Modified carbon fiber / polyimide composite material and preparation method thereof

Abstract

The invention provides a modified carbon fiber / polyimide composite material, the surface of carbon fiber is sequentially coated with a metal polyphenol network layer and a polyimide layer, and boron nitride is arranged between the metal polyphenol network layer and the polyimide layer. The invention also provides a preparation method of the modified carbon fiber / polyimide composite material. Compared with an unmodified composite material, the interlaminar shear strength (ILSS) of the composite material provided by the invention can be improved by 20% or above, and the problem of interface debonding is effectively solved. The introduction of boron nitride enables the interface layer to work in a high-temperature environment of 300 DEG C or above. After high-temperature aging, the mechanical property retention rate of the composite material is higher than that of a traditional composite material.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of carbon fiber materials, and particularly to a high-performance carbon fiber / polyimide composite material based on metal polyphenol network / boron nitride modification and a preparation method thereof. BACKGROUND

[0002] Polyimide is a kind of heat-resistant polymer material with excellent comprehensive performance, which not only has good thermal performance, mechanical properties and chemical stability, but also has low dielectric constant and thermal expansion coefficient. At the same time, due to the diversity of dianhydride and diamine monomer structure in the preparation of polyimide molecules, the polyimide molecule structure is diverse, and the designability is strong, and the application field is very wide. With the development of aerospace, nuclear power equipment, shipbuilding industry, medical devices, new energy and other fields, in order to meet the application requirements of these fields, at present, many researches are devoted to the development of polyimide materials with higher thermal stability and mechanical strength, but this often leads to high apparent density, reduced mechanical elasticity and thermal insulation performance; on the contrary, the polyimide material with light apparent density, flexibility and good thermal insulation performance often has poor mechanical performance and thermal performance. For example, Chinese patent CN101735457B discloses a production method of soft polyimide foam, and the prepared material has low density, softness and elasticity, but its mechanical properties and thermal properties are poor, which cannot meet the application of many fields. Ren et al. successfully prepared a light isocyanate-based polyimide material with poor thermal performance.

[0003] Therefore, it is a difficult problem in the field to prepare a polyimide material with excellent mechanical properties, high temperature resistance and thermal insulation performance. How to improve the mechanical properties of polyimide materials while ensuring their heat resistance and thermal insulation performance needs further exploration. It is of great significance to provide a polyimide material with outstanding high temperature resistance and thermal insulation performance and excellent mechanical strength through simple and effective technology, which will have broad application prospects in many important fields such as aerospace, nuclear power equipment, shipbuilding industry, medical devices and new energy.

[0004] Carbon fibers have been widely used in aerospace, automobiles, wind power generation and other fields due to their excellent mechanical properties, low density and good thermal stability. However, the interface bonding ability between carbon fibers and polyimide matrix is weak, which leads to the mechanical properties and heat resistance of the composite material cannot meet the expected requirements. In order to improve the bonding force between carbon fibers and matrix, common surface treatment methods include plasma treatment, chemical plating, nitriding, etc. However, these methods usually have the disadvantages of high cost, complex treatment and unstable effect.

[0005] Therefore, there is an urgent need for a new, efficient and low-cost method for modifying the surface of carbon fibers to improve the interfacial bonding between the carbon fibers and the polyimide matrix and significantly enhance the mechanical properties and heat resistance of the composite material. SUMMARY

[0006] The present application provides a method for preparing high-performance carbon fiber / polyimide composite material by combining metal polyphenol network chemical modification and boron nitride soaking treatment. The method can effectively improve the interfacial bonding between carbon fibers and polyimide, and significantly enhance the mechanical strength, heat resistance and corrosion resistance of the composite material.

[0007] Item 1. A modified carbon fiber / polyimide composite material, wherein the surface of the carbon fiber is coated with a metal polyphenol network layer and a polyimide layer in sequence, and boron nitride is further included between the metal polyphenol network layer and the polyimide layer.

[0008] Item 2. The composite material according to item 1, wherein the metal polyphenol network layer is formed from tannic acid and ferric chloride hexahydrate.

[0009] Item 3. The composite material according to item 1, wherein the boron nitride is a nanosheet.

