CN102296459A - Method for improving strength of carbon fiber - Google Patents
Method for improving strength of carbon fiber Download PDFInfo
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- CN102296459A CN102296459A CN 201010211410 CN201010211410A CN102296459A CN 102296459 A CN102296459 A CN 102296459A CN 201010211410 CN201010211410 CN 201010211410 CN 201010211410 A CN201010211410 A CN 201010211410A CN 102296459 A CN102296459 A CN 102296459A
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Abstract
The invention relates to a method for improving the strength of carbon fiber, and an electrostatic spraying method is adopted for coating carbon nano-tubes on the surface of the carbon fiber for compensating for the structure defects on the surface of the carbon fiber. The method comprises the following steps: using dispersion liquid to prepare the carbon nano-tubes into spraying solution, wherein the dispersion liquid is one of dimethyl formamide, acetone or ethanol and the content of the carbon nano-tubes in the spraying solution is 10-40g/L; and applying positive pole static electricity of 10-40kV on the spraying solution, setting out and grounding a carbon fiber tow for constituting a spraying solution receptor, and then spraying the spraying solution on the surface of the carbon fiber through electrostatic spraying, wherein the spraying quantity is controlled to be 1000: (0.5-10) in weight ratio of the carbon fiber to the carbon nano-tubes. The tensile strength of the carbon fiber after repair can be improved by above 97%; compared with the prior art, the method has the advantages of simple process, low cost, high efficiency, good effect of repairing the structure defects on the surface of the carbon fiber and the like, and is easy to realize industrialized application.
Description
Technical field
The present invention relates to a kind of method that increases carbon fiber strength, particularly adopt electrostatic spray that CNT is coated on carbon fiber surface to remedy the method for its surface texture defective and then increase carbon fiber strength.
Background technology
Carbon fiber almost can be considered to specific strength and the highest nonmetallic materials of specific modulus up to now, has been widely used in communications and transportation, athletic sports appliance, building and even aerospace field.Yet in fact the intensity of existing carbon fiber product and elastic modelling quantity exist very big gap with theoretical value, are example with the TENSILE STRENGTH, only are 3～5% of theoretical value generally.The basic reason that causes this phenomenon is a carbon fiber ubiquity fault of construction, carbon fiber as acrylonitrile group prepares with solution spinning because of its precursor especially, fiber is followed the effusion of solvent in solidification forming, the carbon fiber structural defective that finally makes is particularly serious.The fault of construction of carbon fiber comprises internal flaw (as the cavity) and blemish (as depression and crackle), and blemish is to cause the principal element of intensity decreases, its weight even can reach 90%.
In the prior art, people pass through to improve former yarn quality, improve the formation in the hope of the minimizing fault of construction such as pre-oxidation and carbonization technique morely, but produce little effect with regard to the improvement ratio of carbon fiber product intensity actual value and theoretical value gap." Nanotube composite carbon fibers " [" Applied Physics Letters " 1999,75 (7), P1329～1334] literary composition discloses a kind of co-blended spinning method that adopts Single Walled Carbon Nanotube sneaked into the method that precursor prepares asphalt base carbon fiber, to improve the mechanical property and the electrical property of carbon fiber, it is said that the asphaltic base carbon fiber reinforce plastic TENSILE STRENGTH and the elastic modelling quantity that contain the 5wt.% Single Walled Carbon Nanotube have improved 90% and 150% respectively.Yet this method has mainly remedied carbon fiber internal structure defective, acts on limited to remedying of surperficial fault of construction.In addition, the surface energy of CNT is very big, be scattered in the spinning solution by no means easyly equably, uses so be difficult to realize large-scale industrialization.The trial of also visible " later stage reparation " in addition discloses a kind of manufacture method of high-strength carbon fiber as Chinese patent application 03137023.3, and it is with CH
4Feed plasma generator with Ar with certain proportioning, satisfy carbon fiber by the plasma high-temperature district, carry out the graphited while at carbon fiber, methane cracking under the effect of high-temperature electric arc plasma produces the carburizing of ion carbon to carbon fiber surface and inside, thereby remedies its fault of construction.The good news is that very it is stronger to the specific aim of carbon fiber surface fault of construction reparation, but " reparation " efficient of obvious this method is not ideal enough, the cost of industrial applications can be higher.
Summary of the invention
The invention provides a kind of method that increases carbon fiber strength, it has adopted a kind of method of " later stage reparation " newly to remedy the carbon fiber surface fault of construction, and then increases the intensity of carbon fiber.Effect and efficient are all very good, are suitable for industrializing implementation, have solved the technical problem that prior art exists preferably.
