High-radial-direction heat conduction carbon fiber composite material and preparation method thereof

Abstract

The invention relates to the technical field of heat-conducting composite materials, in particular to a high-radial-direction heat-conducting carbon fiber composite material and a preparation method thereof.The preparation method comprises the following steps that S1, the surface of carbon fiber cloth is pretreated; s2, treating the carbon fiber cloth subjected to surface pretreatment in the step S1 through dopamine; s3, preparing carbon fiber cloth with a zinc oxide micro-nano structure by adopting a hydrothermal method; s4, performing modification treatment on the carbon fiber cloth with the zinc oxide micro-nano structure obtained in the step S3 through polyvinyl alcohol; s5, impregnating a product in the step S4 into a carbon nanotube, and freezing and casting to obtain modified carbon fiber cloth; and S6, mixing the modified carbon fiber cloth in the step S5 with epoxy resin and a curing agent through a vacuum bag press molding process to obtain the high-radial-direction heat conduction carbon fiber composite material. According to the prepared high-radial-heat-conduction carbon fiber composite material, the carbon nanotubes form a uniform sheet structure on the surface of the carbon fiber, and the prepared composite material is high in comprehensive performance.

Description

Technical Field

[0001] The present invention relates to the technical field of thermally conductive composite materials, and particularly relates to a high-radial thermal conductivity carbon fiber composite material and a preparation method thereof. Background Art

[0002] The structural-functional integration of carbon fiber composite materials is a development trend in fields such as aerospace, precision instruments, vehicle structural components, or electronic devices. With the development of electronic devices in the aerospace field towards high frequency, high integration, and high power, the problem of thermal energy management of materials has become increasingly prominent. In addition, a large amount of heat is generated in the carbon fiber composite material structures in fields such as aircraft, space stations, and satellites during operation or under the influence of the environment, which needs to be discharged in a timely manner to avoid affecting the working accuracy and efficiency of the devices.

[0003] However, due to the difference in the molecular arrangement of carbon fiber and resin matrix, the coupling degree of the vibration modes that dominate phonon heat transfer is relatively low, thus causing the generation of interfacial thermal resistance, reducing the thermal conductivity of the composite material, and easily resulting in the aggregation of heat to generate large thermal stress, which affects its service performance and service life. Therefore, traditional carbon fiber composite materials urgently need to improve their thermal conductivity while maintaining their original excellent mechanical properties. In the application of carbon fiber composite materials in structural components, they often appear in the form of plates, and the carbon fibers in the plates are usually arranged in the in-plane direction. The graphite sheets in the carbon fiber structure have excellent thermal conductivity, so the composite material has good thermal conductivity in the in-plane direction. However, the carbon fibers are mainly bonded to each other by epoxy resin, and there is a lack of a three-dimensional structure between the layers. Therefore, the carbon fiber composite laminate is mainly limited by the thermal conductivity of the interlayer resin and generally exhibits low thermal conductivity in the thickness direction. The literature (Composites Part B: Engineering, 2022, 229: 109468.) introduced poly(p-phenylene benzobisoxazole) (PBO) macromolecules onto the surface of PAN-CF to prepare coaxial PAN / PBO carbon fibers (PAN / PBO-CF). The introduction of PBO macromolecules can provide a new conduction path, alleviate the interfacial temperature gradient problem between CF and the resin matrix, and greatly enhance the in-plane and out-of-plane thermal conductivity of the composite material. However, there are still significant differences in the vibration modes of phonon heat transfer between carbon nanoparticles and the resin matrix, resulting in the generation of interfacial thermal resistance between carbon nanoparticles and the resin matrix; at the same time, carbon nanoparticles are prone to agglomeration at the composite material interface, causing more serious interfacial defects.

[0004] Therefore, how to improve the thermal conductivity of the carbon fiber composite laminate in the thickness direction has become a key problem that urgently needs to be solved in the development of high-thermal conductivity carbon fiber composite materials. Summary of the Invention

[0005] The object of the present invention is to provide a high-radial thermal conductivity carbon fiber composite material and a preparation method thereof, so as to solve the problems raised in the above-mentioned background technology.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] A preparation method of a high-radial thermal conductivity carbon fiber composite material includes the following steps:

[0008] S1. Pretreat the surface of the carbon fiber cloth.

[0009] S2. Immerse the carbon fiber cloth after surface pretreatment in step S1 in a tris(hydroxymethyl)aminomethane slow-release solution containing dopamine hydrochloride with a pH of 8.5 for 24 h. After the immersion ends, wash it with deionized water and place it in an oven at 80 °C to dry for 6 h to obtain a polydopamine-modified carbon fiber cloth.

[0010] S3. In-situ construct a zinc oxide seed layer and a zinc oxide nanorod structure on the surface of the polydopamine-modified carbon fiber cloth obtained in step S2 by the hydrothermal method. After rinsing with deionized water, place it in an oven to dry to obtain a carbon fiber cloth with a zinc oxide micro-nano structure.

[0011] S4. Modify the carbon fiber cloth with a zinc oxide micro-nano structure obtained in step S3 through polyvinyl alcohol treatment to obtain a pretreated carbon fiber cloth with a zinc oxide micro-nano structure.

[0012] S5. Mix carbon nanotubes, a dispersant, epoxy resin and deionized water, and disperse them with a high-speed shear emulsifier for 6 - 12 h to prepare a uniform carbon nanotube slurry. Dilute the carbon nanotube slurry to obtain a carbon nanotube dispersion. Then, vacuum-assisted immerse the pretreated carbon fiber cloth with a zinc oxide micro-nano structure obtained in step S4 in the diluted carbon nanotube dispersion for 1 - 3 h. Subsequently, perform unidirectional freeze casting on a unidirectional freeze casting device, and then perform freeze-drying treatment to obtain the final modified carbon fiber cloth.