[0010] Item 4. The composite material according to item 1, wherein the thickness of the metal polyphenol network layer is 50-400 nm, preferably 80-250 nm.

[0011] Item 5. A method for preparing a modified carbon fiber / polyimide composite material, comprising, preparing a metal polyphenol network solution from tannic acid and ferric chloride hexahydrate; immersing carbon fibers in the metal polyphenol network solution and performing ultrasonic treatment to coat the surface of the carbon fibers with a metal polyphenol network layer, thereby obtaining carbon fiber@MPN; immersing the carbon fiber@MPN in a boron nitride solution and performing ultrasonic treatment to attach boron nitride to the surface of the metal polyphenol network layer, thereby obtaining carbon fiber@MPN / BN; immersing the carbon fiber@MPN / BN in a polyimide glue solution for infiltration, and after heating and curing, obtaining a carbon fiber / polyimide composite material.

[0012] Item 6. The preparation method according to item 5, wherein the molar ratio of tannic acid to ferric chloride hexahydrate is 1:(1-5).

[0013] Item 7. The preparation method according to item 5, wherein the carbon fibers are immersed in the metal polyphenol network solution and subjected to ultrasonic treatment for 10-60 min.

[0014] Item 8. The preparation method according to Item 5, wherein the concentration of the boron nitride solution is 0.3-2 mol / L, preferably 0.3-1.5 mol / L, and more preferably 0.5-1.2 mol / L.

[0015] Item 9. According to the preparation method described in Item 5, wherein the carbon fiber@MPN is immersed in boron nitride solution and subjected to ultrasonic treatment for 30-180 min.

[0016] Application of the method described in any one of items 10 and 5-9 in the preparation of carbon fiber / polyimide composite materials.

[0017] This application has the following beneficial effects: The interlaminar shear strength (ILSS) of the composite material provided in this application is more than 20% higher than that of the unmodified composite material, effectively solving the problem of interfacial debonding. The introduction of boron nitride enables the interfacial layer to operate in high-temperature environments above 300°C. After high-temperature aging, the mechanical property retention rate of the composite material described in this application is higher than that of traditional composite materials. Attached Figure Description

[0018] Figure 1 This is a longitudinal section SEM image of the carbon fiber / polyimide composite material prepared in Comparative Example 3 of this application after it has been damaged. The image shows that after the fiber is damaged, its surface is smooth and there is no residue of polyimide layer, indicating that the interfacial bonding ability between carbon fiber and polyimide is poor.

[0019] Figure 2 This is a longitudinal section SEM image of the carbon fiber / polyimide composite material prepared in Example 1 of this application after it has been damaged. The image shows that after the fiber is damaged, polyimide remains on its surface, indicating that the interfacial bonding ability between the carbon fiber and the polyimide is very good. Detailed Implementation

[0020] Specific embodiments of this application will now be described in more detail with reference to the accompanying drawings. While specific embodiments of this application are shown in the drawings, it should be understood that this application can be implemented in various forms and should not be limited to the embodiments or examples set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of this application and to fully convey the scope of this application to those skilled in the art.

[0021] The term "carbon fiber / polyimide composite material" in this application refers to a composite material combining carbon fiber and polyimide, wherein carbon fiber is the reinforcing phase and polyimide is the matrix phase.

[0022] The term "carbon fiber@MPN" refers to carbon fiber with a metal polyphenol network (MPN) coating on its surface. "Carbon fiber@MPN / BN" refers to carbon fiber with a metal polyphenol network coating on its surface, and boron nitride is also attached to the surface. The boron nitride can be nanoparticles or nanosheets.

[0023] The term "metal polyphenol network" (MPN) refers to a new type of functional material that is formed by the self-assembly of metal ions and polyphenolic compounds through coordination, and combines the properties of metal ions and polyphenols.

[0024] This application provides a modified carbon fiber / polyimide composite material, wherein the surface of the carbon fiber is sequentially coated with a metal polyphenol network layer and a polyimide layer, and boron nitride particles and / or boron nitride nanosheets are further included between the metal polyphenol network layer and the polyimide layer.

