Carbon fiber surface modification method and modified carbon fiber

Abstract

The application discloses a carbon fiber surface modification method and modified carbon fiber. The carbon fiber surface modification method comprises the following steps: performing desizing treatment on carbon fiber, and then placing the carbon fiber in an aramid nanofiber electrophoresis solution with a concentration of 0.005wt%-0.1wt% to perform electrophoretic deposition, so as to preliminarily modify the carbon fiber; drying the preliminarily modified carbon fiber, and then immersing the carbon fiber in an MXene dispersion liquid to perform secondary modification, wherein the concentration of the MXene dispersion liquid is 0.05wt%-0.5wt%; and drying the secondarily modified carbon fiber, so that the surface modified carbon fiber is obtained. The aramid nanofiber and the MXene are used to cooperatively treat the carbon fiber, so that the interfacial bonding performance between the carbon fiber and resin can be effectively improved, the interlaminar shear strength of the composite material is improved, and the overall mechanical performance of the composite material is further improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of carbon fiber surface modification, and particularly relates to a carbon fiber surface modification method and modified carbon fiber. BACKGROUND

[0002] The statements herein are provided only to enhance understanding of the present application and are not necessarily intended to constitute the prior art.

[0003] Carbon fiber is a kind of special fiber with high strength and high modulus, and has the advantages of light weight, stable chemical composition and good high-temperature resistance. Polypropylene is a kind of non-toxic and odorless thermoplastic resin with regular structure and high crystallinity, and has excellent mechanical properties and stable chemical properties, and is easy to process into a general-purpose thermoplastic resin with the widest application. Carbon fiber / polypropylene composite has a wide application prospect in many fields such as aerospace, national defense and military due to its outstanding performance such as light weight, high strength and high specific stiffness. Carbon fiber has low surface activity and chemical inertness, and the interface adhesion of the composite obtained by combining the carbon fiber with resin is weak, which leads to poor mechanical properties of the composite and greatly limits the application range and functional development. The existing carbon fiber surface treatment methods are a series of physical and chemical reactions on the surface of carbon fiber, which increase the roughness of the fiber surface or the number of active groups on the fiber surface. For example, introducing graphene, graphene oxide and carbon nanotube into the surface of carbon fiber can increase the roughness of the fiber surface and improve the wettability of the resin. The inventors found that the interface adhesion between the modified carbon fiber obtained by the modification method and the polypropylene resin is poor, and the interlaminar shear strength of the composite is weak, which is difficult to meet the actual application requirements. SUMMARY

[0004] In view of the deficiencies of the prior art, the present application aims to provide a carbon fiber surface modification method and modified carbon fiber.

[0005] In order to achieve the above-mentioned purpose, the present application is realized by the following technical scheme:

[0006] In the first aspect, the present application provides a carbon fiber surface modification method, comprising the following steps:

[0007] The carbon fiber is subjected to desizing treatment, and then is placed in an aramid nanofiber electrophoresis liquid with a concentration of 0.005wt%-0.1wt% to perform electrophoretic deposition, so as to preliminarily modify the carbon fiber;

[0008] After the preliminarily modified carbon fiber is dried, it is immersed in an MXene dispersion liquid to perform secondary modification, and the concentration of the MXene dispersion liquid is 0.05wt%-0.5wt%;

[0009] or first modifying the carbon fiber by impregnating MXene, and then performing electrophoretic deposition of aramid nanofiber after drying;

[0010] The surface-modified carbon fiber is obtained by drying the secondarily modified carbon fiber.

[0011] MXene is a new type of two-dimensional layered material composed of transition metal carbon / nitrogen / carbon nitride, which has the characteristics of high specific surface area and high conductivity. The surface of MXene has active oxygen-containing groups and hydrophilicity. The introduction of MXene on the surface of carbon fiber can significantly improve the surface inertness of carbon fiber, and further improve the interfacial bonding performance of the composite material.

[0012] Aramid nanofiber is a new type of nanometer polymer material, which has excellent mechanical properties and thermal stability, and has unique nanometer size structure and specific surface area. The synergistic treatment of aramid nanofiber and MXene on carbon fiber can effectively improve the interfacial bonding performance between carbon fiber and resin, improve the interlaminar shear strength of the composite material, and further improve the overall mechanical properties of the composite material.

