A high-strength composite carbon fiber and preparation method thereof

Abstract

The invention discloses a high-strength composite carbon fiber and a preparation method thereof, belonging to the technical field of carbon fibers. The method comprises the following steps: step S1, placing the carbon fibers after desizing treatment in a polydiallyldimethylammonium chloride aqueous solution for immersion, taking out to obtain positively charged carbon fibers; step S2, immersing the positively charged carbon fibers in a hybrid nanosheet suspension, taking out, washing in deionized water, and vacuum drying, repeating the above operation 7-11 times to obtain modified carbon fibers; step S3, adding a pyrrole monomer into a sulfuric acid solution, stirring and dissolving the mixture to obtain a mixed solution, then placing the modified carbon fibers as an anode and a stainless steel plate as a cathode in the mixed solution for electrical reaction, washing with anhydrous ethanol and deionized water after the reaction is completed, and vacuum drying to obtain the high-strength composite carbon fibers. The composite carbon fibers prepared by the invention have good surface wettability, contain abundant active groups, and have excellent interface properties and mechanical properties.

Description

Technical Field

[0001] The present invention belongs to the technical field of carbon fibers, and in particular relates to a high-strength composite carbon fiber and a preparation method thereof. Background Art

[0002] Carbon fiber, with its excellent properties of high strength, high modulus, corrosion resistance, high temperature resistance, good electrical conductivity, and thermal insulation, has become a high-tech fiber currently being vigorously developed in my country, with broad application prospects in aerospace, electromagnetic shielding, electronics, civil engineering, and other fields. In recent years, carbon fiber has become an important reinforcement material for metal, ceramic, and resin-based composites. However, the high surface inertness of carbon fiber and its poor adhesion and wettability with the matrix result in limited reinforcement efficiency, which to some extent restricts its application.

[0003] In the prior art, in order to prevent delamination at the interface between carbon fiber and resin matrix, the carbon fiber surface is usually pretreated before being impregnated with resin. Common pretreatment methods include degumming, degreasing, roughening, sensitization, and activation. Among them, the roughening process is to use strong oxidants such as strong acids to etch the carbon fiber surface to obtain a rough surface microstructure, thereby increasing the surface area available for bonding between the carbon fiber and the matrix interface, which helps to mechanically interlock the resin matrix and the fiber; the carbon fiber surface can also be oxidized to form a small amount of reactive chemical groups, such as carboxylic acid groups, on the carbon fiber surface.

[0004] However, this pretreatment can also lead to unpredictable performance degradation of the carbon fibers, significantly reducing their strength and modulus, limiting their practical use. Therefore, how to obtain composite carbon fibers containing more reactive chemical groups without reducing their strength is an urgent problem that needs to be solved. Summary of the Invention

[0005] The object of the present invention is to provide a high-strength composite carbon fiber and a preparation method thereof, so as to solve the problems in the background technology.

[0006] The purpose of the present invention can be achieved through the following technical solutions:

[0007] A method for preparing high-strength composite carbon fiber comprises the following steps:

[0008] Step S1, placing the desizing carbon fiber in a polydiallyldimethylammonium chloride aqueous solution and soaking it for 10-20 minutes, and then taking it out to obtain a positively charged carbon fiber;

[0009] Step S2, immersing the positively charged carbon fiber in the negatively charged hybrid nanosheet suspension for 10-20 minutes, taking it out and washing it in deionized water 2-3 times to remove excess hybrid nanosheets, and then drying it in a vacuum drying oven at 60-80°C for 6-8 hours. Repeat the above operation 7-11 times to obtain modified carbon fiber;

[0010] Step S3, adding pyrrole monomer to sulfuric acid solution and stirring until completely dissolved to obtain a mixed solution, then placing the modified carbon fiber as the anode and the stainless steel plate as the cathode in the mixed solution, and applying power under direct current for 7-10 minutes to allow the pyrrole monomer to electropolymerize on the surface of the modified carbon fiber to form a coating. After the reaction is completed, repeatedly washing with anhydrous ethanol and deionized water, and vacuum drying at 60-80°C for 6-8 hours to obtain high-strength composite carbon fiber.

[0011] Furthermore, a method of the deslurry treatment is:

[0012] Place the carbon fiber in an acetone solution, reflux and soak at 60-80°C for 12-24 hours, then repeatedly wash with anhydrous ethanol and deionized water, and transfer to a vacuum drying oven at 60-80°C to dry for 6-8 hours.