[0025] In some embodiments, the thickness of the metal polyphenol network layer is 50-400 nm, specifically, it can be 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, 110 nm, 120 nm, 130 nm, 140 nm, 150 nm, 160 nm, 170 nm, 180 nm, 190 nm, 200 nm, 210 nm, 220 nm, 230 nm, 240 nm, 250 nm, 260 nm, 270 nm, 280 nm, 290 nm, 300 nm, 310 nm, 320 nm, 330 nm, 340 nm, 350 nm, 360 nm, 370 nm, 380 nm, 390 nm, or 400 nm. In this application, the thickness of the metal polyphenol network layer is measured by scanning electron microscopy (SEM).

[0026] In some embodiments, the thickness of the metal polyphenol network layer is 80-250 nm.

[0027] In some embodiments, the metal polyphenol network is formed from tannic acid and ferric chloride hexahydrate.

[0028] In some embodiments, the boron nitride is boron nitride nanosheets.

[0029] This application also provides a method for preparing a modified carbon fiber / polyimide composite material, comprising the following steps.

[0030] 1. Desizing the carbon fiber. Specifically, the carbon fiber is treated with a solvent at 60-100℃ for 12-60 hours, and then washed with deionized water to desizing, thus obtaining desizing carbon fiber.

[0031] 2. A metal polyphenol network solution was prepared using tannic acid and ferric chloride hexahydrate (FeCl3·6H2O) as raw materials. Specifically, Tris powder and dilute hydrochloric acid solution were added to water to prepare a Tris solution with a pH of 8-10 as a solvent. Tannic acid and ferric chloride hexahydrate were then added to the solvent and stirred until completely dissolved to form a metal polyphenol network solution.

[0032] 3. Immerse the desized carbon fibers in the metal polyphenol network solution and sonicate them for 10-60 minutes to coat the surface of the carbon fibers with a metal polyphenol network layer, thus obtaining carbon fiber@MPN.

[0033] 4. Immerse the carbon fiber@MPN in a boron nitride (BN) solution with a concentration of 0.3-1.5 mol / L and perform ultrasonic treatment for 30-180 min to allow the boron nitride to adhere to the surface of the metal polyphenol network layer, thereby obtaining carbon fiber@MPN / BN.

[0034] 5. The carbon fiber@MPN / BN is immersed in polyimide adhesive and then cured by heating to obtain carbon fiber / polyimide composite material.

[0035] In this application, the purpose of desizing carbon fiber is to remove the slurry coating on the surface of carbon fiber, expose its intrinsic surface structure, and create favorable conditions for subsequent surface modification and composite interface bonding. Therefore, desizing carbon fiber can be performed using technical means known to those skilled in the art.

[0036] In some implementations, polar solvents can be used to desizing carbon fibers, specifically acetone, butanone (MEK), ethanol, or N,N-dimethylformamide (DMF).

[0037] In some implementations, the desizing temperature for carbon fibers can be 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, or 100°C.

[0038] In some implementations, the desizing time for carbon fibers can be 12h, 18h, 24h, 30h, 36h, 42h, 48h, 54h, or 60h.

[0039] In some implementations, the carbon fibers are treated with acetone at 80°C for 48 hours to obtain desized carbon fibers.

[0040] In some implementations, when preparing the metal polyphenol network solution, the molar ratio of tannic acid to ferric chloride hexahydrate is 1:(1-5), specifically, it can be 1:1, 1:2, 1:3, 1:4, or 1:5.

[0041] In some implementations, the molar ratio of tannic acid to ferric chloride hexahydrate is 1:3.

[0042] In some embodiments, the pH of the Tris solution can be 8, 8.5, 9, 9.5, or 10 when preparing the metal polyphenol network solution.

[0043] In some embodiments, the pH of the Tris solution is 8.5 when preparing the metal polyphenol network solution.

[0044] In some embodiments, the desized carbon fibers are immersed in the metal polyphenol network solution and subjected to ultrasonic treatment for 10-60 minutes. Specifically, the ultrasonic treatment time can be 10 minutes, 20 minutes, 30 minutes, 40 minutes, 50 minutes, or 60 minutes.