[0013] S6. Mix the modified carbon fiber cloth in step S5 with epoxy resin and a curing agent through a vacuum bag molding process to obtain a high-radial thermal conductivity carbon fiber composite material.

[0014] Further, in step S1, the surface pretreatment of the carbon fiber cloth is to place the carbon fiber cloth in acetone for reflux at 70 °C for 24 h, and then wash it with deionized water and place it in an oven at 80 °C to dry.

[0015] Further, in step S2, the mass ratio of tris(hydroxymethyl)aminomethane, dopamine hydrochloride and deionized water is 1:1.24:826, and the immersion time of the carbon fiber cloth after surface pretreatment in the slow-release solution is 24 h.

[0016] Further, the specific steps of in-situ constructing a zinc oxide seed layer and a zinc oxide nanorod structure on the surface of the polydopamine-modified carbon fiber cloth in step S3 by hydrothermal method are as follows:

[0017] S101. Place the carbon fiber cloth of the polydopamine-modified carbon fiber cloth in a mixed solution containing sodium hydroxide, zinc acetate dihydrate and ethanol, impregnate at 60 °C for 30 min, then place it in a high-temperature oven at 150 °C and dry for 10 min. Then repeat the operations of impregnation and high-temperature drying for 3-5 times to obtain a carbon fiber cloth with a seed layer grown on its surface;

[0018] S102. Put the carbon fiber cloth with a seed layer grown on its surface obtained in step S101 into a mixed solution of hexamethylenetetramine, zinc nitrate hexahydrate and deionized water, stir and react at 85-95 °C for 2-8 h. After the reaction ends and cools to room temperature, take it out, wash it with deionized water, and then dry it in an oven at 80 °C for 6 h to obtain a carbon fiber cloth with a zinc oxide micro-nano structure.

[0019] Further, the mass ratio of sodium hydroxide, zinc acetate dihydrate and ethanol in step S101 is 1:2.75:8000, and the mass ratio of hexamethylenetetramine, zinc nitrate hexahydrate and deionized water in step S102 is 1:2.12:235.3.

[0020] Further, the step of modifying the carbon fiber cloth with zinc oxide micro-nano structure in step S4 is as follows:

[0021] Put the carbon fiber cloth with a zinc oxide micro-nano structure into a mixed solution containing γ-aminopropyltriethoxysilane, ethanol and deionized water, impregnate at 60-70 °C for 3-4 h, and then wash with deionized water; then put the carbon fiber cloth with a zinc oxide micro-nano structure into a mixed solution of polyvinyl alcohol and deionized water, impregnate at 80-90 °C for 1-3 h, and then wash with deionized water; finally, put it into an oven at 90-110 °C and dry for 2-3 h to obtain a pretreated carbon fiber cloth with a zinc oxide micro-nano structure.

[0022] Further, the mass ratio of γ-aminopropyltriethoxysilane, ethanol and deionized water in the mixed solution of γ-aminopropyltriethoxysilane, ethanol and deionized water is 1:(20-40):(50-100), and the mass ratio of polyvinyl alcohol and deionized water in the mixed solution of polyvinyl alcohol and deionized water is 1:(80-140).

[0023] Further, the mass ratio of carbon nanotubes, dispersant, epoxy resin to deionized water in step S5 is (8-12):(1-3):1:(90-95), and the mass fraction of the dispersed carbon nanotubes in step S5 is 0.25-0.75 wt%; the unidirectional freezing casting temperature in step S5 is -196°C to -100°C, the freezing time is 2-15 min; the freeze-drying time is 6-24 h.

[0024] A high radial thermal conductivity carbon fiber composite material is prepared by the above-mentioned high radial thermal conductivity carbon fiber composite material and its preparation method.

[0025] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0026] 1. When pretreating carbon fibers, the present invention does not select a strong acid or strong base environment, which reduces the influence on the original strength of carbon fiber filaments and is environmentally friendly.

[0027] 2. Zinc oxide nanorods are in-situ grown on carbon fibers and carbon nanotubes are grafted in the present invention, which reduces the interfacial thermal resistance between carbon fibers and resin. There are two reasons for reducing the interfacial thermal resistance. On the one hand, in-situ growth of zinc oxide nanorods and grafting of carbon nanotubes on modified carbon fibers increase the surface roughness of carbon fibers, which helps to form a mechanical meshing effect between carbon fibers and epoxy resin, improves the interfacial bonding between carbon fibers / resin, reduces the interfacial thermal resistance. At the same time, the multi-dimensional heat conduction network of the composite interface phase constructed on the carbon fiber surface effectively couples the dominant vibration modes of carbon fibers and resin matrix in the phonon heat transfer process, reduces the possibility of carrier-phonon scattering at the interface, and greatly reduces the interfacial thermal resistance, thereby improving the thermal conductivity of the composite material. On the other hand, by in-situ growing zinc oxide nanorods and grafting carbon nanotubes on the carbon fiber surface, a radial three-dimensional heat conduction channel is constructed, which reduces the interfacial thermal resistance between carbon fibers and forms a more complete heat conduction path in the radial direction.