[0013] Furthermore, another method of the deslurry treatment is:

[0014] Under nitrogen protection, the carbon fibers were placed in a high-temperature furnace cavity, treated at 400°C for 3-4 hours, and vacuum dried at 60-80°C to constant weight.

[0015] Furthermore, the concentration of the polydiallyldimethylammonium chloride aqueous solution is 0.5 wt %. The polydiallyldimethylammonium chloride can form a film on the surface of the carbon fiber, so that the carbon fiber has a positive charge in the aqueous solution.

[0016] Furthermore, the usage ratio of the pyrrole monomer to the sulfuric acid solution is 33-35 g:500 mL, and the concentration of the sulfuric acid solution is 0.5 mol / L.

[0017] Furthermore, the current density of the energized reaction is 0.2-0.3A / m 2 .

[0018] Furthermore, the hybrid nanosheet suspension is prepared by the following steps:

[0019] Step A1, adding lithium fluoride powder to a hydrochloric acid solution and stirring to dissolve, then adding titanium aluminum carbide powder in an ice-water bath and stirring for 10 minutes, then stirring and reacting at 35°C and 500-600 rpm for 24 hours. After the reaction is completed, centrifugation and filtration are performed, and the precipitate is washed with deionized water until neutral. The precipitate is then ultrasonically dispersed in deionized water, and after centrifugation and stratification, the supernatant is retained, and a single layer or a few layers of titanium carbide nanosheets are extracted from the supernatant;

[0020] Step A2: ultrasonically disperse graphene oxide in deionized water, then add titanium carbide nanosheets, ultrasonically disperse for 10 minutes, and then stir and mix at 800-1000 rpm for 4-6 hours to obtain a hybrid nanosheet suspension; the surface of the hybrid nanosheet is negatively charged because it is rich in -F and -0H.

[0021] Furthermore, the usage ratio of the lithium fluoride powder, the hydrochloric acid solution and the titanium aluminum carbide powder is 1 g:20-25 mL:1 g; and the concentration of the hydrochloric acid solution is 9-10 mol / L.

[0022] Furthermore, the usage ratio of the graphene oxide, deionized water and titanium carbonized nanosheets is 2.5 mg:400-500 mL:2.5 mg.

[0023] A high-strength composite carbon fiber is prepared by the above preparation method.

[0024] Beneficial effects of the present invention:

[0025] The present invention mixes graphene oxide with a single layer or a few layers of titanium carbide nanosheets. The graphene oxide and the titanium carbide nanosheets are bonded via Ti-OC covalent bonds. On the one hand, the dispersibility of the two can be optimized and promoted, self-stacking of the titanium carbide nanosheets and agglomeration of the graphene oxide can be avoided, and the obtained hybrid nanosheets are facilitated to be uniformly deposited on the surface of the carbon fiber. On the other hand, the active functional groups at the edges of the graphene oxide and the active functional groups within the plane of the titanium carbide nanosheets act together to achieve surface-to-surface interaction between the hybrid nanosheets and the carbon fiber, thereby obtaining an orderly and dense interface layer on the surface of the carbon fiber. The interface layer can not only increase the surface energy of the carbon fiber and improve the wettability of the carbon fiber, but also enhance the mechanical meshing between the carbon fiber and the resin matrix, thereby increasing the interfacial shear strength between the two phases.

[0026] The present invention assembles hybrid nanosheets layer by layer onto the surface of desizing carbon fibers through electrostatic action, and then forms a polypyrrole conjugated polymer film on the surface of the carbon fibers deposited with the hybrid nanosheets through electrochemical polymerization. This method only desizings the carbon fibers, avoiding damage to the strength of the carbon fibers themselves caused by pretreatments such as coarsening, making the operation simpler. Furthermore, the pyrrole monomer can penetrate deeply into the interface layer and electropolymerize in the gaps of the hybrid nanosheets, thereby improving the toughness of the interface layer and further enriching the active groups on the carbon fiber surface, thereby synergistically enhancing the interface properties of the composite carbon fibers.

[0027] After the composite carbon fibers prepared by the present invention are laminated and composited with a resin matrix, the composite carbon fibers can be well combined with the resin matrix, so that the obtained composite material has more excellent mechanical properties. DETAILED DESCRIPTION

[0028] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0029] Example 1

[0030] The hybrid nanosheet suspension was prepared by the following steps:

[0031] Step A1, adding 1g of lithium fluoride powder to 20mL of 9mol / L hydrochloric acid solution and stirring to dissolve, then adding 1g of titanium aluminum carbide powder to the above solution in an ice-water bath and stirring for 10min, then stirring and reacting at a temperature of 35°C and a speed of 500r / min for 24h, after the reaction is completed, centrifuging at a speed of 3500r / min, and washing the precipitate with deionized water until neutral, then ultrasonically dispersing the precipitate in deionized water, centrifuging at a speed of 3500r / min to separate the layers, retaining the supernatant, and extracting titanium carbide nanosheets from the supernatant;

[0032] Step A2: ultrasonically disperse 2.5 mg of graphene oxide in 400 mL of deionized water for 10 min, then add 2.5 mg of titanium carbide nanosheets, continue ultrasonic dispersion for 10 min, and then stir and mix at 800 r / min for 4 h to obtain a negatively charged hybrid nanosheet suspension.

