fiber-reinforced resin-based composite waste.
本发明的另一目的在于其提供一种纤维增强树脂基复合材料(废弃物)中回收纤维的方法，其中本发明提供的该纤维回收方法的所需化学试剂毒性小、对生产设备的要求低、反应条件温和。本发明提供的该纤维回收方法无需对纤维增强复合材料进行剪切和/或破碎处理，因此，可以对任意尺寸的材料进行回收。同时，无需对纤维增强复合材料进行剪切和/或破碎处理，也使得回收得到的纤维材料的长度几乎未收到任何损伤，回收得到的纤维材料的经济价值更高。Another object of the present invention is to provide a method for recovering fibers in a fiber-reinforced resin-based composite material (waste), wherein the fiber-recovering method provided by the present invention has low toxicity and low requirements on production equipment. The reaction conditions are mild. The fiber recovery method provided by the present invention does not require shearing and/or crushing of the fiber-reinforced composite material, and therefore, materials of any size can be recovered. At the same time, it is not necessary to shear and/or crush the fiber reinforced composite material, and the length of the recovered fiber material is hardly damaged, and the economic value of the recovered fiber material is higher.
本发明的另一目的在于其提供一种用于纤维增强树脂基复合材料(废弃物)中回收纤维的组合物。Another object of the present invention is to provide a composition for recovering fibers in a fiber-reinforced resin-based composite material (waste).
本发明的其它优势和特点通过下述的详细说明得以充分体现并可通过所附权利要求中特地指出的手段和装置的组合得以实现。Other advantages and features of the invention will be apparent from the description and appended claims appended claims
依本发明，能够实现前述目的和其他目的和优势的本发明纤维增强树脂基复合材料 (废弃物)中回收纤维的方法包括下述步骤:According to the present invention, a method for recovering fibers in the fiber-reinforced resin-based composite material (waste) of the present invention capable of achieving the aforementioned objects and other objects and advantages includes the following steps:
(A)于25℃～75℃的反应温度将纤维增强树脂基复合材料放置在电解液中，其中该电解液含有重量比为0.5％～3％的NaCl和0.5g/L～1.5g/L的催化剂；(A) placing the fiber-reinforced resin-based composite material in an electrolyte at a reaction temperature of 25 ° C to 75 ° C, wherein the electrolyte contains 0.5% to 3% by weight of NaCl and 0.5 g/L to 1.5 g/L. Catalyst
(B)对放置在电解液中的纤维增强树脂基复合材料通电，其中该纤维增强树脂基复合材料与电源的正极相连，并控制电流密度为3333.3～15000mA/m 2，其中所述电流密度的大小根据所述纤维增强树脂基复合材料暴露于所述电解液的表面积大小进行计算；和 (B) energizing the fiber-reinforced resin-based composite material placed in the electrolyte, wherein the fiber-reinforced resin-based composite material is connected to the positive electrode of the power source and controlling the current density to be 3333.3 to 15000 mA/m 2 , wherein the current density is The size is calculated according to the surface area of the fiber-reinforced resin-based composite exposed to the electrolyte; and
(C)通电反应0.5～200小时后，自该电解液中取出生成的纤维回收物。(C) After the energization reaction is carried out for 0.5 to 200 hours, the produced fiber recovered product is taken out from the electrolytic solution.
依本发明较佳实施例，本发明进一步提供一种用于纤维增强树脂基复合材料(废弃物)中回收纤维的电解液，其含有：According to a preferred embodiment of the present invention, the present invention further provides an electrolyte for recovering fibers in a fiber-reinforced resin-based composite material (waste), comprising:
0.5％～3％的NaCl；0.5% to 3% NaCl;
0.5g/L～1.5g/L的KOH；和KOH from 0.5g/L to 1.5g/L; and
80％～98％的水。80% to 98% water.
通过对随后的描述和附图的理解，本发明进一步的目的和优势将得以充分体现。Further objects and advantages of the present invention will be fully realized from the understanding of the appended claims.
本发明的这些和其它目的、特点和优势，通过下述的详细说明，附图和权利要求得以充分体现。These and other objects, features and advantages of the present invention will become apparent from
附图说明DRAWINGS
图1显示的是常见碳纤维电化学回收***的结构示意图。Figure 1 shows a schematic diagram of the structure of a common carbon fiber electrochemical recovery system.
图2为碳纤维增强树脂基复合材料的剖视图，该图显示碳纤维增强树脂基复合材料板由碳纤维布和环氧树脂逐层交替叠加制成。2 is a cross-sectional view of a carbon fiber reinforced resin-based composite material, which is shown in which a carbon fiber reinforced resin-based composite material sheet is alternately laminated with a carbon fiber cloth and an epoxy resin layer by layer.
图3显示的是碳纤维回收过程中，碳纤维增强树脂基复合材料板的电压值。Figure 3 shows the voltage values of the carbon fiber reinforced resin-based composite sheet during the carbon fiber recovery process.
图4显示的是大电流回收条件下，电解液中的黑色沉淀物的SEM图像，该图表明大电流条件下，碳纤维增强树脂基复合材料板中的碳纤维发生劣化剥落。Figure 4 shows an SEM image of a black precipitate in an electrolyte under high current recovery conditions, which shows that the carbon fibers in the carbon fiber reinforced resin-based composite sheet are deteriorated and peeled off under a large current condition.
图5显示的是大电流回收条件下，电解液中的黑色沉淀物的能谱检测分析图像，该图表明电解液中的黑色沉淀物的主要成分是碳。Figure 5 shows an energy spectrum detection analysis image of a black precipitate in an electrolyte under a large current recovery condition, which shows that the main component of the black precipitate in the electrolyte is carbon.
图6显示的是40mA电流条件下，自碳纤维增强树脂基复合材料回收得到的碳纤维的长度。Figure 6 shows the length of carbon fiber recovered from a carbon fiber reinforced resin matrix composite at a current of 40 mA.
图7显示的是不同电流条件下，同样碳纤维增强树脂基复合材料板回收得到的碳纤维的量。Figure 7 shows the amount of carbon fiber recovered from the same carbon fiber reinforced resin matrix composite sheet under different current conditions.
图8显示的是不同电流条件下，自碳纤维增强树脂基复合材料回收得到的碳纤维的除 胶率。Figure 8 shows the degumming rate of carbon fibers recovered from carbon fiber reinforced resin matrix composites under different current conditions.
图9显示的是不同电流条件下，自碳纤维增强树脂基复合材料回收得到的碳纤维的单丝拉伸强度。Figure 9 shows the tensile strength of the monofilament of the carbon fiber recovered from the carbon fiber reinforced resin matrix composite under different current conditions.
图10显示的是不同电流条件下，自碳纤维增强树脂基复合材料回收得到的碳纤维的SEM图像。Figure 10 shows SEM images of carbon fibers recovered from carbon fiber reinforced resin matrix composites under different current conditions.
图11显示的是在低NaCl浓度时，不同电流条件下，自碳纤维增强树脂基复合材料回收得到的碳纤维的SEM图像。Figure 11 shows an SEM image of carbon fibers recovered from a carbon fiber reinforced resin matrix composite under different current conditions at a low NaCl concentration.
图12显示的是不同量的催化剂(KOH)条件下，不同反应时间，电解液中碳纤维增强树脂基复合材料的电压。Figure 12 shows the voltage of the carbon fiber reinforced resin matrix composite in the electrolyte at different reaction times under different amounts of catalyst (KOH) conditions.
图13显示的是无任何催化剂条件下，不同反应时间，电解液中碳纤维增强树脂基复合材料的电压。Figure 13 shows the voltage of the carbon fiber reinforced resin matrix composite in the electrolyte at different reaction times without any catalyst conditions.
图14显示的是不同量的催化剂(KOH)条件下，自碳纤维增强树脂基复合材料回收得到的碳纤维的量。Figure 14 shows the amount of carbon fiber recovered from the carbon fiber reinforced resin-based composite material under different amounts of catalyst (KOH).
图15显示的是不同量的催化剂(KOH)条件下，自碳纤维增强树脂基复合材料回收得到的碳纤维的单丝拉伸强度。Figure 15 shows the tensile strength of the monofilament of the carbon fiber recovered from the carbon fiber reinforced resin-based composite material under different amounts of catalyst (KOH).
图16显示的是不同量的催化剂(KOH)条件下，自碳纤维增强树脂基复合材料回收得到的碳纤维的界面剪切强度。Figure 16 shows the interfacial shear strength of carbon fibers recovered from carbon fiber reinforced resin-based composites under varying amounts of catalyst (KOH).
图17显示的是不同量的催化剂(KOH)条件下，自碳纤维增强树脂基复合材料回收得到的碳纤维的界面破坏。Figure 17 shows the interfacial destruction of carbon fibers recovered from carbon fiber reinforced resin matrix composites under varying amounts of catalyst (KOH).
图18显示的是不同量的催化剂(KOH)条件下，电流强度为20mA和40mA时，自碳纤维增强树脂基复合材料回收得到的碳纤维的SEM(扫描电子显微镜)图像。Figure 18 shows an SEM (Scanning Electron Microscope) image of carbon fibers recovered from a carbon fiber reinforced resin-based composite material under different amounts of catalyst (KOH) at a current intensity of 20 mA and 40 mA.
图19显示的是当催化剂(KOH)的量较高时，电流强度为20mA条件下，自碳纤维增强树脂基复合材料回收得到的碳纤维的SEM图像。Figure 19 shows an SEM image of carbon fibers recovered from a carbon fiber reinforced resin-based composite material at a current intensity of 20 mA when the amount of the catalyst (KOH) is high.
图20显示的是不同量的催化剂(KOH)、电流强度条件下，自碳纤维增强树脂基复合材料回收得到的碳纤维的AFM(原子力显微镜)图像。Fig. 20 is a view showing an AFM (atomic force microscope) image of carbon fibers recovered from a carbon fiber reinforced resin-based composite material under different amounts of catalyst (KOH) and current intensity.
图21A显示的是20mA电流强度，不同浓度NaCl条件下，自碳纤维增强树脂基复合材料回收得到的碳纤维的XRD(X射线衍射)图像。Fig. 21A shows an XRD (X-ray diffraction) image of a carbon fiber recovered from a carbon fiber reinforced resin-based composite material under a current concentration of 20 mA under different NaCl conditions.
图21B显示的是40mA电流强度，不同浓度NaCl条件下，自碳纤维增强树脂基复合材料回收得到的碳纤维的XRD图像。Fig. 21B shows an XRD image of carbon fiber recovered from a carbon fiber reinforced resin-based composite material under a current concentration of 40 mA under different NaCl conditions.
图22A显示的是20mA电流强度，不同量的催化剂(KOH)条件下，自碳纤维增强 树脂基复合材料回收得到的碳纤维的XRD图像。Fig. 22A shows an XRD image of a carbon fiber recovered from a carbon fiber reinforced resin-based composite material under a different amount of catalyst (KOH) at a current intensity of 20 mA.
图22B显示的是40mA电流强度，不同量的催化剂(KOH)条件下，自碳纤维增强树脂基复合材料回收得到的碳纤维的XRD图像。Fig. 22B shows an XRD image of a carbon fiber recovered from a carbon fiber reinforced resin-based composite material under a different amount of catalyst (KOH) at a current intensity of 40 mA.
图23A显示的是碳纤维原丝(VCF)的XPS(X射线光电子能谱扫描)图像。Figure 23A shows an XPS (X-ray photoelectron spectroscopy) image of carbon fiber precursor (VCF).
图23B显示的是碳纤维原丝(VCF)的C1s高分辨率窄谱图像。Figure 23B shows a high resolution narrow spectrum image of C1s of carbon fiber precursor (VCF).
图24A显示的是20mA电流强度，低剂量催化剂(KOH)条件下，自碳纤维增强树脂基复合材料回收得到的碳纤维的XPS图像。Fig. 24A shows an XPS image of carbon fibers recovered from a carbon fiber reinforced resin-based composite material under a low-dose catalyst (KOH) at a current intensity of 20 mA.
图24B显示的是20mA电流强度，低剂量催化剂(KOH)条件下，自碳纤维增强树脂基复合材料回收得到的碳纤维的C1s高分辨率窄谱图像。Figure 24B shows a high-resolution narrow-spectrum image of C1s of carbon fibers recovered from carbon fiber-reinforced resin-based composites at a current intensity of 20 mA under low-dose catalyst (KOH) conditions.
图25A显示的是20mA电流强度，中等剂量催化剂(KOH)条件下，自碳纤维增强树脂基复合材料回收得到的碳纤维的XPS图像。Figure 25A shows an XPS image of a carbon fiber recovered from a carbon fiber reinforced resin-based composite material at a current intensity of 20 mA and a medium dose catalyst (KOH).
图25B显示的是20mA电流强度，中等剂量催化剂(KOH)条件下，自碳纤维增强树脂基复合材料回收得到的碳纤维的C1s高分辨率窄谱图像。Figure 25B shows a C1s high resolution narrow-spectrum image of a carbon fiber recovered from a carbon fiber reinforced resin-based composite material at a current intensity of 20 mA and a medium dose catalyst (KOH).
图26A显示的是20mA电流强度，高剂量催化剂(KOH)条件下，自碳纤维增强树脂基复合材料回收得到的碳纤维的XPS图像。Fig. 26A shows an XPS image of carbon fiber recovered from a carbon fiber reinforced resin-based composite material under a high-dose catalyst (KOH) at a current intensity of 20 mA.
图26B显示的是20mA电流强度，高剂量催化剂(KOH)条件下，自碳纤维增强树脂基复合材料回收得到的碳纤维的C1s高分辨率窄谱图像。Fig. 26B shows a C1s high resolution narrow-spectrum image of carbon fiber recovered from a carbon fiber reinforced resin-based composite material under a high-dose catalyst (KOH) at a current intensity of 20 mA.
图27A显示的是20mA电流强度，低浓度NaCl，中等剂量催化剂(KOH)条件下，自碳纤维增强树脂基复合材料回收得到的碳纤维的XPS图像。Fig. 27A shows an XPS image of carbon fibers recovered from a carbon fiber reinforced resin-based composite material at a current intensity of 20 mA, a low concentration of NaCl, and a medium dose catalyst (KOH).
图27B显示的是20mA电流强度，低浓度NaCl，中等剂量催化剂(KOH)条件下，自碳纤维增强树脂基复合材料回收得到的碳纤维的C1s高分辨率窄谱图像。Fig. 27B shows a C1s high resolution narrow-spectrum image of carbon fiber recovered from a carbon fiber reinforced resin-based composite material under a current intensity of 20 mA, a low concentration of NaCl, and a medium dose catalyst (KOH).
图28A显示的是20mA电流强度，高浓度NaCl，中等剂量催化剂(KOH)条件下，自碳纤维增强树脂基复合材料回收得到的碳纤维的XPS图像。Fig. 28A shows an XPS image of carbon fibers recovered from a carbon fiber reinforced resin-based composite material at a current intensity of 20 mA, a high concentration of NaCl, and a medium dose catalyst (KOH).
图28B显示的是20mA电流强度，高浓度NaCl，中等剂量催化剂(KOH)条件下，自碳纤维增强树脂基复合材料回收得到的碳纤维的C1s高分辨率窄谱图像。Fig. 28B shows a C1s high resolution narrow-spectrum image of carbon fiber recovered from a carbon fiber reinforced resin-based composite material under a current intensity of 20 mA, a high concentration of NaCl, and a medium dose catalyst (KOH).
图29A显示的是40mA电流强度，中等剂量催化剂(KOH)条件下，自碳纤维增强树脂基复合材料回收得到的碳纤维的XPS图像。Figure 29A shows an XPS image of a carbon fiber recovered from a carbon fiber reinforced resin-based composite material under a medium dose catalyst (KOH) at a current intensity of 40 mA.
图29B显示的是40mA电流强度，中等剂量催化剂(KOH)条件下，自碳纤维增强树脂基复合材料回收得到的碳纤维的C1s高分辨率窄谱图像。Figure 29B shows a C1s high resolution narrow-spectrum image of a carbon fiber recovered from a carbon fiber reinforced resin-based composite material at a current intensity of 40 mA and a medium dose catalyst (KOH).
图30A显示的是20mA电流强度，不同剂量催化剂(KOH)条件下，自碳纤维增强 树脂基复合材料回收得到的碳纤维的表面官能团含量。Fig. 30A shows the surface functional group content of the carbon fiber recovered from the carbon fiber reinforced resin-based composite material at a current intensity of 20 mA under different doses of catalyst (KOH).
图30B显示的是20mA电流强度，不同浓度NaCl条件下，自碳纤维增强树脂基复合材料回收得到的碳纤维的表面官能团含量。Fig. 30B shows the surface functional group content of the carbon fiber recovered from the carbon fiber reinforced resin-based composite material at a current intensity of 20 mA under different NaCl conditions.
图30C显示的是20mA和40mA电流强度，相同剂量催化剂(KOH)条件下，自碳纤维增强树脂基复合材料回收得到的碳纤维的表面官能团含量。Fig. 30C shows the surface functional group content of the carbon fiber recovered from the carbon fiber reinforced resin-based composite material under the same dose catalyst (KOH) at a current intensity of 20 mA and 40 mA.
图31显示的是20mA和40mA电流强度，不同温度条件下，不同反应时间，电解液中碳纤维增强树脂基复合材料的电压。Figure 31 shows the currents of 20 mA and 40 mA, the temperature of the carbon fiber reinforced resin matrix composite in the electrolyte at different temperatures and different reaction times.
图32显示的是20mA和40mA电流强度，不同温度条件下，碳纤维回收量。Figure 32 shows the 20 mA and 40 mA current intensities, carbon fiber recovery at different temperatures.
图33显示的是20mA和40mA电流强度，不同温度条件下，回收得到的碳纤维的单丝拉伸强度。Figure 33 shows the tensile strength of the monofilament of the recovered carbon fiber at different current conditions for 20 mA and 40 mA current intensities.
图34显示的是20mA和40mA电流强度，不同温度条件下，回收得到的碳纤维的界面剪切强度。Figure 34 shows the 20 mA and 40 mA current intensities, and the interfacial shear strength of the recovered carbon fibers at different temperatures.
图35显示的是20mA和40mA电流强度，不同温度条件下，自碳纤维增强树脂基复合材料回收得到的碳纤维的界面破坏。Figure 35 shows the 20 mA and 40 mA current intensities, and the interface damage of the carbon fibers recovered from the carbon fiber reinforced resin matrix composite at different temperatures.
图36显示的是20mA和40mA电流强度，不同温度条件下，自碳纤维增强树脂基复合材料回收得到的碳纤维的SEM图像。Figure 36 shows SEM images of carbon fibers recovered from carbon fiber reinforced resin matrix composites at 20 mA and 40 mA current intensities at different temperatures.
图37显示的是20mA和40mA电流强度，不同温度条件下，自碳纤维增强树脂基复合材料回收得到的碳纤维的AFM(原子力显微镜)图像。Figure 37 shows AFM (atomic force microscope) images of carbon fibers recovered from carbon fiber reinforced resin matrix composites at 20 mA and 40 mA current intensities at different temperatures.
图38显示的是20mA电流强度，不同温度条件下，自碳纤维增强树脂基复合材料回收得到的碳纤维的XRD(X射线衍射)图像。Figure 38 shows the XRD (X-ray diffraction) image of the carbon fiber recovered from the carbon fiber reinforced resin-based composite material at a current intensity of 20 mA under different temperature conditions.
图39显示的是40mA电流强度，不同温度条件下，自碳纤维增强树脂基复合材料回收得到的碳纤维的XRD图像。Figure 39 shows the XRD image of the carbon fiber recovered from the carbon fiber reinforced resin-based composite material at a current intensity of 40 mA under different temperature conditions.
图40A显示的是20mA电流强度，40℃温度条件下，自碳纤维增强树脂基复合材料回收得到的碳纤维的XPS图像。Fig. 40A shows an XPS image of carbon fiber recovered from a carbon fiber reinforced resin-based composite material at a current intensity of 20 mA at a temperature of 40 °C.
图40B显示的是20mA电流强度，40℃温度条件下，自碳纤维增强树脂基复合材料回收得到的碳纤维的C1s高分辨率窄谱图像。Fig. 40B shows a C1s high resolution narrow-spectrum image of carbon fiber recovered from a carbon fiber reinforced resin-based composite material at a current intensity of 20 mA at a temperature of 40 °C.
图41A显示的是20mA电流强度，60℃温度条件下，自碳纤维增强树脂基复合材料回收得到的碳纤维的XPS图像。Fig. 41A shows an XPS image of carbon fiber recovered from a carbon fiber reinforced resin-based composite material at a current intensity of 20 mA at a temperature of 60 °C.
图41B显示的是20mA电流强度，60℃温度条件下，自碳纤维增强树脂基复合材料回收得到的碳纤维的C1s高分辨率窄谱图像。Fig. 41B shows a C1s high resolution narrow-spectrum image of carbon fiber recovered from a carbon fiber reinforced resin-based composite material at a current intensity of 20 mA at a temperature of 60 °C.
图42A显示的是20mA电流强度，75℃温度条件下，自碳纤维增强树脂基复合材料回收得到的碳纤维的XPS图像。Fig. 42A shows an XPS image of carbon fiber recovered from a carbon fiber reinforced resin-based composite material at a current intensity of 20 mA at a temperature of 75 °C.
图42B显示的是20mA电流强度，75℃温度条件下，自碳纤维增强树脂基复合材料回收得到的碳纤维的C1s高分辨率窄谱图像。Fig. 42B shows a C1s high resolution narrow-spectrum image of carbon fiber recovered from a carbon fiber reinforced resin-based composite material at a current intensity of 20 mA at a temperature of 75 °C.
图43显示的是20mA电流强度，75℃温度条件下，自碳纤维增强树脂基复合材料回收得到的碳纤维的表面官能团含量。Figure 43 shows the surface functional group content of the carbon fiber recovered from the carbon fiber reinforced resin-based composite material at a current intensity of 20 mA at a temperature of 75 °C.
图44阐释了根据本发明的较佳实施例的一自碳纤维增强树脂基复合材料回收碳纤维的方法。Figure 44 illustrates a method of recovering carbon fibers from a carbon fiber reinforced resin-based composite material in accordance with a preferred embodiment of the present invention.
具体实施方式Detailed ways
下述描述被揭露以使本领域技术人员可制造和使用本发明。下述描述中提供的较佳实施例仅作为对本领域技术人员显而易见的示例和修改，其并不构成对本发明范围的限制。下述描述中所定义的一般原理可不背离本发明精神和发明范围地应用于其它实施例、可选替代、修改、等同实施和应用。The following description is disclosed to enable any person skilled in the art to make and use the invention. The preferred embodiments provided in the following description are merely exemplary and modifications that are obvious to those skilled in the art, and are not intended to limit the scope of the invention. The general principles defined in the following description may be applied to other embodiments, alternatives, modifications, equivalents and applications without departing from the spirit and scope of the invention.
参考说明书附图之图1至图43，依本发明较佳实施例的用于纤维增强树脂基复合材料回收纤维的方法被详细说明。所述纤维包括各种类型的纤维材料，包括但不局限于玻璃纤维、碳纤维、碳化硅纤维、PBO等，优选为碳纤维、碳化硅纤维，其中所述纤维增强树脂基复合材料中回收纤维的方法包括以下步骤：Referring to Figures 1 through 43 of the accompanying drawings, a method for recovering fibers of a fiber-reinforced resin-based composite material in accordance with a preferred embodiment of the present invention is described in detail. The fiber includes various types of fiber materials including, but not limited to, glass fiber, carbon fiber, silicon carbide fiber, PBO, etc., preferably carbon fiber, silicon carbide fiber, wherein the fiber reinforced resin matrix composite material recovers fiber Includes the following steps:
(A)于25℃～75℃的反应温度将纤维增强树脂基复合材料放置在电解液中，其中该电解液含有重量比为0.5％～3％的可溶性盐酸盐和0.5g/L～1.5g/L的催化剂；(A) placing the fiber-reinforced resin-based composite material in an electrolyte at a reaction temperature of 25 ° C to 75 ° C, wherein the electrolyte contains 0.5% to 3% by weight of soluble hydrochloride and 0.5 g/L to 1.5 by weight. a catalyst of g/L;
(B)对放置在电解液中的纤维增强树脂基复合材料通电，其中该纤维增强树脂基复合材料与电源的正极相连，控制电流密度为3333.3～15000mA/m 2，其中所述电流密度的大小根据所述纤维增强树脂基复合材料暴露于所述电解液的表面积大小进行计算；和 (B) energizing the fiber-reinforced resin-based composite material placed in the electrolyte, wherein the fiber-reinforced resin-based composite material is connected to the positive electrode of the power source, and the current density is controlled to be 3333.3 to 15000 mA/m 2 , wherein the current density is Calculating according to the surface area of the fiber-reinforced resin-based composite material exposed to the electrolyte; and
(C)通电反应0.5～200小时后，自该电解液中取出生成的纤维回收物。(C) After the energization reaction is carried out for 0.5 to 200 hours, the produced fiber recovered product is taken out from the electrolytic solution.
在下文中，以回收碳纤维为例进行说明，电解液指的是含有NaCl、水和催化剂，其被用于自碳纤维增强树脂基复合材料回收碳纤维。示例性地，NaCl浓度分别为水质量的x1(0.5％)、x2(1％)、x3(2％)和x4(3％)。电流大小的衡量尺度为mA，如20mA、40mA、62.5mA、78.1mA、104.2mA和156.3mA，相应电流密度的计算方法和数值见示例3中的3.1。具体的碳纤维增强树脂基复合材料的分组及实验参数见表3.1。碳纤维增强树脂基复合材料的编号由所作用的电流大小和NaCl溶液浓度共同确定，比如，编号“I20S x1”， 前半部分“I20”表示碳纤维增强树脂基复合材料名义作用电流大小为20mA；后半部分“S x1”则表示样本(碳纤维增强树脂基复合材料板)所作用的NaCl溶液浓度x1(0.5％)。 Hereinafter, the description will be made by taking carbon fiber as an example, and the electrolyte means containing NaCl, water, and a catalyst, which is used for recovering carbon fiber from the carbon fiber reinforced resin-based composite material. Illustratively, the NaCl concentration is x1 (0.5%), x2 (1%), x3 (2%), and x4 (3%) of water mass, respectively. The current magnitude is measured by mA, such as 20mA, 40mA, 62.5mA, 78.1mA, 104.2mA, and 156.3mA. The calculation method and value of the corresponding current density are shown in 3.1 of Example 3. The grouping and experimental parameters of specific carbon fiber reinforced resin matrix composites are shown in Table 3.1. The number of carbon fiber reinforced resin matrix composites is determined by the magnitude of the applied current and the concentration of NaCl solution, for example, the number "I20S x1 ", and the first half "I20" indicates that the nominal current of the carbon fiber reinforced resin matrix composite is 20 mA; the second half The part "S x1 " indicates the concentration of the NaCl solution x1 (0.5%) of the sample (carbon fiber reinforced resin-based composite sheet).
如说明书附图之图1所示，用于自碳纤维增强树脂基复合材料回收碳纤维的(电化学)回收***包括直流电源、为***提供单向工作电流；阴阳极，碳纤维增强树脂基复合材料板(回收样本)作为阳极与电源正极相连，消耗降解环氧树脂，不锈钢片作为阴极与电源负极相连；电解液，含有NaCl、水(溶剂)和催化剂；数据记录仪(Datalog)，与回收样本及不锈钢片并联，监测样本电压变化。示例性地，碳纤维增强树脂基复合材料板与不锈钢片平行放置，且两者距离固定为50mm。As shown in Figure 1 of the accompanying drawings, the (electrochemical) recovery system for recovering carbon fibers from carbon fiber reinforced resin-based composite materials includes a DC power source to provide a unidirectional operating current for the system; a cathode anode, a carbon fiber reinforced resin-based composite material sheet. (Recycled sample) is connected as an anode to the positive electrode of the power supply, consuming degraded epoxy resin, and the stainless steel piece is connected as a cathode to the negative electrode of the power source; the electrolyte contains NaCl, water (solvent) and catalyst; the data log (Datalog), and the recovered sample and The stainless steel sheets are connected in parallel to monitor sample voltage changes. Illustratively, the carbon fiber reinforced resin-based composite sheet is placed in parallel with the stainless steel sheet, and the distance between the two is fixed at 50 mm.
如说明书附图之图2所示，碳纤维增强树脂基复合材料(板)由碳纤维布和环氧树脂逐层交替叠加制成。As shown in Fig. 2 of the accompanying drawings, the carbon fiber reinforced resin-based composite material (plate) is formed by alternately stacking carbon fiber cloth and epoxy resin layer by layer.
如说明书附图之图3所示，碳纤维增强树脂基复合材料电压监测表明，电流越小的碳纤维增强树脂基复合材料组在电化学回收过程中电压值越小，同时也越稳定。As shown in Figure 3 of the accompanying drawings, the voltage monitoring of the carbon fiber reinforced resin matrix composite shows that the smaller the current, the smaller the voltage value and the more stable the carbon fiber reinforced resin matrix composite material group during electrochemical recovery.
