CN115305598B - Core-shell structure shielding material and preparation method thereof - Google Patents

Core-shell structure shielding material and preparation method thereof Download PDF

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Publication number
CN115305598B
CN115305598B CN202211017241.8A CN202211017241A CN115305598B CN 115305598 B CN115305598 B CN 115305598B CN 202211017241 A CN202211017241 A CN 202211017241A CN 115305598 B CN115305598 B CN 115305598B
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core
shell
spinning
layer
solution
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CN115305598A (en
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高心蕊
何宗倍
李书良
宋鹏程
吴莹
杨静
喻冲
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Nuclear Power Institute of China
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Nuclear Power Institute of China
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    • D—TEXTILES; PAPER
    • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
    • D01F—CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
    • D01F8/00—Conjugated, i.e. bi- or multicomponent, artificial filaments or the like; Manufacture thereof
    • D01F8/04—Conjugated, i.e. bi- or multicomponent, artificial filaments or the like; Manufacture thereof from synthetic polymers
    • D01F8/10—Conjugated, i.e. bi- or multicomponent, artificial filaments or the like; Manufacture thereof from synthetic polymers with at least one other macromolecular compound obtained by reactions only involving carbon-to-carbon unsaturated bonds as constituent
    • D—TEXTILES; PAPER
    • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
    • D01D—MECHANICAL METHODS OR APPARATUS IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS
    • D01D5/00—Formation of filaments, threads, or the like
    • D01D5/0007—Electro-spinning
    • D01D5/0015—Electro-spinning characterised by the initial state of the material
    • D01D5/003—Electro-spinning characterised by the initial state of the material the material being a polymer solution or dispersion
    • D—TEXTILES; PAPER
    • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
    • D01D—MECHANICAL METHODS OR APPARATUS IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS
    • D01D5/00—Formation of filaments, threads, or the like
    • D01D5/28—Formation of filaments, threads, or the like while mixing different spinning solutions or melts during the spinning operation; Spinnerette packs therefor
    • D01D5/30—Conjugate filaments; Spinnerette packs therefor
    • D01D5/34—Core-skin structure; Spinnerette packs therefor
    • D—TEXTILES; PAPER
    • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
    • D01F—CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
    • D01F1/00—General methods for the manufacture of artificial filaments or the like
    • D01F1/02—Addition of substances to the spinning solution or to the melt
    • D01F1/09—Addition of substances to the spinning solution or to the melt for making electroconductive or anti-static filaments
    • D—TEXTILES; PAPER
    • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
    • D01F—CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
    • D01F1/00—General methods for the manufacture of artificial filaments or the like
    • D01F1/02—Addition of substances to the spinning solution or to the melt
    • D01F1/10—Other agents for modifying properties
    • D—TEXTILES; PAPER
    • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
    • D01F—CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
    • D01F8/00—Conjugated, i.e. bi- or multicomponent, artificial filaments or the like; Manufacture thereof
    • D01F8/04—Conjugated, i.e. bi- or multicomponent, artificial filaments or the like; Manufacture thereof from synthetic polymers
    • D01F8/08—Conjugated, i.e. bi- or multicomponent, artificial filaments or the like; Manufacture thereof from synthetic polymers with at least one polyacrylonitrile as constituent
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K9/00—Screening of apparatus or components against electric or magnetic fields
    • H05K9/0073—Shielding materials
    • H05K9/0081—Electromagnetic shielding materials, e.g. EMI, RFI shielding
    • 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
    • Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
    • Y02A30/00—Adapting or protecting infrastructure or their operation

Abstract

The invention discloses a core-shell structure shielding material and a preparation method thereof, wherein the core-shell structure shielding material comprises a core layer and a shell layer, and the shell layer is coaxially arranged outside the core layer; the core layer takes polyvinyl alcohol as a matrix and adopts carbon filler as electromagnetic shielding functional filler; the shell layer takes polyacrylonitrile as a matrix and heavy metal as ionization shielding function filler; the core-shell structure shielding material is prepared by adopting coaxial spinning for electrostatic spinning. The core-shell structure shielding material is prepared by adopting a coaxial spinning technology, so that the internal fibers of the shielding material can be uniformly distributed by coaxial spinning, and the degradation of the screen performance caused by the uneven internal fiber distribution of the shielding material is avoided, namely, the core-shell structure shielding material has higher electromagnetic shielding function and ionization shielding function.