[0033] Example 2

[0034] The hybrid nanosheet suspension was prepared by the following steps:

[0035] Step A1, adding 1g of lithium fluoride powder to 23mL of 9mol / L hydrochloric acid solution and stirring to dissolve, then adding 1g of titanium aluminum carbide powder to the above solution in an ice-water bath and stirring for 10min, then stirring at a temperature of 35°C and a speed of 550r / min for 24h, after the reaction is completed, centrifuging at a speed of 3500r / min, and washing the precipitate with deionized water until neutral, then ultrasonically dispersing the precipitate in deionized water, centrifuging at a speed of 3500r / min to separate the layers, retaining the supernatant, and extracting titanium carbide nanosheets from the supernatant;

[0036] Step A2: ultrasonically disperse 2.5 mg of graphene oxide in 450 mL of deionized water for 10 min, then add 2.5 mg of titanium carbide nanosheets, continue ultrasonic dispersion for 10 min, and then stir and mix at 900 r / min for 5 h to obtain a negatively charged hybrid nanosheet suspension.

[0037] Example 3

[0038] The hybrid nanosheet suspension was prepared by the following steps:

[0039] Step A1, adding 1g of lithium fluoride powder to 25mL of 10mol / L hydrochloric acid solution and stirring to dissolve, then adding 1g of titanium aluminum carbide powder to the above solution in an ice-water bath and stirring for 10min, then stirring and reacting at a temperature of 35°C and a speed of 600r / min for 24h, after the reaction is completed, centrifuging at a speed of 3500r / min, and washing the precipitate with deionized water until neutral, then ultrasonically dispersing the precipitate in deionized water, centrifuging at a speed of 3500r / min to separate the layers, retaining the supernatant, and extracting titanium carbide nanosheets from the supernatant;

[0040] Step A2: ultrasonically disperse 2.5 mg of graphene oxide in 500 mL of deionized water for 10 min, then add 2.5 mg of titanium carbide nanosheets, continue ultrasonic dispersion for 10 min, and then stir and mix at 1000 r / min for 6 h to obtain a negatively charged hybrid nanosheet suspension.

[0041] Comparative Example 1

[0042] Compared with Example 2, this comparative example does not add graphene oxide for hybridization treatment, and the remaining raw material amounts and steps are the same to obtain a titanium carbide nanosheet suspension.

[0043] Comparative Example 2

[0044] Compared with Example 2, in this comparative example, graphene oxide was directly ultrasonically dispersed in deionized water, and the amounts of other raw materials and steps were the same to obtain a graphene oxide nanosheet suspension.

[0045] Example 4

[0046] This embodiment provides a method for preparing high-strength composite carbon fiber, comprising the following steps:

[0047] Step S1, placing the carbon fiber in an acetone solution, reflux soaking at 60° C. for 24 hours, then repeatedly washing with anhydrous ethanol and deionized water, and drying in a vacuum drying oven at 60° C. for 8 hours to obtain desizing carbon fiber, placing the desizing carbon fiber in a 0.5wt% polydiallyldimethylammonium chloride aqueous solution and soaking it for 10 minutes, and taking it out to obtain positively charged carbon fiber;

[0048] Step S2, soaking the positively charged carbon fiber in the hybrid nanosheet suspension prepared in Example 1 for 10 minutes, taking it out and washing it twice in deionized water to remove excess hybrid nanosheets, and then drying it in a vacuum drying oven at 60°C for 8 hours. Repeat the above operation 7 times to obtain modified carbon fiber;

[0049] Step S3: 33 g of pyrrole monomer was added to 500 mL of 0.5 mol / L sulfuric acid solution and stirred until completely dissolved to obtain a mixed solution. The modified carbon fiber was used as an anode and the stainless steel plate was used as a cathode. The mixture was placed in the mixed solution and a DC current density of 0.2 A / m was used. 2 The reaction was carried out under electric current for 10 minutes to allow the pyrrole monomer to be electropolymerized on the surface of the modified carbon fiber to form a coating. After the reaction was completed, it was repeatedly washed with anhydrous ethanol and deionized water, and vacuum dried at 60°C for 6 hours to obtain a high-strength composite carbon fiber.

