CN111719311A - Modified carbon fiber, modified carbon fiber reinforced epoxy resin composite material and preparation method thereof - Google Patents

Abstract

The present application relates to a modified carbon fiber, a method for preparing the modified carbon fiber, a modified carbon fiber reinforced epoxy resin composite material with interface self-healing properties, and a method for preparing the modified carbon fiber reinforced epoxy resin composite material. The modified carbon fiber reinforced epoxy resin composite material described in this paper has the advantages of simple repair conditions, easy realization, low repair cost, and can be repaired multiple times, which can effectively prolong the service life of the carbon fiber reinforced epoxy resin composite material.

Description

Modified carbon fiber, modified carbon fiber reinforced epoxy resin composite material and preparation thereof method

technical field

The invention relates to the technical field of composite materials, in particular to a modified carbon fiber, a method for preparing the modified carbon fiber, a modified carbon fiber reinforced epoxy resin composite material with interface self-healing properties, and the preparation of the modified carbon fiber reinforced epoxy resin composite material method.

Background technique

Carbon fiber reinforced epoxy resin composites have the advantages of high specific strength, fatigue resistance, high specific modulus, chemical corrosion resistance, strong designability, small thermal expansion coefficient, and stable structure and dimensions. As a new type of high-performance composite material, carbon fiber reinforced epoxy resin composite material can meet the strict requirements of weight, strength, stiffness, fatigue resistance, dimensional stability, etc. in special fields. At present, carbon fiber reinforced epoxy resin composite materials have been widely used in aerospace, automobile, transportation, energy, construction, medical equipment, electronic appliances and other fields. As a two-phase composite material, a large number and area of interfacial phases exist between carbon fiber and epoxy resin. The interfacial phase is directly related to the transfer and diffusion of internal stress, electricity, magnetism, heat, etc., and plays an important and even decisive role in the overall performance of the composite material.

In the long-term service process of carbon fiber reinforced epoxy resin composites, different forms of damage such as internal delamination are likely to occur due to the influence of service conditions. Most of these failures originate from microcracks generated at the interface structure of materials. The growth, expansion and convergence of these interface microcracks will lead to the decline of the mechanical, electrical, thermal, and electromagnetic shielding properties of the composite material, which in turn affects the service life of the composite material. Therefore, the repair of interface microcracks and the inhibition of microcrack growth have become urgent problems to be solved in the application process of composite materials.

In recent years, researchers at home and abroad have carried out research on the repair of micro-cracks at the interface of carbon fiber composites from different angles. The Chinese patent application with publication number CN103113745A discloses that gold nanoparticles are introduced into the interface of carbon fiber/polyethersulfone composite material, and the interface of the composite material is repaired by using the ionon resonance effect of gold nanoparticles. However, this repair method is driven by light with a specific wavelength and light intensity, and it is obviously incapable of repairing the interface micro-cracks existing in the large-sized composite material. However, there are few reports in China on the repair of microcracks on the interface of carbon fiber composites.

SUMMARY OF THE INVENTION

The purpose of this application is to provide a modified carbon fiber that can be used to prepare a carbon fiber reinforced epoxy resin with self-healing properties of the interface, so as to solve the above-mentioned technical problems.

The purpose of the present application is also to provide a method for preparing the modified carbon fiber as described above.

The purpose of the present application is also to provide a modified carbon fiber reinforced epoxy resin composite material with interface self-healing properties.

The purpose of the present application is also to provide a method for preparing the above-mentioned modified carbon fiber reinforced epoxy resin composite material.