Description

Core-shell structure shielding material and preparation method thereof
Technical Field
The invention relates to the technical field of functional materials, in particular to a shielding material with a core-shell structure and a preparation method thereof.
Background
The electrostatic spinning process is one simple and efficient nanometer fiber preparing technology, and is mainly to utilize polymer solution or melt to form jet flow under the action of strong electric field, stretch and bend to volatilize solvent and to obtain nanometer continuous fiber in the receiver. Unlike conventional spinning process, electrostatic spinning is one process of preparing superfine fiber under the action of high voltage electrostatic field to prepare continuous nanometer fiber.
Due to the spinneret structure limitations, conventional electrospinning can only be performed with a single spinning solution. The main drawbacks include (1) limited variety of spinnable materials. Many poorly spinnable polymers cannot be electrospun alone due to limitations such as poor solubility or compactness of the molecular chain. (2) it is not easy to perform multicomponent spinning. If the multi-component material is prepared based on the traditional electrostatic spinning, a plurality of raw materials can only be prepared into the same spinning solution for spinning. And therefore are limited by the compatibility of the components. Meanwhile, the phenomenon of uneven distribution inside the fiber is very easy to occur due to different interfacial tension of different groups.
The coaxial electrostatic spinning can drive 2 or more different spinning solutions under the electric field force to prepare the continuous composite nanofiber through the outlet of the coaxial spinneret. The spinnability requirement on the core layer material in coaxial spinning is not high, and the multi-component material can be conveniently prepared, so that the defects of the traditional electrostatic spinning can be overcome.
The core-shell structure fiber is a composite fiber with a double-layer or even multi-layer structure, and the inner core and the outer shell of the core-shell structure fiber respectively consist of components with different structures and physical properties. The core-shell structure fiber prepared by the coaxial electrostatic spinning technology can fully exert the characteristics of small diameter, large specific surface area, high porosity and the like of the electrospun fiber. By changing the core/shell component of the fiber and controlling the proportion of the core/shell, various nanofibers with different components and functions can be prepared. The core/shell structure fiber has the advantages of both core and shell components, is a novel functional fiber with performance superior to that of core or shell materials, has wide application prospect in various aspects, and has the main application fields: the tissue engineering aspect can be used as a degradable bracket, can promote wound healing, drug delivery and the like; the filtering aspect can be used as a filtering membrane; can be used for ion batteries in energy storage and generation; can be used for manufacturing optical or chemical sensors; and can also be applied to enzymes, catalysts and the like.
Disclosure of Invention
The invention aims to provide a shielding material with a core-shell structure, wherein the internal fibers of the shielding material are uniformly distributed, and the shielding material has a high electromagnetic shielding function and an ionization shielding function.
In addition, the invention also provides a preparation method for preparing the shielding material with the core-shell structure.
The invention is realized by the following technical scheme:
the shielding material comprises a core layer and a shell layer, wherein the shell layer is coaxially arranged outside the core layer;
the core layer takes polyvinyl alcohol as a matrix and adopts carbon filler as electromagnetic shielding functional filler; the shell layer takes polyacrylonitrile as a matrix and heavy metal as ionization shielding function filler;
the core-shell structure shielding material is prepared by adopting coaxial spinning for electrostatic spinning.
The shell layer and the core layer of the core-shell structure shielding material respectively have ionization shielding function and electromagnetic shielding function filling materials, so that the core-shell structure shielding material has both electromagnetic shielding function and ionization shielding function.
The core-shell structure shielding material is prepared by adopting a coaxial spinning technology, so that the internal fibers of the shielding material can be uniformly distributed by coaxial spinning, and the degradation of the screen performance caused by the uneven internal fiber distribution of the shielding material is avoided, namely, the core-shell structure shielding material has higher electromagnetic shielding function and ionization shielding function.
Further, the heavy metals include W, WO 3 、Bi 2 O 3 Or Gd 2 O 3 。
The heavy metals have ionization shielding function.
Further, the carbon-based filler includes multi-walled carbon nanotubes (MWNTs) or Graphene Oxide (GO).
The carbon-based fillers all have an electromagnetic shielding function.
Further, in the shell layer, the mass ratio of the ionization shielding functional filler is 5-15wt%.
Further, in the core layer, the mass ratio of the electromagnetic shielding functional filler is 1-5wt%.
Excessive addition of the filler may result in inability to spin, and thus, it is necessary to reasonably control the addition amount of the filler.