Below be the concrete technical scheme of the present invention:
A kind of method that increases carbon fiber strength, it adopts electrostatic spray that CNT is coated on carbon fiber surface to remedy its surface texture defective.This method comprises:
CNT is mixed with spray coating liquor with dispersion liquid, and dispersion liquid is a kind of in dimethyl formamide, the acetone or alcohol, and the content of CNT is 10～40g/L in the spray coating liquor;
Spray coating liquor applies the anodal static of 10～40kV, the open and flat and ground connection formation spray coating liquor acceptor of carbon fibre tow;
By electrostatic spraying spray coating liquor is sprayed at carbon fiber surface, jet length is controlled to be 5～30cm, and in the weight ratio of carbon fiber and CNT, the quantity for spray of CNT is controlled to be 1000 on the carbon fiber: (0.5～10).
Above-mentioned CNT can be Single Walled Carbon Nanotube and/or multi-walled carbon nano-tubes, and length is generally 10～30 μ m; The content of CNT is preferably 15～30g/L in the spray coating liquor.
Above-mentioned jet length preferably is controlled to be 10～20cm; Spray coating liquor preferably applies the anodal static of 20～30kV; In the weight ratio of carbon fiber and CNT, the quantity for spray of CNT preferably is controlled to be 1000 on the carbon fiber: (3～8).
One of key problem in technology of the present invention is that this desirable repair materials of selection CNT is implemented the reparation to the carbon fiber surface fault of construction.It is generally acknowledged when carbon fiber is subjected to external force and do the time spent, the easiest breakaway poing that becomes fiber of the crackle of fiber surface, under external force, the tip of crackle will produce stress and concentrate, owing to lack plastic deformation, the stress of concentrating is difficult for relaxing and discharges, and can only form new surface with crackle bamboo telegraph and expansion, finally causes the carbon fiber fracture.The diameter of CNT is a nanoscale, and far below the carbon fiber surface crack size, under the electrostatic spraying electric field action, CNT is very easy to be filled in the crackle.Have characteristics such as specific area is big, surface energy is high, surface atom proportion height because of CNT, intermolecular force between CNT and CNT, CNT and the carbon fiber (Van der Waals force) is high, the load of crackle one side can be passed to the opposite side of crackle by the CNT that is filled in the crackle fast, and then the stress that can effectively suppress cracks is concentrated.In addition, CNT has great draw ratio and very excellent mechanical strength, the easily entanglement mutually of CNT that is filled in the carbon fiber surface fault of construction and is coated on the surface, form physical crosslinking and constitute network structure, when being subjected to external force, carbon fiber does the time spent, this network structure has been shared external force load effectively, makes load in length and breadth to even diffusion, and this has further improved the overall load ability to bear of carbon fiber.
Yet, just, very easily gather because the surface energy and the draw ratio of CNT is very big, thus CNT before coating self even dispersion and apply after even distribution be to reach above-mentioned desirable reparation state necessary precondition.Another key problem in technology of the present invention is to utilize this technological means of electrostatic spraying dexterously, and is that suitable spraying condition is determined on the basis with a large amount of experiments, thereby has successfully realized above-mentioned target.After the spray coating liquor that contains CNT has applied high-voltage positive electrode static, spray coating liquor outpour a little and the carbon fiber of ground connection between form a high-voltage electrostatic field, after spray coating liquor outpours,, be vaporific dispersion with dispersion liquid thereby repel mutually because of CNT band like charges.Positively charged spray coating liquor droplet sprays to carbon fiber under the effect of electrostatic field force, follows the volatilization of solvent, and CNT is coated on carbon fiber surface equably.Suitable quantity for spray is very important, the very few effect that is difficult to manifest enhancing, the excessive mechanical property that then can have influence on carbon fiber self.
Although the diameter of single wall or multi-walled carbon nano-tubes is different, but its difference still belongs to very small for the size of carbon fiber surface fault of construction after all, simultaneously this species diversity is unlikely to cause the condition of repair process to change to some extent, so no matter the CNT of single wall or many walls uses separately or both use with the mixing of any ratio and all do not influence realization of the present invention.Just higher relatively because of the mechanical property of Single Walled Carbon Nanotube, and be easier to tangle and produce more network node, experimental data shows that the usage ratio when Single Walled Carbon Nanotube increases, strengthening effect can improve thereupon.
Coating procedure can carry out after carbon fiber is made, and also can carry out in that the carbonisation of precursor is online, and apply operation this moment preferably between carbonation process and last glue process.It is 0.5～5min only usually that carbon fiber reaches the necessary required time of staying of CNT coated weight, and the tensile strength of carbon fibers of gaining in strength after the reparation can improve more than 97%.Therefore compared with prior art, the present invention has advantages such as technology is simple, cost is low, efficient is high, the repairing effect of carbon fiber surface fault of construction is good, and is easy to realize industrial applications.