如说明书附图之图4和图5所示，大电流回收条件下，碳纤维增强树脂基复合材料板中的碳纤维发生劣化剥落。As shown in FIG. 4 and FIG. 5 of the drawings of the specification, under the condition of large current recovery, the carbon fibers in the carbon fiber reinforced resin-based composite material sheet are deteriorated and peeled off.
如说明书附图之图6所示，40mA电流条件下，自碳纤维增强树脂基复合材料回收得到的碳纤维的长度较好。As shown in Fig. 6 of the accompanying drawings, the carbon fiber recovered from the carbon fiber reinforced resin-based composite material has a good length at a current of 40 mA.
如说明书附图之图7所示，不同电流条件下，同样碳纤维增强树脂基复合材料板，回收得到的碳纤维的量具有差异。As shown in Figure 7 of the accompanying drawings, the amount of carbon fiber recovered is different for the same carbon fiber reinforced resin-based composite sheet under different current conditions.
如说明书附图之图8所示，20mA电流和40mA电流条件下，自碳纤维增强树脂基复合材料回收得到的碳纤维的除胶率差异并不明显。As shown in Fig. 8 of the accompanying drawings, the difference in the removal rate of carbon fibers recovered from the carbon fiber reinforced resin-based composite material is not significant under the conditions of 20 mA current and 40 mA current.
如说明书附图之图9所示，大电流(62.5mA)条件下，自碳纤维增强树脂基复合材料回收得到的碳纤维的单丝拉伸强度明显劣化。As shown in Fig. 9 of the accompanying drawings, the tensile strength of the monofilament of the carbon fiber recovered from the carbon fiber reinforced resin-based composite material is significantly deteriorated under a large current (62.5 mA).
如说明书附图之图10所示，大电流条件下，自碳纤维增强树脂基复合材料回收得到的碳纤维明显劣化。As shown in Fig. 10 of the accompanying drawings, the carbon fiber recovered from the carbon fiber reinforced resin-based composite material is significantly deteriorated under a large current condition.
如说明书附图之图11所示，在低NaCl浓度条件下，自碳纤维增强树脂基复合材料回收得到的碳纤维明显劣化。As shown in Fig. 11 of the accompanying drawings, the carbon fibers recovered from the carbon fiber reinforced resin-based composite material are significantly deteriorated under a low NaCl concentration.
如说明书附图之图12和图13所示，催化剂KOH具有稳定碳纤维增强树脂基复合材料的电压的作用。As shown in Figures 12 and 13 of the accompanying drawings, the catalyst KOH has a function of stabilizing the voltage of the carbon fiber reinforced resin-based composite material.
如说明书附图之图14所示，低剂量催化剂KOH条件下，KOH剂量越高，自碳纤维增强树脂基复合材料回收得到的碳纤维的量越大；高剂量催化剂KOH条件下，KOH剂 量越高，自碳纤维增强树脂基复合材料回收得到的碳纤维的量越小。As shown in Figure 14 of the accompanying drawings, the higher the KOH dose, the higher the amount of carbon fiber recovered from the carbon fiber reinforced resin-based composite material under the low-dose catalyst KOH condition; the higher the KOH dose, the higher the KOH dose under the high-dose catalyst KOH condition. The smaller the amount of carbon fibers recovered from the carbon fiber reinforced resin-based composite material.
如说明书附图之图15所示，催化剂KOH剂量越高，自碳纤维增强树脂基复合材料回收得到的碳纤维的单丝拉伸强度越小。As shown in Fig. 15 of the accompanying drawings, the higher the catalyst KOH dose, the smaller the tensile strength of the monofilament of the carbon fiber recovered from the carbon fiber reinforced resin-based composite material.
如说明书附图之图16所示，低剂量催化剂KOH条件下，KOH剂量越高，自碳纤维增强树脂基复合材料回收得到的碳纤维的界面剪切强度越大；高剂量催化剂KOH条件下，KOH剂量越高，自碳纤维增强树脂基复合材料回收得到的碳纤维的界面剪切强度越小。As shown in Figure 16 of the accompanying drawings, the higher the KOH dose, the higher the interfacial shear strength of the carbon fiber recovered from the carbon fiber reinforced resin-based composite material under the low-dose catalyst KOH condition; the KOH dose under the high-dose catalyst KOH condition The higher the interfacial shear strength of the carbon fiber recovered from the carbon fiber reinforced resin-based composite material, the smaller.
如说明书附图之图17至图20所示，催化剂KOH剂量越高，自碳纤维增强树脂基复合材料回收得到的碳纤维的界面破坏越严重。As shown in Figures 17 to 20 of the accompanying drawings, the higher the catalyst KOH dose, the more severe the interface damage of the carbon fibers recovered from the carbon fiber reinforced resin matrix composite.
如说明书附图之图21A至图29B所示，催化剂KOH剂量增加会加剧回收得到的碳纤维表面的氧化刻蚀，改善界面剪切性能；过低或过高的NaCl浓度均会降低回收得到的碳纤维的界面剪切性能；电流过大不但不利于提高回收得到的碳纤维界面剪切性能，而且还会降低回收得到的碳纤维拉伸强度。As shown in Figures 21A to 29B of the accompanying drawings, the increase in the dose of the catalyst KOH will exacerbate the oxidative etching of the recovered carbon fiber surface and improve the interfacial shear performance; the too low or too high NaCl concentration will reduce the recovered carbon fiber. The interfacial shear performance; excessive current is not only conducive to improving the shear properties of the recovered carbon fiber interface, but also reduces the tensile strength of the recovered carbon fiber.
如说明书附图之图30A至图30C所示，20mA电流强度条件下，高剂量催化剂会使回收得到碳纤维表面氧化程度变高；高NaCl浓度电解液会降低碳纤维表面氧化程度；电流越大，回收得到的碳纤维受到的氧化程度越高，同时受到的氯腐蚀也越严重。As shown in Fig. 30A to Fig. 30C of the accompanying drawings, under the condition of 20 mA current intensity, the high-dose catalyst will increase the surface oxidation degree of the carbon fiber recovered; the high NaCl concentration electrolyte will reduce the oxidation degree of the carbon fiber surface; the larger the current, the recovery The higher the degree of oxidation of the obtained carbon fiber, the more severe the corrosion of chlorine.
如说明书附图之图31所示，20mA和40mA电流强度，不同温度条件下，不同反应时间，电解液中碳纤维增强树脂基复合材料的电压变化不明显。As shown in Figure 31 of the accompanying drawings, the current intensity of 20 mA and 40 mA, different temperature conditions, different reaction times, the voltage change of the carbon fiber reinforced resin matrix composite in the electrolyte is not obvious.
如说明书附图之图32所示，20mA和40mA电流强度条件下，温度越高，碳纤维回收量越大。As shown in Figure 32 of the accompanying drawings, at 20 mA and 40 mA current intensity, the higher the temperature, the greater the amount of carbon fiber recovered.
如说明书附图之图33所示，20mA和40mA电流强度条件下，升高回收温度，缩短回收周期能够减少碳纤维遭受的电化学损伤，提高回收得到的碳纤维的单丝拉伸强度。As shown in Figure 33 of the accompanying drawings, at 20 mA and 40 mA current intensity, increasing the recovery temperature and shortening the recovery period can reduce the electrochemical damage suffered by the carbon fiber and increase the tensile strength of the recovered carbon fiber.
如说明书附图之图34至图37所示，20mA和40mA电流强度条件下，回收得到的碳纤维的界面剪切强度随着温度的升高，呈现先降低再升高的趋势。As shown in Fig. 34 to Fig. 37 of the accompanying drawings, under the conditions of current intensity of 20 mA and 40 mA, the interfacial shear strength of the recovered carbon fiber tends to decrease first and then increase with increasing temperature.
如说明书附图之图38至图42B所示，温度越高，回收得到的碳纤维的拉伸强度随温度上升而不断增强，界面剪切强度不断增大。As shown in Fig. 38 to Fig. 42B of the drawings, the higher the temperature, the tensile strength of the recovered carbon fiber is continuously increased as the temperature rises, and the interfacial shear strength is continuously increased.
如说明书附图之图43所示，20mA电流强度条件下，自碳纤维增强树脂基复合材料回收得到的碳纤维的表面官能团含量随温度的升高而升高。As shown in FIG. 43 of the accompanying drawings, the surface functional group content of the carbon fiber recovered from the carbon fiber reinforced resin-based composite material increases with an increase in temperature under a current of 20 mA.
所述碳纤维增强树脂基复合材料，又称待回收纤维增强树脂基复合材料，其包括采用各种有机胶凝材料(如环氧树脂)固化、粘贴或制作的，和采用各种无机胶凝材料(如水泥基胶凝材料)固化、粘贴或制作的纤维增强树脂基复合材料。The carbon fiber reinforced resin matrix composite material, also referred to as a fiber reinforced resin matrix composite material to be recycled, comprises curing, pasting or fabricating with various organic cementing materials (such as epoxy resin), and adopting various inorganic cementing materials. A fiber reinforced resin-based composite material that is cured, pasted, or fabricated (such as a cementitious cementitious material).
进一步地，本文将结合下述具体示例，详细说明本发明。Further, the present invention will be described in detail in conjunction with the following specific examples.
示例1：原材料(碳纤维增强树脂基复合材料)的准备Example 1: Preparation of raw materials (carbon fiber reinforced resin matrix composite)
对待回收纤维增强树脂基复合材料进行预处理：Pretreatment of recycled fiber reinforced resin matrix composites:
对所述待回收纤维增强树脂基复合材料进行预处理的方法包括但不局限于将所述待回收纤维增强树脂基复合材料通过本学科所熟知的方法进行清洗、裁剪和打磨。The method of pretreating the fiber-reinforced resin-based composite material to be recycled includes, but is not limited to, cleaning, cutting, and grinding the fiber-reinforced resin-based composite material to be recycled by a method well known in the art.
当前纤维材料回收或老化技术中所公开的各种预处理或回收方法，包括且不局限于将所述待回收的碳纤维增强树脂基复合材料进行溶液浸泡、化学分解、加热、加压、超声强化、微波强化，以及各种方法的结合使用。所述加热温度为0～800摄氏度，加热时间为0.5～200小时。所述加压的压力大小为0.5～20大气压，加压时间为0.5～200小时。视所述待回收碳纤维增强树脂基复合材料的情况不同，还可将所述待回收碳纤维增强树脂基复合材料置于液体中加热加压，所述液体的特征为可促使树脂发生膨胀和分解，包括但不局限于水、液体乙醇、液体乙二醇、各种弱酸溶液(包括H 2SiO 3(偏硅酸)、HCN(氢氰酸)、H 2CO 3(碳酸)、HF(氢氟酸)、CH 3COOH(也作C 2H 4O 2乙酸，又叫醋酸)、H 2S(氢硫酸)、HClO(次氯酸)、HNO 2(亚硝酸)、所有的有机酸、H 2SO 3(亚硫酸)等)、各种碱性溶液(包括但不局限于氢氧化钾溶液、氢氧化钠溶液等)、各种含氯离子溶液(包括但不局限于氯化钠溶液、氯化锌溶液等)。上述各种溶液的浓度为0.001％～99.9％，优选为0.5％～3％。 Various pretreatment or recovery methods disclosed in current fiber material recovery or aging techniques include, but are not limited to, solution immersion, chemical decomposition, heating, pressurization, ultrasonic strengthening of the carbon fiber reinforced resin-based composite material to be recovered. , microwave enhancement, and a combination of various methods. The heating temperature is 0 to 800 degrees Celsius, and the heating time is 0.5 to 200 hours. The pressure of the pressurization is 0.5 to 20 atm, and the pressurization time is 0.5 to 200 hours. Depending on the case of the carbon fiber reinforced resin-based composite material to be recovered, the carbon fiber reinforced resin-based composite material to be recovered may be heated and pressurized in a liquid, and the liquid is characterized in that the resin is caused to expand and decompose. Including but not limited to water, liquid ethanol, liquid glycol, various weak acid solutions (including H 2 SiO 3 (metasilicate), HCN (hydrocyanic acid), H 2 CO 3 (carbonic acid), HF (hydrogen fluoride Acid), CH 3 COOH (also known as C 2 H 4 O 2 acetic acid, also known as acetic acid), H 2 S (hydrogen sulfuric acid), HClO (hypochlorous acid), HNO 2 (nitrous acid), all organic acids, H 2 SO 3 (sulfurous acid), etc., various alkaline solutions (including but not limited to potassium hydroxide solution, sodium hydroxide solution, etc.), various chloride ion solutions (including but not limited to sodium chloride solution, Zinc chloride solution, etc.). The concentration of each of the above solutions is from 0.001% to 99.9%, preferably from 0.5% to 3%.
碳纤维增强树脂基复合材料板(或CFRP样本)尺寸为30mm 245mm，厚度为2mm。CFRP样本沿其长度方向被分为三个区域：一区即为试验区(Test region)，被用来回收碳纤维的区域，长度为100mm；二区即保护区(Protected region),该区域绝缘防水，以确保试验区面积在实验过程中的保持大小一致，长度为80mm；三区即接电区(Electrical connection region)，用来连接线路不锈钢片接头，保证电路连通性，长度为65mm。The carbon fiber reinforced resin matrix composite sheet (or CFRP sample) has a size of 30 mm 245 mm and a thickness of 2 mm. The CFRP sample is divided into three regions along its length: one region is the test region, the region used to recover carbon fibers, and the length is 100 mm; the second region is the protected region, which is insulated and waterproof. In order to ensure that the area of the test area is consistent during the experiment, the length is 80mm; the third area is the electrical connection region, which is used to connect the stainless steel plate joints to ensure the circuit connectivity and the length is 65mm.
本实验采用的碳纤维增强树脂基复合材料板(CFRP)样本由碳纤维布和环氧树脂逐层交替叠加压制而成，环氧树脂质量含量为31.5％，其中每层碳纤维布均为纵横向碳纤维正交编织而成(详见图2)。该碳纤维增强树脂基复合材料板中的碳纤维是T700型碳纤维(产自日本东丽公司)，环氧树脂为LAM-125/226型环氧树脂，详细化学成分见表1.1。The carbon fiber reinforced resin matrix composite material sheet (CFRP) sample used in this experiment was formed by alternately stacking carbon fiber cloth and epoxy resin layer by layer. The epoxy resin mass content was 31.5%, and each layer of carbon fiber cloth was longitudinal and horizontal carbon fiber. Interwoven (see Figure 2). The carbon fiber in the carbon fiber reinforced resin matrix composite sheet is T700 type carbon fiber (produced by Toray Co., Japan), and the epoxy resin is LAM-125/226 type epoxy resin. The detailed chemical composition is shown in Table 1.1.
表1.1 CFRP中环氧树脂的化学成分组成Table 1.1 Chemical composition of epoxy resin in CFRP
Figure PCTCN2018075923-appb-000001
Figure PCTCN2018075923-appb-000001
Figure PCTCN2018075923-appb-000002
Figure PCTCN2018075923-appb-000002
示例2：实验测试方法Example 2: Experimental test method
2.1样本电压监测2.1 sample voltage monitoring
选用日本日置电机株式会社生产的HIOKI-LR8400型号数据记录仪(Datalog)。采频频率为1h/次，电源频率为50HZ。The HIOKI-LR8400 model data logger (Datalog) manufactured by Nippon Electric Co., Ltd. was used. The frequency of the frequency is 1h/time and the power frequency is 50HZ.
2.2热重分析(TGA)测试2.2 Thermogravimetric Analysis (TGA) Test
选用德国NETZSCH公司生产的STA409PC型号综合热分析仪。设定样品最高上升温度为800℃，升温速率为10℃，氮气流速为100。本热重分析实验中每个样本的测试3个，结果取平均值。The STA409PC model integrated thermal analyzer manufactured by NETZSCH of Germany was selected. The maximum rise temperature of the sample was set to 800 ° C, the heating rate was 10 ° C, and the nitrogen flow rate was 100. In this thermogravimetric analysis, three samples were tested for each sample, and the results were averaged.
环氧树脂的热裂解温度范围约为300℃～600℃，该区间是本实验所用LAM-125/226型环氧树脂的最佳热裂解温度，至600℃时环氧树脂完全裂解。The thermal cracking temperature range of the epoxy resin is about 300 ° C ~ 600 ° C, which is the optimum thermal cracking temperature of the LAM-125/226 epoxy resin used in this experiment, and the epoxy resin is completely cracked at 600 ° C.
2.3碳纤维单丝拉伸性能测试2.3 carbon fiber monofilament tensile performance test
依照碳纤维单丝拉伸强度测试规范ISO 11566[54]，选用美国安捷伦公司生产的nano UTM 150型号纳米拉伸仪进行碳纤维单丝拉伸实验；测试***为UTM-Bionix Standard Toecomp Quasistatic。测试参数设定如下：作用荷载750μN，拉伸速率为0.2μm/s，荷载分辨率为50nN，位移分辨率<0.1nm，拉伸分辨率为35nm，作动器最大位移1mm。测试温度为20℃～30℃，空气湿度40％。According to the carbon fiber monofilament tensile strength test specification ISO 11566 [54], the carbon fiber monofilament tensile test was carried out using a nano UTM 150 model nano-stretcher manufactured by Agilent, USA; the test system was UTM-Bionix Standard Toecomp Quasistatic. The test parameters were set as follows: application load 750 μN, tensile rate 0.2 μm/s, load resolution 50 nN, displacement resolution <0.1 nm, tensile resolution 35 nm, actuator maximum displacement 1 mm. The test temperature is 20 ° C ~ 30 ° C, the air humidity is 40%.
进行碳纤维单丝拉伸测试前，需将碳纤维单丝固定在尺寸为15mm 20mm的相片纸上，相片纸中间为直径6mm的圆孔，使用膏状胶水将碳纤维单丝粘在圆孔水平方向直径上，纤维不能过紧或过于松弛。Before the carbon fiber monofilament tensile test, the carbon fiber monofilament should be fixed on the photo paper of 15mm 20mm in size, and the middle of the photo paper is a circular hole with a diameter of 6mm. The carbon fiber monofilament is adhered to the horizontal diameter of the round hole by using the paste glue. On the fiber, the fiber should not be too tight or too loose.
样本制作完成后，置于实验室条件一天，待胶水自然晾干。即可将样本装进纳米拉伸仪夹具，然后将相片纸两侧边沿剪断，最后开始进行测试。碳纤维单丝测试长度为61mm，每个样本需测试的样品为20个，碳纤维单丝强度结果为20个样品强度平均值。单丝拉伸强度公式如下：After the sample is prepared, it is placed in laboratory conditions for one day, and the glue is allowed to dry naturally. The sample can be loaded into the nano-tensile fixture, then the edges of the photo paper are cut and the test begins. The carbon fiber monofilament test length is 61 mm, the number of samples to be tested per sample is 20, and the carbon fiber monofilament strength result is 20 sample intensity average. The tensile strength formula of the monofilament is as follows:
Figure PCTCN2018075923-appb-000003
Figure PCTCN2018075923-appb-000003
式中σ f—单丝拉伸强度(MPa) Where σ f — tensile strength of monofilament (MPa)
F f—单丝断裂最大荷载(N) F f — monofilament fracture maximum load (N)
d—单丝直径(mm)D—monofilament diameter (mm)
选用长春产业光电技术有限公司生产的激光测径仪测量碳纤维单丝直径。将样本放 置于样品架上，利用衍射原理，测量单丝的衍射暗纹间距，通过公式换算即可计算得到单丝的精确直径，公式如下：The diameter of the carbon fiber monofilament was measured using a laser caliper manufactured by Changchun Industrial Optoelectronic Technology Co., Ltd. The sample is placed on the sample holder, and the diffraction dark line spacing of the monofilament is measured by the diffraction principle. The exact diameter of the monofilament can be calculated by formula conversion, and the formula is as follows:
d＝kLλ/x k＝Lλ/S   (2-2) d=kLλ/x k =Lλ/S (2-2)
式中d—单丝直径(nm)Where d-monofilament diameter (nm)
S—暗纹直径(cm)S—dark line diameter (cm)
L—样品到衍射屏的距离L—the distance from the sample to the diffraction screen
x k—第k极暗纹到光轴的距离 x k — the distance from the kth to the optical axis
参数设置：L＝60cm，λ＝532nmParameter setting: L=60cm, λ=532nm
2.4碳纤维单丝界面剪切强度测试2.4 Carbon fiber monofilament interface shear strength test
选用日本东荣株式会社生产的HM410复合材料界面特征评价装置进行微滴包埋测试。测试参数设定如下：测试速度为0.12mm/min，显微镜倍率为2倍。The HM410 composite interface feature evaluation device manufactured by Japan Toyon Co., Ltd. was used for the droplet embedding test. The test parameters were set as follows: the test speed was 0.12 mm/min, and the microscope magnification was 2 times.
根据文献研究 [55]，测试树脂球的直径范围宜选定为40μm～80μm。每个样本测试的树脂球为5个，界面剪切强度结果取其平均值。界面剪切强度公式如下： According to literature studies [55] , the diameter of the test resin sphere should be selected from 40 μm to 80 μm. The number of resin balls tested in each sample was 5, and the interfacial shear strength results were averaged. The interface shear strength formula is as follows:
Figure PCTCN2018075923-appb-000004
Figure PCTCN2018075923-appb-000004
式中F—荷载值(μN)Where F - load value (μN)
d—单丝直径(μm)D—monofilament diameter (μm)
l—树脂球直径(μm)L—resin ball diameter (μm)
2.5环境扫描电子显微镜(ESEM)测试2.5 Environmental Scanning Electron Microscopy (ESEM) Test
选用美国FEI公司的Quanta TM 250FEG型号环境扫描电子显微镜，对回收得到的碳纤维表面形貌状况进行观察分析。选择高真空模式，工作距离约为10mm，测试加速电压为20KV。为了得到更加清晰准确的表面形貌，需要增加碳纤维的导电性，因此样品在进行测试前，先在离子溅射仪中进行喷金处理。The surface morphology of the recovered carbon fiber was observed and analyzed by using the FINA company's Quanta TM 250FEG model scanning electron microscope. Select high vacuum mode, the working distance is about 10mm, and the test acceleration voltage is 20KV. In order to obtain a clearer and more accurate surface topography, it is necessary to increase the conductivity of the carbon fiber, so the sample is subjected to gold spray treatment in an ion sputtering apparatus before being tested.
2.6原子力显微镜(AFM)测试2.6 Atomic Force Microscopy (AFM) test
选用美国布鲁克公司生产的ICON-PT-PKG型号扫描探针显微镜，对回收得到的碳纤维进行测试，可得到其表面微观形貌及起伏情况的二维和三维图。The ICON-PT-PKG model scanning probe microscope produced by Bruker Company of USA was used to test the recovered carbon fiber to obtain two-dimensional and three-dimensional images of the surface topography and undulation.
因此本实验的样品扫描范围选择4μm，采用轻敲模式，扫描速率为1.0Hz。为了保证测试成功率，碳纤维单丝的长度不应低于20mm。Therefore, the sample scanning range of this experiment was 4 μm, and the tapping mode was adopted, and the scanning rate was 1.0 Hz. In order to ensure the success rate of the test, the length of the carbon fiber monofilament should not be less than 20 mm.
利用NanoScope Analysis 1.8软件对图像进行分析计算，在软件的四种粗糙度表达公式中，选择Ra来表征粗糙度，其计算公式如下：The image was analyzed and calculated using NanoScope Analysis 1.8 software. In the four roughness expression formulas of the software, Ra was selected to characterize the roughness. The calculation formula is as follows:
Figure PCTCN2018075923-appb-000005
Figure PCTCN2018075923-appb-000005
式中N x—X轴的步数 N x - the number of steps in the X axis
N y—Y轴的步数 N y — the number of steps in the Y axis
2.7 X-射线光电子能谱(XPS)2.7 X-ray photoelectron spectroscopy (XPS)
选用ULVAC-PHI VPII型号光电子能谱仪，对回收得到的碳纤维进行先进行0eV～800eV范围的全谱扫描，得到其表面元素信息，再对C1s进行高分辨扫描，使用XPSPeak4.1软件对结果进行高斯函数和洛伦兹函数拟合，分析官能团的种类和含量情况信息。测试时，需要保证碳纤维平整的放置在测试台上。单色器的X射线源为Al靶，测试元素包括：C、O、Cl、N、Si、Ca，选择90°作为入射角。The ULVAC-PHI VPII model photoelectron spectrometer was used to perform the full-spectrum scanning of the recovered carbon fiber in the range of 0eV～800eV to obtain the surface element information, and then the C1s were scanned with high resolution, and the results were performed by XPSPeak4.1 software. Gaussian function and Lorentz function fitting, analysis of the type and content of functional groups. When testing, it is necessary to ensure that the carbon fiber is placed flat on the test bench. The X-ray source of the monochromator is an Al target, and the test elements include: C, O, Cl, N, Si, Ca, and 90° is selected as the incident angle.
示例3：电流密度和NaCl浓度对碳纤维回收的影响Example 3: Effect of current density and NaCl concentration on carbon fiber recovery
3.1电流密度和NaCl浓度对碳纤维回收的影响的确认3.1 Confirmation of the influence of current density and NaCl concentration on carbon fiber recovery
为了确定电流密度和NaCl浓度对碳纤维回收的影响，发明人共设计六种不同恒定电流密度和四种不同钠盐浓度条件下，回收碳纤维，其中NaCl溶液由去离子水和氯化钠配制而成，浓度分别为0.5(％)、1.0(％)、2.0(％)和3.0(％)。恒定电流大小分别为20mA、40mA、62.5mA、78.1mA、104.2mA和156.3mA，CFRP试件暴露于电解液中的实验表面积(A)为2×100×30＝6000mm 2，因此对应的电流密度(i＝I/A)分别为3333.3、6666.7、10416.7、13016.7、17366.7和26005.0mA/m 2。具体的样本分组及实验参数见表3.1。样本编号由所作用的电流强度大小和NaCl溶液浓度共同确定。 In order to determine the effect of current density and NaCl concentration on carbon fiber recovery, the inventors designed six different constant current densities and four different sodium salt concentrations to recover carbon fibers, wherein the NaCl solution was prepared from deionized water and sodium chloride. The concentrations were 0.5 (%), 1.0 (%), 2.0 (%), and 3.0 (%), respectively. The constant current magnitudes were 20 mA, 40 mA, 62.5 mA, 78.1 mA, 104.2 mA, and 156.3 mA, respectively. The experimental surface area (A) of the CFRP test piece exposed to the electrolyte was 2 x 100 x 30 = 6000 mm 2 , so the corresponding current density (i=I/A) were 3333.3, 6666.7, 10416.7, 13016.7, 17366.7, and 26005.0 mA/m 2 , respectively . The specific sample grouping and experimental parameters are shown in Table 3.1. The sample number is determined by the magnitude of the applied current intensity and the concentration of the NaCl solution.
整个电化学回收过程将在实验室条件下持续18天，在此过程将保持溶液体积不变。The entire electrochemical recovery process will last for 18 days under laboratory conditions, during which time the solution volume will remain constant.
表3.1实验样本分组及参数Table 3.1 Experimental sample grouping and parameters
Figure PCTCN2018075923-appb-000006
Figure PCTCN2018075923-appb-000006
Figure PCTCN2018075923-appb-000007
Figure PCTCN2018075923-appb-000007
回收周期结束后，用镊子和剪刀轻轻取下样本上的碳纤维。回收得到的碳纤维将会在超声波清洗机中先用洗液(如酒精)清洗一遍，再用洗液(如去离子水)清洗三遍，每一遍的清洗时间为5分钟。然后将清洗过后的碳纤维放置于干燥箱烘干，时间设定为三天，温度设定为50℃。At the end of the recovery cycle, gently remove the carbon fibers from the sample with tweezers and scissors. The recovered carbon fiber will be washed first with a washing liquid (such as alcohol) in an ultrasonic cleaner, and then washed three times with a washing liquid (such as deionized water), and the cleaning time per one time is 5 minutes. The washed carbon fibers were then placed in a dry box for drying for three days and the temperature was set at 50 °C.
在所有样本电流组中，只有小电流组(I20、I40和I62.5)可以回收得到柔软的碳纤维丝，此处所给出的回收得到的碳纤维图片是I40S2.0样本回收所得的碳纤维丝，可见回收得到的碳纤维丝长度相比试验长度(100mm)几乎无损。Among all the sample current groups, only the small current group (I20, I40, and I62.5) can recover the soft carbon fiber yarn. The recovered carbon fiber picture given here is the carbon fiber wire recovered from the I40S2.0 sample. The length of the recovered carbon fiber filament was almost non-destructive compared to the test length (100 mm).
3.2.样本电压检测3.2. Sample voltage detection