The preparation method of the core-shell structure shielding material comprises the following steps:
s1, preparing a nucleation layer spinning solution from polyvinyl alcohol and carbon-based filler;
s2, preparing polyacrylonitrile and heavy metal into a shell spinning solution;
s3, carrying out electrostatic spinning on the core layer spinning solution and the shell layer spinning solution by adopting coaxial spinning to obtain the shielding material with the core-shell structure: specifically: and respectively adding the prepared nuclear layer spinning solution and the prepared shell layer spinning solution into a syringe, connecting a special coaxial spinning needle, and carrying out electrostatic spinning. For the material system, a coaxial spinning needle is customized, the inner diameter is 0.35mm, and the outer diameter is 1.22mm.
The spinning parameters were set as: the core layer push rate is 0.55mL/h, and the shell layer push rate is 1.15mL/h; spinning voltage is 20kV; the receiving distance is 15cm; the ambient relative humidity was 60%. And after spinning, taking off the aluminum foil which receives the fiber on the collector, and vacuum drying for 24 hours to remove the solvent which is not volatilized in the spinning process.
The formula compositions of the core layer spinning solution and the shell layer spinning solution of the invention are shown in table 1:
TABLE 1
Figure BDA0003810987450000021
Figure BDA0003810987450000031
Further, in the step S1, the viscosity of the core layer spinning solution is controlled to be 100-190 mPa.S, and the content of the carbon-based filler is controlled to be 1-5wt%.
Further, in step S1, the preparation process of the core layer spinning solution is as follows:
preparing dispersion liquid of polyvinyl alcohol and carbon-based filler respectively, mixing the two dispersion liquid, performing ultrasonic treatment, and when the carbon-based filler is a multi-wall carbon nano tube, performing acid treatment on the multi-wall carbon nano tube, and then preparing the dispersion liquid of the multi-wall carbon nano tube.
Specifically, in order to improve the dispersibility of MWNTs in polyvinyl alcohol (PVA), it is necessary to subject them to an acid treatment. The conditions of the acid treatment are as follows: MWNT were sonicated in a mixed solution of hydrochloric acid and nitric acid at 55℃for 3 hours and then left to stand for one day. And (3) washing for 4-5 times by using deionized water until the PH value reaches neutral, and then putting the mixture into a vacuum oven to dry for 8 hours at 60 ℃. Adding the MWNT subjected to acid treatment into deionized water, and carrying out ultrasonic treatment for 5 hours to obtain MWNT dispersion liquid. A certain amount of polyvinyl alcohol (PVA) particles are dissolved in deionized water to obtain PVA dispersion liquid with a certain concentration, and the concentration of the PVA dispersion liquid is controlled to be 8.5 weight percent. And mixing the PVA dispersion liquid with the MWNT subjected to acid treatment, and performing ultrasonic treatment to obtain the MWNT/PVA solution. For GO filler, GO is not required to be pretreated, and after being added into deionized water for ultrasonic dispersion for 5 hours, the GO filler is poured into PVA dispersion liquid with the concentration of 8.5wt% prepared in advance, and ultrasonic treatment is continued for 3 hours, so that GO/PVA solution is obtained.
Further, in the step S2, the viscosity of the shell spinning solution is controlled to be 200-300 mPa.S, and the mass fraction of heavy metal in the shell spinning solution is 5-15wt%.
In order to ensure that the viscous stress of the shell layer solution to the core layer solution in the coaxial spinning process is enough to overcome the internal tension between the two solutions and ensure that the shell layer has enough surface tension to be balanced with the electric field force, the shell layer solution must have larger viscosity and be in a certain range so as to guide the core layer solution to better form fibers. Therefore, the mass fraction of the heavy metal filler in the shell spinning solution needs to be controlled to be 5-15wt%.
Further, in step S2, the preparation process of the shell spinning solution is as follows:
a certain amount of Polyacrylonitrile (PAN) powder was weighed and added to the N, N-Dimethylformamide (DMF) solution, and the PAN/DMF solution concentration was controlled to 15wt%. And then adding heavy metal fillers with different masses, stirring for 36 hours at a constant temperature of 65 ℃ on a magnetic stirrer, and standing for a period of time to eliminate bubbles to obtain the shell spinning solution.
The viscosity is determined by the type of filler and the amount of filler added; viscosity directly affects spinnability and spinning effect; either too high or too low a viscosity does not spin uniform fibers. In addition, the type of the material and the addition amount of the filler also influence the electromagnetic and ionization shielding effect. Therefore, the type and the addition amount of the filler are required to be reasonably controlled, so that the prepared shielding material with the core-shell structure not only can spin uniform fibers, but also has electromagnetic and ionization shielding effects.