Below will the invention will be further described by specific embodiment.
The specific embodiment
[embodiment 1～12]
One, the preparation of spray coating liquor:
Getting commercially available CNT places container to mix with dispersion liquid in required ratio, adopting frequency then is that the ultrasonic wave of 25kHz carries out ultrasonic concussion, continue about 5 hours, CNT is fully disperseed in dispersion liquid, the spray coating liquor that is mixed with desired concn then is standby.The spray coating liquor composition of each embodiment sees Table 1, and the diameter of the Single Walled Carbon Nanotube that is adopted is distributed as 0.5～5nm, and the diameter of multi-walled carbon nano-tubes is distributed as 10～20nm, and distribution of lengths is 10～30 μ m.
Table 1.
| CNT | Dispersion liquid | Content of carbon nanotubes (g/L) | |
| Embodiment 1 | Single Walled Carbon Nanotube | Dimethyl formamide | 40 |
| Embodiment 2 | Single Walled Carbon Nanotube | Dimethyl formamide | 38 |
| Embodiment 3 * | Single Walled Carbon Nanotube and multi-walled carbon nano-tubes | Dimethyl formamide | 25 |
| Embodiment 4 | Multi-walled carbon nano-tubes | Dimethyl formamide | 22 |
| Embodiment 5 | Single Walled Carbon Nanotube | Acetone | 33 |
| Embodiment 6 | Single Walled Carbon Nanotube | Acetone | 30 |
| Embodiment 7 * | Single Walled Carbon Nanotube and multi-walled carbon nano-tubes | Acetone | 21 |
| Embodiment 8 | Multi-walled carbon nano-tubes | Acetone | 18 |
| Embodiment 9 | Single Walled Carbon Nanotube | Ethanol | 29 |
| Embodiment 10 | Single Walled Carbon Nanotube | Ethanol | 26 |
| Embodiment 11 | Multi-walled carbon nano-tubes | Ethanol | 15 |
| Embodiment 12 | Multi-walled carbon nano-tubes | Ethanol | 10 |
* the weight ratio of Single Walled Carbon Nanotube and multi-walled carbon nano-tubes is 1: 1.
Two, carbon fiber surface electrostatic spraying CNT
Adopt self-produced PAN base carbon fibre without gluing to test, the specification of carbon fiber is: 3K, single fiber average diameter 7.5 μ m.The roller traction of carbon fibre tow with a pair of rotation launched, and be tiled on the stainless convoying curtain, convoying curtain ground connection makes carbon fibre tow constitute the spray coating liquor acceptor, and the carbon fibre tow translational speed is controlled at 1～10m/min.The spray coating liquor that one spininess head is set above convoying curtain outpours device, and the syringe needle number is 100～500, and pinhole diameter is 0.2～1mm, syringe needle spacing 10～20mm, and syringe needle is placed side by side with the carbon fibre tow direct of travel is vertical.Syringe needle connects with the positive pole of HV generator so that the spray coating liquor that outpours via syringe needle is applied high-voltage positive electrode static by lead, is outpoured the spray coating liquor of the foregoing description 1～12 preparation quantitatively respectively by syringe needle by measuring pump.Change electrostatic potential, convoying curtain translational speed and spray coating liquor and outpour speed (regulating the quantity for spray of CNT on the carbon fiber with this), the distance that changes syringe needle and convoying curtain simultaneously is to regulate jet length.The spraying condition of each embodiment control sees Table 2.
Measure TENSILE STRENGTH and the tensile strength calculated raising rate of carbon fiber before and after CNT applies, the results are shown in Table 2.
Table 2.
| Electrostatic potential (kV) | Jet length (cm) | Quantity for spray (weight ratio) | TENSILE STRENGTH I (GPa) | TENSILE STRENGTH II (GPa) | TENSILE STRENGTH raising rate (%) | |
| Embodiment 1 | 40 | 15 | 1000∶10.0 | 3.02 | 7.01 | 132.1 |
| Embodiment 2 | 37 | 18 | 1000∶9.0 | 3.04 | 6.97 | 129.2 |
| Embodiment 3 | 26 | 11 | 1000∶4.0 | 3.15 | 6.64 | 110.8 |
| Embodiment 4 | 23 | 12 | 1000∶2.0 | 3.17 | 6.59 | 107.8 |
| Embodiment 5 | 35 | 14 | 1000∶8.0 | 3.08 | 6.98 | 126.6 |
| Embodiment 6 | 32 | 16 | 1000∶6.0 | 3.12 | 6.83 | 118.9 |
| Embodiment 7 | 22 | 10 | 1000∶1.0 | 3.14 | 6.47 | 106.0 |
| Embodiment 8 | 20 | 20 | 1000∶3.0 | 3.12 | 6.32 | 102.5 |
| Embodiment 9 | 30 | 13 | 1000∶7.0 | 3.11 | 6.75 | 117.0 |
| Embodiment 10 | 28 | 17 | 1000∶5.0 | 3.15 | 6.71 | 113.0 |
| Embodiment 11 | 14 | 5 | 1000∶0.9 | 3.09 | 6.17 | 99.6 |
| Embodiment 12 | 10 | 30 | 1000∶0.5 | 3.01 | 5.95 | 97.6 |
Annotate: 1) weight ratio of quantity for spray is a carbon fiber: CNT;
2) TENSILE STRENGTH I, TENSILE STRENGTH II are respectively the TENSILE STRENGTH of carbon fiber before and after CNT applies;
3) TENSILE STRENGTH raising rate=[(TENSILE STRENGTH II-TENSILE STRENGTH I)/TENSILE STRENGTH I] * 100%.