样本电压监测表明，电流越小的样本组在电化学回收过程中电压值越小，同时也越稳定，如下图3。从图3中可以看出，在电化学回收初始阶段，施加大电流的样本电压就比较高，I156.3电流组比I20电流组电压高2V左右，不同电流组之间的电压并不与所施加电流的倍数关系相对应。六个电流组样本的电压可大致分为两大类，一类：小电流组(I20、I40和I62.5)样本电压基本稳定在3～4V之间，且同电流组中不同NaCl浓度样本电压相差不大；I20与I40组电压波动值不超过8％与15％；I62.5组样本I62.5S 0.5在370h开始电压骤增，至回收结束时电压达到8.3V。大电流组(I78.1、I104.2和I156.3)样本电压大约从50h开始快速上升，呈非线性变化，接近200h后电压增速放缓。同电流组中不同NaCl浓度样本电压相差较大，电压随着NaCl浓度的增大呈现先下降再增大趋势，S 2.0系列样本电压最低。现有研究表明，当阳极材料遭受到某种损坏时，电压会急剧上升，高于稳定值3V以上。本试验中大电流组的样本电压比初始电压快速上升超过了3V，表明大电流作用会对CFRP造成严重的劣化。 Sample voltage monitoring showed that the smaller the current, the smaller the voltage value and the more stable the electrochemical recovery process, as shown in Figure 3 below. It can be seen from Fig. 3 that in the initial stage of electrochemical recovery, the sample voltage applied with a large current is relatively high, and the I156.3 current group is about 2V higher than the I20 current group voltage, and the voltage between the different current groups is not the same. The multiple relationship of the applied current corresponds. The voltages of the six current group samples can be roughly divided into two categories, one type: the small current group (I20, I40, and I62.5) sample voltage is basically stable between 3 and 4V, and different NaCl concentration samples in the same current group. voltage or less; I20 and I40 set voltage fluctuation value does not exceed 8% and 15%; I62.5 set of samples 370h I62.5S 0.5 at the start surge voltage, to the recovery when the end voltage reached 8.3V. In the high current group (I78.1, I104.2, and I156.3), the sample voltage rises rapidly from 50h, showing a nonlinear change. After nearly 200h, the voltage increase slows down. The voltage difference of different NaCl concentration samples in the same current group is larger, the voltage decreases first and then increases with the increase of NaCl concentration, and the S 2.0 series sample voltage is the lowest. Existing studies have shown that when the anode material is subjected to some damage, the voltage rises sharply, above the stable value of 3V. In this test, the sample voltage of the large current group rises faster than the initial voltage by more than 3V, indicating that the large current effect causes severe degradation of CFRP.
从样本电压结果可知，在同样NaCl浓度下，施加大电流使CFRP的氧化程度更严重；在相同电流作用下，低NaCl浓度环境(如0.5％)的CFRP氧化程度会更严重一些。From the sample voltage results, it is known that under the same NaCl concentration, the application of large current makes the oxidation degree of CFRP more serious; under the same current, the CFRP oxidation degree of the low NaCl concentration environment (such as 0.5%) will be more serious.
3.3不同电流密度下CFRP劣化结果3.3 CFRP degradation results at different current densities
在回收早期阶段，电解液溶液澄清，随着电化学回收反应的进行，溶液颜色逐渐变深。从溶液颜色变化情况，可以大致分为两大类，一类：小电流组(I20、I40和I62.5)，溶液先由澄清逐渐变为淡黄色，再变成暗黄色。二类：大电流组(I78.1、I104.2和I156.3)，溶液从澄清开始变成褐色，然后慢慢变成黑色。在相同浓度的NaCl条件下，施加电流越大的样本电解液颜色越深；在相同电流作用下，NaCl浓度越高的样本电解液颜色越呈黄色。在大电流组的电解反应池中沉淀着许多黑色物质，将其过滤置于烘箱中50℃干燥3天，然后利用环境扫描电镜(ESEM)进行观测，以及能谱检测(EDS)分析，结果分别见图4和5。从图4中看到，沉淀物质为疏松结构，从图5可知，沉淀物质主要元素为碳，此外还检测出少量的氮、氧和金元素，金元素是扫描前喷金所引入。上述结果表明，反应池中的黑色沉淀物来自CFRP中的碳纤维劣化剥落。大电流作用或低NaCl浓度环境的CFRP表面以析氧反应为主会导致CFRP中碳纤维的过度氧化而劣化破损。In the early stage of recovery, the electrolyte solution is clarified, and as the electrochemical recovery reaction proceeds, the color of the solution gradually becomes darker. From the color change of the solution, it can be roughly divided into two categories, one type: small current group (I20, I40 and I62.5), the solution first turns from clarification to pale yellow, then turns into dark yellow. Class 2: Large current groups (I78.1, I104.2, and I156.3), the solution turns brown from clarification and then slowly turns black. Under the same concentration of NaCl, the darker the sample electrolyte is, the darker the sample electrolyte is; the higher the NaCl concentration is, the more yellow the sample electrolyte is. Many black substances were precipitated in the electrolytic cell of the high current group, and the filter was dried in an oven at 50 ° C for 3 days, and then observed by environmental scanning electron microscopy (ESEM) and energy spectrum detection (EDS) analysis. See Figures 4 and 5. As seen from Fig. 4, the precipitated material is a loose structure. As can be seen from Fig. 5, the main element of the precipitated substance is carbon, and a small amount of nitrogen, oxygen and gold elements are also detected, and the gold element is introduced by gold injection before scanning. The above results indicate that the black precipitate in the reaction cell is degraded from the carbon fibers in the CFRP. The CFRP surface of the CFRP surface with high current action or low NaCl concentration environment mainly causes excessive oxidation of carbon fibers in CFRP and deteriorates damage.
图4图53.4不同分组回收得到的碳纤维特性Figure 4 Figure 53.4 Characteristics of carbon fiber recovered from different groups
电化学回收后得到的回收得到的碳纤维的相关性能信息如表3.2，The relevant performance information of the recovered carbon fiber obtained after electrochemical recovery is shown in Table 3.2.
表3.2回收得到的碳纤维的质量及除胶率Table 3.2 Quality and Degumming Rate of Carbon Fibers Recovered
Figure PCTCN2018075923-appb-000008
Figure PCTCN2018075923-appb-000008
注：除胶率＝(1～回收得到的碳纤维中树脂残余值/原CFRP树脂含量)×100％Note: The gel removal rate = (1 - Residual resin value of recycled carbon fiber / original CFRP resin content) × 100%
3.5碳纤维回收量及除胶率分析3.5 Carbon fiber recovery and degumming rate analysis
如图7所示，碳纤维回收量随电流的增大先上升再下降，I40系列样本的碳纤维回收量最大；当电流超过40mA后，碳纤维回收量减少；当电流继续增大超过62.5mA后，就 会回收不到柔软的碳纤维。在施加同一种电流条件下，碳纤维回收量随NaCl浓度的增大呈现先上升后下降趋势，S 0.5系列样本的回收量最低在80mg～100mg之间；S 2.0系列样本回收量最高在230mg～430mg之间，是S 0.5系列样本回收量的数倍；I40S 2.0的回收量甚至是I40S 0.5的4倍多；S 3.0系列比S 2.0系列回收量低一些，但是高于S 1.0。增大电解液NaCl浓度会提高碳纤维回收量。但是当浓度达到3.0时，环氧树脂的降解反而降低。 As shown in Fig. 7, the carbon fiber recovery amount increases first and then decreases with the increase of current. The carbon fiber recovery of the I40 series sample is the largest; when the current exceeds 40 mA, the carbon fiber recovery amount decreases; when the current continues to increase beyond 62.5 mA, Soft carbon fiber will not be recovered. Under the same current application, the recovery of carbon fiber increased first and then decreased with the increase of NaCl concentration. The recovery of S 0.5 series samples was between 80mg and 100mg. The highest recovery of S 2.0 series samples was from 230mg to 430mg. Between the S 0.5 series sample recovery is several times; the I40S 2.0 recovery is even more than 4 times that of the I40S 0.5 ; the S 3.0 series is lower than the S 2.0 series, but higher than the S 1.0 . Increasing the electrolyte NaCl concentration increases the amount of carbon fiber recovered. However, when the concentration reaches 3.0, the degradation of the epoxy resin is rather reduced.
如图8所示，回收得到的碳纤维的除胶率随电流的增大而下降，I40系列样本虽然回收量高于I20系列，然而碳纤维除胶率却稍微下降，I62.5系列碳纤维除胶率非常低，在63.3％～68.5％之间。回收得到的碳纤维除胶率随NaCl浓度的增大呈现先上升再下降趋势,与回收量情况相似，S 2.0系列碳纤维除胶率最高，然而相比S 1.0与S 3.0系列差值很小，S 0.5系列碳纤维除胶率很低，在63.3％～68.3％之间。 As shown in Fig. 8, the gel removal rate of the recovered carbon fiber decreases with the increase of current. Although the I40 series sample is higher than the I20 series, the carbon fiber removal rate is slightly decreased, and the I62.5 series carbon fiber removal rate is slightly decreased. Very low, between 63.3% and 68.5%. The carbon removal rate of the recovered carbon fiber increases first and then decreases with the increase of NaCl concentration. Similar to the recovery amount, the S 2.0 series carbon fiber has the highest gel removal rate, but the difference between the S 1.0 and S 3.0 series is small, S The debonding rate of 0.5 series carbon fiber is very low, ranging from 63.3% to 68.3%.
上述除胶率结果结合回收量分析可知，施加小电流虽然回收速度比较慢但是更有利于除掉碳纤维表面的环氧树脂，增大电流到40mA提高了CFRP中环氧树脂的降解效率，然而并没有使回收得到的碳纤维更干净，当电流增大到62.5mA时，CFRP中的碳纤维氧化作用加剧，回收量和除胶率都下降；低NaCl(0.5％)浓度环境下阳极的反应与大电流作用时类似，因而碳纤维回收量和除胶率都很低。The above-mentioned degumming rate results combined with the recovery amount analysis show that although the application of a small current is slower but it is more advantageous to remove the epoxy resin on the surface of the carbon fiber, increasing the current to 40 mA increases the degradation efficiency of the epoxy resin in the CFRP, however The recycled carbon fiber is not cleaned. When the current is increased to 62.5 mA, the carbon fiber oxidation in the CFRP is intensified, and the recovery amount and the degreasing rate are decreased. The reaction and high current of the anode in the low NaCl (0.5%) concentration environment The effect is similar, so the carbon fiber recovery and the removal rate are very low.
3.6回收得到的碳纤维单丝拉伸强度3.6 Recovered carbon fiber monofilament tensile strength
回收得到的碳纤维单丝拉伸强度结果见表3.2，其中碳纤维原丝(VCF)与CFRP中的碳纤维型号相同。从表中可知，相比VCF(包裹有上浆剂)直径为7μm，除了I62.5S 0.5，回收得到的碳纤维直径均有轻微下降。原因可能是回收得到的碳纤维表面的环氧树脂被降解后，暴露在电解液中受到电化学氧化刻蚀作用，表面环氧上浆剂受到侵蚀，开始降解剥落，甚至碳纤维基体也可能被氧化剥落。I62.5S 0.5直径增大的原因应该是表面包裹的环氧过多。所有回收得到的碳纤维的拉伸强度(抗拉强度)对比VCF(4641MPa)都出现不同程度的下降，具体拉伸强度和参数之间的关系，见图9。 The tensile strength results of the recovered carbon fiber monofilaments are shown in Table 3.2, in which the carbon fiber precursor (VCF) is the same as the carbon fiber model in CFRP. As can be seen from the table, compared to VCF (coated with sizing agent), the diameter is 7 μm, except for I62.5S 0.5 , the diameter of the recovered carbon fiber is slightly decreased. The reason may be that the epoxy resin on the surface of the recovered carbon fiber is degraded, exposed to the electrochemical oxidation etching in the electrolyte, the surface epoxy sizing agent is eroded, and the degradation and flaking are started, and even the carbon fiber matrix may be oxidized and peeled off. The reason for the increase in diameter of I62.5S 0.5 should be excessive epoxy coating on the surface. The tensile strength (tensile strength) of all recovered carbon fibers showed different degrees of decline compared with VCF (4641 MPa). The relationship between specific tensile strength and parameters is shown in Fig. 9.
如图9所示，随着NaCl浓度的增大，回收得到的碳纤维拉伸强度呈现先上升再下降趋势，碳纤维拉伸强度分别在0.5％和2.0％浓度处取得最小值和最大值，表明较高NaCl浓度更有利于保持回收得到的碳纤维拉伸强度。回收得到的碳纤维拉伸强度随电流的增大而下降，其中I20组与I40组碳纤维拉伸强度很接近，I62.5组碳纤维拉伸强度较低，仅为碳纤维原丝的51.41％～55.2％；说明施加更高电流会降低碳纤维的拉伸强度，大电流对碳纤维造成的劣化更严重。回收得到的碳纤维的拉伸强度在本质上跟回收过程所遭受的损伤程度有关，在高电流作用或者低NaCl浓度环境，CFRP表面生成的氧气更多，对碳纤维 造成的氧化以及气动刻蚀作用更强，导致碳纤维表层劣化剥落，缺陷形成，拉伸强度下降，大电流长时间作用甚至可能扰动碳纤维石墨块状结构，造成更大损伤。As shown in Fig. 9, with the increase of NaCl concentration, the tensile strength of the recovered carbon fiber first rises and then decreases. The tensile strength of carbon fiber reaches the minimum and maximum values at the concentrations of 0.5% and 2.0%, respectively. The high NaCl concentration is more conducive to maintaining the tensile strength of the recovered carbon fiber. The tensile strength of the recovered carbon fiber decreases with the increase of current. The tensile strength of carbon fiber in I20 group and I40 group is very close. The tensile strength of carbon fiber in I62.5 group is lower, only 51.41%-55.2% of carbon fiber precursor. It shows that the application of higher current will reduce the tensile strength of the carbon fiber, and the deterioration of the carbon fiber by the large current is more serious. The tensile strength of the recovered carbon fiber is essentially related to the degree of damage suffered by the recycling process. In the high current action or low NaCl concentration environment, more oxygen is generated on the CFRP surface, and the oxidation and aerodynamic etching of the carbon fiber are more effective. Strong, leading to degradation of carbon fiber surface, defects, formation of tensile strength, long-term effects of large currents may even disturb the carbon fiber graphite block structure, resulting in greater damage.
如图9所示，当NaCl浓度在0.5％～3.0％时，回收的到的碳纤维的拉伸强度较为理想，最佳NaCl浓度在2.0％。然而，考虑到实际生产的控制难度和成本，NaCl浓度控制在1.25％～2.5％，可获得理想拉伸强度。As shown in Fig. 9, when the NaCl concentration is 0.5% to 3.0%, the tensile strength of the recovered carbon fiber is ideal, and the optimum NaCl concentration is 2.0%. However, considering the control difficulty and cost of actual production, the NaCl concentration is controlled at 1.25% to 2.5%, and the desired tensile strength can be obtained.
当NaCl浓度为2.0％时，三个电流组(I20、I40、和I62.5)的回收得到的碳纤维单丝拉伸强度取得最大值，分别为3768MPa、3693MPa和2562MPa，相当于VCF的81.19％、79.57％和55.2％。回收得到的碳纤维中最佳样本为I20S 2.0(81.19％)和I40S 2.0(79.57％)，且两者的差别并不明显。相应地，当电流强度在20mA～40mA时，回收的到的碳纤维的拉伸强度较为理想，如图9所示。 When the NaCl concentration is 2.0%, the tensile strength of the carbon fiber monofilament obtained by the three current groups (I20, I40, and I62.5) is the maximum, which is 3768MPa, 3693MPa, and 2562MPa, respectively, which is equivalent to 81.19% of VCF. , 79.57% and 55.2%. The best samples of recycled carbon fiber were I20S 2.0 (81.19%) and I40S 2.0 (79.57%), and the difference between the two was not obvious. Accordingly, when the current intensity is between 20 mA and 40 mA, the tensile strength of the recovered carbon fiber is ideal, as shown in FIG.
3.7 SEM扫描碳纤维表面3.7 SEM scan carbon fiber surface
通过SEM测试手段可以看清碳纤维表面的形貌情况，直观评价回收得到的碳纤维的质量。S 1.0、S 2.0和S 3.0系列回收得到的碳纤维除胶率非常接近，而S 0.5系列除胶率低很多，选取S 2.0系列回收得到的碳纤维做SEM测试，如图10所示。从图10(a)可以看出，碳纤维原丝表面光洁干净，没有裂纹缝隙和凹坑等物理缺陷。从图10(b)可以看出，I20S 2.0表面非常干净，看不到环氧树脂颗粒，没有看到裂纹裂缝缺陷。当电流继续增大时，图10(c)中可以看出，I40S 2.0表面零星的附着极少量环氧树脂颗粒，但仍然很干净，碳纤维表面同样没看到物理缺陷。当电流变得更大时，图10(d)中可以看出，I62.5S 2.0残余的环氧树脂更多，呈白色膨胀块状，碳纤维表面可观察到较浅的纵向沟槽结构，部分碳纤维有表皮剥落。以上结果表明：随着电流的增大，回收得到的碳纤维在电化学回收过程受到的氧化加剧，形成纵向沟槽结构，甚至造成表皮剥落，造成碳纤维的损伤，力学强度下降。由此可以说明增大电流会对碳纤维造成更大劣化，降低拉伸强度。 The SEM test method can be used to see the surface morphology of the carbon fiber and visually evaluate the quality of the recovered carbon fiber. The carbon fiber removal rate of the S 1.0 , S 2.0 and S 3.0 series is very close, while the S 0.5 series has a much lower gel removal rate. The carbon fiber recovered from the S 2.0 series is selected for SEM test, as shown in Fig. 10. As can be seen from Fig. 10(a), the surface of the carbon fiber precursor is smooth and clean, and there are no physical defects such as crack gaps and pits. As can be seen from Figure 10(b), the surface of the I20S 2.0 is very clean, no epoxy particles are visible, and crack crack defects are not seen. As the current continues to increase, it can be seen in Figure 10(c) that the I40S 2.0 surface sporadically adheres to a very small amount of epoxy particles, but is still very clean, and the carbon fiber surface also sees no physical defects. When the current becomes larger, it can be seen in Fig. 10(d) that the residual epoxy resin of I62.5S 2.0 is more, it is a white expansion block, and a shallow longitudinal groove structure can be observed on the surface of the carbon fiber. Carbon fiber has peeling off the skin. The above results show that with the increase of current, the recovered carbon fiber is intensified by oxidation in the electrochemical recovery process, forming a longitudinal groove structure, and even causing skin peeling, resulting in damage of carbon fiber and a decrease in mechanical strength. This shows that increasing the current causes greater deterioration of the carbon fiber and lowers the tensile strength.
示例4：催化剂A(KOH)对碳纤维回收的影响Example 4: Effect of Catalyst A (KOH) on Carbon Fiber Recovery
上述碳纤维回收结果均是在没有任何催化剂参与的情况下得到的。然而，考虑到电化学法回收碳纤维的过程，仍是化学反应过程。因此，合适的催化剂应该能加快反应进程、提高收率和改善最终产物的质量。本发明人在对多种化合物进行筛选后，选定KOH作为候选催化剂。同样地，多组样本(如下表3.4所示)被用于测试催化剂合适剂量，其中被选用的电流强度分别为20mA、40mA，对应电流密度分别为3333.3mA/m 2和6666.7mA/m 2，NaCl浓度分别为水质量的1.0(％)、2.0(％)和3.0(％)，通过检测回收得到的碳纤维的回收量(收率)、除胶率、碳纤维单丝拉伸强度和碳纤维单丝界面剪切强度等来确定回收 得到的碳纤维的质量和最佳催化剂用量。样本编号由作用电流强度、NaCl浓度和A浓度共同确定，比如样本编号“I20S 1.0A 0.5g/L”，第一部分“I20”是指样本施加的电流强度是20mA，第二部分“S 1.0”是指电解液中NaCl浓度为去离子水质量的1.0，第三部分“A 0.5g/L”是指电解液中催化剂KOH浓度是0.5g/L。详细的样本分组和实验参数如下表4.1所示。 The above carbon fiber recovery results were obtained without any catalyst participation. However, considering the process of electrochemically recovering carbon fibers, it is still a chemical reaction process. Therefore, a suitable catalyst should accelerate the progress of the reaction, increase the yield and improve the quality of the final product. The inventors selected KOH as a candidate catalyst after screening various compounds. Similarly, multiple sets of samples (shown in Table 3.4 below) were used to test the appropriate dose of catalyst, with the selected current intensities of 20 mA and 40 mA, respectively, corresponding to current densities of 3333.3 mA/m 2 and 6666.7 mA/m 2 , respectively. The NaCl concentration is 1.0 (%), 2.0 (%), and 3.0 (%) of the water mass, and the recovered amount (yield) of the carbon fiber recovered by the detection, the gel removal rate, the tensile strength of the carbon fiber monofilament, and the carbon fiber monofilament The interfacial shear strength and the like are used to determine the quality of the recovered carbon fiber and the optimum amount of catalyst. The sample number is determined by the applied current intensity, NaCl concentration and A concentration, such as the sample number “I20S 1.0 A 0.5g/L ”. The first part “I20” means the current intensity applied by the sample is 20mA, the second part “S 1.0 ” It means that the NaCl concentration in the electrolyte is 1.0 by mass of deionized water, and the third part "A 0.5g/L " means that the concentration of the catalyst KOH in the electrolyte is 0.5 g/L. Detailed sample grouping and experimental parameters are shown in Table 4.1 below.
表4.1实验样本分组及参数Table 4.1 Experimental sample grouping and parameters
Figure PCTCN2018075923-appb-000009
Figure PCTCN2018075923-appb-000009
4.1样本电压4.1 sample voltage
对比图12和图13可以看到，添加了催化剂KOH的样本的电压更加稳定，并且电压值普遍降低了0.5V左右。图12中样本电压按大小值可大概分为两组：a组I40样本电压范围为3V～3.6V，电压随NaCl浓度增大呈现先下降再上升趋势，浓度为2.0时电压最低，NaCl浓度差异导致样本间的电压差值较明显；同一种NaCl浓度环境下，不同催化剂KOH浓度间样本电压差值很微小。b组I20样本电压范围大约在2.75V～2.9V之间，所以样本电压在回收周期内非常稳定，并且电压差值非常小。上述结果表明催化剂KOH浓度和NaCl浓度参数差异对样本电压的影响极小，尤其是在小电流条件下，推测I40组和I20组样本未发生严重的氧化劣化。As can be seen by comparing Fig. 12 and Fig. 13, the voltage of the sample to which the catalyst KOH was added was more stable, and the voltage value was generally lowered by about 0.5 V. The sample voltage in Figure 12 can be roughly divided into two groups according to the size: the voltage range of group A40 is 3V~3.6V, the voltage decreases first and then increases with the increase of NaCl concentration, the voltage is the lowest when the concentration is 2.0, and the difference of NaCl concentration The voltage difference between the samples is obvious; in the same NaCl concentration environment, the sample voltage difference between different catalyst KOH concentrations is very small. The b-group I20 sample voltage range is approximately between 2.75V and 2.9V, so the sample voltage is very stable during the recovery cycle and the voltage difference is very small. The above results indicate that the difference between the catalyst KOH concentration and the NaCl concentration parameter has little effect on the sample voltage, especially under the condition of small current, it is speculated that the I40 group and the I20 group sample did not undergo serious oxidative degradation.
4.2碳纤维回收量及除胶率4.2 Carbon fiber recovery and gel removal rate
从下表4.2中可以发现，所有样本分组的回收得到的碳纤维的环氧树脂去除率相当高，基本接近100％，最低的I40S 3.0A 1.5g/L样本也达到99.3％。在18天的回收周期后，不同催化剂KOH浓度的除胶效果基本相同，并且电流和NaCl浓度参数的差异对除胶率几乎没有影响，表明对单根碳纤维彻底清除掉表面环氧树脂而言，18天的回收周期过长。表明将催化剂KOH作为应用于电化学方法，碳纤维除胶率得到明显提高。添加催化剂KOH明显提高了碳纤维回收量，详细的回收量与催化剂KOH浓度关系见图14。 It can be seen from Table 4.2 below that the epoxy resin removal rate of the carbon fiber recovered from all sample groups is quite high, almost close to 100%, and the lowest I40S 3.0 A 1.5g/L sample also reaches 99.3%. After the 18-day recovery period, the gel removal effect of the different catalyst KOH concentrations was basically the same, and the difference between the current and NaCl concentration parameters had little effect on the gel removal rate, indicating that for the single carbon fiber to completely remove the surface epoxy resin, The 18-day recycling cycle is too long. It is shown that the catalyst KOH is applied to the electrochemical method, and the carbon fiber removal rate is significantly improved. The addition of catalyst KOH significantly increased the amount of carbon fiber recovered. The relationship between the detailed recovery and the catalyst KOH concentration is shown in Figure 14.
表4.2碳纤维回收量及除胶率Table 4.2 Carbon fiber recovery and gel removal rate
Figure PCTCN2018075923-appb-000010
Figure PCTCN2018075923-appb-000010
注：1)DB：表示破坏模式为环氧树脂层剥离破坏Note: 1) DB: indicates that the failure mode is the epoxy layer peeling damage
2)CB：表示破坏模式为碳纤维与环氧树脂界面剥离破坏2) CB: indicates that the failure mode is the peeling failure of the interface between carbon fiber and epoxy resin
从图14可以看到，碳纤维回收量跟催化剂KOH浓度密切相关，随着催化剂KOH浓度的增大碳纤维回收量呈现先上升再下降趋势，当催化剂KOH浓度超过1.0g/L后，增大催化剂浓度反而降低了碳纤维回收量，催化剂KOH 1.0g/L系列样本碳纤维回收量最大。在1.5g/L的催化剂KOH浓度时，各参数样本的回收量差值变小，分布更集中，似乎环氧树脂的分解受到了抑制，表明高浓度的催化剂KOH不利于碳纤维回收。在本实验条件下，就碳纤维回收量而言，催化剂KOH浓度的最优值是1.0g/L。从图14可知，碳纤维回收量随 NaCl浓度增大先上升再下降，S 2.0系列回收量最高，然后依次是S 3.0、S 0.5；I40组样本整体上碳纤维回收量比I20更高，I40S 2.0A 1.0g/L样本的回收量最大达到1217mg,远高于其他参数样本。 It can be seen from Fig. 14 that the carbon fiber recovery amount is closely related to the catalyst KOH concentration. As the catalyst KOH concentration increases, the carbon fiber recovery amount first rises and then decreases. When the catalyst KOH concentration exceeds 1.0 g/L, the catalyst concentration increases. On the contrary, the amount of carbon fiber recovered was reduced, and the amount of carbon fiber recovered from the catalyst sample of KOH 1.0g/L was the largest. At the catalyst KOH concentration of 1.5g/L, the difference in the recovery amount of each parameter sample becomes smaller and the distribution is more concentrated. It seems that the decomposition of the epoxy resin is inhibited, indicating that the high concentration of the catalyst KOH is not conducive to carbon fiber recovery. Under the experimental conditions, the optimum value of the catalyst KOH concentration was 1.0 g/L in terms of carbon fiber recovery. It can be seen from Fig. 14 that the recovery of carbon fiber increases first and then decreases with the increase of NaCl concentration, and the recovery of S 2.0 series is the highest, followed by S 3.0 and S 0.5 . The total carbon fiber recovery of I40 group is higher than I20, I40S 2.0 A The recovery of 1.0g/L samples reached a maximum of 1217mg, which was much higher than other parameter samples.
因此，在电解液中添加催化剂KOH后，碳纤维回收量和环氧树脂的降解效率均得到了极大提高。Therefore, after the catalyst KOH is added to the electrolyte, both the amount of carbon fiber recovered and the degradation efficiency of the epoxy resin are greatly improved.
4.3回收得到的碳纤维单丝拉伸强度4.3 Recovered carbon fiber monofilament tensile strength