Specifically, the present application introduces thermally reversible Diels-Alder covalent bonds into the interface area of carbon fiber reinforced epoxy resin composite materials by the method of carbon fiber surface modification, and prepares carbon fiber reinforced epoxy resin composite materials with interface self-healing properties. In the present invention, dopamine, polyethyleneimine, furoyl chloride and bismaleimide are used as raw materials to prepare carbon fibers with grafted bismaleimide rings, and then the carbon fibers are compounded with 2-furancarboxamide and epoxy resin. The carbon fiber reinforced epoxy resin composite material with interface self-healing properties is prepared, and the self-healing of interface micro-cracks is realized through a two-step heating process. The invention solves the problem that the interface microcrack expansion of the traditional carbon fiber reinforced epoxy resin matrix composite material causes the material performance to decline or even fails, and has the advantages of simple repair conditions, easy realization, low repair cost, multiple repairs, etc., and can effectively extend the The service life of carbon fiber reinforced epoxy resin composites.

In order to solve the above technical problems, the present application provides the following technical solutions.

In a first aspect, the present application provides a method for preparing modified carbon fibers, characterized in that the method comprises the following steps:

S1: soak the carbon fibers in a first mixed solution at room temperature for 18-30 hours, and obtain amine-functionalized carbon fibers after drying, wherein the first mixed solution is obtained by mixing a buffer solution, dopamine and polyethyleneimine;

S2: soak the amine functionalized carbon fibers in the second mixed solution in advance, and then dropwise add the anhydrous solution of the diene body containing acid chloride groups to the second mixed solution, and continue at a temperature of 30-60° C. The reaction is carried out for 6-12 hours, and after drying, the carbon fiber of the grafted diene body is obtained, wherein the second mixed solution is obtained by mixing an anhydrous solvent, an acid binding agent and a catalyst;

S3: The carbon fiber of the grafted diene body and the solution of the dienophile containing two double bonds in a good solvent are stirred and reacted at a temperature of 50-70° C. for 4-8 hours to obtain the grafted dienephile Body modified carbon fiber.

In an embodiment of the first aspect, in step S1, the pH value of the buffer solution is 7.5-9.5, preferably the pH value is 8.5;

The buffer solution can be prepared from tris-hydrochloric acid buffer pair, glycine-sodium hydroxide buffer pair, borax-sodium hydroxide buffer pair or boric acid-borax buffer pair;

The number-average molecular weight of the polyethyleneimine is 600-10000;

The mass ratio of the dopamine, polyethyleneimine and buffer solution is 1:(0.25-4):(400-600).

In an embodiment of the first aspect, in step S2, the anhydrous solvent should be a good solvent for a diene body containing an acid chloride group, preferably anhydrous dichloromethane, anhydrous dichloroethane , mixed solution of one or more of anhydrous chloroform and anhydrous carbon dichloride;

The acid binding agent is one or more of triethylamine, sodium bicarbonate, sodium carbonate, sodium hydroxide, carbonate, phosphate, acetate, etc.;

Described catalyzer is a kind of in N,N'-dimethylformamide or pyridine;

The diene body containing an acyl chloride group is one or more mixtures of furoyl chloride or an acyl chloride containing a butadiene structure, and the furoyl chloride is preferably 2-furoyl chloride, 2-furan acetyl chloride, etc., The acid chloride containing a butadiene structure may be 3,5-dialenyl chloride and 4,6-dialenyl chloride.

In an embodiment of the first aspect, the mixed mass ratio of the anhydrous solvent, the acid binding agent, and the catalyst is 100:(30-50):(0.5-1).

In an embodiment of the first aspect, the dienophile containing two double bonds is a mixture of one or more of bismaleimides or unsaturated double bond compounds, bismaleimides The imides are preferably 1,4-bismaleimidobutane, 1,2-bismaleimidoethane, 1,6-bismaleimidohexane Alkane, N,N'-(4,4-methylenediphenyl)bismaleimide, etc. The unsaturated double bond compound can be 1,4-pentadiene, 1,5-hexadiene, etc. ; The mass fraction of dienophiles containing two double bonds in the solution is 20% to 40%.

In a second aspect, the present application provides a dienophile-grafted modified fiber prepared by the method described in the first aspect.