[0028] 3. When impregnating carbon fiber cloth with carbon nanotubes, a small amount of carbon nanotubes are first mixed with epoxy resin. The epoxy resin effectively increases the viscosity of carbon nanotubes, effectively increases the adhesion amount of carbon nanotubes on the carbon fiber surface. At the same time, treating the carbon fiber cloth with zinc oxide micro-nano structure by polyvinyl alcohol can improve the compatibility and the dispersion uniformity of carbon nanotubes. The carbon nanotubes can connect the carbon fiber cloth to form a sheet-like heat conduction network, further enhancing the interfacial bonding between it and the resin, reducing the thermal resistance, and at the same time broadening the heat conduction path, improving the comprehensive performance of the composite material. Description of the Drawings

[0029] Figure 1 is the process flow chart of the present invention;

[0030] Figure 2It is the structural diagram of the device for the vacuum bag pressing forming process in the present invention;

[0031] Figure 3 It is the scanning electron microscope image of the modified carbon fiber cloth in Example 2 of the present invention;

[0032] Figure 4 It is the scanning electron microscope image of the modified carbon fiber cloth in Comparative Example 1 of the present invention;

[0033] Figure 5 It is the scanning electron microscope image of the modified carbon fiber cloth in Comparative Example 2 of the present invention;

[0034] Figure 6 It is the scanning electron microscope image of the modified carbon fiber cloth in Comparative Example 4 of the present invention;

[0035] Figure 7 It is the scanning electron microscope image of the modified carbon fiber cloth in Comparative Example 5 of the present invention. Detailed implementation manners

[0036] Next, in combination with the accompanying drawings in the embodiments of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0037] Please refer to Figures 1 to 7 , the present invention provides:

[0038] Example 1

[0039] A preparation method of a high radial thermal conductivity carbon fiber composite material, comprising the following steps:

[0040] S1. Place 20 g of carbon fiber cloth in acetone, heat it to 70 °C and reflux for 24 h, then wash it with deionized water and place it in an oven at 80 °C to dry, obtaining pretreated carbon fiber cloth;

[0041] S2. Immerse the carbon fiber cloth after surface pretreatment in step S1 in a tris(hydroxymethyl)aminomethane slow-release solution containing dopamine hydrochloride with a pH of 8.5 for 24 h, where the masses of dopamine hydrochloride, tris(hydroxymethyl)aminomethane, and deionized water are 1.5 g, 1.21 g, and 1000 g respectively. After the immersion, wash it with deionized water and place it in an oven at 80 °C to dry for 6 h to obtain polydopamine-modified carbon fiber cloth;

[0042] S3. Using the hydrothermal method, in-situ construct a zinc oxide seed layer and a zinc oxide nanorod structure on the surface of the polydopamine-modified carbon fiber cloth obtained in step S2 in sequence. After rinsing with deionized water, place it in an oven to dry to obtain a carbon fiber cloth with a zinc oxide micro-nano structure;

[0043] S4. Modify and process the carbon fiber cloth with a zinc oxide micro-nano structure obtained in step S3 through polyvinyl alcohol to obtain a pretreated carbon fiber cloth with a zinc oxide micro-nano structure;

[0044] S5. Mix 5 g of carbon nanotubes, 1 g of dispersant, 0.5 g of epoxy resin with 92.5 g of deionized water and disperse them for 12 h using a high-speed shear emulsifier to prepare a uniform carbon nanotube slurry. Dilute the carbon nanotube slurry with deionized water to obtain a carbon nanotube dispersion. The mass fraction of carbon nanotubes in the carbon nanotube dispersion is 0.5 wt%. Then, vacuum-assisted impregnate the pretreated carbon fiber cloth with a zinc oxide micro-nano structure obtained in step S4 in 100 g of the diluted carbon nanotube dispersion for 2 h. Subsequently, perform unidirectional freeze casting at -196 °C on a unidirectional freeze casting device for 2 min, and then perform freeze-drying treatment for 6 h to obtain the final modified carbon fiber cloth;

[0045] S6. Mix the modified carbon fiber cloth in step S5 with epoxy resin and curing agent through a vacuum bag molding process to obtain a high-radial thermal conductivity carbon fiber composite.

[0046] The specific steps of using the hydrothermal method to in-situ construct a zinc oxide seed layer and a zinc oxide nanorod structure on the surface of the polydopamine-modified carbon fiber cloth in the above step S3 are as follows:

[0047] S101. Place the carbon fiber cloth of the polydopamine-modified carbon fiber cloth in a mixed solution containing sodium hydroxide, zinc acetate dihydrate and ethanol, impregnate it at 60 °C for 30 min, then place it in a high-temperature oven at 150 °C to dry for 10 min, and then repeat the operations of impregnation and high-temperature drying for a total of 4 times to obtain a carbon fiber cloth with a seed layer grown on the surface;

[0048] The preparation process of the mixed solution containing sodium hydroxide, zinc acetate dihydrate and ethanol is as follows: Dissolve 0.275 g of zinc acetate dihydrate in 400 g of ethanol solution under magnetic stirring in a 60 °C water bath; Disperse 0.1 g of sodium hydroxide in 80 g of ethanol solution under magnetic stirring in a 60 °C water bath. Then mix the above two solutions, add 320 g of ethanol, and continue magnetic stirring at 60 °C for 2 h to obtain the mixed solution containing sodium hydroxide, zinc acetate dihydrate and ethanol;

[0049] S102. Place the carbon fiber cloth with the surface growth seed layer obtained in step S101 into a mixed solution of hexamethylenetetramine, zinc nitrate hexahydrate, and deionized water, stir, and react at 90 °C for 4 h. After the reaction ends and cools to room temperature, take it out, wash it with deionized water, and then dry it in an oven at 80 °C for 6 h to obtain a carbon fiber cloth with a zinc oxide micro-nano structure;