[0050] Example 5

[0051] This embodiment provides a method for preparing high-strength composite carbon fiber, comprising the following steps:

[0052] Step S1, placing the carbon fiber in an acetone solution, reflux soaking at 80° C. for 12 hours, then repeatedly washing with anhydrous ethanol and deionized water, and drying in a vacuum drying oven at 80° C. for 6 hours to obtain desizing carbon fiber, placing the desizing carbon fiber in a 0.5wt% polydiallyldimethylammonium chloride aqueous solution and soaking it for 20 minutes, and taking it out to obtain positively charged carbon fiber;

[0053] Step S2, immersing the positively charged carbon fiber in the hybrid nanosheet suspension prepared in Example 2 for 15 minutes, taking it out and washing it three times in deionized water to remove excess hybrid nanosheets, and then drying it in a vacuum drying oven at 70°C for 7 hours. Repeat the above operation 9 times to obtain modified carbon fiber;

[0054] Step S3: 34 g of pyrrole monomer was added to 500 mL of 0.5 mol / L sulfuric acid solution and stirred until completely dissolved to obtain a mixed solution. The modified carbon fiber was used as an anode and the stainless steel plate was used as a cathode. The mixture was placed in the mixed solution and a DC current density of 0.25 A / m was used. 2 The reaction was carried out under electric current for 9 minutes to allow the pyrrole monomer to be electropolymerized on the surface of the modified carbon fiber to form a coating. After the reaction was completed, the modified carbon fiber was repeatedly washed with anhydrous ethanol and deionized water, and vacuum dried at 70°C for 7 hours to obtain a high-strength composite carbon fiber.

[0055] Example 6

[0056] This embodiment provides a method for preparing high-strength composite carbon fiber, comprising the following steps:

[0057] Step S1, under nitrogen protection, placing the carbon fiber in a high-temperature furnace cavity, treating it at a temperature of 400° C. for 4 hours, and vacuum drying it at 60° C. to constant weight to obtain desizing carbon fiber, and placing the desizing carbon fiber in a 0.5wt% polydiallyldimethylammonium chloride aqueous solution for 15 minutes, and then taking it out to obtain positively charged carbon fiber;

[0058] Step S2, immersing the positively charged carbon fiber in the hybrid nanosheet suspension prepared in Example 3 for 20 minutes, taking it out and washing it in deionized water three times to remove excess hybrid nanosheets, and then drying it in a vacuum drying oven at 80°C for 6 hours. Repeat the above operation 11 times to obtain modified carbon fiber;

[0059] Step S3: 35 g of pyrrole monomer was added to 500 mL of 0.5 mol / L sulfuric acid solution and stirred until completely dissolved to obtain a mixed solution. The modified carbon fiber was used as an anode and the stainless steel plate was used as a cathode. The mixture was placed in the mixed solution and a DC current density of 0.3 A / m was used. 2 The reaction was carried out under electric current for 7 minutes to allow the pyrrole monomer to be electropolymerized on the surface of the modified carbon fiber to form a coating. After the reaction was completed, the modified carbon fiber was repeatedly washed with anhydrous ethanol and deionized water, and vacuum dried at 80°C for 8 hours to obtain a high-strength composite carbon fiber.

[0060] Comparative Example 3

[0061] Compared with Example 5, this comparative example uses the titanium carbide nanosheet suspension prepared in Comparative Example 1 to replace the hybrid nanosheet suspension prepared in Example 2, and the remaining raw materials and preparation process are the same.

[0062] Comparative Example 4

[0063] Compared with Example 5, this comparative example uses the graphene oxide nanosheet suspension prepared in Comparative Example 2 to replace the hybrid nanosheet suspension prepared in Example 2, and the remaining raw materials and preparation process are the same.

[0064] Comparative Example 5

[0065] Compared with Example 5, this comparative example does not repeat the operation in step S2, and the remaining steps are the same.