In a third aspect, the present application provides a method for preparing a modified carbon fiber reinforced epoxy resin composite material, characterized in that the method comprises the following steps:

(1) mixing the amine group-containing diene body or the epoxy group-containing diene body and the epoxy resin according to a mass ratio of (5-30):100 to obtain an epoxy resin mixed solution;

(2) pre-curing the modified fiber grafted with dienophile as described in the second aspect and the epoxy resin mixture solution obtained in step (1), and then curing again to obtain modified carbon fiber reinforced epoxy resin resin composite.

In an embodiment of the third aspect, in step (1), the monoamine-containing diene is 2-furanmethylamine, 2-furanethylamine, 2-furanpropylamine, 2,4 -One or more of pentadien-1-amine and 1,3-butadiene-1-amine. The epoxy-containing diene body is one or more of glycidyl furfuryl ether and 2-epoxymethylfuran. In an embodiment of the third aspect, the pre-curing temperature is 50-70° C., and the pre-curing time is 4-8 hours.

In a third aspect, the present application provides a modified carbon fiber reinforced epoxy resin composite material prepared by the method as described in the third aspect.

In an embodiment of the third aspect, the modified carbon fiber reinforced epoxy resin composite material has interface self-healing properties, and the self-healing method is carried out as follows: first, the prepared modified carbon fiber reinforced epoxy resin composite material is composited The material was heated at 100-120°C for 1-3 hours, then at 50-70°C for 1-3 hours.

Compared with the prior art, the beneficial effect of the present application is that the present invention introduces thermally reversible Diels-Alder covalent bonds into the carbon fiber reinforced epoxy resin interface through the method of surface co-deposition and chemical graft modification. When the composite material is in service for a long time, the thermally reversible covalent bond in the interface region can be disconnected and reconstructed through a two-step heating process, and then the interface of carbon fiber reinforced epoxy resin can be accurately repaired, which is suitable for repairing carbon fiber reinforced epoxy resin with complex structure. Resin matrix composites. The repairing method provided by the present invention requires a repairing temperature of up to 120° C., the repairing conditions are simple and easy to realize, and the repairing cost is low. According to the composite material preparation method and repairing method provided by the present invention, carbon fiber reinforced epoxy resin composite materials can be realized. Multiple accurate repairs of materials, interface repair efficiency up to 70%. In addition, the preparation method provided by the present invention can also improve the interface adhesion performance of the carbon fiber reinforced epoxy resin composite material.

Description of drawings

The present application can be better understood by describing the embodiments of the present application in conjunction with the accompanying drawings, in which:

Fig. 1 is the surface element test result of the carbon fiber grafted with maleimide ring prepared in Example 1 of the present invention and the carbon fiber of Comparative Example 1, specifically showing the XPS broad spectrum and O1s peak spectrum of different carbon fibers. In Figure 1, a and b represent undesized carbon fibers; c and d represent carbon fibers grafted with maleimide rings.

Fig. 2 is the initial interface shear strength test curve of the carbon fiber reinforced epoxy resin composite material with interface self-healing properties prepared in Example 1 and the carbon fiber reinforced epoxy resin composite material of Comparative Example 1 and the interface shear strength after two self-healing Shear strength test curve. In FIG. 2 , a represents the modified carbon fiber-reinforced epoxy resin composite material of Example 1, and b represents the composite material according to Comparative Example 1.

3 is a schematic diagram of the thermally reversible Diels-Alder covalent bond structure in the interface region of the carbon fiber reinforced epoxy resin composite material with interface self-healing properties prepared in Example 1 of the present invention.

Detailed ways

Unless otherwise defined, technical or scientific terms used in the specification and claims shall have the ordinary meaning as understood by one of ordinary skill in the art to which this invention belongs. All numerical values listed in this article from the lowest value to the highest value refer to all the values obtained in increments of one unit between the lowest value and the highest value when the difference between the lowest value and the highest value is more than two units. numerical value.