从表3.5可以看到，回收得到的碳纤维的直径都有轻微的减小，原因是在回收过程，当碳纤维从环氧树脂中释放出来后，会受到电化学氧化刻蚀作用，表面的上浆剂首先被侵蚀掉，然后碳纤维基体也可能受到氧化而剥落。同一种电流作用下，A 1.5g/L系列回收得到的碳纤维直径最小；I40组样本的回收得到的碳纤维直径稍微小于I20组；表明高催化剂KOH浓度环境和施加大电流导致碳纤维的氧化更严重，劣化剥落程度更深。从表3.5发现回收得到的碳纤维的拉伸强度残余值并不高，更加直观的碳纤维拉伸强度与各参数关系情况，如图15。 As can be seen from Table 3.5, the diameter of the recovered carbon fiber is slightly reduced because during the recovery process, when the carbon fiber is released from the epoxy resin, it is subjected to electrochemical oxidation etching, and the surface sizing agent It is first eroded and the carbon fiber matrix may also be oxidized and peeled off. Under the same current, the carbon fiber recovered from the A 1.5g/L series has the smallest diameter; the diameter of the carbon fiber recovered from the I40 group is slightly smaller than that in the I20 group; indicating that the high catalyst KOH concentration environment and the application of a large current cause the carbon fiber to be more oxidized. The degree of deterioration and peeling is deeper. It is found from Table 3.5 that the residual value of the tensile strength of the recovered carbon fiber is not high, and the more intuitive relationship between the tensile strength of the carbon fiber and each parameter is as shown in FIG.
从图15中看到，回收得到的碳纤维的拉伸强度随着催化剂KOH浓度的增大而呈下降趋势，表明催化剂KOH在回收过程对碳纤维有一定的力学损伤，并且催化剂KOH浓度越高，碳纤维劣化越严重。I40电流组样本的回收得到的碳纤维拉伸强度值比I20组低，说明大电流作用下碳纤维的劣化更严重，小电流受到的劣化影响会低一些，更利于保持力学性能。值得注意的是,在催化剂KOH浓度从0增大到0.5g/L阶段，S 1.0和S 3.0系列样本的回收得到的碳纤维拉伸强度下降幅度很低，而S 2.0系列的回收得到的碳纤维拉伸强度下降幅度达到大约9％。随着催化剂KOH浓度的继续增大，回收得到的碳纤维的拉伸强度明显的分成两组，I20组回收得到的碳纤维的强度下降幅度较I40组小。而I40组碳纤维在A浓度为1.0g/L和1.5g/L时，单丝拉伸强度很接近，尤其是I40S 2.0。 It can be seen from Fig. 15 that the tensile strength of the recovered carbon fiber decreases with the increase of the catalyst KOH concentration, indicating that the catalyst KOH has certain mechanical damage to the carbon fiber during the recovery process, and the higher the catalyst KOH concentration, the carbon fiber. The more serious the deterioration. The tensile strength of the carbon fiber obtained by the recovery of the I40 current group sample is lower than that of the I20 group, indicating that the deterioration of the carbon fiber is more serious under the action of the large current, and the influence of the deterioration of the small current is lower, which is more favorable for maintaining the mechanical properties. It is worth noting that in the stage where the catalyst KOH concentration is increased from 0 to 0.5 g/L, the tensile strength of the carbon fiber recovered from the S 1.0 and S 3.0 series samples is very low, and the carbon fiber of the S 2.0 series is recovered. The tensile strength decreased by approximately 9%. As the concentration of KOH in the catalyst continues to increase, the tensile strength of the recovered carbon fibers is clearly divided into two groups. The strength of the carbon fibers recovered in the I20 group is smaller than that in the I40 group. When the A40 carbon fiber has a concentration of 1.0g/L and 1.5g/L, the tensile strength of the monofilament is very close, especially I40S 2.0 .
4.4回收得到的碳纤维界面剪切性能4.4 recovered carbon fiber interfacial shear properties
碳纤维与环氧树脂的界面粘结能力是评估回收得到的碳纤维质量的关键参数之一。本实验通过微滴包埋实验来测定回收得到的碳纤维的界面剪切强度，反映碳纤维和环氧树脂的结合性能。从表3.5可以看到，测试的样本环氧树脂微滴直径范围为42.18μm～51.07μm，包含在合理直径测试范围40μm～80μm内，测试数据有效。碳纤维原丝的界面剪切强度为31MPa,破坏模式为DB，而回收得到的碳纤维界面强度随参数变化较大，直观的回收得到的碳纤维界面剪切强度(IFSS)情况如图16所示。The interfacial adhesion capability of carbon fiber to epoxy resin is one of the key parameters for evaluating the quality of recycled carbon fiber. In this experiment, the interfacial shear strength of the recovered carbon fibers was measured by a droplet embedding experiment, reflecting the bonding properties of carbon fibers and epoxy resins. It can be seen from Table 3.5 that the sample epoxy droplet diameter ranged from 42.18 μm to 51.07 μm, which is included in the reasonable diameter test range of 40 μm to 80 μm, and the test data is valid. The interfacial shear strength of the carbon fiber precursor is 31 MPa, the failure mode is DB, and the recovered carbon fiber interface strength varies greatly with the parameters. The visually recovered carbon fiber interfacial shear strength (IFSS) is shown in Fig. 16.
可以看到，随着催化剂KOH浓度增大，碳纤维界面剪切强度呈现先升高再下降的趋 势，在催化剂KOH浓度为1.0g/L时，界面剪切强度取得最大值。在I20组，A 0.5g/L系列碳纤维剪切强度最低，大约比碳纤维原丝下降了5％～7％；A 1.0g/L和A 1.5g/L系列剪切强度值均比碳纤维原丝高，I20S 2.0A 1.0g/L的界面剪切强度最高为37.43MPa，比碳纤维原丝提高了20.74％，而剪切强度较低的I20S 1.0A 1.5g/L为原丝的105.68％。在I40组，所有样本的剪切强度均比碳纤维原丝低，A 1.5g/L系列碳纤维剪切强度最低，而样本I40I20S 2.0A 1.5g/L的剪切强度仅为原丝值的79.69％。 It can be seen that as the KOH concentration of the catalyst increases, the shear strength of the carbon fiber interface increases first and then decreases. When the KOH concentration of the catalyst is 1.0g/L, the interfacial shear strength reaches a maximum. In the I20 group, the A 0.5g/L series carbon fiber has the lowest shear strength, which is about 5% to 7% lower than the carbon fiber strand; the A 1.0g/L and A 1.5g/L series shear strength values are better than the carbon fiber precursor. High, I20S 2.0 A 1.0g/L interface shear strength is up to 37.43MPa, which is 20.74% higher than carbon fiber precursor, while I20S 1.0 A 1.5g/L with lower shear strength is 105.68% of original yarn. In the I40 group, the shear strength of all samples was lower than that of the carbon fiber precursor, and the shear strength of the A 1.5g/L series carbon fiber was the lowest, while the shear strength of the sample I40I20S 2.0 A 1.5g/L was only 79.69% of the original silk value. .
本次微滴包埋测试实验样本的破坏模式大概可分为两种，即环氧树脂层剥离破坏(DB)和碳纤维与环氧树脂界面层剥离破坏(CB)。从图17(a)可以看到，碳纤维原丝样品发生的是典型的环氧树脂层剥离破坏模式(DB)，在这种破坏模式中碳纤维与环氧树脂界面粘结非常好，环氧树脂成了薄弱层，当样品破坏时，环氧树脂层断开；仍然包裹在碳纤维表面的树脂层厚度较大，完整光滑，没有裂纹裂缝等缺陷，和碳纤维的粘结依然非常牢固。而从图17(g)可以看到，I40S 2.0A 1.5g/L发生的是另一种典型破坏模式，即碳纤维与环氧树脂界面剥离破坏(CB)，这种界面破坏模式不够理想，碳纤维与树脂的粘结较差，界面成为薄弱层被破坏，剪切强度只有24.7MPa。当样品破坏时，环氧树脂从界面完全剥离，在碳纤维表面几乎没有残留。碳纤维表面可以看到整齐规则的纵向沟槽，但是并未发现裂纹凹坑等损伤。 The failure mode of the experimental sample of the droplet embedding test can be roughly divided into two types, namely, epoxy resin layer peeling damage (DB) and carbon fiber and epoxy resin interface layer peeling damage (CB). It can be seen from Fig. 17(a) that the carbon fiber precursor sample is a typical epoxy resin layer peeling failure mode (DB), in which the carbon fiber and epoxy resin interface bond very well, epoxy resin. It becomes a weak layer. When the sample is broken, the epoxy layer is broken; the resin layer still wrapped on the surface of the carbon fiber is thick, complete and smooth, free from cracks and the like, and the bond with the carbon fiber is still very strong. From Fig. 17(g), it can be seen that I40S 2.0 A 1.5g/L is another typical failure mode, namely, carbon fiber and epoxy resin interface peeling damage (CB). This interface failure mode is not ideal, carbon fiber. The bond with the resin is poor, the interface becomes a weak layer and the shear strength is only 24.7 MPa. When the sample is broken, the epoxy resin is completely peeled off from the interface and hardly remains on the surface of the carbon fiber. A regular longitudinal groove can be seen on the surface of the carbon fiber, but no damage such as crack pits is found.
从实验结果来看，样品的破坏模式与催化剂KOH浓度和电流有极大的关联，而NaCl浓度对破坏模式影响非常小，因此在此只列出I20S 2.0和I40S 2.0系列样本的界面破坏图片。当催化剂KOH浓度为0.5g/L时，样品发生的破坏模式均为CB；催化剂KOH浓度增大到1.0g/L时，样品发生的破坏模式都是DB；当A浓度继续增大至1.5g/L时，I20组样本发生DB破坏模式，I40组样本发生CB破坏模式。上述结果表明，催化剂KOH浓度为1.0g/L时界面力得到大幅度提高；在大电流作用下，界面力会更容易受到损害，样品倾向于环氧树脂层剥离破坏。 From the experimental results, the failure mode of the sample has a great correlation with the catalyst KOH concentration and current, and the NaCl concentration has little effect on the failure mode. Therefore, only the interface damage pictures of the I20S 2.0 and I40S 2.0 series samples are listed here. When the catalyst KOH concentration is 0.5g/L, the failure mode of the sample is CB; when the catalyst KOH concentration is increased to 1.0g/L, the failure mode of the sample is DB; when the A concentration continues to increase to 1.5g In the case of /L, the DB destruction mode occurred in the I20 group samples, and the CB failure mode occurred in the I40 group samples. The above results show that the interface force is greatly improved when the catalyst KOH concentration is 1.0g/L; under the action of large current, the interface force is more susceptible to damage, and the sample tends to peel off the epoxy layer.
4.5 SEM扫描结果4.5 SEM scan results
电镜扫描结果显示各个分组回收得到的碳纤维非常干净，表面并未发现树脂的残留，说明添加催化剂KOH作为催化剂能够有效的提高环氧树脂的降解，完全除掉碳纤维表面的环氧树脂。不同NaCl浓度的回收得到的碳纤维的表面形貌之间差异很小，所以在此只列出S 2.0系列回收得到的碳纤维的SEM图片进行分析，如图18。当A浓度为0.5g/L时，见图18(a)和图18(b)，碳纤维表面比较光圆，I20S 2.0A 0.5g/L碳纤维表面几乎看不到纵向沟槽结构，I40S 2.0A 0.5g/L可以发现不太明显的纵向沟槽结构，表明在此条件下，碳纤维表 面受到的氧化程度非常轻微，碳纤维本体并未损伤，所以碳纤维的拉伸强度对比未添加催化剂KOH的样本，仅有微弱下降。随着催化剂KOH浓度的增加，碳纤维受到的氧化刻蚀、OH -离子的插层作用等变得严重，碳纤维表面变得不再光圆平整，比较清晰的看到纵向沟槽结构，见图18(c)～(f)。I40组样本受到的损伤作用更严重，I40S 2.0A 1.0g/L和I40S 2.0A 1.5g/L碳纤维表面甚至可以看到裂纹的存在，因此对这两个样本进行最更高倍数(20000)扫描，如图19。 The results of scanning electron microscopy showed that the carbon fiber recovered from each group was very clean, and no residual resin was found on the surface, indicating that the addition of catalyst KOH as a catalyst can effectively improve the degradation of the epoxy resin and completely remove the epoxy resin on the surface of the carbon fiber. The difference in surface morphology of the carbon fibers recovered by different NaCl concentrations is small, so only the SEM images of the carbon fibers recovered in the S 2.0 series are listed here, as shown in Fig. 18. When the concentration of A is 0.5g/L, as shown in Fig. 18(a) and Fig. 18(b), the surface of the carbon fiber is relatively round, and the surface of the I20S 2.0 A 0.5g/L carbon fiber is almost invisible to the longitudinal groove structure. I40S 2.0 A 0.5g/L can find a less obvious longitudinal groove structure, indicating that under this condition, the surface of the carbon fiber is slightly oxidized, and the carbon fiber body is not damaged, so the tensile strength of the carbon fiber is compared with the sample without the catalyst KOH added. Only a slight decline. With the increase of KOH concentration of the catalyst, the carbon fibers by oxidation etching, OH - ion intercalation and the like becomes severe, the carbon fiber surface is no longer smooth light circle, see clearer longitudinal groove structure shown in Figure 18 (c) ~ (f). The damage of the I40 group was more serious. The surface of the I40S 2.0 A 1.0g/L and I40S 2.0 A 1.5g/L carbon fiber could even see the presence of cracks, so the highest multiple (20000) scan of the two samples was performed. , as shown in Figure 19.
从图19(a)可以看到，碳纤维被刻蚀掉小部分表皮，截面变小，形成明显的纵向沟槽结构；当进行单丝拉伸强度测试时，被刻蚀部分截面会变成薄弱层，形成应力集中，造成断裂破坏。图19(b)中碳纤维表面已经被氧化作用所磨平，形成了凹坑和裂纹缺陷，当进行单丝拉伸强度测试时，此处会变成薄弱环节，应力集中在凹坑周围，沿着裂纹把碳纤维撕开，造成更大应力集中，直至达到应力极限状态，碳纤维断裂破坏。因此，被氧化刻蚀严重的I40S 2.0A 1.0g/L和I40S 2.0A 1.5g/L的单丝拉伸强度大幅度下降，只达到碳纤维原丝强度的59.81％和58.93％。 It can be seen from Fig. 19(a) that the carbon fiber is etched away from a small portion of the skin, and the cross section becomes smaller, forming a distinct longitudinal groove structure; when the tensile strength test of the monofilament is performed, the cross section of the etched portion becomes weak. The layer forms stress concentration and causes fracture damage. In Figure 19(b), the surface of the carbon fiber has been smoothed by oxidation, forming pits and crack defects. When the tensile strength test of the monofilament is performed, it becomes a weak link, and the stress is concentrated around the pit. The crack tears the carbon fiber, causing greater stress concentration until the stress limit state is reached, and the carbon fiber breaks and breaks. Therefore, the tensile strength of the monofilament of I40S 2.0 A 1.0g/L and I40S 2.0 A 1.5g/L which were severely oxidized and etched was greatly reduced, and only 59.81% and 58.93% of the strength of the carbon fiber precursor were obtained.
4.6 AFM扫描结果4.6 AFM scan results
回收得到的碳纤维的表面微观形貌结构是影响碳纤维界面性能的重要因素，影响到界面的机械咬合力和环氧树脂的浸润性。利用探针显微镜来观测回收得到的碳纤维表面形貌结构，并用粗糙度Ra和AFM图像来大致表征，测试结果见下表4.3和图30。需要指出的是，同一种电流作用下，不同NaCl浓度的回收得到的碳纤维AFM图像差异非常小，所以在此处只列出S 2.0系列的回收得到的碳纤维AFM图像。从表中可以看到，碳纤维原丝的Ra值为201nm。NaCl浓度的差异对回收得到的碳纤维的Ra值影响很小。因此在下面进行AFM分析时，以I20S 2.0与I40S 2.0系列为例。 The surface topography of the recovered carbon fiber is an important factor affecting the interfacial properties of the carbon fiber, affecting the mechanical bite force of the interface and the wettability of the epoxy resin. The surface morphology of the recovered carbon fibers was observed by a probe microscope and roughly characterized by roughness Ra and AFM images. The test results are shown in Table 4.3 and Figure 30 below. It should be pointed out that under the same current, the difference in carbon fiber AFM images obtained by different NaCl concentrations is very small, so only the recovered carbon fiber AFM images of the S 2.0 series are listed here. As can be seen from the table, the carbon fiber precursor has an Ra value of 201 nm. The difference in NaCl concentration has little effect on the Ra value of the recovered carbon fiber. Therefore, in the following AFM analysis, the I20S 2.0 and I40S 2.0 series are taken as an example.
表4.3不同参数的回收得到的碳纤维的粗糙度Table 4.3 Roughness of carbon fiber obtained by recycling different parameters
Figure PCTCN2018075923-appb-000011
Figure PCTCN2018075923-appb-000011
Figure PCTCN2018075923-appb-000012
Figure PCTCN2018075923-appb-000012
注：I40S 1.0系列由于长度不够并未进行微滴包埋测试，所以相应的在此处就没有进行AFM测试。 Note: The I40S 1.0 series has not been tested for droplet embedding due to insufficient length, so there is no AFM test here.
从图30(a)与图30(b)可以看到，碳纤维原丝表面光滑平整，没有裂纹裂缝等缺陷，且为规整的纵向沟槽结构，沟槽的宽度较大，尺寸约为0.3μm。在I20组，当A浓度为0.5g/L时，见图30(c)和图30(d)，可以看到碳纤维表面右侧有两个环氧颗粒，原因是此条件下环氧树脂的降解速率比较平缓，接近回收周期结束时，环氧树脂才完全清除(偶尔会有极少量的附着颗粒)；碳纤维暴露在电解液中的时间不长，所以电化学氧化刻蚀并不严重，碳纤维仍然保持着明显的纵向沟槽结构，但是纵向沟槽宽度加大；OH -离子被活性碳原子吸附，发生了轻微的插层反应，造成了碳纤维表面有很少量的表皮膨胀凸起；因此计算得到的粗糙度比碳纤维原丝有轻微下降，Ra值为195nm，造成碳纤维的界面剪切强度有微弱下降。当A浓度增加到1.0g/L时，见图30(g)和图30(h),环氧树脂的降解速度加快，碳纤维表面环氧树脂完全被清除掉，碳纤维很快就暴露在较高浓度的电解液中，较为剧烈的电化学氧化刻蚀使原来的纵向沟槽结构宽度变小，计算得到的粗糙度提高，Ra值为219nm,这些小宽度沟槽不但加大了碳纤维与树脂的机械咬合作用，而且大幅增大了比表面积，改善碳纤维与环氧树脂的浸润性能，因此I20S 2.0A 1.0g/L的界面剪切强度达到37.43MPa，为碳纤维原丝值的120.74％。随着催化剂KOH浓度继续增大到1.5g/L时，见 图30(k)和图30(l)，电解液中的OH -浓度加大，碳纤维遭受的氧化作用和OH -离子的插层反应程度增强，造成表皮膨胀凸起，从中看到碳纤维表面隐约的纵向小宽度沟槽和大量凸起结构，这些凸起结构的尺寸大约在几十纳米到几百纳米范围内，增大了碳纤维与树脂界面间的比表面积和机械咬合作用，计算得到的Ra值为213nm,因此，碳纤维的界面剪切强度比碳纤维原丝高，为33.06MPa。 It can be seen from Fig. 30(a) and Fig. 30(b) that the surface of the carbon fiber precursor is smooth and flat, free from cracks and the like, and is a regular longitudinal groove structure, and the width of the groove is large, and the size is about 0.3 μm. . In the I20 group, when the A concentration is 0.5g/L, as shown in Fig. 30(c) and Fig. 30(d), it can be seen that there are two epoxy particles on the right side of the carbon fiber surface because of the epoxy resin under this condition. The degradation rate is relatively flat. Near the end of the recovery cycle, the epoxy resin is completely removed (occasionally there will be a very small amount of attached particles); the carbon fiber is not exposed to the electrolyte for a long time, so the electrochemical oxidation etching is not serious, carbon fiber remained significant longitudinal groove structure, but increasing the width of the longitudinal groove; OH - ions are adsorbed active carbon atom, a slight intercalation, resulting in carbon fibers with a very small amount of the skin surface projections expansion; therefore The calculated roughness is slightly lower than that of the carbon fiber precursor, and the Ra value is 195 nm, resulting in a slight decrease in the interfacial shear strength of the carbon fiber. When the A concentration is increased to 1.0g/L, as shown in Fig. 30(g) and Fig. 30(h), the degradation rate of the epoxy resin is accelerated, the epoxy resin on the surface of the carbon fiber is completely removed, and the carbon fiber is quickly exposed to a higher temperature. In the concentration of the electrolyte, the more severe electrochemical oxidation etching makes the original longitudinal groove structure width smaller, and the calculated roughness is improved, and the Ra value is 219 nm. These small width grooves not only increase the carbon fiber and the resin. The mechanical bite is used together, and the specific surface area is greatly increased to improve the wettability of carbon fiber and epoxy resin. Therefore, the interfacial shear strength of I20S 2.0 A 1.0g/L is 37.43 MPa, which is 120.74% of the carbon fiber raw yarn value. As the catalyst KOH concentration continues to increase to 1.5 g/L, see Figure 30 (k) and Figure 30 (l), the OH - concentration in the electrolyte increases, the oxidation of the carbon fiber and the intercalation of OH - ions The degree of reaction is enhanced, causing the expansion of the epidermis, from which the longitudinal small-width groove of the carbon fiber surface and a large number of convex structures are seen. The size of these convex structures is in the range of several tens of nanometers to several hundred nanometers, and the carbon fiber is increased. The specific surface area and mechanical bite interaction with the resin interface, the calculated Ra value is 213 nm, therefore, the interfacial shear strength of the carbon fiber is higher than the carbon fiber precursor, which is 33.06 MPa.
当电流从20mA增大到40mA时，I40组样本碳纤维的AFM形貌和I20组对应样本基本类似，有纵向沟槽结构和膨胀的表皮凸起，但是沟槽结构深度较浅，不够明显，显得比较平整。分组I40S 2.0A 0.5g/L、I40S 2.0A 1.0g/L和I40S 2.0A 1.5g/L组计算得到的Ra值分别为185nm、199nm和175nm，低于I20组对应样本，碳纤维与环氧树脂界面的比表面积和机械咬合作用都出现不同程度的下降，相应的碳纤维界面剪切强度只能达到碳纤维原丝的87.11％、90.57％和79.69％。 When the current is increased from 20 mA to 40 mA, the AFM morphology of the sample carbon fiber of the I40 group is similar to that of the I20 group. There are longitudinal groove structures and expanded skin protrusions, but the groove structure is shallow and not obvious enough. More flat. Group I40S 2.0 A 0.5g/L , I40S 2.0 A 1.0g/L and I40S 2.0 A 1.5g/L group calculated Ra values of 185nm, 199nm and 175nm, respectively, lower than I20 group corresponding samples, carbon fiber and epoxy resin The specific surface area and mechanical bite of the interface decreased to different extents. The corresponding carbon fiber interface shear strength can only reach 87.11%, 90.57% and 79.69% of the carbon fiber precursor.
4.7碳纤维XPS扫描图谱4.7 carbon fiber XPS scan map
回收得到的碳纤维的XPS扫描全谱及C1s高分辨窄谱，如图21，左列是样本的扫描全谱，右列是其对应的C1s高分辨窄谱及其分峰拟合图。从扫描全谱图看到，图中主要有五个峰，即两个主峰：C(284.6eV)和O(532.0eV)；三个次要峰：Si(99.5eV)、Cl(199.8eV)和N(399.5eV)。碳纤维表面基本元素为碳、氧、氮和硅，检测出来的少量氯很可能是在生产或运输过程中的引入。从扫描全谱图可以看到，回收得到的碳纤维C1s峰、Si2p峰和N1s峰均比碳纤维原丝要降低，而O1s峰、Cl2p峰明显比碳纤维原丝高，表明电化学回收过程对碳纤维产生了较大作用，使表面化学元素含量发生很大变化，具体的化学元素含量情况见下表4.4。The XPS scanning full spectrum and the C1s high resolution narrow spectrum of the recovered carbon fiber are shown in Fig. 21. The left column is the scanning full spectrum of the sample, and the right column is the corresponding C1s high resolution narrow spectrum and its peak fitting map. From the scanning full spectrum, there are five main peaks in the figure, namely two main peaks: C (284.6eV) and O (532.0eV); three secondary peaks: Si (99.5eV), Cl (199.8eV) And N (399.5 eV). The basic elements on the surface of carbon fiber are carbon, oxygen, nitrogen and silicon. The small amount of chlorine detected is likely to be introduced during production or transportation. It can be seen from the scanning full spectrum that the recovered carbon fiber C1s peak, Si2p peak and N1s peak are lower than the carbon fiber precursor, and the O1s peak and Cl2p peak are significantly higher than the carbon fiber strand, indicating that the electrochemical recovery process produces carbon fiber. A large role, the surface chemical element content has changed a lot, the specific chemical element content is shown in Table 4.4 below.
表4.4 VCF和回收得到的碳纤维表面元素含量(％)Table 4.4 VCF and recovered carbon fiber surface element content (%)
Figure PCTCN2018075923-appb-000013
Figure PCTCN2018075923-appb-000013
从表4.4中可以看到，碳纤维原丝表面碳含量和氧含量分别为75.2％和18.3％，氧碳比为0.2434。回收得到的碳纤维表面的碳含量均出现小幅度的下降，碳含量最低的I20S 3.0A 1.0g/L为71.2％；而氧含量则出现较大上升，回收得到的碳纤维除了I20S 2.0A 0.5g/L外，其余氧含量都在20.3％以上。由此计算得出的回收得到的碳纤维氧碳比都相对原碳纤 维原丝高，其中I20S 2.0A 1.0g/L和I20S 2.0A 1.5g/L的氧碳比最高分别达到0.3187和0.3192。表面氧含量的增多能够改善碳纤维的表面活性，碳纤维表面活性增大能提高其界面剪切强度，碳纤维表面碳氧比的提高可以明显改善碳纤维与树脂的粘结性能。大部分回收得到的碳纤维的界面剪切强度都比碳纤维原丝高，而I20S 2.0A 1.0g/L和I20S 2.0A 1.5g/L样本的剪切强度相接近且在所有样本中最高。值得注意的是，在回收得到的碳纤维中，I20S 2.0A 0.5g/L的氮含量最高，为3.1％，然后依次是I40S 2.0A 1.0g/L和I20S 1.0A 1.0g/L，分别为2.9％和2.3％，I20S 3.0A 1.0g/L氮含量为0.8％，I20S 2.0A 1.0g/L和I20S 2.0A 1.5g/L的氮含量为零，从样本的单丝拉伸强度值结果来看，氮含量越高的样本其拉伸强度越低。 As can be seen from Table 4.4, the carbon content and oxygen content of the carbon fiber precursor were 75.2% and 18.3%, respectively, and the oxygen to carbon ratio was 0.2434. The carbon content of the recovered carbon fiber surface decreased slightly, and the lowest carbon content of I20S 3.0 A 1.0g/L was 71.2%. The oxygen content increased greatly. The recovered carbon fiber except I20S 2.0 A 0.5g/ Except for L , the remaining oxygen content is above 20.3%. The thus calculated carbon fiber oxygen to carbon ratio is higher than that of the original carbon fiber precursor, and the oxygen to carbon ratio of I20S 2.0 A 1.0g/L and I20S 2.0 A 1.5g/L is 0.3187 and 0.3192, respectively. The increase of surface oxygen content can improve the surface activity of carbon fiber. The increase of surface activity of carbon fiber can improve the interfacial shear strength. The increase of carbon-oxygen ratio on the surface of carbon fiber can significantly improve the bonding performance between carbon fiber and resin. Most of the recovered carbon fibers had higher interfacial shear strength than carbon fiber strands, while the shear strengths of the I20S 2.0 A 1.0 g/L and I20S 2.0 A 1.5 g/L samples were similar and highest in all samples. It is worth noting that in the recovered carbon fiber, I20S 2.0 A 0.5g / L has the highest nitrogen content of 3.1%, followed by I40S 2.0 A 1.0g / L and I20S 1.0 A 1.0g / L , respectively 2.9 % and 2.3%, I20S 3.0 A 1.0g/L nitrogen content is 0.8%, I20S 2.0 A 1.0g/L and I20S 2.0 A 1.5g/L nitrogen content is zero, from the sample tensile strength value results It can be seen that the higher the nitrogen content, the lower the tensile strength of the sample.
对比I20S 2.0A 0.5g/L、I20S 2.0A 1.0g/L和I20S 2.0A 1.5g/L发现，随着催化剂KOH浓度的增大，碳纤维表面的氧碳比和硅元素含量亦随之增大，而氯元素的含量呈下降趋势，N元素含量则从3.1％降至0，表明增大催化剂KOH浓度会加剧碳纤维表面的氧化刻蚀，改善界面剪切性能，减少其表面的氯元素含量。在I20S 1.0A 1.0g/L、I20S 2.0A 1.0g/L和I20S 3.0A 1.0g/L组，NaCl浓度从1.0(％)上升到3.0(％)过程，氧碳比先升高后降低，I20S 1.0A 1.0g/L和I20S 3.0A 1.0g/L的氧碳比基本接近，分别为0.2781和0.2795，氯元素含量则呈先降低再升高趋势，I20S 3.0A 1.0g/L的氯含量激增至4.3％，氮元素从2.3％降到0再升到2.8，硅元素呈一直增高趋势，表明2.0的NaCl是最佳浓度，过低或过高的NaCl浓度不能取得更好的碳纤维的界面剪切性能，还会增大碳纤维表面的氯含量，尤其是在高NaCl浓度条件下。对比I20S 2.0A 1.0g/L和I40S 2.0A 1.0g/L可以发现，大电流作用会造成较低的氧碳比和硅含量，表面更高的氯含量和氮含量，表面较高电流作用不利于提高碳纤维界面剪切性能，甚至降低拉伸强度。 Comparing I20S 2.0 A 0.5g/L , I20S 2.0 A 1.0g/L and I20S 2.0 A 1.5g/L, it is found that the oxygen-carbon ratio and silicon content of the carbon fiber surface increase with the increase of catalyst KOH concentration. The content of chlorine decreased, and the content of N decreased from 3.1% to 0, indicating that increasing the concentration of KOH in the catalyst will increase the oxidative etching of the surface of carbon fiber, improve the interfacial shear performance and reduce the chlorine content on the surface. In the I20S 1.0 A 1.0g/L , I20S 2.0 A 1.0g/L and I20S 3.0 A 1.0g/L groups, the NaCl concentration increased from 1.0 (%) to 3.0 (%), and the oxygen-carbon ratio increased first and then decreased. The oxygen-carbon ratio of I20S 1.0 A 1.0g/L and I20S 3.0 A 1.0g/L is close to 0.2781 and 0.2795 respectively, and the chlorine content is first decreased and then increased. I20S 3.0 A 1.0g/L chlorine content The surge rate to 4.3%, the nitrogen element decreased from 2.3% to 0 and then rose to 2.8. The silicon element showed an increasing trend, indicating that 2.0 NaCl is the optimum concentration. The too low or too high NaCl concentration can not achieve a better carbon fiber interface. Shear properties also increase the chlorine content of the carbon fiber surface, especially at high NaCl concentrations. Comparing I20S 2.0 A 1.0g/L and I40S 2.0 A 1.0g/L, it can be found that the high current effect will result in lower oxygen to carbon ratio and silicon content, higher chlorine content and nitrogen content on the surface, and higher surface current effect. It is beneficial to improve the shear properties of carbon fiber interface and even reduce the tensile strength.