[0013] In some embodiments, the method for sizing the carbon fiber is acetone immersion, H2O2 immersion treatment or flame spray treatment.

[0014] In some embodiments, the carbon fiber is a plain carbon fiber fabric, and the specification is selected from 3K, 6K, 12K, 24K or 36K.

[0015] In some embodiments, the voltage for electrophoretic deposition is 5-20V, and the deposition time is 1-15min.

[0016] Preferably, the solvent of the aramid nanofiber electrophoretic solution is deionized water or dimethyl sulfoxide.

[0017] Preferably, the pH value of the aramid nanofiber electrophoretic solution is 7-10.

[0018] In some embodiments, the carbon fiber is impregnated in the MXene dispersion for 5-60min.

[0019] In some embodiments, the drying is performed by vacuum oven drying, the drying temperature is 50-80℃, and the drying time is 6-24h.

[0020] In a second aspect, the present application provides a modified carbon fiber prepared by the surface modification method of the carbon fiber.

[0021] In a third aspect, the present application provides a preparation method of carbon fiber reinforced composite material, comprising the following steps: laminating polypropylene adhesive film and modified carbon fiber cloth and hot pressing, the hot pressing temperature is 150-210 DEG C, the pressure is 0.5-2 MPa, the pressure time is 20-60 min, then stop heating and keep for 10-30 min, to obtain prepreg;

[0022] Laminating the prepreg and performing mold pressing, the temperature of the press is 180-210 DEG C, the pressure is 0.5-2 MPa, the pressure time is 20-60 min, then stop heating and keep for 40-60 min, after the mold is cooled, demolding treatment is performed, and the carbon fiber reinforced composite material is obtained.

[0023] The beneficial effects of one or more embodiments of the present application are as follows:

[0024] The aramid nanofiber is introduced on the surface of the carbon fiber in an electrophoretic deposition manner, the method is flexible and easy to adjust, and the thickness and morphology of the aramid nanofiber coating on the surface of the carbon fiber can be controlled by changing the deposition time, deposition time and electrophoretic liquid concentration.

[0025] The surface inertness of the carbon fiber can be obviously improved by introducing MXene on the surface of the carbon fiber, and the interfacial bonding performance of the composite material is improved.

[0026] The interfacial bonding performance between the carbon fiber and the resin can be effectively improved by treating the carbon fiber with aramid nanofiber and MXene, and the mechanical properties of the composite material are more excellent. BRIEF DESCRIPTION OF DRAWINGS

[0027] The drawings accompanying the specification of the present application serve to provide a further understanding of the present application, and the illustrative embodiments of the present application and their descriptions serve to explain the present application, and do not constitute an improper limitation on the present application.

[0028] Figure 1 It is a 2000 times electron microscope graph of the carbon fiber surface of the present application, a mixed surface interfacial treatment method and process of carbon fiber, and aramid nanofiber is introduced on the surface of the carbon fiber.

[0029] Figure 2 It is a 2000 times electron microscope graph of the present application, aramid nanofiber is first introduced on the surface of the carbon fiber, and then MXene is introduced.

[0030] Figure 3 It is a 2000 times electron microscope graph of the present application, MXene is first introduced on the surface of the carbon fiber, and then aramid nanofiber is introduced. DETAILED DESCRIPTION

[0031] It should be noted that the following detailed description is illustrative only, and is intended to further explain the present application. All technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present application belongs unless otherwise specifically defined herein.

[0032] The present application is further illustrated by the following examples.

[0033] Example 1

[0034] Polypropylene thermoplastic adhesive film and 3K plain carbon fiber fabric were selected and cut into 7cm x 7cm squares. The carbon fiber fabric was subjected to electrophoretic deposition in an aramid nanofiber electrophoretic solution with a solvent of water, a pH value of 7, and a concentration of 0.05wt%. The carbon fiber fabric was used as the anode, and a copper sheet was used as the anode, with a distance between the two controlled to be 10mm. The direct current voltage during electrophoretic deposition was set to 10V, and the deposition time was 10min. After the deposition was completed, the modified carbon cloth was placed in a vacuum oven and dried at 80℃ for 6h. The modified and dried carbon cloth was placed in a 0.015wt% MXene dispersion liquid for 15min to obtain a second modified carbon fiber, and the second modified carbon fiber was again placed in a vacuum oven and dried at 80℃ for 6h. The 2000 times electron microscope image of the modified carbon fiber is shown in FIG. 1. Figure 2