[0050] The preparation process of the mixed solution of hexamethylenetetramine, zinc nitrate hexahydrate, and deionized water is as follows: Dissolve 7.2 g of zinc nitrate hexahydrate in 400 g of deionized water under magnetic stirring, disperse 3.4 g of hexamethylenetetramine in 400 g of deionized water, and then mix the two solutions to obtain a mixed solution of hexamethylenetetramine, zinc nitrate hexahydrate, and deionized water;

[0051] The step of modifying the carbon fiber cloth with zinc oxide micro-nano structure in the above step S4 is as follows:

[0052] Place the carbon fiber cloth with a zinc oxide micro-nano structure into a mixed solution containing γ-aminopropyltriethoxysilane, ethanol, and deionized water, impregnate it at 65 °C for 3.5 h. The masses of γ-aminopropyltriethoxysilane, ethanol, and deionized water are 3.6 g, 108 g, and 250 g respectively, and then wash it with deionized water; Then place the carbon fiber cloth with a zinc oxide micro-nano structure into a mixed solution of 2.4 g of polyvinyl alcohol and 250 g of deionized water, impregnate it at 85 °C for 2 h, and then wash it with deionized water; Finally, place it in an oven at 100 °C and dry it for 2.5 h to obtain a pretreated carbon fiber cloth with a zinc oxide micro-nano structure.

[0053] Example 2

[0054] A preparation method of a high radial thermal conductivity carbon fiber composite material includes the following steps:

[0055] S1. Place 20 g of carbon fiber cloth in acetone, heat it to 70 °C and reflux for 24 h, then wash it with deionized water and place it in an oven at 80 °C to dry, obtaining a pretreated carbon fiber cloth;

[0056] S2. Immerse the carbon fiber cloth after surface pretreatment in step S1 in a tris(hydroxymethyl)aminomethane slow-release solution containing hydrochloric acid dopamine with a pH of 8.5 for 24 h. The masses of hydrochloric acid dopamine, tris(hydroxymethyl)aminomethane, and deionized water are 1.5 g, 1.21 g, and 1000 g respectively. After the impregnation ends, wash it with deionized water and place it in an oven at 80 °C to dry for 6 h to obtain a poly(dopamine)-modified carbon fiber cloth;

[0057] S3. Use the hydrothermal method to in-situ construct a zinc oxide seed layer and a zinc oxide nanorod structure on the surface of the polydopamine-modified carbon fiber cloth obtained in step S2 in sequence. After rinsing with deionized water, place it in an oven to dry and obtain a carbon fiber cloth with a zinc oxide micro-nano structure;

[0058] S4. Modify and process the carbon fiber cloth with a zinc oxide micro-nano structure obtained in step S3 through polyvinyl alcohol to obtain a pretreated carbon fiber cloth with a zinc oxide micro-nano structure;

[0059] S5. Mix 5 g of carbon nanotubes, 1 g of dispersant, 0.5 g of epoxy resin and 92.5 g of deionized water, and use a high-speed shear emulsifier to disperse for 6 h to prepare a uniform carbon nanotube slurry. Dilute the carbon nanotube slurry with deionized water to obtain a carbon nanotube dispersion. The mass fraction of carbon nanotubes in the carbon nanotube dispersion is 0.25 wt%. Then, vacuum-assisted impregnate the pretreated carbon fiber cloth with a zinc oxide micro-nano structure obtained in step S4 in 100 g of the diluted carbon nanotube dispersion for 1 h. Subsequently, perform unidirectional freeze casting at -100 °C on a unidirectional freeze casting device for 15 min, and then perform freeze-drying treatment for 24 h to obtain the final modified carbon fiber cloth

[0060] S6. Mix the modified carbon fiber cloth in step S5 with epoxy resin and curing agent through a vacuum bag molding process to obtain a high-radial thermal conductivity carbon fiber composite.

[0061] The specific steps for in-situ constructing a zinc oxide seed layer and a zinc oxide nanorod structure on the surface of the polydopamine-modified carbon fiber cloth in step S3 above are as follows:

[0062] S101. Place the carbon fiber cloth of the polydopamine-modified carbon fiber cloth in a mixed solution containing sodium hydroxide, zinc acetate dihydrate and ethanol, immerse it at 60 °C for 30 min, then place it in a high-temperature oven at 150 °C to dry for 10 min, and then repeat the operations of immersion and high-temperature drying for a total of 3 times to obtain a carbon fiber cloth with a seed layer grown on the surface;

[0063] The preparation process of the mixed solution containing sodium hydroxide, zinc acetate dihydrate and ethanol is as follows: Dissolve 0.275 g of zinc acetate dihydrate in 400 g of ethanol solution under magnetic stirring in a 60 °C water bath; Disperse 0.1 g of sodium hydroxide in 80 g of ethanol solution under magnetic stirring in a 60 °C water bath, then mix the above two solutions, add 320 g of ethanol, and continue magnetic stirring at 60 °C for 2 h to obtain the mixed solution containing sodium hydroxide, zinc acetate dihydrate and ethanol;

[0064] S102. Place the carbon fiber cloth with the surface growth seed layer obtained in step S101 into a mixed solution of hexamethylenetetramine, zinc nitrate hexahydrate, and deionized water, stir, and react at 85 °C for 2 h. After the reaction ends and cools to room temperature, take it out, wash it with deionized water, and then dry it in an oven at 80 °C for 6 h to obtain a carbon fiber cloth with zinc oxide micro-nano structures.