利用软件XPSPeak4.1，将C1s高分辨窄谱依据结合能分为六种化学键峰进行高斯洛伦茨拟合：石墨态C-C(284.4eV)、非晶态C-C(284.8eV)、C＝O(285.5eV)、C-O(286.2eV)、C-Cl(287.2)和O-C＝O(288.5eV)。C1s分峰拟合见图21右列，得到的碳纤维表面官能团含量见如下表4.5所示。Using the software XPSPeak4.1, the C1s high-resolution narrow spectrum is divided into six chemical bond peaks according to the binding energy for Gauss Lorenz fitting: graphite CC (284.4 eV), amorphous CC (284.8 eV), C=O ( 285.5 eV), CO (286.2 eV), C-Cl (287.2) and OC=O (288.5 eV). The C1s peak fitting is shown in the right column of Figure 21. The surface functional group content of the carbon fiber obtained is shown in Table 4.5 below.
表4.5 VCF和回收得到的碳纤维表面官能团含量(％)Table 4.5 VCF and recovered carbon fiber surface functional group content (%)
Figure PCTCN2018075923-appb-000014
Figure PCTCN2018075923-appb-000014
碳纤维在生产过程被高温惰化处理后，表面含氧官能团较少，活性低，呈憎水性，而 碳～氧官能团的增多能够改善其亲水性，增大浸润性，此外～COOR等含氧活性官能团可以增大碳纤维与树脂的反应作用，生成牢固的化学键，提高界面粘结性能。从表3.10可以发现，碳纤维表面的C1s峰官能团分为三类：碳～碳官能团、碳～氧官能团和碳～氯官能团。碳纤维原丝的石墨态及非晶态C～C键总含量为69.3，各种碳氧键含量为30.7％；回收得到的碳纤维的C～C键总含量均出现不同程度的下降，碳氧键含量增多，表明回收得到的碳纤维表面经历了一定程度的氧化，尤其是I40S 2.0A 1.0g/L的C～C键仅为53.3％，然而过度的氧化会深入到碳纤维表层内部，造成与羧基连接的碳层变得脆弱，降低拉伸强度；碳纤维原丝的C～Cl键含量为0，说明氯元素只是吸附在碳纤维表面，并非以化学键形式存在，而大部分回收得到的碳纤维含有一定量的C～Cl键，说明回收过程产生的氯气，在降解环氧树脂外，还会和碳纤维作用形成化学键，起到腐蚀劣化影响。 After the carbon fiber is inerted by high temperature in the production process, the surface contains less oxygen functional groups, low activity and hydrophobicity, and the increase of carbon-oxygen functional groups can improve its hydrophilicity, increase the wettability, and further contain oxygen such as COOR. The reactive functional group can increase the reaction between the carbon fiber and the resin, form a strong chemical bond, and improve the interfacial bonding performance. It can be seen from Table 3.10 that the C1s peak functional groups on the surface of carbon fibers are classified into three types: carbon-carbon functional groups, carbon-oxygen functional groups, and carbon-chlorine functional groups. The total content of C-C bonds in the graphite and amorphous carbon fiber precursors is 69.3, and the content of various carbon-oxygen bonds is 30.7%. The total content of C-C bonds in the recovered carbon fibers shows a different degree of decline, carbon-oxygen bonds. The increased content indicates that the surface of the recovered carbon fiber has undergone a certain degree of oxidation, especially the C-C bond of I40S 2.0 A 1.0g/L is only 53.3%, however, excessive oxidation will penetrate into the surface of the carbon fiber, causing connection with the carboxyl group. The carbon layer becomes weak and reduces the tensile strength; the carbon fiber precursor has a C-C bond content of 0, indicating that the chlorine element is only adsorbed on the surface of the carbon fiber, not in the form of a chemical bond, and most of the recovered carbon fiber contains a certain amount. The C~Cl bond indicates the chlorine gas generated during the recovery process. In addition to degrading the epoxy resin, it also acts on the carbon fiber to form a chemical bond, which has the effect of corrosion degradation.
从图22(a)可以看到，在I20S 2.0A 0.5g/L和I20S 2.0A 1.0g/L的C～C键含量与碳纤维原丝基本相同，I20S 2.0A 1.5g/L的C～C键含量则减少了11.4％，原因是碳纤维表面发生较为剧烈的氧化反应，形成了更多的碳氧键，表明高浓度的催化剂KOH会使碳纤维氧化程度更高；I20S 2.0A 0.5g/L和I20S 2.0A 1.5g/L的C～Cl键含量分别为6.3％和6％，而I20S 2.0A 1.0g/L的C～Cl键含量为0，表明1g/L的催化剂KOH浓度条件下，碳纤维所受的氯腐蚀最轻微。从(b)发现，C～C键含量随NaCl浓度的增大呈现先升高后降低趋势，说明NaCl浓度为2.0％时，碳纤维所受的氧化程度会低一些；当NaCl浓度为1.0％和2.0％时，C～Cl键含量均为0，随着NaCl浓度增大到3.0，C～Cl键含量为1.9％，说明高NaCl浓度作用下，碳纤维更容易受到氯的腐蚀。从(c)可以明显看到，I40S 2.0A 1.0g/L的C～C键含量比I20S 2.0A 1.0g/L低很多，而I40S 2.0A 1.0g/L的C～Cl键含量为6.8％，I20S 2.0A 1.0g/L的C～Cl键含量为0，表明作用电流越大，回收得到的碳纤维受到的氧化程度越高，同时受到的氯腐蚀也越严重。 As can be seen from Fig. 22(a), the C-C bond content of I20S 2.0 A 0.5g/L and I20S 2.0 A 1.0g/L is basically the same as that of carbon fiber precursor, I20S 2.0 A 1.5g/L C-C The bond content was reduced by 11.4% due to the more intense oxidation reaction on the surface of the carbon fiber, which formed more carbon-oxygen bonds, indicating that the high concentration of the catalyst KOH will cause the carbon fiber to oxidize more; I20S 2.0 A 0.5g/L and I20S 2.0 A 1.5g/L C-Cl bond content is 6.3% and 6%, respectively, while I20S 2.0 A 1.0g/L C-Cl bond content is 0, indicating 1g/L catalyst KOH concentration, carbon fiber The chlorine corrosion received is the slightest. From (b), it is found that the content of C-C bond increases first and then decreases with the increase of NaCl concentration, indicating that the carbon fiber is less oxidized when the NaCl concentration is 2.0%; when the NaCl concentration is 1.0% and At 2.0%, the C~Cl bond content is 0. With the NaCl concentration increasing to 3.0, the C~Cl bond content is 1.9%, indicating that the carbon fiber is more susceptible to chlorine corrosion under the action of high NaCl concentration. From (c) can be clearly seen, I40S 2.0 A 1.0g / L is C ~ C bond content than I20S 2.0 A 1.0g / L much lower, and I40S 2.0 A 1.0g / L C ~ Cl bond content of 6.8% The content of C~Cl bond of I20S 2.0 A 1.0g/L is 0, indicating that the larger the working current is, the higher the degree of oxidation of the recovered carbon fiber is, and the more severe the chlorine corrosion is.
根据本发明的该优选实施例，在自碳纤维增强树脂基复合材料中回收碳纤维的方法中，所述电解液含有0.5g/L～1.5g/L的催化剂A，其中该催化剂A为可溶性碱，可以是但不限于是KOH。如图14、15、16所示，当KOH浓度在1.0g/L时，碳纤维的回收量和界面剪切强度最高，并且拉伸强度较为理想，表明最佳KOH浓度约为1.0g/L。然而，考虑到实际生产的控制难度和成本，KOH浓度控制在0.75g/L～1.25g/L时，可获得理想回收效果。According to this preferred embodiment of the present invention, in the method for recovering carbon fibers from a carbon fiber reinforced resin-based composite material, the electrolytic solution contains 0.5 g/L to 1.5 g/L of catalyst A, wherein the catalyst A is a soluble base, It may be, but is not limited to, KOH. As shown in Figs. 14, 15, and 16, when the KOH concentration was 1.0 g/L, the carbon fiber recovery amount and the interfacial shear strength were the highest, and the tensile strength was ideal, indicating that the optimum KOH concentration was about 1.0 g/L. However, considering the control difficulty and cost of actual production, when the KOH concentration is controlled at 0.75 g/L to 1.25 g/L, an ideal recovery effect can be obtained.
示例5：温度对碳纤维回收的影响Example 5: Effect of temperature on carbon fiber recovery
与其它化学反应相似，电化学法回收碳纤维的化学反应过程也应当有其合适的反应条 件。前述试验均于室温环境下进行，但较高的反应温度有望提高回收速度和回收后的纤维材料的质量，因此，本发明通过下述实验结果，确定本发明电化学回收方法的合适温度。Similar to other chemical reactions, the chemical reaction process for the recovery of carbon fibers by electrochemical methods should also have suitable reaction conditions. The foregoing tests are all carried out at room temperature, but a higher reaction temperature is expected to increase the recovery rate and the quality of the recovered fibrous material. Therefore, the present invention determines the appropriate temperature of the electrochemical recovery method of the present invention by the following experimental results.
同样地，多组样本(如下表5.1所示)被用于测试合适反应温度，其中被选用的电流强度分别为20mA和40mA，对应电流密度分别为3333.3mA/m 2和6666.7mA/m 2，NaCl浓度为2.0(％)，KOH剂量为1.0g/L；温度梯度为0℃和100℃之间的三个温度梯度，共6种参数条件，以降低对实验装置的要求并降低工业化应用成本。样本编号由作用电流强度、NaCl浓度、催化剂KOH浓度和温度梯度共同确定，比如样本编号“I20S 2.0A 1.0g/L40”，第一部分“I20”是指样本施加的电流是20mA，第二部分“S 2.0”是指电解液中NaCl浓度为2.0，第三部分“A 1.0g/L”是指电解液中添加的催化剂KOH浓度是1.0g/L。第四部分“40”是指实验过程中电解液的温度保持在40℃。详细的实验分组和实验参数见表5.1。 Similarly, multiple sets of samples (shown in Table 5.1 below) were used to test the appropriate reaction temperatures, with the selected current intensities of 20 mA and 40 mA, respectively, corresponding to current densities of 3333.3 mA/m 2 and 6666.7 mA/m 2 , respectively. The concentration of NaCl is 2.0 (%), the dose of KOH is 1.0g/L, and the temperature gradient is three temperature gradients between 0 °C and 100 °C. There are 6 parameters to reduce the requirements on the experimental device and reduce the cost of industrial application. . The sample number is determined by the applied current intensity, NaCl concentration, catalyst KOH concentration and temperature gradient. For example, the sample number is “I20S 2.0 A 1.0g/L 40”. The first part “I20” means the current applied by the sample is 20mA. "S 2.0 " means that the NaCl concentration in the electrolytic solution is 2.0, and the third portion "A 1.0 g/L " means that the concentration of the catalyst KOH added to the electrolytic solution is 1.0 g/L. The fourth part "40" means that the temperature of the electrolyte is maintained at 40 ° C during the experiment. Detailed experimental grouping and experimental parameters are shown in Table 5.1.
表5.1实验样本分组及参数Table 5.1 Experimental sample grouping and parameters
Figure PCTCN2018075923-appb-000015
Figure PCTCN2018075923-appb-000015
实验分两个阶段，每个阶段回收周期9天，共18天。第一阶段结束后，切断电源，取下样本上的碳纤维，然后继续通电进行回收实验。第二阶段结束后，取下碳纤维进行清洗和干燥。两个阶段回收得到的碳纤维在宏观形貌上无明显差异，非常干净，富有光泽，表明碳纤维受到的氧化损伤很轻微。需要指出，回收得到的碳纤维从样本上取下时呈整齐的纵向条状，超声波清洗过程导致其卷成密实的团状。The experiment was divided into two phases, each of which was recycled for 9 days for a total of 18 days. At the end of the first phase, the power was turned off, the carbon fiber on the sample was removed, and the power was continued for recovery experiments. After the second stage, the carbon fibers are removed for washing and drying. The carbon fiber recovered in the two stages showed no significant difference in macroscopic morphology, and was very clean and shiny, indicating that the carbon fiber was slightly damaged by oxidative damage. It should be pointed out that the recovered carbon fiber is neatly stripped when removed from the sample, and the ultrasonic cleaning process causes it to roll into a dense mass.
5.1样本电压结果5.1 sample voltage results
从图31可以看出，所有样本电压分布区间为2.5V～3.1V，样本电压在整个回收期间基本保持稳定，波动幅度很小，可以推测样本没有发生严重的劣化。I20组样本电压在温度为40℃时与I40组比较接近，在60℃和75℃时比I40组高，说明电流对样本电压影响仍较大。需要指出的是，无论在I20还是I40电流组中，60℃与75℃样本的电压相当接近，差值大约在0.1V以内；而40℃与60℃和75℃样本的电压差距较大，差值大约在0.2V～0.5V左右。表明在温度为60℃和75℃时，样本间的阻值已经基本接近，而在40℃作用下的样本阻值跟60℃和75℃有一定差距一阶段电压和二阶段电压基本相同，说明短暂切断 电源取下回收得到的碳纤维对样本的影响非常微弱，并未阻碍到后续的电化学回收进程。As can be seen from Fig. 31, the voltage distribution range of all samples is 2.5V to 3.1V, and the sample voltage is basically stable throughout the recovery period, and the fluctuation range is small, and it can be inferred that the sample does not deteriorate seriously. The sample voltage of the I20 group is close to the I40 group at a temperature of 40 °C, and higher than the I40 group at 60 °C and 75 °C, indicating that the current has a large influence on the sample voltage. It should be noted that in the I20 or I40 current group, the voltages of the 60°C and 75°C samples are quite close, and the difference is about 0.1V. The voltage difference between the 40°C and 60°C and 75°C samples is large and poor. The value is approximately 0.2V to 0.5V. It shows that the resistance between samples is almost close at 60 °C and 75 °C, and the resistance of sample under 40 °C is different from that of 60 °C and 75 °C. The voltage of the first stage is basically the same as that of the second stage. The short-cut power cut and the recovered carbon fiber have a very weak effect on the sample and do not hinder the subsequent electrochemical recovery process.
5.2碳纤维回收量及除胶率5.2 Carbon fiber recovery and gel removal rate
在进行碳纤维回收量和除胶率分析之前，需要指出，表5.2的数据是电化学回收两个阶段的成果。即两个阶段得到的碳纤维先分别进行三次TGA测试，结果表明两个阶段的碳纤维的除胶率基本没有差别，所以除胶率取六次实验的平均值；两个阶段的碳纤维回收量同样差别不大，为了方便对比分析，碳纤维回收量取两个阶段之和；I20S 2.0A 1.0g/L25即为I20S 2.0A 1.0g/L(实验室常温条件)，列在表中作对比分析用。从表3.2可以看到，40、60和75系列参数条件下的回收得到的碳纤维除胶率都非常高，在99.3％～99.9％之间，跟25系列相差不大，而40～75系列碳纤维的实际回收周期只有9天，为25的一半；同时，40～75系列碳纤维回收量对比25有了极大提高，当实验温度为75时，碳纤维回收量为25的两到三倍。上述结果表明，回收周期虽然缩短为原来一半，但是提高电解液温度能够大幅度提高环氧树脂的分解效率，提高碳纤维回收量，彻底清除碳纤维表面树脂。直观的碳纤维回收量与温度的关系如图32。 Before conducting carbon fiber recovery and degumming rate analysis, it should be noted that the data in Table 5.2 is the result of two stages of electrochemical recovery. That is, the carbon fiber obtained in the two stages was first tested three times by TGA, and the results showed that there was basically no difference in the removal rate of the carbon fiber in the two stages, so the removal rate was taken as the average of six experiments; the carbon fiber recovery in the two stages was also the same. Not large, in order to facilitate comparative analysis, the carbon fiber recovery amount is taken as the sum of two stages; I20S 2.0 A 1.0g/L 25 is I20S 2.0 A 1.0g/L (laboratory normal temperature condition), which is listed in the table for comparative analysis. . It can be seen from Table 3.2 that the carbon fiber removal rate obtained under the 40, 60 and 75 series parameters is very high, between 99.3% and 99.9%, which is similar to the 25 series, and the 40-75 series carbon fiber. The actual recovery period is only 9 days, which is half of 25; at the same time, the recovery of 40-75 series carbon fiber is greatly improved. When the experimental temperature is 75, the carbon fiber recovery is two to three times that of 25. The above results show that although the recovery cycle is shortened to half of the original, increasing the electrolyte temperature can greatly improve the decomposition efficiency of the epoxy resin, increase the amount of carbon fiber recovered, and completely remove the carbon fiber surface resin. The relationship between the amount of carbon fiber recovered and temperature is shown in Figure 32.
表5.2不同温度梯度样本的碳纤维回收量和除胶率Table 5.2 Carbon fiber recovery and gel removal rate for different temperature gradient samples
Figure PCTCN2018075923-appb-000016
Figure PCTCN2018075923-appb-000016
注：此处的碳纤维回收量为回收过程一阶段和二阶段之和Note: The carbon fiber recovery amount here is the sum of the first and second stages of the recovery process.
从图32可以看到，碳纤维回收量与温度是正相关关系，碳纤维回收量随温度的增加呈不断上升趋势，在25℃～40℃温度区间，碳纤维回收量增速稍慢；在40℃～60℃温度区间，碳纤维回收量增速加快；在60℃～75℃温度区间，碳纤维回收量增速放缓。当温 度上升到75℃时，I20S 2.0A 1.0g/L75回收量达到2287mg,I40S 2.0A 1.0g/L75回收量达到2353mg，分别是其在25℃时的3.05倍和1.93倍。可以推测，在一定区间内，进一步提升温度，能够继续提高碳纤维回收量。说明温度在环氧树脂的降解过程起到关键的作用，反应温度的提高能够极大提升环氧树脂的降解效率。在碳纤维回收量中可以明显的看到施加电流差异的影响，I40S 2.0A 1.0g/L的碳纤维回收量一直大于I20S 2.0A 1.0g/L，在25℃温度时回收量是I20S 2.0A 1.0g/L的1.6倍多。然而随着温度的上升，二者间的差距越来越小，但温度达到75℃时，I40S 2.0A 1.0g/L的回收量仅为I20S 2.0A 1.0g/L的1.03倍。表明温度的上升能够减小电流作用在碳纤维回收量上的影响，在高温状态，温度超过电流成为碳纤维回收量中的决定性因素。 It can be seen from Fig. 32 that the carbon fiber recovery amount is positively correlated with the temperature, and the carbon fiber recovery amount is increasing with the increase of temperature. In the temperature range of 25 ° C to 40 ° C, the carbon fiber recovery rate is slightly slower; at 40 ° C ~ 60 In the temperature range of °C, the growth rate of carbon fiber recovery is accelerated; in the temperature range of 60 °C to 75 °C, the growth rate of carbon fiber recovery is slowed down. When the temperature rises to 75 ° C, the recovery of I20S 2.0 A 1.0g / L 75 reaches 2287mg, and the recovery of I40S 2.0 A 1.0g / L 75 reaches 2353mg, which is 3.05 times and 1.93 times respectively at 25 °C. It can be speculated that in a certain interval, the temperature can be further increased, and the amount of carbon fiber recovered can be continuously increased. It shows that the temperature plays a key role in the degradation process of epoxy resin, and the increase of reaction temperature can greatly improve the degradation efficiency of epoxy resin. The effect of the difference in applied current can be clearly seen in the carbon fiber recovery. The carbon fiber recovery of I40S 2.0 A 1.0g/L is always greater than I20S 2.0 A 1.0g/L , and the recovery at 25°C is I20S 2.0 A 1.0g. /L is 1.6 times more. However, as the temperature rises, the gap between the two smaller, but when the temperature reached 75 ℃, I40S 2.0 A 1.0g / L, the recovery amount was only I20S 2.0 A 1.0g / L to 1.03 times. It is indicated that the increase in temperature can reduce the influence of current on the amount of carbon fiber recovered. In the high temperature state, the temperature exceeds the current and becomes a decisive factor in the amount of carbon fiber recovered.
需要指出，碳纤维复合材料中的环氧树脂，在氮气或者空气氛围下的热裂解温度范围大约在300℃～600℃之间，而本章实验最高温度75℃，远低于环氧树脂的热分解温度，因此碳纤维回收量的大幅度增加，不能归于温度造成的树脂热分解。升高温度能够提高碳纤维的回收量，可能跟温度和催化剂KOH的相互协同作用有关，提高温度会增加催化剂KOH的反应性能，同时催化剂KOH的存在相当于提升了一定程度的温度。It should be pointed out that the thermal cracking temperature of epoxy resin in carbon fiber composites is about 300 ° C ~ 600 ° C under nitrogen or air atmosphere, and the highest temperature of this experiment is 75 ° C, far lower than the thermal decomposition of epoxy resin. The temperature, therefore, the large increase in the amount of carbon fiber recovered cannot be attributed to the thermal decomposition of the resin caused by temperature. Increasing the temperature can increase the recovery of carbon fiber, which may be related to the synergy between temperature and catalyst KOH. Increasing the temperature increases the reaction performance of the catalyst KOH, and the presence of the catalyst KOH is equivalent to increasing the temperature to a certain extent.
5.3碳纤维单丝拉伸强度5.3 carbon fiber monofilament tensile strength
一阶段和二阶段的碳纤维直径基本没有减小，表明9天的回收周期会明显减少碳纤维所受的电化学氧化刻蚀、OH -离子插层反应和碱腐蚀等作用。对比两个阶段得到的回收得到的碳纤维拉伸强度，可以发现，同一参数下的碳纤维强度差值不超过1％，阶段性的差异非常小，同样从前面的结果知道两个阶段的回收得到的碳纤维除胶率和回收量基本接近，综合以上，往后的碳纤维性能测试和分析只列出第一阶段的数据，代表本章实验的整个电化学回收周期结果。直观的碳纤维拉伸强度与温度的关系见图33。 The carbon fiber diameters of the first and second stages are not substantially reduced, indicating that the 9-day recovery cycle significantly reduces the effects of electrochemical oxidation etching, OH - ion intercalation, and alkali corrosion on the carbon fibers. Comparing the tensile strength of the recovered carbon fiber obtained in the two stages, it can be found that the difference in the strength of the carbon fiber under the same parameter does not exceed 1%, and the difference in the stage is very small, and the recovery from the two stages is also known from the previous results. The carbon fiber removal rate and recovery amount are basically close to each other. The above carbon fiber performance test and analysis only lists the first stage data, which represents the entire electrochemical recovery cycle results of the experiments in this chapter. The relationship between the intuitive carbon fiber tensile strength and temperature is shown in Figure 33.
从图中可以看到，回收得到的碳纤维的拉伸强度随温度的升高而不断增大，从25℃到40℃，拉伸强度的增速最大；在40℃到60℃区间，拉伸强度的增速放缓；当温度从60℃上升到75℃过程，拉伸强度的增速基本趋近与零。I20S 2.0A 1.0g/L75与I40S 2.0A 1.0g/L75回收得到的碳纤维拉伸强度分别达到4077MPa和4169MPa，为碳纤维原丝值的87.85％和89.83％，高于机械回收方法(50％～65％)和热分解方法(50～85％)，低于溶剂分解方法(85％～98％)。在9天的回收周期下，I20系列与I40系列样品回收得到的碳纤维拉伸强度非常接近，电流的作用影响很小。上述结果表明，升高回收温度，缩短回收周期能够减少碳纤维遭受的电化学损伤，提高拉伸强度。 It can be seen from the figure that the tensile strength of the recovered carbon fiber increases with increasing temperature, and the tensile strength increases most from 25 ° C to 40 ° C; stretching in the range of 40 ° C to 60 ° C The growth rate of strength slows down; when the temperature rises from 60 °C to 75 °C, the growth rate of tensile strength is almost close to zero. The tensile strength of the carbon fiber recovered by I20S 2.0 A 1.0g/L 75 and I40S 2.0 A 1.0g/L 75 is 4077MPa and 4169MPa, respectively, which is 87.85% and 89.83% of the carbon fiber raw yarn value, which is higher than the mechanical recovery method (50%). ~65%) and thermal decomposition method (50-85%), lower than the solvent decomposition method (85% to 98%). Under the 9-day recovery cycle, the tensile strength of the carbon fiber recovered from the I20 series and the I40 series sample is very close, and the effect of the current is small. The above results show that increasing the recovery temperature and shortening the recovery cycle can reduce the electrochemical damage suffered by carbon fibers and increase the tensile strength.
5.4碳纤维界面剪切性能5.4 carbon fiber interface shear performance
在回收得到的碳纤维中，仅有I20S2.0A1.0g/L40与I40S2.0A1.0g/L40样本的破坏模式为CB,且界面剪切强度分别只达到碳纤维原丝的82％和79.39％；而其他样本的破坏模式都为DB，界面剪切强度接近或超过碳纤维原丝。直观的碳纤维界面剪切强度与温度关系见图34。Among the recovered carbon fibers, only the I20S2.0A1.0g/L40 and I40S2.0A1.0g/L40 samples have a failure mode of CB, and the interfacial shear strength is only 82% and 79.39% of the carbon fiber precursor, respectively; The failure modes of the other samples were all DB, and the interfacial shear strength was close to or exceeded that of the carbon fiber precursor. The intuitive carbon fiber interface shear strength versus temperature is shown in Figure 34.
从图34中可以看到，碳纤维界面剪切强度随着温度的升高，呈现先降低再升高的趋势。当温度从25℃上升到40℃，I20S 2.0A 1.0g/L和I40S 2.0A 1.0g/L的剪切强度从原来的37.43MPa和28.08MPa下降到25.42MPa和24.61MPa，下降幅度达到32.09％和12.36％，原因应该是回收周期从18天缩短到9天后，碳纤维受到的表面氧化刻蚀和OH -离子插层反应减少，造成表面纵向沟槽结构不够明显和表皮凸起减少，粗糙度减小和比表面积减少，所以剪切强度下降。从图35(a)和图35(b)可以看到，I20S 2.0A 1.0g/L40与I40S 2.0A 1.0g/L40的破坏模式都是CB，在破坏时，环氧树脂与碳纤维完全剥离，碳纤维表面基本看不到环氧树脂残留，碳纤维并未被撕裂，说明碳纤维与环氧树脂的粘结性能很差，这是由于碳纤维表面粗糙度不够导致的机械咬合力不足和碳纤维的浸润性不好造成粘结差，从而使碳纤维和环氧树脂能够轻易分离。 It can be seen from Fig. 34 that the shear strength of the carbon fiber interface tends to decrease first and then increase with the increase of temperature. When the temperature rises from 25 °C to 40 °C, the shear strength of I20S 2.0 A 1.0g/L and I40S 2.0 A 1.0g/L decreases from the original 37.43MPa and 28.08MPa to 25.42MPa and 24.61MPa, and the decrease rate reaches 32.09%. And 12.36%, the reason should be that after the recovery cycle is shortened from 18 days to 9 days, the surface oxidation etching and OH - ion intercalation reaction of carbon fiber are reduced, resulting in insufficient surface longitudinal groove structure and reduced skin protrusion and roughness reduction. The small and specific surface area is reduced, so the shear strength is lowered. As can be seen from Fig. 35(a) and Fig. 35(b), the failure modes of I20S 2.0 A 1.0g/L 40 and I40S 2.0 A 1.0g/L 40 are both CB, and the epoxy resin and carbon fiber are completely destroyed when broken. Peeling, the surface of the carbon fiber is almost invisible to the epoxy resin, and the carbon fiber is not torn, indicating that the bonding property between the carbon fiber and the epoxy resin is poor, which is due to insufficient mechanical bite force and carbon fiber due to insufficient surface roughness of the carbon fiber. Poor wettability results in poor adhesion, allowing carbon fiber and epoxy to be easily separated.