[0035] The dried and second modified carbon fiber was layered and laminated with a polypropylene resin film to prepare a single layer prepreg by hot pressing. The hot pressing machine temperature was set to 140℃, the pressure was 2MPa, three times of pressure relief was performed before pressing, the time interval was 10s, the pressing time was 45min, and the holding time was 50min. The molded prepreg was cut, and 13 pieces of sheet-shaped carbon fiber polypropylene composite material were placed in a special mold for molding, the machine temperature was set to 200℃, the pressure was 2MPa, the pressing time was 30min, and the holding time was 50min. The interlaminar shear strength of the composite material plate after molding was tested, the average thickness was 1.83mm, and the ILSS value was 29.20MPa.

[0036] Example 2

[0037] ​The polypropylene thermoplastic adhesive film and the 6K plain carbon fiber fabric are cut into a 7cm x 7cm square. The carbon fiber fabric is placed in an aramid nanofiber electrophoresis solution with a solvent of dimethyl sulfoxide, a pH value of 7, and a concentration of 0.05wt%. The carbon fiber fabric is used as the anode, and a copper sheet is used as the anode. The distance between the two is controlled to be 10mm. The direct current voltage during electrophoretic deposition is set to 20V, and the deposition time is 5min. After the deposition is completed, the modified carbon cloth is placed in a vacuum oven and dried at 70°C for 7h. The modified and dried carbon cloth is placed in a 0.02wt% MXene dispersion liquid for 10min to obtain a second modified carbon fiber. The second modified carbon fiber is placed in a vacuum oven and dried at 70°C for 7h.

[0038] The dried and second modified carbon fiber is layered and laminated with a polypropylene resin film to prepare a single-layer prepreg by hot pressing. The hot pressing machine temperature is set to 150°C, the pressure is 1MPa, three times of decompression is performed before pressing, the time interval is 10s, the pressing time is 40min, and the holding time is 40min. The molded prepreg is cut, and 15 pieces of sheet-shaped carbon fiber polypropylene composite material are placed in a special mold for molding. The pressing machine temperature is set to 200°C, the pressure is 2MPa, the pressing time is 30min, and the holding time is 50min. The interlaminar shear strength of the composite material plate after molding is tested, the average thickness is 1.94mm, and the ILSS value is 30.88MPa.

[0039] Example 3

[0040] The polypropylene thermoplastic adhesive film and the 12K plain carbon fiber fabric are cut into a 7cm x 7cm square. The carbon fiber fabric is placed in a 0.02wt% MXene dispersion liquid for 15min, and then placed in a vacuum oven and dried at 60°C for 10h. The modified and dried carbon cloth is placed in an aramid nanofiber electrophoresis solution with a solvent of dimethyl sulfoxide, a pH value of 8, and a concentration of 0.1wt%. The carbon fiber fabric is used as the anode, and a copper sheet is used as the anode. The distance between the two is controlled to be 20mm. The direct current voltage during electrophoretic deposition is set to 5V, and the deposition time is 2min. After the deposition is completed, the second modified carbon cloth is placed in a vacuum oven and dried at 60°C for 10h. The 2000 times electron microscope image of the modified carbon cloth is shown in Figure 3 .

[0041] The dried secondary modified carbon fiber is laminated with polypropylene resin film for hot pressing to prepare a single-layer prepreg, the temperature of the hot pressing machine is set to 150°C, the pressure is 1 MPa, three decompressions are performed before pressing, the time interval is 10 s, the pressing time is 40 min, and the holding time is 40 min. The prepreg after molding is cut, and 14 pieces of sheet-shaped carbon fiber polypropylene composite materials are placed in a special mold for molding, the temperature of the pressing machine is set to 210°C, the pressure is 2 MPa, the pressing time is 30 min, and the holding time is 40 min. The composite material plate after molding is tested for interlaminar shear strength, the average thickness is 1.89 mm, and the ILSS value is 30.01 MPa.