Compared with the prior art, the invention has the following advantages and beneficial effects:
1. the core-shell structure shielding material provided by the invention uses the fillers with electromagnetic shielding effect and ionization shielding effect in the core layer and the shell layer respectively, so that the core-shell structure shielding material has electromagnetic ionization composite shielding function.
2. The core-shell structure shielding material adopts a coaxial spinning technology, reasonably designs a shell spinning solution and a core spinning solution for coaxial spinning, and matches parameters of coaxial spinning, so that the prepared core-shell structure shielding material has uniform distribution of internal fibers and higher electromagnetic shielding function and ionization shielding function.
3. The core-shell structure shielding material has strong designability and wearing comfort, and is suitable for being used as protective clothing and protective fabric.
4. The invention adopts the coaxial electrostatic spinning technology, and prepares the shielding material with the core-shell composite structure by regulating and controlling solution parameters such as shielding components, viscosity, electrospinning property and the like, flow speed, voltage and the like in the spinning process, so that the shielding material has electromagnetic shielding function and ionization shielding function.
Detailed Description
The present invention will be described in further detail with reference to the following examples, for the purpose of making the objects, technical solutions and advantages of the present invention more apparent, and the description thereof is merely illustrative of the present invention and not intended to be limiting.
Example 1:
the shielding material comprises a core layer and a shell layer, wherein the shell layer is coaxially arranged outside the core layer;
the core layer takes polyvinyl alcohol as a matrix and adopts multi-wall carbon nano tubes (MWNTs) as electromagnetic shielding functional fillersThe method comprises the steps of carrying out a first treatment on the surface of the The shell layer takes polyacrylonitrile as a matrix and adopts WO 3 As an ionization shielding function filler;
the core-shell structure shielding material is prepared by adopting coaxial spinning for electrostatic spinning.
The preparation method of the core-shell structure shielding material of the embodiment comprises the following steps:
s1, preparing a nuclear layer spinning solution (MWNT/PVA solution):
the concentration of MWNT in the MWNT/PVA solution is 1wt%, the viscosity of the spinning solution is 105 mPa.S, and the preparation process is as follows:
ultrasonically treating MWNT in a mixed solution of hydrochloric acid and nitric acid (the volume ratio of hydrochloric acid to nitric acid is 1:1) at 55 ℃ for 3 hours, and standing for one day; and (3) washing for 4-5 times by using deionized water until the pH value reaches neutrality, and then putting the mixture into a vacuum oven to dry for 8 hours at 60 ℃. Adding the MWNT subjected to acid treatment into deionized water, and carrying out ultrasonic treatment for 5 hours to obtain MWNT dispersion liquid. A PVA dispersion having a concentration of 8.5wt% was mixed with the acid-treated MWNT and then sonicated to give a MWNT/PVA solution.
S2, preparation of Shell spinning solution (WO) 3 PAN solution):
WO 3 WO in PAN solution 3 The concentration is 10wt%, the viscosity of the spinning solution is 245 mPa.S, and the preparation process is as follows:
polyacrylonitrile (PAN) was dissolved in N, N-Dimethylformamide (DMF), and the PAN/DMF solution concentration was controlled to 15wt%. After which a certain mass of WO is added 3 The concentration in the PAN/DMF solution was brought to 10wt%; and stirring at a constant temperature of 65 ℃ on a magnetic stirrer, and standing to obtain the shell spinning solution.
S3, carrying out electrostatic spinning on the core-layer spinning solution and the shell-layer spinning solution by adopting coaxial spinning to obtain a shielding material with a core-shell structure, and specifically:
and (3) carrying out electrostatic spinning on the prepared nuclear layer spinning solution and the prepared shell layer spinning solution by using a special needle head for special coaxial spinning. The spinning parameters were set as: the core layer push rate is 0.55mL/h, and the shell layer push rate is 1.15mL/h; spinning voltage is 20kV; the receiving distance is 15cm; the ambient relative humidity was 60%. And after spinning, vacuum drying is carried out for 24 hours, and the shielding material with the core-shell structure is obtained.