[0065] The preparation process of the mixed solution of hexamethylenetetramine, zinc nitrate hexahydrate, and deionized water is as follows: Dissolve 7.2 g of zinc nitrate hexahydrate in 400 g of deionized water under magnetic stirring, disperse 3.4 g of hexamethylenetetramine in 400 g of deionized water, and then mix the two solutions to obtain a mixed solution of hexamethylenetetramine, zinc nitrate hexahydrate, and deionized water.

[0066] The step of modifying the carbon fiber cloth with zinc oxide micro-nano structures in step S4 above is as follows:

[0067] Place the carbon fiber cloth with zinc oxide micro-nano structures into a mixed solution containing γ-aminopropyltriethoxysilane, ethanol, and deionized water, impregnate at 60 °C for 3 h. The masses of γ-aminopropyltriethoxysilane, ethanol, and deionized water are 3.6 g, 72 g, and 180 g respectively, and then wash with deionized water. Then place the carbon fiber cloth with zinc oxide micro-nano structures into a mixed solution of 2.4 g of polyvinyl alcohol and 192 g of deionized water, impregnate at 80 °C for 1 h, and then wash with deionized water. Finally, place it in an oven at 90 °C and dry for 2 h to obtain a pretreated carbon fiber cloth with zinc oxide micro-nano structures.

[0068] Example 3

[0069] A preparation method of a high radial thermal conductivity carbon fiber composite material includes the following steps:

[0070] S1. Place 20 g of carbon fiber cloth in acetone, heat to 70 °C and reflux for 24 h, then wash with deionized water and place it in an oven at 80 °C to dry, obtaining a pretreated carbon fiber cloth.

[0071] S2. Immerse the carbon fiber cloth after surface pretreatment in step S1 in a tris(hydroxymethyl)aminomethane slow-release solution with a pH of 8.5 containing dopamine hydrochloride for 24 h. The masses of dopamine hydrochloride, tris(hydroxymethyl)aminomethane, and deionized water are 1.5 g, 1.21 g, and 1000 g respectively. After the impregnation ends, wash with deionized water and place it in an oven at 80 °C to dry for 6 h to obtain a carbon fiber cloth modified with polydopamine.

[0072] S3. Use the hydrothermal method to in-situ construct a zinc oxide seed layer and a zinc oxide nanorod structure on the surface of the carbon fiber cloth modified with polydopamine obtained in step S2 in sequence. After rinsing with deionized water, place it in an oven to dry to obtain a carbon fiber cloth with zinc oxide micro-nano structures.

[0073] S4. Modify the carbon fiber cloth with zinc oxide micro-nano structure obtained in step S3 through polyvinyl alcohol modification to obtain a pretreated carbon fiber cloth with zinc oxide micro-nano structure;

[0074] S5. Mix 5 g of carbon nanotubes, 1 g of dispersant, 0.5 g of epoxy resin and 92.5 g of deionized water, and disperse them with a high-speed shear emulsifier for 12 h to prepare a uniform carbon nanotube slurry. Dilute the carbon nanotube slurry with deionized water to obtain a carbon nanotube dispersion. The mass fraction of carbon nanotubes in the carbon nanotube dispersion is 0.75 wt%. Then, vacuum-assisted impregnate the pretreated carbon fiber cloth with zinc oxide micro-nano structure obtained in step S4 in 100 g of the diluted carbon nanotube dispersion for 3 h, then perform unidirectional freeze casting at -120 °C on a unidirectional freeze casting device for 5 min, and then perform freeze-drying treatment for 10 h to obtain the final modified carbon fiber cloth;

[0075] S6. Mix the modified carbon fiber cloth in step S5 with epoxy resin and curing agent through a vacuum bag molding process to obtain a high-radial thermal conductivity carbon fiber composite.

[0076] The specific steps for in-situ constructing a zinc oxide seed layer and a zinc oxide nanorod structure on the surface of the poly-dopamine modified carbon fiber cloth in step S3 by hydrothermal method are as follows:

[0077] S101. Place the carbon fiber cloth of the poly-dopamine modified carbon fiber cloth in a mixed solution containing sodium hydroxide, zinc acetate dihydrate and ethanol, impregnate it at 60 °C for 30 min, then place it in a high-temperature oven at 150 °C and dry it for 10 min. Then repeat the operations of impregnation and high-temperature drying for a total of 5 times to obtain a carbon fiber cloth with a seed layer grown on its surface;

[0078] The preparation process of the mixed solution containing sodium hydroxide, zinc acetate dihydrate and ethanol is as follows: Dissolve 0.275 g of zinc acetate dihydrate in 400 g of ethanol solution under magnetic stirring in a 60 °C water bath; Disperse 0.1 g of sodium hydroxide in 80 g of ethanol solution under magnetic stirring in a 60 °C water bath. Then mix the above two solutions, add 320 g of ethanol, and continue magnetic stirring at 60 °C for 2 h to obtain the mixed solution containing sodium hydroxide, zinc acetate dihydrate and ethanol;

[0079] S102. Put the carbon fiber cloth with a seed layer grown on its surface obtained in step S101 into a mixed solution of hexamethylenetetramine, zinc nitrate hexahydrate and deionized water, stir and react at 95 °C for 8 h. After the reaction ends and cools to room temperature, take it out, wash it with deionized water, and then dry it in an oven at 80 °C for 6 h to obtain a carbon fiber cloth with zinc oxide micro-nano structure;

[0080] The preparation process of the mixed solution of hexamethylenetetramine, zinc nitrate hexahydrate and deionized water is as follows: Under magnetic stirring, 7.2 g of zinc nitrate hexahydrate is dissolved in 400 g of deionized water, and 3.4 g of hexamethylenetetramine is dispersed in 400 g of deionized water. Then the two solutions are mixed to obtain the mixed solution of hexamethylenetetramine, zinc nitrate hexahydrate and deionized water;