[0042] Example 4

[0043] A polypropylene thermoplastic adhesive film and a 6K plain carbon fiber fabric are cut into a 7cm x 7cm square. The carbon fiber cloth is immersed in a 0.015wt% MXene dispersion liquid for 15 min, and then placed in a vacuum oven for drying at 80°C for 5h. The modified dried carbon cloth is placed in a solvent dimethyl sulfoxide, pH 10, aramid nanofiber electrophoresis liquid with a concentration of 0.1wt% for electrophoretic deposition. The carbon fiber cloth is an anode, and a copper sheet is an anode, with a distance of 20mm between them. The direct current voltage during electrophoretic deposition is set to 10V, and the deposition time is 2min. After deposition, the secondary modified carbon cloth is placed in a vacuum oven for drying at 80°C for 5h.

[0044] The dried secondary modified carbon fiber is laminated with polypropylene resin film for hot pressing to prepare a single-layer prepreg, the temperature of the hot pressing machine is set to 160°C, the pressure is 1 MPa, three decompressions are performed before pressing, the time interval is 10 s, the pressing time is 40 min, and the holding time is 40 min. The prepreg after molding is cut, and 14 pieces of sheet-shaped carbon fiber polypropylene composite materials are placed in a special mold for molding, the temperature of the pressing machine is set to 200°C, the pressure is 2 MPa, the pressing time is 20 min, and the holding time is 50 min. The composite material plate after molding is tested for interlaminar shear strength, the average thickness is 1.88 mm, and the ILSS value is 26.90 MPa.

[0045] Comparative Example 1

[0046] The difference from Example 2 is that the step of immersing the carbon cloth in the MXene dispersion liquid is omitted, and the others are the same as Example 2.

[0047] Comparative Example 2

[0048] The difference from Example 2 is that the step of electrophoretically depositing aramid nanofibers on the surface of the carbon cloth is omitted, and the others are the same as Example 2.

[0049] The interlaminar shear strength data of the modified carbon fiber reinforced polypropylene resin composite prepared in Examples 1 to 4 and Comparative Examples 1 and 2 are shown in Table 1.

[0050] Table 1 Interlaminar shear strength of modified carbon fiber reinforced polypropylene resin composite

[0051] Example Average thickness (mm) ILSS (MPa) Example 1 1.83 29.20 Example 2 1.94 30.88 Example 3 1.89 30.01 Example 4 1.88 26.90 Comparative Example 1 1.92 30.51 Comparative Example 2 1.91 29.52

[0052] The preferred embodiments of the present application are described above, but the present application is not limited to the above examples, and various modifications and changes can be made by those skilled in the art. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present application should be included in the scope of the present application.

Claims

1. A method of producing a carbon fiber-reinforced composite material, characterized by: Comprising the following steps: Selecting polypropylene thermoplastic adhesive film and 6K plain carbon fiber fabric to cut into 7cm x 7cm square; carbon fiber fabric is electrophoresed in aramid nanofiber electrophoresis solution with dimethyl sulfoxide as solvent, pH value of 7 and concentration of 0.05wt%; The carbon fiber fabric is used as anode and copper sheet as cathode, the distance between them is controlled to be 10mm; the direct current voltage during electrophoresis deposition is set to be 20V, and the deposition time is 5min; After deposition, the modified carbon cloth is placed in a vacuum oven for drying at 70℃ for 7h; the modified and dried carbon cloth is immersed in 0.02wt% MXene dispersion liquid for 10min to obtain secondary modified carbon fiber, and the secondary modified carbon fiber is again placed in a vacuum oven for drying at 70℃ for 7h; The dried secondary modified carbon fiber is layered and laminated with polypropylene resin film for hot pressing to prepare single-layer prepreg, the hot pressing machine temperature is set to be 150℃, the pressure is 1MPa, three times of pressure relief is performed before pressing, the time interval is 10s, the pressing time is 40min, and the holding time is 40min; the molded prepreg is cut, 15 pieces of sheet-shaped carbon fiber polypropylene composite material are placed in the mold for molding, the pressing machine temperature is set to be 200℃, the pressure is 2MPa, the pressing time is 30min, and the holding time is 50min.

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