Claims (6)
1. method that increases carbon fiber strength, its adopts electrostatic spray that CNT is coated on carbon fiber surface to remedy its surface texture defective, it is characterized in that this method comprises:
CNT is mixed with spray coating liquor with dispersion liquid, and dispersion liquid is a kind of in dimethyl formamide, the acetone or alcohol, and the content of CNT is 10～40g/L in the spray coating liquor;
Spray coating liquor applies the anodal static of 10～40kV, the open and flat and ground connection formation spray coating liquor acceptor of carbon fibre tow;
By electrostatic spraying spray coating liquor is sprayed at carbon fiber surface, jet length is controlled to be 5～30cm, and in the weight ratio of carbon fiber and CNT, the quantity for spray of CNT is controlled to be 1000 on the carbon fiber: (0.5～10).
2. the method for increase carbon fiber strength according to claim 1 is characterized in that described CNT is Single Walled Carbon Nanotube and/or multi-walled carbon nano-tubes, and length is 10～30 μ m.
3. the method for increase carbon fiber strength according to claim 1 and 2, the content that it is characterized in that CNT in the described spray coating liquor is 15～30g/L.
4. the method for increase carbon fiber strength according to claim 1 is characterized in that described jet length is controlled to be 10～20cm.
5. the method for increase carbon fiber strength according to claim 1 is characterized in that described spray coating liquor applies the anodal static of 20～30kV.
6. the method for increase carbon fiber strength according to claim 1 is characterized in that the weight ratio in carbon fiber and CNT, and the quantity for spray of CNT is controlled to be 1000 on the described carbon fiber: (3～8).
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103015155A (en) * | 2012-12-03 | 2013-04-03 | 天津工业大学 | Method for improving tensile strength of carbon fiber |
| CN106367952A (en) * | 2015-07-23 | 2017-02-01 | 徐海波 | Surface treatment method for carbon fibers using oxidized graphene quantum dots as coating, and composite material |
| CN106381610A (en) * | 2016-10-21 | 2017-02-08 | 常州亚环环保科技有限公司 | Preparation method of high-strength weather-proof type geotextile |
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| JP2005256221A (en) * | 2004-03-12 | 2005-09-22 | Univ Okayama | Method for coating carbon nanotube onto natural fiber |
| CN101649508A (en) * | 2009-09-17 | 2010-02-17 | 东华大学 | Preparation method of high-strength carbon fiber |
| CN101698975A (en) * | 2009-09-23 | 2010-04-28 | 北京航空航天大学 | Method for modifying carbonized pre-oxidized fiber preform interface by carbon nanotube |
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Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
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| JP2005256221A (en) * | 2004-03-12 | 2005-09-22 | Univ Okayama | Method for coating carbon nanotube onto natural fiber |
| CN101649508A (en) * | 2009-09-17 | 2010-02-17 | 东华大学 | Preparation method of high-strength carbon fiber |
| CN101698975A (en) * | 2009-09-23 | 2010-04-28 | 北京航空航天大学 | Method for modifying carbonized pre-oxidized fiber preform interface by carbon nanotube |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103015155A (en) * | 2012-12-03 | 2013-04-03 | 天津工业大学 | Method for improving tensile strength of carbon fiber |
| CN106367952A (en) * | 2015-07-23 | 2017-02-01 | 徐海波 | Surface treatment method for carbon fibers using oxidized graphene quantum dots as coating, and composite material |
| CN106381610A (en) * | 2016-10-21 | 2017-02-08 | 常州亚环环保科技有限公司 | Preparation method of high-strength weather-proof type geotextile |
| CN106381610B (en) * | 2016-10-21 | 2018-11-23 | 纤科工业（珠海）有限公司 | A kind of preparation method of high-strength weather-resistant geotextiles |
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Application publication date: 20111228 |