随着温度的继续增加，碳纤维剪切强度不断增大，在温度为60℃时，I20S 2.0A 1.0g/L60℃与I40S 2.0A 1.0g/L60℃剪切强度分别为33.59MPa和29.84MPa，为碳纤维原丝值的108.35％和96.26％，同时从图35(c)和图35(d)二者的破坏模式都是DB，破坏发生在环氧树脂层，I20S 2.0A 1.0g/L60℃破坏断面还黏附有细长针状的树脂，I40S 2.0A 1.0g/L60℃样品表面还包裹着一层光滑的树脂，表明温度增高使碳纤维表面的氧化刻蚀程度加剧，界面粘结力得到改善，剪切强度变大。当温度达到75℃时，I20S 2.0A 1.0g/L和I40S 2.0A 1.0g/L的剪切强度分别为33.72MPa和35.79MPa，为碳纤维原丝的108.77％和115.45％。这两个样品的剥离模式都是DB，如图35(e)和图35(f),环氧树脂层的破坏界面为棱状和凹凸状，增加了破坏表面积，特别是I40S 2.0A 1.0g/L呈现破碎性剥离趋势，破坏时强大的作用力使微滴内部破裂。这是因为温度升高使碳纤维受到的表面作用增大，比表面积和粗糙度都变大，碳纤维的浸润性得到改善，界面的机械咬合效应增强，形成所谓的锚定作用，因而碳纤维界面剪切强度变大，破坏模式更理想。在9天的回收周期中，I20与I40系列的剪切强度差距较小，电流影响变弱。 As the temperature continues to increase, the shear strength of carbon fiber increases continuously. At 60 °C, the shear strength of I20S 2.0 A 1.0g/L 60°C and I40S 2.0 A 1.0g/L 60°C is 33.59MPa and 29.84, respectively. MPa, which is 108.35% and 96.26% of the carbon fiber precursor value, and the failure mode from both Fig. 35(c) and Fig. 35(d) is DB, and the damage occurs in the epoxy layer, I20S 2.0 A 1.0g/ L 60 ° C fracture section also adhered to the slender needle-like resin, I40S 2.0 A 1.0g / L 60 ° C sample surface is also wrapped with a smooth layer of resin, indicating that the temperature increase, the carbon fiber surface oxidized etching degree, the interface stick The joint force is improved and the shear strength is increased. When the temperature reached 75 ° C, the shear strengths of I20S 2.0 A 1.0g / L and I40S 2.0 A 1.0g / L were 33.72MPa and 35.79MPa, respectively, which were 108.77% and 115.45% of the carbon fiber precursor. The stripping mode of both samples is DB. As shown in Fig. 35(e) and Fig. 35(f), the destruction interface of the epoxy layer is prismatic and concave, which increases the surface area of damage, especially I40S 2.0 A 1.0g. /L exhibits a tendency to break apart, and a strong force during breakage causes the inside of the droplet to rupture. This is because the increase in temperature causes the surface effect of the carbon fiber to increase, the specific surface area and roughness become larger, the wettability of the carbon fiber is improved, the mechanical occlusion effect of the interface is enhanced, and a so-called anchoring action is formed, thereby shearing the carbon fiber interface. The intensity becomes larger and the damage mode is more desirable. In the 9-day recovery cycle, the I20 and I40 series have a small difference in shear strength and the current effect is weak.
上述情况表明缩短回收周期会减少碳纤维所受的氧化刻蚀等表面作用，从而降低碳纤维界面剪切强度，同时减小施加电流差异造成的剪切强度差距；温度增大能够改善碳纤维表面粗糙度和浸润性，增大碳纤维界面剪切强度，改善碳纤维～环氧树脂界面破坏模式。The above situation indicates that shortening the recovery cycle will reduce the surface effect of the carbon fiber on the oxidative etching, thereby reducing the shear strength of the carbon fiber interface, and reducing the shear strength difference caused by the difference in applied current; the temperature increase can improve the surface roughness of the carbon fiber and Wettability, increase the shear strength of carbon fiber interface, and improve the interface mode of carbon fiber to epoxy resin interface.
5.5碳纤维SEM扫描5.5 carbon fiber SEM scanning
SEM扫描结果显示所有回收得到的碳纤维非常干净，见图36。在温度为40℃时，碳纤维表面可以看到几颗极小的环氧树脂颗粒，见图36(a)和图36(b)，但是所占比例非常低，碳纤维仍然很干净，表面没有裂纹裂缝和凹坑等物理缺陷。当温度继续上升，在60℃和75℃时，碳纤维表面基本看不到环氧树脂残留，同样表面没有裂纹裂缝和凹坑等物理缺陷。从SEM图像可以看到，在不同电流作用下，回收得到的碳纤维表面状况几乎没有差异。上述情况表明在9天的回收周期内，碳纤维由于暴露在电解液中的样本较短，受到电化学氧化刻蚀、OH -离子插层反应和碱腐蚀等作用程度比较轻微，碳纤维本体受到的损伤很小，因此回收得到的碳纤维的拉伸强度得到提升；温度越高，回收得到的碳纤维的表面环氧树脂残留越少，虽然所有温度梯度下，回收得到的碳纤维的环氧树脂含量都非常少。 The SEM scan showed that all recovered carbon fibers were very clean, see Figure 36. At a temperature of 40 ° C, several tiny epoxy particles can be seen on the surface of the carbon fiber, as shown in Figure 36 (a) and Figure 36 (b), but the proportion is very low, the carbon fiber is still very clean, and there is no crack on the surface. Physical defects such as cracks and pits. When the temperature continues to rise, at 60 ° C and 75 ° C, the surface of the carbon fiber is substantially invisible to the epoxy resin, and the surface is free from physical defects such as crack cracks and pits. It can be seen from the SEM image that there is almost no difference in the surface condition of the recovered carbon fibers under different currents. The above situation indicates that the carbon fiber is less affected by electrochemical oxidation etching, OH - ion intercalation reaction and alkali corrosion during the 9-day recovery period due to the shorter sample exposed to the electrolyte, and the carbon fiber body is damaged. Very small, so the tensile strength of the recovered carbon fiber is improved; the higher the temperature, the less residual epoxy resin on the surface of the recovered carbon fiber, although the recycled carbon fiber has very little epoxy resin content under all temperature gradients. .
5.6碳纤维AFM扫描5.6 carbon fiber AFM scanning
从表5.3可以发现，回收得到的碳纤维与碳纤维原丝的粗糙度比较接近，可能的解释是9天的回收周期较短，回收得到的碳纤维受到的电化学氧化程度很浅。同一温度下样本的回收得到的碳纤维粗糙度比较接近。It can be found from Table 5.3 that the recovered carbon fiber and the carbon fiber precursor have similar roughness, and the possible explanation is that the 9-day recovery period is short, and the recovered carbon fiber is subjected to a slight degree of electrochemical oxidation. The carbon fiber roughness obtained by the recovery of the sample at the same temperature is relatively close.
在40℃时，I20S 2.0A 1.0g/L40℃和I40S 2.0A 1.0g/L40℃的粗糙度分别为190nm和195nm，低于碳纤维原丝的201nm，从图37(a)～(d)可以看到，I20S 2.0A 1.0g/L40℃碳纤维表面比较平整，没有纵向沟槽结构，只有很细的麻面，在几纳米到几十纳米之间，机械咬合效应非常小，在剪切实验破坏时，环氧树脂和碳纤维能够轻易的分离，剪切强度不高；I40S 2.0A 1.0g/L40℃的表面结构相对会好些，可以看到深度很浅的纵向沟槽结构，同时有少量尺寸很小的凸起结构，这些都增加了表面的粗糙度，加大机械咬合作用，改善界面粘结性能。当温度提升至时60℃时，见图37(e)～(h)，I20S 2.0A 1.0g/L60℃表面的凸起结构增多，这些结构的尺寸在几十纳米到几百纳米之间，极大的增大碳纤维的比表面积，加大浸润性；I40S 2.0A 1.0g/L60℃的纵向结构则变得明显，沟槽加深，增强了机械咬合作用，需要说明的是，该表面极深的纵向凹槽是生产阶段造成的，并非氧化刻蚀所致。当温度继续提高到75℃时，见图37(i)～(l)，碳纤维表面的纵向沟槽加深，表皮凸起结构更多，使得I20S 2.0A 1.0g/L75和I40S 2.0A 1.0g/L75的碳纤维表面粗糙度分别达到208nm和211nm，环氧树脂与碳纤维的咬合力和浸润性得到加强，界面剪切强度大幅度提高，破坏模式呈破碎性剥离的DB模式。回收得到的碳纤维的表面微观结构情况表明，温度升高能够提升碳纤维表面的刻蚀和OH -离子插层反应，造成碳纤维表面沟槽加深，纳米级别的凸起结构增多， 改善界面粘结性能，提高了碳纤维的界面剪切强度。 At 40 ° C, the roughness of I20S 2.0 A 1.0g / L 40 ° C and I40S 2.0 A 1.0g / L 40 ° C is 190nm and 195nm, respectively, lower than the 201nm of carbon fiber precursor, from Figure 37 (a) ~ (d Can be seen, I20S 2.0 A 1.0g / L 40 ° C carbon fiber surface is relatively flat, no longitudinal groove structure, only very fine pockmark, between a few nanometers to tens of nanometers, mechanical occlusion effect is very small, in the shear When the test is destroyed, the epoxy resin and carbon fiber can be easily separated, and the shear strength is not high; the surface structure of I40S 2.0 A 1.0g/L 40°C is relatively better, and the shallow groove structure with shallow depth can be seen. There are a small number of raised structures with small dimensions, which increase the surface roughness, increase mechanical bite and improve interfacial adhesion. When the temperature is raised to 60 ° C, see Figure 37 (e) ~ (h), I20S 2.0 A 1.0g / L 60 ° C surface of the raised structure, the size of these structures between tens of nanometers to hundreds of nanometers Greatly increase the specific surface area of carbon fiber and increase the wettability; the longitudinal structure of I40S 2.0 A 1.0g/L 60°C becomes obvious, and the groove is deepened, which enhances the mechanical bite. It should be noted that the surface Extremely deep longitudinal grooves are caused during the production phase and are not due to oxidative etching. When the temperature continues to increase to 75 ° C, see Figure 37 (i) ~ (l), the longitudinal grooves on the surface of the carbon fiber are deepened, and the skin convex structure is more, making I20S 2.0 A 1.0g / L 75 and I40S 2.0 A 1.0g The surface roughness of the carbon fiber of /L 75 is 208 nm and 211 nm, respectively. The bite force and wettability of the epoxy resin and the carbon fiber are strengthened, the interfacial shear strength is greatly improved, and the failure mode is a DB mode of fractured peeling. The surface microstructure of the recovered carbon fiber shows that the temperature increase can enhance the etching and OH - ion intercalation reaction on the surface of the carbon fiber, resulting in deepening of the groove on the surface of the carbon fiber, increasing the nano-scale convex structure and improving the interfacial adhesion performance. The interfacial shear strength of carbon fibers is increased.
表5.3不同温度梯度的回收得到的碳纤维粗糙度Table 5.3 Carbon fiber roughness obtained by recovery of different temperature gradients
Figure PCTCN2018075923-appb-000017
Figure PCTCN2018075923-appb-000017
5.7碳纤维XPS扫描图谱5.7 carbon fiber XPS scan map
回收得到的碳纤维扫描全谱及C1s高分辨窄谱，如图40A至42B所示，左列是扫描全谱，右列是其对应的C1s窄谱及其分峰拟合图。从扫描全谱图可以看到，图中主要有五个峰，两个主峰：C(284.6eV)和O(532.0eV)；三个次要峰：Si(99.5eV)、Cl(199.8eV)和N(399.5eV)。碳纤维表面基本元素为碳、氧、氮和硅，检测出来的少量氯可能是在生产或运输过程中的引入。回收得到的碳纤维表面具体元素含量情况见表5.4。The recovered carbon fiber scanning full spectrum and C1s high resolution narrow spectrum, as shown in Figures 40A to 42B, the left column is the scanning full spectrum, and the right column is the corresponding C1s narrow spectrum and its peak fitting map. It can be seen from the scanning full spectrum that there are mainly five peaks in the figure, two main peaks: C (284.6 eV) and O (532.0 eV); three secondary peaks: Si (99.5 eV), Cl (199.8 eV) And N (399.5 eV). The basic elements on the surface of carbon fiber are carbon, oxygen, nitrogen and silicon, and the small amount of chlorine detected may be introduced during production or transportation. The content of specific elements on the surface of the recovered carbon fiber is shown in Table 5.4.
表5.4不同温度梯度的回收得到的碳纤维表面元素含量(％)Table 5.4 Surface element content of carbon fiber obtained by recovery of different temperature gradients (%)
Figure PCTCN2018075923-appb-000018
Figure PCTCN2018075923-appb-000018
从表中看到，不同温度下的回收得到的碳纤维跟碳纤维原丝相比，其表面的C元素含量均出现小幅度下降，这是由于氧化作用使碳纤维表面活性碳粒少量脱落；而氧含量都有一定程度的上升，从氧碳比可以看到，碳纤维原丝仅为0.2434，而I20S 2.0A 1.0g/L60和I20S 2.0A 1.0g/L75的氧碳比分别为0.2890和0.2898，二者比较接近，I20S 2.0A 1.0g/L40的碳氧比更大一些为0.2961，表明碳纤维在回收过程经历了一定程度的氧化，引入了更多的氧，其表面活性增加，I20S 2.0A 1.0g/L40的氧化程度会更高一些；本章的回收得到的碳纤维氧碳比均比第二章I20S 2.0A 1.0g/L在25℃时(氧碳比为0.3187)低，这是由于9天的回收周期较 短，碳纤维在电解液中暴露氧化时间很短所致；回收得到的碳纤维的Cl元素含量都出现上升，应该与电解液中的氯离子吸附有关；相比碳纤维原丝，N元素和Si元素含量都有一定程度的下降，尤其是N元素。 It can be seen from the table that the carbon fiber recovered at different temperatures has a small decrease in the content of C on the surface of the carbon fiber compared with the carbon fiber precursor. This is due to the oxidation of the carbon fiber surface active carbon particles to a small amount; There is a certain degree of increase. From the oxygen to carbon ratio, the carbon fiber precursor is only 0.2434, while the oxygen and carbon ratios of I20S 2.0 A 1.0g/L 60 and I20S 2.0 A 1.0g/L 75 are 0.2890 and 0.2898, respectively. The two are relatively close. The carbon-oxygen ratio of I20S 2.0 A 1.0g/L 40 is 0.2961, which indicates that the carbon fiber undergoes a certain degree of oxidation during the recovery process, introduces more oxygen, and its surface activity increases. I20S 2.0 A The oxidation degree of 1.0g/L 40 will be higher; the carbon fiber oxygen-carbon ratio obtained in this chapter is lower than that of Chapter 2 I20S 2.0 A 1.0g/L at 25 °C (oxygen-carbon ratio is 0.3187), which is due to The 9-day recovery period is short, and the exposure time of carbon fiber in the electrolyte is very short; the content of Cl element in the recovered carbon fiber increases, which should be related to the adsorption of chloride ions in the electrolyte; compared with the carbon fiber precursor, N element and Si element content Decreased to some extent, especially N element.
利用软件XPSPeak4.1，将C1s高分辨窄谱依据结合能分为以下六种化学键峰进行高斯洛伦茨拟合：石墨态C～C(284.4eV)、非晶态C～C(284.8eV)、C＝O(285.5eV)、C～O(286.2eV)、C～Cl(287.2)和O～C＝O(288.2eV)。C1s分峰拟合见图4.12右列，需要指出的是，在软件的拟合过程中参照第三章的拟合方法，此外还进行了峰位的适当偏移等手段去拟合，然而最终得出的拟合结果显示，回收得到的碳纤维表面的C～Cl键含量仍然为零，说明回收得到的碳纤维表面的氯仅以吸附状态存在，并非以化学键结合。Using the software XPSPeak4.1, the C1s high-resolution narrow spectrum is divided into the following six chemical bond peaks according to the binding energy: Gauss Lorenz fitting: graphite state C~C (284.4eV), amorphous C~C (284.8eV) C=O (285.5 eV), C~O (286.2 eV), C-Cl (287.2), and O-C=O (288.2 eV). The C1s peak fitting is shown in the right column of Figure 4.12. It should be pointed out that in the fitting process of the software, the fitting method of Chapter 3 is used, and the appropriate offset of the peak position is also used to fit, but finally The obtained fitting results show that the content of C-Cl bond on the surface of the recovered carbon fiber is still zero, indicating that the chlorine on the surface of the recovered carbon fiber exists only in the adsorption state, and is not chemically bonded.
从表5.5和图43可以看到，回收得到的碳纤维和碳纤维原丝的C～Cl键含量均为0，说明在I20S 2.0A 1.0g/L参数条件下，所有温度梯度(包括25)回收得到的碳纤维都基本没有受到氯的腐蚀作用。相比碳纤维原丝，回收得到的碳纤维表面的石墨态及非晶态C～C键总含量都出现了下降，碳～氧键含量增多，其中C＝O键和C～O键含量都有小幅度上升，O～C＝O键含量则增大到2～3倍，含氧官能团的增多，加大了碳纤维和环氧树脂的化学键能作用，改善界面粘结性能。在40℃、60℃和75℃三个温度梯度碳纤维中，75℃的含氧官能团含量最少，60℃的含氧官能团含量略多一些，40℃的含氧官能团含量最多，说明温度越高碳纤维遭受的氧化程度越低，其与羧基连接的碳层因氧化而变脆的程度更低一些，因此拉伸强度损伤也较少，强度残余值更高。氧化程度过高还会造成碳纤维表面被刻蚀磨平，不利于表面微观结构，所以温度越低其界面剪切强度呈现变弱趋势。 It can be seen from Table 5.5 and Figure 43 that the C-Cl bond content of the recovered carbon fiber and carbon fiber precursor is 0, indicating that all temperature gradients (including 25) are recovered under the I20S 2.0 A 1.0g/L parameter. The carbon fibers are substantially free of corrosion by chlorine. Compared with the carbon fiber precursor, the total content of graphite and amorphous C-C bonds on the surface of the recovered carbon fiber decreased, and the content of carbon-oxygen bond increased, and the content of C=O bond and C~O bond were small. When the amplitude increases, the content of O~C=O bond increases to 2~3 times, and the increase of oxygen-containing functional groups increases the chemical bond energy of carbon fiber and epoxy resin, and improves the interface bonding performance. Among the three temperature gradient carbon fibers at 40 ° C, 60 ° C and 75 ° C, the content of oxygen-containing functional groups at 75 ° C is the least, the content of oxygen-containing functional groups at 60 ° C is slightly more, and the content of oxygen-containing functional groups at 40 ° C is the highest, indicating that the higher the temperature, the carbon fiber The lower the degree of oxidation suffered, the lower the degree of embrittlement of the carbon layer connected to the carboxyl group due to oxidation, so that the tensile strength is less damaged and the residual value of the strength is higher. If the degree of oxidation is too high, the surface of the carbon fiber will be etched and smoothed, which is not conducive to the surface microstructure. Therefore, the lower the temperature, the weaker the interface shear strength.
表5.5不同温度梯度的回收得到的碳纤维表面官能团含量(％)Table 5.5 Surface functional group content of carbon fiber obtained by recovery of different temperature gradients (%)
Figure PCTCN2018075923-appb-000019
Figure PCTCN2018075923-appb-000019
值得一提的是，在上述继续通电进行回收的实验中，所使用的电解装置可为本领域所熟知的各种点解池、电解槽等。It is worth mentioning that in the above experiments in which the power is continuously recovered, the electrolyzer used may be various decanting cells, electrolytic cells, and the like which are well known in the art.
作为回收容器的上述电解装置中装有预先设计的回收剂和催化剂相混合的化学溶液，其可以有效侵入所述待回收碳纤维增强树脂基复合材料中已经固化的树脂基体材料，并破坏其化学键，促使树脂发生膨胀和分解。所述化学溶液包括但不局限于水、液体乙醇、液体乙二醇、各种酸性溶液(包括但不局限于H 2SiO 3(偏硅酸)、HCN(氢氰酸)、H 2CO 3(碳酸)、HF(氢氟酸)、CH 3COOH(也作C 2H 4O 2乙酸，又叫醋酸)、H 2S(氢硫酸)、 HClO(次氯酸)、HNO 2(亚硝酸)、所有的有机酸、H 2SO 3(亚硫酸)等)、各种碱性溶液(包括但不局限于氢氧化钾溶液、氢氧化钠溶液等)、各种含氯离子溶液(包括但不局限于氯化钠溶液、氯化锌溶液等)。上述化学液体的特征为可以是上述各种溶液的混合溶液，各种溶液的浓度为0.001％-99.9％， The above electrolysis device as a recovery container is provided with a chemical solution in which a pre-designed recyclant and a catalyst are mixed, which can effectively invade the resin matrix material which has been solidified in the carbon fiber reinforced resin-based composite material to be recovered, and destroy the chemical bond thereof. Promotes expansion and decomposition of the resin. The chemical solution includes, but is not limited to, water, liquid ethanol, liquid ethylene glycol, various acidic solutions (including but not limited to H 2 SiO 3 (metasilicate), HCN (hydrocyanic acid), H 2 CO 3 (carbonic acid), HF (hydrofluoric acid), CH 3 COOH (also known as C 2 H 4 O 2 acetic acid, also known as acetic acid), H 2 S (hydrogen sulfuric acid), HClO (hypochlorous acid), HNO 2 (nitrous acid ), all organic acids, H 2 SO 3 (sulfurous acid), etc., various alkaline solutions (including but not limited to potassium hydroxide solution, sodium hydroxide solution, etc.), various chloride ion solutions (including but It is not limited to sodium chloride solution, zinc chloride solution, etc.). The above chemical liquid is characterized by being a mixed solution of the above various solutions, and the concentration of each solution is 0.001% to 99.9%,
根据本发明的该优选实施例，在通电过程中，所述待回收纤维增强树脂基复合材料中的纤维材料采用所熟知的方法与电源的阳极连接，以确保在回收过程中电路稳定运行。所述纤维材料与电源的阳极进行连接的方法包括但不局限于溶解树脂、磨去树脂等，以暴露出内部纤维材料，便于电路连接。According to this preferred embodiment of the invention, the fiber material in the fiber-reinforced resin-based composite material to be recycled is connected to the anode of the power source in a well-known manner during the energization to ensure stable operation of the circuit during the recovery process. The method of joining the fibrous material to the anode of the power source includes, but is not limited to, dissolving the resin, grinding away the resin, etc. to expose the internal fibrous material to facilitate electrical connection.
根据本发明的该优选实施例，通电过程中的阴极材料为熟知的导电材料，包括但不局限于钢材、铁、各种金属、各种形式石墨材料。In accordance with this preferred embodiment of the invention, the cathode material during energization is a well known conductive material including, but not limited to, steel, iron, various metals, various forms of graphite materials.
所述通电过程中，电流密度大小的特征在于与上述化学溶液的共同作用下，可以促使所述待回收碳纤维增强树脂基复合材料中的树脂材料发生膨胀和分解，同时不影响回收碳纤维的各种力学性能、导电性能、与树脂材料的粘接性能和再加工性能，同时不影响回收树脂材料的循环使用功能。所述电流密度大小根据所述待回收纤维增强树脂基复合材料暴露于所述化学溶液的表面积大小进行设计，范围为3333.3～15000mA/m 2，优选为3500～10000mA/m 2，更优选为5000～7500mA/m 2。 In the energization process, the current density is characterized by cooperating with the above chemical solution, which can promote expansion and decomposition of the resin material in the carbon fiber reinforced resin matrix composite material to be recovered, without affecting various types of carbon fiber recovery. Mechanical properties, electrical conductivity, adhesion to resin materials and reworkability, while not affecting the recycling function of recycled resin materials. The current density is designed according to the surface area of the fiber-reinforced resin matrix composite to be recovered exposed to the chemical solution, and ranges from 3333.3 to 15000 mA/m 2 , preferably from 3500 to 10000 mA/m 2 , more preferably 5000. ~7500mA/m 2 .
所述通电过程中，通电时间的特征是在与上述化学溶液和电流的共同作用下，可以促使所述待回收碳纤维增强树脂基复合材料中的树脂材料发生膨胀和分解，同时不影响回收碳纤维的各种力学性能、导电性能、与树脂材料的粘接性能和再加工性能，同时不影响回收树脂材料的循环使用功能。所述通电时间为0.5～200小时，优选为2-120小时，更优选为4–48小时。During the energization process, the energization time is characterized in that, in combination with the above chemical solution and current, the resin material in the carbon fiber reinforced resin matrix composite material to be recovered can be expanded and decomposed without affecting the recovery of the carbon fiber. Various mechanical properties, electrical conductivity, adhesion to resin materials and reworkability, while not affecting the recycling function of recycled resin materials. The energization time is from 0.5 to 200 hours, preferably from 2 to 120 hours, more preferably from 4 to 48 hours.
所述通电过程中，可采用各种本行业熟知的树脂老化方法加快回收速度，例如紫外线强化、超声强化、微波强化。During the energization process, various resin aging methods well known in the art can be used to speed up the recovery, such as ultraviolet ray strengthening, ultrasonic strengthening, and microwave strengthening.
在所述环保无损的纤维增强复合材料回收方法中，反应温度为25℃～75℃，优选为25℃～30℃或55℃～75℃。需注意的是，继续提高温度可以提高回收速度和质量，但同时也会提高对反应装置的要求，并提高生产成本。In the environmentally friendly non-destructive fiber reinforced composite material recovery method, the reaction temperature is from 25 ° C to 75 ° C, preferably from 25 ° C to 30 ° C or from 55 ° C to 75 ° C. It should be noted that continuing to increase the temperature can increase the recovery speed and quality, but at the same time increase the requirements of the reaction device and increase the production cost.
所述回收容器中的压力调整至预设大小，其与上述化学溶液、电流和温度的共同作用下，促使所述待回收碳纤维增强树脂基复合材料中的树脂材料发生膨胀和分解，同时不影响回收碳纤维的各种力学性能、导电性能、与树脂材料的粘接性能和再加工性能，同时不影响回收树脂材料的循环使用功能。其压力范围为0.5～20大气压，加压时间为0.5～200 小时。The pressure in the recovery container is adjusted to a predetermined size, which, together with the above chemical solution, current and temperature, causes the resin material in the carbon fiber reinforced resin matrix composite to be recovered to expand and decompose without affecting The various mechanical properties, electrical conductivity, adhesion to resin materials and reworkability of carbon fiber are recovered without affecting the recycling function of the recycled resin material. The pressure range is from 0.5 to 20 atm and the pressurization time is from 0.5 to 200 hours.
所述电化学回收方法中，阳极与阴极材料间距离对回收效果、回收速度和回收成本有影响，优选为1mm～1000mm，更优选为20mm～60mm。In the electrochemical recovery method, the distance between the anode and the cathode material has an effect on the recovery effect, the recovery rate, and the recovery cost, and is preferably from 1 mm to 1000 mm, and more preferably from 20 mm to 60 mm.
此外，所述电化学回收方法中，将碳纤维和树脂材料取出后分别保存，即可投入再生产。所述取出方法为各种所熟知的方法，包括且不局限于超声、干燥、加热等、以及各种方法的结合。Further, in the electrochemical recovery method, the carbon fiber and the resin material are taken out and stored separately, and then put into production. The method of removal is a variety of well known methods including, but not limited to, ultrasound, drying, heating, and the like, as well as combinations of various methods.
回收得到的碳纤维的长度是其再利用价值的一个重要因素。对回收得到的碳纤维，进行拉直，可以看到碳纤维的长度大约在80mm～100mm之间，而实验设计的样本回收部分长度为100mm，考虑到在剪取回收得到的碳纤维存在的长度损耗，可以知道在电化学回收过程碳纤维的长度基本没有损耗，表明在整个回收过程，碳纤维遭受的电化学氧化等损害非常轻微。The length of the recovered carbon fiber is an important factor in its reuse value. The carbon fiber recovered is straightened, and the length of the carbon fiber is about 80 mm to 100 mm. The length of the sample recovery part of the experimental design is 100 mm. Considering the length loss of the carbon fiber obtained by the shear recovery, It is known that there is substantially no loss in the length of the carbon fiber during the electrochemical recovery process, indicating that the damage caused by the electrochemical oxidation of the carbon fiber is very slight throughout the recovery process.
本领域技术人员会明白附图中所示的和以上所描述的本发明实施例仅是对本发明的示例而不是限制。Those skilled in the art will appreciate that the embodiments of the invention, which are illustrated in the drawings and described above, are merely illustrative and not limiting.
由此可以看到本发明目的可被充分有效完成。用于解释本发明功能和结构原理的该实施例已被充分说明和描述，且本发明不受基于这些实施例原理基础上的改变的限制。因此，本发明包括涵盖在附属权利要求书要求范围和精神之内的所有修改。It can thus be seen that the object of the invention can be fully and efficiently accomplished. The embodiment has been described and described in detail to explain the principles of the present invention and the invention is not to be construed as limited. Accordingly, the present invention includes all modifications that come within the scope and spirit of the appended claims.