The specific embodiments of the present invention will be described below with reference to the specific drawings. It should be pointed out that, in the specific description of these embodiments, in order to carry out a concise and concise description, it is impossible for this specification to describe all the features of the actual embodiments. Detailed description.

As mentioned above, it is difficult for the carbon fiber reinforced epoxy resin materials in the prior art to achieve self-healing cracks. Therefore, the purpose of the present application is to firstly provide a grafted dienophile modified carbon fiber, which can form a thermally reversible Diels-Alder covalent bond with an amine group-modified epoxy resin, thereby providing a carbon fiber with Modified carbon fiber reinforced epoxy resin composites with interfacial self-healing properties.

In a preferred embodiment, the present application provides a method for preparing a carbon fiber reinforced epoxy resin composite material with interface self-healing properties, which is specifically prepared according to the following steps:

Step 1: prepare a buffer solution with a mass fraction of 1.2‰, and adjust the pH to 7.5-9.5;

Step 2: mixing dopamine, polyethyleneimine and the buffer solution prepared in step 1 according to a certain proportion to obtain a mixed solution;

Step 3: adding carbon fiber to the mixed solution prepared in step 2, and soaking at room temperature for 18-30 hours. The carbon fiber is then removed and cleaned. Dry the cleaned carbon fibers to obtain amine-functionalized carbon fibers;

Step 4: Immerse the amine-functionalized carbon fiber prepared in Step 3 into a mixed solution composed of anhydrous solvent, acid binding agent, and catalyst in a certain mass ratio, and dropwise add the diene body containing acid chloride group and The anhydrous solvent is prepared into a solution with a mass fraction of 30% to 50%, and is heated to 30 to 60° C. to make the reaction continue for 6 to 12 hours. After the reaction, the carbon fibers are taken out and cleaned, and then heated and dried to obtain the carbon fibers of the grafted diene;

Step 5: Put the carbon fiber grafted with diene in step 4 into a reactor containing a solution of a dienophile with two double bonds of a certain concentration, heat and stir. The carbon fiber is taken out, washed with a good solvent of the dienophile, and then heated and dried to obtain the carbon fiber grafted with the dienophile;

Step 6: Mix the amine group-containing diene body or the epoxy group diene body and the epoxy resin according to the mass ratio of (5-30):100, and stir evenly;

Step 7: compound the carbon fiber grafted diene body prepared in step 5 with the resin mixture prepared in step 6, then pre-cured at a certain temperature, and then cured according to the resin curing process, and after curing, a Interfacial self-healing properties of carbon fiber reinforced epoxy resin composites.

Example

The present application is further described below by way of examples, but the present application is not limited to the scope of the described embodiments. The experimental methods that do not specify specific conditions in the following examples are selected according to conventional methods and conditions, or according to the product description.

Example 1

The preparation method of carbon fiber reinforced epoxy resin composite material with interface self-healing performance is specifically prepared according to the following steps:

Step 1: prepare an aqueous solution of tris(hydroxymethylaminomethane) with a mass fraction of 1.2‰, and adjust the pH to 8.5 with a hydrochloric acid solution;

Step 2: mixing dopamine, polyethyleneimine with a number average molecular weight of 600 and the solution with a pH of 8.5 prepared in step 1 according to a mass ratio of 1:0.25:400 to obtain a mixed solution;

Step 3: Add carbon fiber to the mixed solution prepared in Step 2, and soak at room temperature for 18 hours. The carbon fiber is then removed and cleaned. Dry the cleaned carbon fibers to obtain amine-functionalized carbon fibers;

Step 4: soak the amine-functionalized carbon fiber prepared in step 3 into anhydrous dichloromethane, triethylamine, and N,N'-dimethylformamide in a mass ratio of 100:30:0.5. In the mixed solution, a solution with a mass fraction of 30% prepared from 2-furoyl chloride and anhydrous dichloromethane was added dropwise, and heated to 30° C. to continue the reaction for 6 hours. After the reaction, the carbon fibers are taken out and cleaned, and then heated and dried to obtain the carbon fibers of the grafted diene;