[0081] The step of modifying the carbon fiber cloth with zinc oxide micro-nano structure in the above step S4 is as follows:

[0082] The carbon fiber cloth with zinc oxide micro-nano structure is put into a mixed solution containing γ-aminopropyltriethoxysilane, ethanol and deionized water and impregnated at 70 °C for 4 h. The masses of γ-aminopropyltriethoxysilane, ethanol and deionized water are 3.6 g, 144 g and 360 g respectively, and then it is washed with deionized water; Then the carbon fiber cloth with zinc oxide micro-nano structure is put into a mixed solution of 2.4 g of polyvinyl alcohol and 336 g of deionized water and impregnated at 90 °C for 3 h, and then it is washed with deionized water; Finally, it is put into an oven at 110 °C and dried for 3 h to obtain the pretreated carbon fiber cloth with zinc oxide micro-nano structure.

[0083] Example 4

[0084] A preparation method of a high-radial thermal conductivity carbon fiber composite material includes the following steps:

[0085] S1. Place 20 g of carbon fiber cloth in acetone, heat it to 70 °C and reflux for 24 h, then wash it with deionized water and place it in an oven at 80 °C to dry, obtaining the pretreated carbon fiber cloth;

[0086] S2. Immerse the carbon fiber cloth pretreated on the surface in step S1 in a tris(hydroxymethyl)aminomethane slow-release solution containing dopamine hydrochloride with a pH of 8.5 for 24 h. The masses of dopamine hydrochloride, tris(hydroxymethyl)aminomethane and deionized water are 1.5 g, 1.21 g and 1000 g respectively. After the impregnation, wash it with deionized water and place it in an oven at 80 °C to dry for 6 h to obtain the carbon fiber cloth modified with polydopamine;

[0087] S3. Use the hydrothermal method to in-situ construct a zinc oxide seed layer and a zinc oxide nanorod structure on the surface of the carbon fiber cloth modified with polydopamine obtained in step S2 in sequence. After rinsing with deionized water, place it in an oven to dry to obtain the carbon fiber cloth with zinc oxide micro-nano structure;

[0088] S4. Modify the carbon fiber cloth with zinc oxide micro-nano structure obtained in step S3 with polyvinyl alcohol to obtain the pretreated carbon fiber cloth with zinc oxide micro-nano structure;

[0089] S5. Mix 5 g of carbon nanotubes, 1 g of dispersant, 0.5 g of epoxy resin with 92.5 g of deionized water, and disperse them for 10 h using a high-speed shear emulsifier to prepare a uniform carbon nanotube slurry. Dilute the carbon nanotube slurry with deionized water to obtain a carbon nanotube dispersion. The mass fraction of carbon nanotubes in the carbon nanotube dispersion is 0.4 wt%. Then, vacuum-assisted impregnate the pretreated carbon fiber cloth with zinc oxide micro-nano structure obtained in step S4 in 100 g of the diluted carbon nanotube dispersion for 2 h. Subsequently, perform unidirectional freeze casting at -120 °C for 5 min on a unidirectional freeze casting device, and then perform freeze-drying treatment for 10 h to obtain the final modified carbon fiber cloth;

[0090] S6. Mix the modified carbon fiber cloth in step S5 with epoxy resin and curing agent through a vacuum bag molding process to obtain a high-radial thermal conductivity carbon fiber composite.

[0091] The specific steps for in-situ constructing a zinc oxide seed layer and a zinc oxide nanorod structure on the surface of the polydopamine-modified carbon fiber cloth by hydrothermal method in the above step S3 are as follows:

[0092] S101. Place the carbon fiber cloth of the polydopamine-modified carbon fiber cloth in a mixed solution containing sodium hydroxide, zinc acetate dihydrate, and ethanol, impregnate it at 60 °C for 30 min, then place it in a high-temperature oven at 150 °C and dry it for 10 min. Then repeat the operations of impregnation and high-temperature drying four times in total to obtain a carbon fiber cloth with a seed layer grown on its surface;

[0093] The preparation process of the mixed solution containing sodium hydroxide, zinc acetate dihydrate, and ethanol is as follows: Dissolve 0.275 g of zinc acetate dihydrate in 400 g of ethanol solution under magnetic stirring in a 60 °C water bath; Disperse 0.1 g of sodium hydroxide in 80 g of ethanol solution under magnetic stirring in a 60 °C water bath. Then mix the above two solutions, add 320 g of ethanol, and continue magnetic stirring at 60 °C for 2 h to obtain the mixed solution containing sodium hydroxide, zinc acetate dihydrate, and ethanol;

[0094] S102. Put the carbon fiber cloth with a seed layer grown on its surface obtained in step S101 into a mixed solution of hexamethylenetetramine, zinc nitrate hexahydrate, and deionized water, stir and react at 90 °C for 4 h. After the reaction ends and cools to room temperature, take it out, wash it with deionized water, and then dry it in an oven at 80 °C for 6 h to obtain a carbon fiber cloth with a zinc oxide micro-nano structure;

[0095] The preparation process of the mixed solution of hexamethylenetetramine, zinc nitrate hexahydrate, and deionized water is as follows: Dissolve 7.2 g of zinc nitrate hexahydrate in 400 g of deionized water under magnetic stirring, disperse 3.4 g of hexamethylenetetramine in 400 g of deionized water, and then mix the two solutions to obtain the mixed solution of hexamethylenetetramine, zinc nitrate hexahydrate, and deionized water;

[0096] The step of modifying the carbon fiber cloth with zinc oxide micro-nano structure in the above step S4 is as follows:

[0097] Put the carbon fiber cloth with zinc oxide micro-nano structure into a mixed solution containing γ-aminopropyltriethoxysilane, ethanol and deionized water, and immerse it at 70 °C for 3 h. The masses of γ-aminopropyltriethoxysilane, ethanol and deionized water are 3.6 g, 90 g and 300 g respectively. Then wash it with deionized water; then put the carbon fiber cloth with zinc oxide micro-nano structure into a mixed solution of 2.4 g of polyvinyl alcohol and 260 g of deionized water, and immerse it at 80 °C for 2.5 h. Then wash it with deionized water; finally, put it into an oven at 105 °C and dry it for 2.5 h to obtain a pretreated carbon fiber cloth with zinc oxide micro-nano structure.