Claims (10)

  1. 一种环保无损的纤维增强复合材料回收方法，其包括下述步骤：An environmentally friendly non-destructive fiber reinforced composite material recovery method comprising the following steps:
    (A)放置纤维增强树脂基复合材料在电解液中，其中该电解液含有重量比为0.5％～3％的可溶性盐酸盐；(A) placing a fiber-reinforced resin-based composite material in an electrolyte, wherein the electrolyte contains a soluble hydrochloride salt in a weight ratio of 0.5% to 3%;
    (B)对放置在电解液中的纤维增强树脂基复合材料通电，其中该纤维增强树脂基复合材料与电源的正极相连，并控制电流密度为3333.3～15000mA/m 2，其中所述电流密度的大小根据所述纤维增强树脂基复合材料暴露于所述电解液的表面积大小进行计算；和 (B) energizing the fiber-reinforced resin-based composite material placed in the electrolyte, wherein the fiber-reinforced resin-based composite material is connected to the positive electrode of the power source and controlling the current density to be 3333.3 to 15000 mA/m 2 , wherein the current density is The size is calculated according to the surface area of the fiber-reinforced resin-based composite exposed to the electrolyte; and
    (C)通电反应0.5～200小时后，自该电解液中取出生成的纤维回收物。(C) After the energization reaction is carried out for 0.5 to 200 hours, the produced fiber recovered product is taken out from the electrolytic solution.
  2. 根据权利要求1所述的方法，其特征在于，进一步包括下述步骤：The method of claim 1 further comprising the step of:
    (D)洗液清洗自电解液中取出的纤维回收物。(D) The washing liquid cleans the fiber recovered from the electrolyte.
  3. 根据权利要求1所述的方法，其特征在于，该电解液进一步含有0.5g/L～1.5g/L的催化剂A，其中该催化剂A为可溶性碱。The method according to claim 1, wherein the electrolyte further contains 0.5 g/L to 1.5 g/L of catalyst A, wherein the catalyst A is a soluble base.
  4. 根据权利要求2所述的方法，其特征在于，该电解液进一步含有0.5g/L～1.5g/L的催化剂A，其中该催化剂A为可溶性碱。The method according to claim 2, wherein the electrolyte further contains 0.5 g/L to 1.5 g/L of catalyst A, wherein the catalyst A is a soluble base.
  5. 根据权利要求1所述的方法，其特征在于，反应温度为25℃～75℃。The method of claim 1 wherein the reaction temperature is from 25 ° C to 75 ° C.
  6. 根据权利要求1所述的方法，其特征在于，所述纤维选自玻璃纤维、碳纤维、碳化硅纤维和PBO中的一种或几种。The method of claim 1 wherein said fibers are selected from one or more of the group consisting of glass fibers, carbon fibers, silicon carbide fibers, and PBO.
  7. 根据权利要求1所述的方法，其特征在于，该电解液含有重量比为1.5％～2.5％的可溶性盐酸盐和0.5g/L～1.5g/L的催化剂A，其中该催化剂A为可溶性碱，其中反应温度被控制为25℃～75℃。The method according to claim 1, wherein the electrolyte contains a soluble hydrochloride of 1.5% to 2.5% by weight and a catalyst A of 0.5 g/L to 1.5 g/L, wherein the catalyst A is soluble. A base in which the reaction temperature is controlled to be 25 ° C to 75 ° C.
  8. 根据权利要求1所述的方法，其特征在于，该电解液含有重量比为1.5％～2.5％的可溶性盐酸盐和0.5g/L～1.5g/L的催化剂A，其中该催化剂A为可溶性碱，反应温度被控制为55℃～75℃。The method according to claim 1, wherein the electrolyte contains a soluble hydrochloride of 1.5% to 2.5% by weight and a catalyst A of 0.5 g/L to 1.5 g/L, wherein the catalyst A is soluble. The base is reacted at a temperature of 55 ° C to 75 ° C.
  9. 一种用于纤维增强树脂基复合材料中回收纤维的电解液，其特征在于，其至少含有：An electrolyte for recovering fibers in a fiber-reinforced resin-based composite material, characterized in that it contains at least:
    重量比0.5％～3％的可溶性盐酸盐；a soluble hydrochloride salt having a weight ratio of 0.5% to 3%;
    0.5g/L～1.5g/L的催化剂A，其中该催化剂A为可溶性碱；和Catalyst A of 0.5 g/L to 1.5 g/L, wherein the catalyst A is a soluble base;
    80％～98％的水。80% to 98% water.
  10. 根据权利要求9所述的电解液，其特征在于，含有重量比为1.5％～2.5％的可溶 性盐酸盐，0.75g/L～1.25g/L的催化剂A和80％～97.5％的水。The electrolytic solution according to claim 9, which comprises a soluble hydrochloride of from 1.5% to 2.5% by weight, a catalyst A of from 0.75 g/L to 1.25 g/L, and water of from 80% to 97.5%.
PCT/CN2018/075923 2018-02-09 2018-02-09 Environmentally friendly non-destructive fiber-reinforced composite material recovering method WO2019153218A1 (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
PCT/CN2018/075923 WO2019153218A1 (en) 2018-02-09 2018-02-09 Environmentally friendly non-destructive fiber-reinforced composite material recovering method
CN201880000077.5A CN108323169B (en) 2018-02-09 2018-02-09 Environment-friendly and nondestructive fiber reinforced composite material recovery method