Example 2:
the preparation method of the core-shell structure shielding material of the embodiment comprises the following steps:
s1, preparing a nuclear layer spinning solution (MWNT/PVA solution):
the concentration of MWNT in the MWNT/PVA solution is 2.5wt%, the viscosity of the spinning solution is 135 mPa.S, and the preparation process is as follows:
ultrasonically treating MWNT in a mixed solution of hydrochloric acid and nitric acid (the volume ratio of hydrochloric acid to nitric acid is 1:1) at 55 ℃ for 3 hours, and standing for one day; and (3) washing for 4-5 times by using deionized water until the pH value reaches neutrality, and then putting the mixture into a vacuum oven to dry for 8 hours at 60 ℃. Adding the MWNT subjected to acid treatment into deionized water, and carrying out ultrasonic treatment for 5 hours to obtain MWNT dispersion liquid. A PVA dispersion having a concentration of 8.5wt% was mixed with the acid-treated MWNT and then sonicated to give a MWNT/PVA solution.
S2, preparing a shell spinning solution (W/PAN solution):
the W concentration in the W/PAN solution is 15wt%, the viscosity of the spinning solution is 294 mPa.S, and the preparation process is as follows:
polyacrylonitrile (PAN) was dissolved in N, N-Dimethylformamide (DMF), and the PAN/DMF solution concentration was controlled to 15wt%. Then adding a certain mass of W to make the concentration of W in the W/PAN solution 15wt%, stirring at constant temperature of 65 ℃ on a magnetic stirrer, and standing to obtain the shell spinning solution.
S3, carrying out electrostatic spinning on the core-layer spinning solution and the shell-layer spinning solution by adopting coaxial spinning to obtain a shielding material with a core-shell structure, and specifically:
and (3) carrying out electrostatic spinning on the prepared nuclear layer spinning solution and the prepared shell layer spinning solution by using a special needle head for special coaxial spinning. The spinning parameters were set as: the core layer push rate is 0.55mL/h, and the shell layer push rate is 1.15mL/h; spinning voltage is 20kV; the receiving distance is 15cm; the ambient relative humidity was 60%. And after spinning, vacuum drying is carried out for 24 hours, and the shielding material with the core-shell structure is obtained.
Example 3:
the electromagnetic shielding functional filler of the embodiment adopts Graphene Oxide (GO) and Bi 2 O 3 As an ionization shielding function filler。
The preparation method of the core-shell structure shielding material of the embodiment comprises the following steps:
s1, preparing a nuclear layer spinning solution (GO/PVA solution):
the GO concentration in the GO/PVA solution is 5wt%, the viscosity of the spinning solution is 187 mPa.S, and the preparation process is as follows:
adding a certain amount of GO into deionized water for ultrasonic dispersion for 5 hours, pouring the mixture into a pre-prepared PVA dispersion liquid with the concentration of 8.5wt%, and continuing ultrasonic treatment for 3 hours to obtain a GO/PVA solution.
S2, preparing a shell spinning solution (Bi) 2 O 3 PAN solution):
Bi 2 O 3 bi in PAN solution 2 O 3 The concentration is 5wt%, the viscosity of the spinning solution is 201 mPa.S, and the specific preparation process is as follows:
PAN was dissolved in DMF and the concentration of PAN/DMF solution was controlled to 15wt%. Adding Bi with a certain mass 2 O 3 To make Bi 2 O 3 Bi in PAN solution 2 O 3 The concentration is 5wt percent, and then the spinning solution of the shell layer is prepared after stirring and standing at the constant temperature of 65 ℃ on a magnetic stirrer.
S3, carrying out electrostatic spinning on the core-layer spinning solution and the shell-layer spinning solution by adopting coaxial spinning to obtain a shielding material with a core-shell structure, and specifically:
and (3) carrying out electrostatic spinning on the prepared nuclear layer spinning solution and the prepared shell layer spinning solution by using a special needle head for special coaxial spinning. The spinning parameters were set as: the core layer push rate is 0.55mL/h, and the shell layer push rate is 1.15mL/h; spinning voltage is 20kV; the receiving distance is 15cm; the ambient relative humidity was 60%. And after spinning, vacuum drying is carried out for 24 hours, and the shielding material with the core-shell structure is obtained.
Example 4:
the electromagnetic shielding functional filler of the embodiment adopts Graphene Oxide (GO) and Gd 2 O 3 As an ionization shielding function filler.