[0045] In some embodiments, the desized carbon fibers are immersed in the metal polyphenol network solution and subjected to ultrasonic treatment for 10-30 minutes.

[0046] In some embodiments, the desized carbon fibers are immersed in the metal polyphenol network solution and subjected to ultrasonic treatment for 30 minutes to obtain carbon fibers@MPN.

[0047] In some embodiments, when the carbon fiber@MPN is immersed in a boron nitride solution, the concentration of the boron nitride solution is 0.3-2 mol / L, specifically, it can be 0.3 mol / L, 0.4 mol / L, 0.5 mol / L, 0.6 mol / L, 0.7 mol / L, 0.8 mol / L, 0.9 mol / L, 1 mol / L, 1.1 mol / L, 1.2 mol / L, 1.3 mol / L, 1.4 mol / L, 1.5 mol / L, 1.6 mol / L, 1.7 mol / L, 1.8 mol / L, 1.9 mol / L, or 2 mol / L.

[0048] In some embodiments, the concentration of the boron nitride solution is 0.3-1.5 mol / L.

[0049] In some embodiments, the concentration of the boron nitride solution is 0.5-1.2 mol / L.

[0050] In some embodiments, the concentration of the boron nitride solution is 1 mol / L.

[0051] In some embodiments, the ultrasonic treatment time of the carbon fiber@MPN in the boron nitride solution is 30-180 min, specifically, it can be 30 min, 40 min, 50 min, 60 min, 70 min, 80 min, 90 min, 100 min, 110 min, 120 min, 130 min, 140 min, 150 min, 160 min, 170 min, or 180 min.

[0052] In some embodiments, the carbon fiber@MPN is ultrasonically treated in a boron nitride solution for 60 minutes.

[0053] The method described in this application achieves a firm and uniform coating of boron nitride on the carbon fiber surface through the "bridging" effect of MPN, which greatly increases the physical interlocking and chemical bonding between the carbon fiber and the polyimide resin, effectively improving the interfacial shear strength. Due to the enhanced interfacial bonding force, the interlaminar shear strength and flexural strength of the composite material are significantly improved.

[0054] In the raw materials used in this application for modified carbon fiber, tannic acid, as a natural polyphenol, can react with Fe under weakly alkaline conditions. 3+ Ions rapidly coordinate to form a metal polyphenol network layer with super-strong adhesion. This application adjusts the ratio of tannic acid and iron ions in the metal polyphenol network to create a more suitable network for fixing boron nitride (MPN), allowing the MPN layer to be firmly anchored to the carbon fiber surface. Simultaneously, the phenolic hydroxyl and other functional groups abundant on the MPN layer surface can form strong hydrogen bonds, van der Waals forces, and even coordination bonds with the groups on the boron nitride nanosheet surface, tightly fixing the boron nitride nanosheets to the carbon fiber surface. This application also optimizes the processing technology of the metal polyphenol network solution to ensure the thickness of the metal network polyphenol layer on the carbon fiber surface is within a suitable range, resulting in higher interlayer shear strength in the modified carbon fiber. Boron nitride is an excellent thermal management material; its introduction into the modified carbon fiber improves interfacial heat transfer. Furthermore, the MPN / BN composite coating exhibits structural stability at high temperatures, thereby increasing the thermal decomposition temperature and long-term service temperature of the composite material. The entire modification process is carried out in the liquid phase and at room temperature, avoiding potential damage to the carbon fiber matrix caused by strong acids, strong oxidants or high-energy plasma. The conditions are mild, the operation is simple, and the environment is friendly.

[0055] The preferred embodiments of this application have been described in detail above; however, this application is not limited thereto. Within the scope of the technical concept of this application, various simple modifications can be made to the technical solution of this application, including combining various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in this application and are all within the protection scope of this application.

[0056] The exemplary embodiments of this application are described below with reference to the accompanying drawings, including various details of the embodiments of this application to aid understanding, and the results demonstrate the technical effects that can generally be achieved by the implementation methods covered by this application.

[0057] Example Example 1 Step 1: 10 g of carbon fiber is refluxed with acetone at 80℃ for 48 h to remove the sizing agent, washed repeatedly in deionized water, and dried in an oven at 60℃ to obtain desized carbon fiber.