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/CN2018/075923 WO2019153218A1 (en) 2018-02-09 2018-02-09 Environmentally friendly non-destructive fiber-reinforced composite material recovering method

Publications (1)

Publication Number Publication Date
WO2019153218A1 true WO2019153218A1 (en) 2019-08-15

Family

ID=62895842

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/CN2018/075923 WO2019153218A1 (en) 2018-02-09 2018-02-09 Environmentally friendly non-destructive fiber-reinforced composite material recovering method

Country Status (2)

Country Link
CN (1) CN108323169B (en)
WO (1) WO2019153218A1 (en)

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN109518264B (en) * 2018-11-09 2020-03-10 深圳大学 Electro-catalysis heterogeneous catalysis recovery device based on CFRP material and control method thereof
CN109485912B (en) * 2018-11-09 2019-12-24 深圳大学 Electro-promotion heterogeneous catalytic device for recycling CFRP (carbon fiber reinforced plastics) and control method thereof
CN111995796A (en) * 2020-06-24 2020-11-27 艾达索高新材料芜湖有限公司 Electrical degradation recovery method of carbon fiber reinforced composite material
CN113736138B (en) * 2021-08-24 2022-04-12 同济大学 Recycling method of fiber reinforced composite material

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2005255835A (en) * 2004-03-11 2005-09-22 Hitachi Chem Co Ltd Method for separating carbon material/acid anhydride-cured epoxy resin composite
JP2013249386A (en) * 2012-05-31 2013-12-12 Institute Of National Colleges Of Technology Japan Method for recovering carbon fiber from carbon fiber composite material
CN104499039A (en) * 2014-12-09 2015-04-08 深圳大学 Recovery method of carbon fibers
WO2015180159A9 (en) * 2014-05-30 2016-02-18 East China University Of Science And Technology Methods and systems for recovering carbon fibers from objects
CN106750507A (en) * 2017-01-06 2017-05-31 东华大学 A kind of recovery method of carbon fiber enhancement resin base composite material

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2005255835A (en) * 2004-03-11 2005-09-22 Hitachi Chem Co Ltd Method for separating carbon material/acid anhydride-cured epoxy resin composite
JP2013249386A (en) * 2012-05-31 2013-12-12 Institute Of National Colleges Of Technology Japan Method for recovering carbon fiber from carbon fiber composite material
WO2015180159A9 (en) * 2014-05-30 2016-02-18 East China University Of Science And Technology Methods and systems for recovering carbon fibers from objects
CN104499039A (en) * 2014-12-09 2015-04-08 深圳大学 Recovery method of carbon fibers
CN106750507A (en) * 2017-01-06 2017-05-31 东华大学 A kind of recovery method of carbon fiber enhancement resin base composite material

Also Published As

Publication number Publication date
CN108323169A (en) 2018-07-24
CN108323169B (en) 2020-04-28

Similar Documents

Publication Publication Date Title
WO2019153218A1 (en) Environmentally friendly non-destructive fiber-reinforced composite material recovering method
Zhu et al. Recycling of carbon fibre reinforced plastics by electrically driven heterogeneous catalytic degradation of epoxy resin
Gkikas et al. Enhanced bonded aircraft repair using nano-modified adhesives
CN108286187B (en) Preparation method of graphene oxide modified carbon fiber initiated by silane coupling agent assisted electrophoretic deposition
Cai et al. Interfacial adhesion of recycled carbon fibers to polypropylene resin: Effect of superheated steam on the surface chemical state of carbon fiber
CN103895287B (en) A kind of method improving interface cohesion between marmem and polymeric material
TWI529204B (en) Composite material and manufacturing method thereof
Molitor et al. Adhesives bonding of a titanium alloy to a glass fibre reinforced composite material
CN114290000A (en) Preparation method of self-cleaning super-hydrophobic micro-nano double microstructure on metal surface
CN108707943B (en) Micro-arc oxidation electrolyte and application thereof in preparation of aluminum alloy plate with high surface hardness
Cheng et al. Adhesive bond strength enhancing between carbon fiber reinforced polymer and aluminum substrates with different surface morphologies created by three sulfuric acid solutions
Pan et al. A new approach to enhancing interlaminar strength and galvanic corrosion resistance of CFRP/Mg laminates
CN108624925B (en) Composite preparation method of magnesium alloy surface super-hydrophobic structure
CN1900384A (en) Process for removing part surface oxidized skin using supersonic wave and electrolytic combination
Chen et al. Sustainable recycling of intact carbon fibres from end-of-service-life composites
Pan et al. Effects of surface pre-treatments on mode I and mode II interlaminar strength of CFRP/Mg laminates
CN104309054B (en) Preparation method of metal-resin composite, and metal-resin composite
Sun et al. Effects of different surface treatments of aluminum alloy 5083 on interlaminar strength and anticorrosion properties of FMLs
Zhang et al. Reinforcement study of anodizing treatment with various temperatures on aluminum substrates for stronger adhesive bonding with carbon fiber composites
WO2020093503A1 (en) Electrically promoted heterogeneous catalytic device for recovering cfrp and control method thereof
CN105200401A (en) Carbon fiber surface metallization method
WO2019153217A1 (en) Method for recovering high-performance carbon fiber from inorganic cementing material
Ye et al. Highly enhanced joint strength of direct-injection-moulded polyphenylene sulphide-magnesium composite by PEO coated interface
CN109518264B (en) Electro-catalysis heterogeneous catalysis recovery device based on CFRP material and control method thereof
CN108624936A (en) A kind of method and its application changing magnesium substrates surface stress

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 18905021

Country of ref document: EP

Kind code of ref document: A1

NENP Non-entry into the national phase

Ref country code: DE

32PN Ep: public notification in the ep bulletin as address of the adressee cannot be established

Free format text: NOTING OF LOSS OF RIGHTS PURSUANT TO RULE 112(1) EPC (EPO FORM 1205 DATED 05.11.2020)

122 Ep: pct application non-entry in european phase

Ref document number: 18905021

Country of ref document: EP

Kind code of ref document: A1