The preparation method of the core-shell structure shielding material of the embodiment comprises the following steps:
s1, preparing a nuclear layer spinning solution (GO/PVA solution):
the concentration of GO in the GO/PVA solution is 1.25wt%, the viscosity of the spinning solution is 122 mPa.S, and the preparation process is as follows:
adding a certain amount of GO into deionized water for ultrasonic dispersion for 5 hours, pouring the mixture into a pre-prepared PVA dispersion liquid with the concentration of 8.5wt%, and continuing ultrasonic treatment for 3 hours to obtain a GO/PVA solution.
S2, preparing a shell spinning solution (Gd) 2 O 3 PAN solution):
Gd 2 O 3 gd in PAN solution 2 O 3 The concentration is 7.5wt%, the viscosity of the spinning solution is 219 mPa.S, and the preparation process is as follows:
PAN was dissolved in DMF and the concentration of PAN/DMF solution was controlled to 15wt%. Then adding Gd with certain mass 2 O 3 Stirring at constant temperature of 65 ℃ on a magnetic stirrer, and standing to obtain the shell spinning solution.
S3, carrying out electrostatic spinning on the core-layer spinning solution and the shell-layer spinning solution by adopting coaxial spinning to obtain a shielding material with a core-shell structure, and specifically:
and (3) carrying out electrostatic spinning on the prepared nuclear layer spinning solution and the prepared shell layer spinning solution by using a special needle head for special coaxial spinning. The spinning parameters were set as: the core layer push rate is 0.55mL/h, and the shell layer push rate is 1.15mL/h; spinning voltage is 20kV; the receiving distance is 15cm; the ambient relative humidity was 60%. And after spinning, vacuum drying is carried out for 24 hours, and the shielding material with the core-shell structure is obtained.
Comparative example 1:
the electromagnetic shielding functional filler of the comparative example adopts MWNT and Bi 2 O 3 As an ionization shielding function filler.
The preparation method of the comparative example comprises the following steps:
s1, preparing a nuclear layer spinning solution (MWNT/PVA solution):
the concentration of MWNT in the MWNT/PVA solution is 8wt%, the viscosity of the spinning solution is 288 mPa.S, and the preparation process is as follows:
ultrasonically treating MWNT in a mixed solution of hydrochloric acid and nitric acid (the volume ratio of hydrochloric acid to nitric acid is 1:1) at 55 ℃ for 3 hours, and standing for one day; and (3) washing for 4-5 times by using deionized water until the pH value reaches neutrality, and then putting the mixture into a vacuum oven to dry for 8 hours at 60 ℃. Adding the MWNT subjected to acid treatment into deionized water, and carrying out ultrasonic treatment for 5 hours to obtain MWNT dispersion liquid. A PVA dispersion having a concentration of 8.5wt% was mixed with the acid-treated MWNT and then sonicated to give a MWNT/PVA solution.
S2, preparing a shell spinning solution (Bi) 2 O 3 PAN solution):
Bi 2 O 3 bi in PAN solution 2 O 3 The concentration is 5wt%, the viscosity of the spinning solution is 201 mPa.S, and the specific preparation process is as follows:
PAN was dissolved in DMF and the concentration of PAN/DMF solution was controlled to 15wt%. Adding Bi with a certain mass 2 O 3 Stirring at constant temperature of 65 ℃ on a magnetic stirrer, and standing to obtain the shell spinning solution.
S3, carrying out electrostatic spinning on the core layer spinning solution and the shell layer spinning solution by adopting coaxial spinning, and specifically:
and (3) carrying out electrostatic spinning on the prepared nuclear layer spinning solution and the prepared shell layer spinning solution by using a special needle head for special coaxial spinning. The spinning parameters were set as: the core layer push rate is 0.55mL/h, and the shell layer push rate is 1.15mL/h; spinning voltage is 20kV; the receiving distance is 15cm; the ambient relative humidity was 60%. After spinning, vacuum drying is carried out for 24 hours.
And observing the cross section of the fiber through a scanning electron microscope, and finding that a complete core-shell structure is not formed. The shell layer does not completely encapsulate the core layer, but rather a mixture of core and shell materials occurs. The main reasons are that the core layer has high viscosity and the shell layer has low viscosity, a composite Taylor cone cannot be formed at a spray head, and then the complete core-shell structure fiber cannot be stretched from the Taylor cone under the action of an electric field.
Comparative example 2:
the electromagnetic shielding function filler of this comparative example adopts GO, and W is used as the ionization shielding function filler.