[0058] Step 2: Add 1.21 g Tris powder and 34.4 ml of 0.1 mol / L dilute hydrochloric acid solution to 200 ml of water to prepare a Tris solution with a pH of 8.5 as the solvent.

[0059] Step 3: Weigh 1 g of tannic acid and 0.47 g of ferric chloride hexahydrate (FeCl3·6H2O) and add them to the solution. Stir slowly for 10 min until completely dissolved to form a metal polyphenol network solution.

[0060] Step 4: Immerse the desized carbon fiber in a metal polyphenol network solution and perform ultrasonic cleaning in an ultrasonic cleaner for 30 minutes to ensure that the solution evenly wets the surface of the carbon fiber.

[0061] Step 5: After soaking, remove the carbon fiber and wash it three times in deionized water to obtain carbon fiber@MPN (CF@MPN).

[0062] Step 6: Immerse the carbon fiber@MPN in a 1.0 mol / L boron nitride (Shanghai Maclean Biochemical Technology Co., Ltd., particle size 5-10 μm) solution and place it in an ultrasonic cleaner for ultrasonic treatment for 60 minutes to allow the boron nitride nanosheets to be uniformly attached to the carbon fiber surface.

[0063] Step 7: After boron nitride treatment, the carbon fiber is washed three times with deionized water to remove excess chemical substances remaining on the surface. The washed carbon fiber is then dried at 60°C until no moisture remains, resulting in carbon fiber@MPN / BN.

[0064] Step 8: After passing carbon fiber@MPN / BN through the polyimide impregnation tank, collect the fiber bundles wetted by the adhesive solution using a rectangular iron frame. After collection, place them in a 150°C forced-air oven and continue heating until all residual solvent is completely removed. Then, perform post-treatment on the polyimide solution to complete the thermal closure process. The post-treatment process is 180°C / h + 230°C / h. After heat treatment, cool to room temperature in the oven and cut into 40 mm × 80 mm prepreg sheet standard samples.

[0065] Step 9: Arrange the prepreg sheets cut in Step 8 neatly into the mold coated with release agent. Place the mold into a hot molding press and heat it to 300℃ at a rate of about 5℃ / min. Hold it at this temperature without pressure for 2 hours. Apply appropriate pressure and vent the air 3 times during the process. After venting, start the curing process. The curing process is as follows: 280℃ / 2 h + 300℃ / 2 h + 340℃ / 2 h + 360℃ / 2 h. Maintain pressure throughout the curing process with a pressure value of 5 MPa.

[0066] The carbon fiber / polyimide composite material was prepared by steps 1-9, and the mechanical properties (IFSS) of the composite material were tested at 300℃. The test results are shown in Table 1.

[0067] Example 2-12 Multiple carbon fiber / polyimide composite materials were prepared according to the method described in Example 1. The differences between other examples and Example 1 are as follows.

[0068] The difference between Example 2 and Example 1 is that the cations used in preparing the metal polyphenol network are different.

[0069] The difference between Examples 3-5 and Example 1 lies in the different molar ratios of tannic acid and ferric chloride hexahydrate during the preparation of the metal polyphenol network.

[0070] The difference between Examples 6-7 and Example 1 is that the carbon fibers are treated in MPN for different times.

[0071] The difference between Examples 8-9 and Example 1 lies in the morphology or particle size of the boron nitride in the boron nitride solution (all purchased from Shanghai Maclean Biochemical Technology Co., Ltd.).

[0072] The difference between Examples 10-12 and Example 1 is the concentration of the boron nitride solution.

[0073] The mechanical properties (ILSS) of the composite materials obtained in Examples 2-12 were tested at 300℃. The test results are shown in Table 1.

[0074] Table 1

[0075] Comparative Example Comparative Example 1 Step 1: 10 g of carbon fiber is refluxed with acetone at 80℃ for 48 h to remove the sizing agent, washed repeatedly in deionized water, and dried in an oven at 60℃ to obtain desized carbon fiber.