[0098] In the present invention, the dispersant for dispersing carbon nanotubes is PVP;

[0099] The vacuum bag molding process in step S6 is to place four layers of modified carbon fiber cloth on the mold, and lay a release cloth, a flow guide net and a vacuum bag on it in sequence. After ensuring the device is sealed, draw epoxy resin and curing agent into the device. The curing is carried out at 60 °C for 4 h. For the working principle diagram of the vacuum bag molding process, refer to Figure 2 ;

[0100] In the present invention, the mass ratio between the epoxy resin and the curing agent is 3:1, and the curing agent uses modified polyetheramine.

[0101] Comparative Example 1

[0102] The difference between Comparative Example 1 and Example 2 is that the process of modifying the carbon fiber cloth with zinc oxide micro-nano structure by polyvinyl alcohol in step S4 is cancelled, and the remaining steps are exactly the same as those in Example 2.

[0103] Comparative Example 2

[0104] The difference between Comparative Example 2 and Example 2 is that the addition of epoxy resin in step S5 is cancelled, and the remaining steps are exactly the same as those in Example 2.

[0105] Comparative Example 3

[0106] Compared with Comparative Example 1, Comparative Example 3 also cancels the addition of epoxy resin in step S5, and the remaining steps are exactly the same as those in Example 2.

[0107] Comparative Example 4

[0108] The difference between Comparative Example 4 and Example 2 is that the freeze casting and freeze drying treatment in step S5 are replaced by heating and drying. The temperature of heating and drying is 80 °C, and the time of heating and drying is 10 h. The remaining steps are exactly the same as those in Example 2.

[0109] Comparative Example 5

[0110] The difference between Comparative Example 5 and Example 2 is that step S5 is completely cancelled, that is, the compounding of carbon nanotubes is cancelled, and the modified carbon fiber cloth is directly obtained after step S4.

[0111] For the specimens obtained in Examples 1-4 and Comparative Examples 1-5, tensile strength tests were carried out in accordance with ASTM D3039, flexural strength tests were carried out in accordance with ASTM D790, impact strength tests were carried out in accordance with ASTM D7136, interlaminar shear strength tests were carried out in accordance with ASTM D2344, and thermal conductivity tests were carried out in accordance with ASTM-E1461. The test results are shown in Table 1:

[0112] Table 1: Performance test results of carbon fiber composites obtained in examples and comparative examples

[0113]

[0114]

[0115] From the data of Example 2 and Comparative Examples 1-2, it can be seen that the tensile strength, flexural strength, interlaminar shear strength and thermal conductivity of the composites prepared in Comparative Examples 1-2 are significantly reduced. Further observation Figures 3 - 5 , where Figure 4 is the electron microscope image of the modified carbon fiber cloth in Comparative Example 1 before the carbon fiber composite is completely compounded with epoxy resin (the same below). When the carbon fiber is impregnated with carbon nanotubes, a small amount of carbon nanotubes are first compounded with epoxy resin, and the epoxy resin effectively increases the viscosity of the carbon nanotubes. However, the process of modifying the carbon fiber cloth with zinc oxide micro-nano structure in step S4 is missing, resulting in the aggregation of carbon nanotubes in some areas and uneven dispersion, and the performance of the composite material decreases; Figure 5 is the electron microscope image of the modified carbon fiber cloth in Comparative Example 2. It can be clearly seen that when the addition of epoxy resin is lacking, the adhesion amount of carbon nanotubes decreases, which also leads to the decrease of the performance of the composite material; Figure 3 In the modified carbon fiber cloth in

[0116] Comparative Example 4 uses a heating and drying method to treat carbon nanotubes in step S5. Figure 6It is the electron microscope image of the carbon fiber cloth obtained in Comparative Example 4. It can be seen from the figure that the amount of carbon nanotubes attached to it is small and no flaky structure appears. When freeze-drying the carbon nanotube dispersion by the freeze-drying method, the carbon nanotubes can connect the carbon fibers to form a flaky heat conduction network, which can greatly enhance the interfacial bonding between it and the resin, reduce the thermal resistance, and at the same time broaden the heat conduction path, improving the comprehensive performance of the composite material.

[0117] Figure 7 It is the motor microscope image of the modified carbon fiber cloth obtained in Comparative Example 5. After the composite material lacks the attachment of carbon nanotubes, the comprehensive performance of the composite material decreases very significantly.