[0066] The composite carbon fibers obtained in Examples 4-6 and Comparative Examples 3-5 were subjected to wettability tests using an interfacial tension meter to obtain contact angles and surface energies in water and diiodomethane, respectively. The composite carbon fibers obtained in Examples 4-6 and Comparative Examples 3-5 were subjected to vacuum-assisted molding processes and epoxy resins to prepare carbon fiber composite materials, specifically by stacking the composite carbon fibers in a mold, placing the release cloth, the guide net, and the adhesive felt in the corresponding positions in sequence, and then sealing them with a vacuum bag. Then, the epoxy resin and the curing agent were mixed in a mass ratio of 100:10.8, and the CF was completely infiltrated under vacuum conditions. After curing for 2 hours at 90°C, 120°C, and 150°C, the final test samples were obtained. The interlaminar shear strength and tensile strength of the samples were tested in accordance with ASTM D2344 and ASTM D3039 standards using a universal testing machine. The results are shown in Table 1:

[0067] Table 1

[0068]

[0069] It can be seen from the data in Table 1 that the composite carbon fibers prepared in Examples 4 to 6 and Comparative Examples 3 to 5 have lower contact angles and higher surface energies, can be well wetted by the resin substrate, and the wettability is improved; at the same time, when applied to epoxy resin composite materials, the interlaminar shear strength and tensile strength are higher, which can significantly improve the strength of the composite material.

[0070] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus.

[0071] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing high-strength composite carbon fiber, characterized in that: The following steps are involved: Step S1, placing the desizing carbon fiber in a polydiallyldimethylammonium chloride aqueous solution and soaking it for 10-20 minutes, and then taking it out to obtain a positively charged carbon fiber; Step S2, soaking the positively charged carbon fiber in the hybrid nanosheet suspension for 10-20 minutes, taking it out and washing it in deionized water, and then vacuum drying it, repeating the above operation 7-11 times to obtain modified carbon fiber; Step S3, adding pyrrole monomer to sulfuric acid solution and stirring until completely dissolved to obtain a mixed solution, then placing the modified carbon fiber as an anode and a stainless steel plate as a cathode in the mixed solution, and applying power under direct current for 7-10 minutes. After the reaction is completed, washing with anhydrous ethanol and deionized water, and vacuum drying to obtain a high-strength composite carbon fiber; The hybrid nanosheet suspension is prepared by the following steps: Step A1, adding lithium fluoride powder to a hydrochloric acid solution and stirring to dissolve, then adding titanium aluminum carbide powder and stirring in an ice-water bath, and then stirring at 35°C and 500-600 rpm for 24 hours. After the reaction is completed, centrifugation and filtration are performed, and the precipitate is washed with deionized water until neutral. The precipitate is then ultrasonically dispersed in deionized water, and the supernatant is retained after centrifugation and stratification, and titanium carbide nanosheets are extracted from the supernatant; Step A2: ultrasonically disperse graphene oxide in deionized water, then add titanium carbide nanosheets, ultrasonically disperse for 10 minutes, and then stir and mix at 800-1000 r / min for 4-6 hours to obtain a hybrid nanosheet suspension.

2. The method for preparing high-strength composite carbon fiber according to claim 1, characterized in that: The desizing method is as follows: Place the carbon fiber in an acetone solution, reflux and soak at 60-80°C for 12-24 hours, then wash with anhydrous ethanol and deionized water, and transfer to a vacuum drying oven at 60-80°C to dry for 6-8 hours.

3. The method for preparing high-strength composite carbon fiber according to claim 1, characterized in that: The desizing method is as follows: Under nitrogen protection, the carbon fiber is placed in a high-temperature furnace cavity, treated at a temperature of 400°C for 3-4 hours, and then vacuum dried at 60-80°C to constant weight.

4. The method for preparing high-strength composite carbon fiber according to claim 1, characterized in that: The concentration of the polydiallyldimethylammonium chloride aqueous solution is 0.5 wt %.

5. The method for preparing high-strength composite carbon fiber according to claim 1, characterized in that: The usage ratio of the pyrrole monomer to the sulfuric acid solution is 33-35 g:500 mL, and the concentration of the sulfuric acid solution is 0.5 mol / L.

6. The method for preparing high-strength composite carbon fiber according to claim 1, characterized in that: The current density of the energization reaction is 0.2-0.3A / m 2 .

7. The method for preparing high-strength composite carbon fiber according to claim 1, characterized in that: The usage ratio of the lithium fluoride powder, the hydrochloric acid solution and the titanium aluminum carbide powder is 1g:20-25mL:1g; and the concentration of the hydrochloric acid solution is 9-10mol / L.

8. The method for preparing high-strength composite carbon fiber according to claim 1, characterized in that: The usage ratio of the graphene oxide, deionized water and titanium carbonized nanosheets is 2.5 mg:400-500 mL:2.5 mg.

9. A high-strength composite carbon fiber, characterized in that: Prepared by the preparation method according to any one of claims 1 to 8.

Images