[0076] Step 2: Add 1.21 g Tris powder and 34.4 ml of 0.1 mol / L dilute hydrochloric acid solution to 200 ml of water to prepare a Tris solution with a pH of 8.5 as the solvent.

[0077] Step 3: Weigh 1 g of tannic acid and 0.47 g of ferric chloride hexahydrate and add them to the solution. Stir slowly for 10 min until completely dissolved to form a metal polyphenol network (MPN) solution.

[0078] Step 4: Immerse the desized carbon fiber in a metal polyphenol network solution and perform ultrasonic cleaning in an ultrasonic cleaner for 30 minutes to ensure that the solution evenly wets the surface of the carbon fiber.

[0079] Step 5: After soaking, remove the carbon fiber and wash it three times in deionized water to obtain CF@MPN.

[0080] Step 6: After passing the carbon fibers obtained in Step 5 through the polyimide impregnation tank, collect the fiber bundles wetted by the adhesive solution by winding them with a rectangular iron frame. After collection, place them in a 150°C forced-air oven and continue heating until all residual solvent is completely removed. Then, perform post-treatment on the polyimide solution to complete the thermal closed-loop process. The post-treatment process is 180°C / h, 230°C / h heat treatment. After the heat treatment is completed, cool to room temperature with the oven and cut into 40 mm × 80 mm prepreg sheet standard samples.

[0081] Step 7: Place the prepreg cut in Step 6 neatly into the mold coated with release agent. Place the mold into a hot molding press and heat it to 300℃ at a rate of about 5℃ / min. Hold it at this temperature for 2 hours without pressure. Apply appropriate pressure and vent the air 3 times during the process. After venting, start the curing process. The curing process is: 280℃ / 2 h + 300℃ / 2 h + 340℃ / 2 h + 360℃ / 2 h. Maintain pressure throughout the curing process with a pressure value of 5 MPa.

[0082] Comparative Example 2 Step 1: 10 g of carbon fiber (CF) was refluxed with acetone at 80°C for 48 h to remove the sizing agent, washed repeatedly in deionized water, and dried in an oven at 60°C to obtain desized CF.

[0083] Step 2: Immerse the carbon fiber (CF) in a boron nitride (BM) solution and then perform ultrasonic treatment in an ultrasonic cleaner for 60 minutes. The boron nitride solution concentration is 1.0 mol / L, and the boron nitride particles are uniformly attached to the surface of the carbon fiber.

[0084] Step 3: After boron nitride treatment, the carbon fiber is washed three times with deionized water to remove excess chemical residues on the surface. The washed carbon fiber is then dried at 60°C until no moisture remains, yielding CF@BN.

[0085] Step 4: After passing the carbon fibers obtained in Step 3 through the polyimide impregnation tank, collect the fiber bundles wetted by the adhesive solution by winding them with a rectangular iron frame. After collection, place them in a 150°C forced-air oven and continue heating until all residual solvent is completely removed. Then, perform post-treatment on the polyimide solution to complete the thermal closed-loop process. The post-treatment process is 180°C / h and 230°C / h. After heat treatment, cool to room temperature with the oven and cut into 40 mm × 80 mm prepreg sheet standard samples.

[0086] Step 5: Place the prepreg cut in Step 4 neatly into the mold coated with release agent. Place the mold into a hot molding press and heat it to 300℃ at a rate of about 5℃ / min. Hold it at this temperature without pressure for 2 hours. Apply appropriate pressure and vent the air 3 times during the process. After venting, start the curing process. The curing process is: 280℃ / 2 h + 300℃ / 2 h + 340℃ / 2 h + 360℃ / 2 h. Maintain pressure throughout the curing process with a pressure value of 5 MPa.

[0087] Comparative Example 3 Step 1: 10 g of carbon fiber is refluxed with acetone at 80℃ for 48 h to remove the sizing agent, washed repeatedly in deionized water, and dried in an oven at 60℃ to obtain desized carbon fiber.