The preparation method of the comparative example comprises the following steps:
s1, preparing a nuclear layer spinning solution (GO/PVA solution):
the concentration of GO in the GO/PVA solution is 3wt%, the viscosity of the spinning solution is 151 mPa.S, and the preparation process is as follows:
adding a certain amount of GO into deionized water for ultrasonic dispersion for 5 hours, pouring the mixture into a pre-prepared PVA dispersion liquid with the concentration of 8.5wt%, and continuing ultrasonic treatment for 3 hours to obtain a GO/PVA solution.
S2, preparing a shell spinning solution (W/PAN solution):
the W concentration in the W/PAN solution is 19wt%, the viscosity of the spinning solution is 345 mPa.S, and the preparation process is as follows:
PAN was dissolved in DMF and the concentration of PAN/DMF solution was controlled to 15wt%. Then adding a certain mass of W, stirring at a constant temperature of 65 ℃ on a magnetic stirrer, and standing to obtain the shell spinning solution.
S3, carrying out electrostatic spinning on the core-layer spinning solution and the shell-layer spinning solution by adopting coaxial spinning to obtain a shielding material with a core-shell structure, and specifically:
and (3) carrying out electrostatic spinning on the prepared nuclear layer spinning solution and the prepared shell layer spinning solution by using a special needle head for special coaxial spinning. The spinning parameters were set as: the core layer push rate is 0.55mL/h, and the shell layer push rate is 1.15mL/h; spinning voltage is 20kV; the receiving distance is 15cm; the ambient relative humidity was 60%.
In this comparative example, the content of the shell filler is too high, resulting in a small charge amount in the shell solution, and the charge cannot be accumulated under the action of an electrostatic field, so that a fiber with a complete shape cannot be obtained, and thus performance test cannot be performed.
Comparative example 3:
the electromagnetic shielding filler of this comparative example was GO, WO was used 3 As an ionization shielding function filler.
The preparation method of the comparative example comprises the following steps:
s1, preparing a nuclear layer spinning solution (GO/PVA solution):
the concentration of GO in the GO/PVA solution is 0.5wt%, the viscosity of the spinning solution is 48 mPa.S, and the preparation process is as follows:
adding a certain amount of GO into deionized water for ultrasonic dispersion for 5 hours, pouring the mixture into a pre-prepared PVA dispersion liquid with the concentration of 8.5wt%, and continuing ultrasonic treatment for 3 hours to obtain a GO/PVA solution.
S2, preparation of Shell spinning solution (WO) 3 PAN solution):
WO 3 WO in PAN solution 3 The concentration is 2.5wt%, the viscosity of the spinning solution is 117 mPa.S, and the preparation process is as follows:
polyacrylonitrile (PAN) was dissolved in N, N-Dimethylformamide (DMF), and the PAN/DMF solution concentration was controlled to 15wt%. After which a certain mass of WO is added 3 The concentration in the PAN/DMF solution was brought to 10wt%; and stirring at a constant temperature of 65 ℃ on a magnetic stirrer, and standing to obtain the shell spinning solution.
S3, carrying out electrostatic spinning on the core-layer spinning solution and the shell-layer spinning solution by adopting coaxial spinning to obtain a shielding material with a core-shell structure, and specifically:
and (3) carrying out electrostatic spinning on the prepared nuclear layer spinning solution and the prepared shell layer spinning solution by using a special needle head for special coaxial spinning. The spinning parameters were set as: the core layer push rate is 0.55mL/h, and the shell layer push rate is 1.15mL/h; spinning voltage is 20kV; the receiving distance is 15cm; the ambient relative humidity was 60%. After spinning, vacuum drying is carried out for 24 hours.
The X-ray shielding properties of the core-shell structured shielding materials prepared in example 1-example 4, comparative example 1, comparative example 3 are shown in table 2:
the test conditions were:
1) The experimental device comprises: si (Li) detector, matching spectrometer, X-ray machine, excitation sample (iron sheet, copper sheet, lead sheet, molybdenum sheet);
2) Experimental conditions: high pressure: 25KV, current: 50 μA, high probe pressure: -1000V, detector gain: 0.7505 ×32.
TABLE 2
Figure BDA0003810987450000091
As can be seen from the data in table 2:
1) The invention not only can spin uniform fiber, but also has ionization shielding effect.
2) From a comparison of the data of comparative example 1 and example 3, it can be seen that: b of bothi 2 O 3 The content was the same, but in comparative example 1, no complete core-shell structure was formed, i.e., the ionization shielding substance Bi in the shell of the outer layer 2 O 3 And not completely distributed over the fibers, the ionization barrier performance is inferior to the examples.