[0118] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principle and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a high radial thermal conductive carbon fiber composite material, characterized in that: The following steps are involved: S1. Pre-treating the surface of the carbon fiber cloth; S2, immersing the carbon fiber cloth after surface pretreatment in step S1 in a tris(hydroxymethyl)aminomethane sustained-release solution containing dopamine hydrochloride at a pH of 8.5 for 24 hours, washing with deionized water after immersion, and drying in an oven at 80° C. for 6 hours to obtain a polydopamine-modified carbon fiber cloth; S3, using a hydrothermal method to sequentially construct a zinc oxide seed layer and a zinc oxide nanorod structure on the surface of the polydopamine-modified carbon fiber cloth obtained in step S2, and then rinsing with deionized water and drying in an oven to obtain a carbon fiber cloth with a zinc oxide micro-nano structure; S4, modifying the carbon fiber cloth with zinc oxide micro-nano structure obtained in step S3 by polyvinyl alcohol to obtain a pretreated carbon fiber cloth with zinc oxide micro-nano structure; S5, mixing carbon nanotubes, dispersant and epoxy resin with deionized water and dispersing them in a high-speed shear emulsifier for 6 to 12 hours to prepare a uniform carbon nanotube slurry, diluting the carbon nanotube slurry to obtain a carbon nanotube dispersion, and then vacuum-assisted impregnating the pretreated carbon fiber cloth with zinc oxide micro-nano structure obtained in step S4 in the diluted carbon nanotube dispersion for 1 to 3 hours, then performing unidirectional freeze casting on a unidirectional freeze casting device, and then freeze-drying to obtain the final modified carbon fiber cloth; S6. Mixing the modified carbon fiber cloth in step S5 with epoxy resin and curing agent through a vacuum bagging molding process to obtain a high radial thermal conductive carbon fiber composite material.

2. The high radial thermal conductive carbon fiber composite material and the preparation method thereof according to claim 1, characterized in that: In the step S1, the surface of the carbon fiber cloth is pretreated by first placing the carbon fiber in acetone at 70° C. and refluxing for 24 hours, then washing it with deionized water and drying it in an oven at 80° C.

3. The high radial thermal conductive carbon fiber composite material and the preparation method thereof according to claim 1, characterized in that: In the step S2, the mass ratio of tris(hydroxymethyl)aminomethane, dopamine hydrochloride and deionized water is 1:1.24:826, and the carbon fiber cloth after surface pretreatment is immersed in the slow-release solution for 24 hours.

4. The high radial thermal conductive carbon fiber composite material and the preparation method thereof according to claim 1, characterized in that: The specific steps of using the hydrothermal method to sequentially construct the zinc oxide seed layer and the zinc oxide nanorod structure in situ on the surface of the polydopamine-modified carbon fiber cloth in step S3 are as follows: S101, immersing the carbon fiber arrangement of the carbon fiber cloth modified with polydopamine in a mixed solution containing sodium hydroxide, zinc acetate dihydrate and ethanol at 60° C. for 30 minutes, then drying in a high-temperature oven at 150° C. for 10 minutes, and then repeating the immersion and high-temperature drying operations for a total of 3-5 times to obtain a carbon fiber cloth with a surface growth seed layer; S102, placing the carbon fiber cloth with the surface growth seed layer obtained in step S101 into a mixed solution of hexamethylenetetramine, zinc nitrate hexahydrate and deionized water, stirring and reacting at 85-95° C. for 2-8 hours. After the reaction is completed and cooled to room temperature, taking out and washing with deionized water, and then drying in an oven at 80° C. for 6 hours, to obtain a carbon fiber cloth with a zinc oxide micro-nano structure.

5. The high radial thermal conductivity carbon fiber composite material and the preparation method thereof according to claim 4, characterized in that: The mass ratio of sodium hydroxide, zinc acetate dihydrate and ethanol in step S101 is 1:2.75:8000, and the mass ratio of hexamethylenetetramine, zinc nitrate hexahydrate and deionized water in step S102 is 1:2.12:235.

3.

6. The high radial thermal conductive carbon fiber composite material and the preparation method thereof according to claim 1, characterized in that: The step of modifying the carbon fiber cloth having zinc oxide micro-nano structure by polyvinyl alcohol in step S4 is as follows: The carbon fiber cloth with zinc oxide micro-nano structure is placed in a mixed solution containing γ-aminopropyltriethoxysilane, ethanol and deionized water at 60-70°C and immersed for 3-4 hours, and then washed with deionized water; then the carbon fiber cloth with zinc oxide micro-nano structure is placed in a mixed solution of polyvinyl alcohol and deionized water at 80-90°C and immersed for 1-3 hours, and then washed with deionized water; finally, it is placed in an oven at 90-110°C and dried for 2-3 hours to obtain a pretreated carbon fiber cloth with zinc oxide micro-nano structure.

7. The high radial thermal conductive carbon fiber composite material and the preparation method thereof according to claim 6, characterized in that: The mass ratio of γ-aminopropyltriethoxysilane, ethanol and deionized water in the mixed solution of γ-aminopropyltriethoxysilane, ethanol and deionized water is 1:(20-40):(50-100), and the mass ratio of polyvinyl alcohol to deionized water in the mixed solution of polyvinyl alcohol and deionized water is 1:(80-140).

8. The high radial thermal conductive carbon fiber composite material and the preparation method thereof according to claim 1, characterized in that: In the step S5, the mass ratio of carbon nanotubes, dispersant and epoxy resin to deionized water is (8-12):(1-3):1:(90-95), and the mass fraction of dispersed carbon nanotubes in the step S5 is 0.25-0.75wt%; the casting temperature of unidirectional freezing in the step S5 is -196°C to -100°C, the freezing time is 2 to 15 minutes, and the freeze-drying time is 6 to 24 hours.

9. A high radial thermal conductivity carbon fiber composite material, characterized in that: The carbon fiber composite material with high radial thermal conductivity and a preparation method thereof are prepared by the method described in any one of claims 1 to 8.

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