[0088] Step 2: After passing the desized carbon fibers through the polyimide impregnation tank, collect the fiber bundles wetted by the adhesive solution using a rectangular iron frame. After collection, place them in a 150℃ forced-air oven and continue heating until all residual solvent is completely removed. Then, perform post-treatment on the polyimide solution to complete the thermal closed-loop process. The post-treatment process is 180℃ / h, 230℃ / h heat treatment. After the heat treatment is completed, cool to room temperature with the oven and cut into 40 mm × 80 mm prepreg sheet standard samples.

[0089] Step 3: Place the prepreg sheets cut in Step 2 neatly into the mold coated with release agent. Place the mold into a hot molding press and heat it to 300℃ at a rate of about 5℃ / min. Hold it at this temperature without pressure for 2 hours. Apply appropriate pressure and vent the air 3 times during the process. After venting, start the curing process. The curing process is: 280℃ / 2 h + 300℃ / 2 h + 340℃ / 2 h + 360℃ / 2 h. Maintain pressure throughout the curing process with a pressure value of 5 MPa.

[0090] Comparative Example 4 According to the method described in Example 1, carbon fiber / polyimide composite material was prepared. The difference from Example 1 is that when preparing the metal polyphenol network solution, the mass of tannic acid and ferric chloride hexahydrate was 1 g and 1.61 g, respectively, that is, the mass ratio of ferric ions in tannic acid and ferric chloride hexahydrate was 3:1.

[0091] The mechanical properties (ILSS) of the composite materials obtained in Comparative Examples 1-4 were tested at 300℃, and the test results are shown in Table 2.

[0092] Table 2

[0093] Comparing the test data of Example 1 and Comparative Example 4, the inventors, in the process of further research based on previous studies (CN117385631A), discovered that when tannic acid and ferric chloride hexahydrate form a metal polyphenol network, when the mass of tannic acid is greater than the mass of ferric chloride hexahydrate, especially when the molar ratio of tannic acid to ferric chloride hexahydrate is 1:3, boron nitride can be better anchored, thereby improving the interlaminar shear strength of the modified fiber. Simultaneously, it also greatly increases the physical interlocking and chemical bonding between carbon fiber and polyimide resin, effectively improving the interfacial shear strength. Due to the enhanced interfacial bonding force, the interlaminar shear strength and flexural strength of the composite material are significantly improved.

Claims

1. A modified carbon fiber / polyimide composite, wherein, The carbon fiber surface is coated with a metal polyphenol network layer and a polyimide layer in sequence, and boron nitride is further included between the metal polyphenol network layer and the polyimide layer.

2. The composite material of claim 1, wherein, The metal polyphenol network layer is formed from tannic acid and ferric chloride hexahydrate.

3. The composite material of claim 1, wherein, The boron nitride is a nanosheet.

4. The composite material of claim 1, wherein, The thickness of the metal polyphenol network layer is 50-400 nm, preferably 80-250 nm.

5. A method for preparing a modified carbon fiber / polyimide composite material, comprising, using tannic acid and ferric chloride hexahydrate as raw materials to prepare a metal polyphenol network solution; immersing carbon fibers in the metal polyphenol network solution and performing ultrasonic treatment to coat the carbon fiber surface with a metal polyphenol network layer to obtain carbon fiber@MPN; immersing the carbon fiber@MPN in a boron nitride solution and performing ultrasonic treatment to attach boron nitride to the surface of the metal polyphenol network layer to obtain carbon fiber@MPN / BN; immersing the carbon fiber@MPN / BN in a polyimide glue solution for infiltration, and after heating and curing, a carbon fiber / polyimide composite material is obtained.

6. The production method according to claim 5, wherein The molar ratio of tannic acid to ferric chloride hexahydrate is 1:(1-5).

7. The production method according to claim 5, wherein The carbon fibers are immersed in the metal polyphenol network solution and subjected to ultrasonic treatment for 10-60 min.

8. The production method according to claim 5, wherein The concentration of the boron nitride solution is 0.3-2 mol / L, preferably 0.3-1.5 mol / L, and more preferably 0.5-1.2 mol / L.

9. The production method according to claim 5, wherein The carbon fiber@MPN is immersed in the boron nitride solution and subjected to ultrasonic treatment for 30-180 min.

10. Use of the method of any one of claims 5-9 in the preparation of a carbon fiber / polyimide composite material.

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