3) Comparative examples 1 and 3, although WO is selected 3 As ionizing shielding filler, but WO in comparative example 3 3 The content is low, so that the ionization shielding performance is poor, and the material cannot be used as an ionization shielding material.
The electromagnetic shielding properties of the core-shell structure shielding materials prepared in example 1 to example 4 and comparative example 1 are shown in table 3:
TABLE 3 Table 3
Sequence number Fabric type SE(dB)
1 Example 1 25
2 Example 2 43
3 Example 3 64
4 Example 4 33
5 Comparative example 1 40
6 Comparative example 3 11
From the data in Table 3, it can be seen that:
1) The electromagnetic shielding fillers in examples 1, 2 and 4 are added less, so the electromagnetic shielding performance is more general.
2) Although the electromagnetic shielding filler was added in a large amount in comparative example 1, the electromagnetic shielding performance was relatively general because the filler distribution was discontinuous, and a complete conductive path could not be formed.
3) In comparative examples 4 and 3, GO was selected as the electromagnetic shielding filler, but the GO content in comparative example 3 was low, so that the electromagnetic shielding performance was poor and it could not be used as an electromagnetic shielding material. (it is generally considered that electromagnetic shielding effectiveness exceeding 20dB can be used as electromagnetic shielding material)
The comprehensive analysis of electromagnetic and ionization shielding performance shows that the core-shell structure shielding fiber prepared by the invention has better electromagnetic ionization comprehensive shielding performance.
The foregoing description of the embodiments has been provided for the purpose of illustrating the general principles of the invention, and is not meant to limit the scope of the invention, but to limit the invention to the particular embodiments, and any modifications, equivalents, improvements, etc. that fall within the spirit and principles of the invention are intended to be included within the scope of the invention.

Claims (4)

1. The shielding material with the core-shell structure is characterized by comprising a core layer and a shell layer, wherein the shell layer is coaxially arranged outside the core layer;
the core layer takes polyvinyl alcohol as a matrix and adopts carbon filler as electromagnetic shielding functional filler; the shell layer takes polyacrylonitrile as a matrix and heavy metal as ionization shielding function filler;
the heavy metals include W, WO 3 、Bi 2 O 3 Or Gd 2 O 3 ；
The carbon-based filler comprises multi-wall carbon nanotubes or graphene oxide;
the core-shell structure shielding material is prepared by adopting coaxial spinning for electrostatic spinning;
in the shell layer, the mass ratio of the ionization shielding function filler is 5-15 wt%; the viscosity of the shell spinning solution used for preparing the shell is controlled to be 200-300 mPa.S; in the core layer, the mass ratio of the electromagnetic shielding functional filler is 1-5wt%, and the viscosity of the core layer spinning solution used for preparing the core layer is controlled to be 100-190 mPa.S.
2. The method for preparing the shielding material of the core-shell structure according to claim 1, comprising the steps of:
s1, preparing a nucleation layer spinning solution from polyvinyl alcohol and a carbon-based filler, wherein the viscosity of the nucleation layer spinning solution is controlled to be 100-190 mPa.S, and the content of the carbon-based filler is controlled to be 1-5 wt%;
s2, preparing polyacrylonitrile and heavy metal into a shell spinning solution; the viscosity of the shell spinning solution is controlled to be 200-300 mPa.S, and the mass fraction of heavy metal in the shell spinning solution is 5-15 wt%;
and S3, carrying out electrostatic spinning on the core-layer spinning solution and the shell-layer spinning solution by adopting coaxial spinning to obtain the shielding material with the core-shell structure.
3. The method for preparing a core-shell structure shielding material according to claim 2, wherein in step S1, the preparation process of the core-layer spinning solution is as follows:
preparing dispersion liquid of polyvinyl alcohol and carbon-based filler respectively, mixing the two dispersion liquid, performing ultrasonic treatment, and when the carbon-based filler is a multi-wall carbon nano tube, performing acid treatment on the multi-wall carbon nano tube, and then preparing the dispersion liquid of the multi-wall carbon nano tube.
4. The method for preparing a core-shell structure shielding material according to claim 2, wherein in step S2, the preparation process of the shell spinning solution is as follows:
and adding polyacrylonitrile powder into the N, N-dimethylformamide solution to obtain PAN/DMF solution, adding heavy metal into the PAN/DMF solution, and stirring at constant temperature to obtain the shell spinning solution.
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