Step 5: Put the carbon fiber grafted with diene in step 4 into a reactor containing an acetonitrile solution of 1,4-bismaleimidobutane with a mass fraction of 20%, and heat to 50°C and stirred for 4 hours. The carbon fiber is taken out, cleaned with acetonitrile, and then heated and dried to obtain the carbon fiber grafted with maleimide ring;

Step 6: Mix 2-furan methylamine and epoxy resin according to the mass ratio of 5:100, and stir evenly;

Step 7: compound the carbon fiber grafted with maleimide ring prepared in step 5 and the resin mixture prepared in step 6, then pre-cured at 50° C. for 5 hours, and then cured according to the resin curing process. Then, the carbon fiber reinforced epoxy resin composite material with interface self-healing performance can be obtained.

The self-healing of the carbon fiber reinforced epoxy resin composite material with interface self-healing properties prepared in this example is performed according to the following steps: firstly, the prepared composite material is heated at 100° C. for 1 hour, and then heated at 50° C. for 1 hour.

Example 2

The preparation method of carbon fiber reinforced epoxy resin composite material with interface self-healing performance is specifically prepared according to the following steps:

Step 1: prepare a sodium hydroxide solution with a mass fraction of 1.2‰, and use glycine to adjust the pH to 7.5;

Step 2: mixing dopamine, polyethyleneimine with a number average molecular weight of 1000 and the solution with a pH of 7.5 prepared in step 1 according to a mass ratio of 1:2:400 to obtain a mixed solution;

Step 3: Add carbon fiber to the mixed solution prepared in Step 2, and soak at room temperature for 21 hours. The carbon fiber is then removed and cleaned. Dry the cleaned carbon fibers to obtain amine-functionalized carbon fibers;

Step 4: soak the amine functionalized carbon fiber prepared in step 3 into anhydrous dichloroethane, sodium bicarbonate, N,N'-dimethylformamide in a mass ratio of 100:40:0.5. In the mixed solution of , a solution with a mass fraction of 40% prepared from 2-furanacetyl chloride and anhydrous dichloroethane was added dropwise, and heated to 40° C. to continue the reaction for 8 hours. After the reaction, the carbon fiber is taken out and cleaned, and then heated and dried to obtain the carbon fiber of the grafted furan ring;

Step 5: Put the carbon fiber grafted with the furan ring in the step 4 into the reaction kettle containing the acetonitrile solution of 1,6-bismaleimidobutane with a mass fraction of 20%, heat it to 60° C. Stir for 6 hours. The carbon fiber is taken out, cleaned with acetonitrile, and then heated and dried to obtain the carbon fiber grafted with maleimide ring;

Step 6: Mix 2-furylethylamine and epoxy resin according to the mass ratio of 13:100, and stir evenly;

Step 7: compound the carbon fiber grafted with maleimide ring prepared in step 5 and the resin mixture prepared in step 6, then pre-cured at 60° C. for 6 hours, and then cured according to the resin curing process. Then, the carbon fiber reinforced epoxy resin composite material with interface self-healing performance can be obtained.

The self-healing of the carbon fiber reinforced epoxy resin composite material with interface self-healing properties prepared in this example is carried out according to the following steps: firstly, the prepared composite material is heated at 100° C. for 2 hours, and then heated at 50° C. for 3 hours.

Example 3

The preparation method of carbon fiber reinforced epoxy resin composite material with interface self-healing performance is specifically prepared according to the following steps:

Step 1: prepare a sodium hydroxide solution with a mass fraction of 1.2‰, and use borax to adjust the pH to 8.5;

Step 2: mixing dopamine, polyethyleneimine with a number average molecular weight of 5000 and the solution with a pH of 8.5 prepared in step 1 according to a mass ratio of 1:3:500 to obtain a mixed solution;

Step 3: Add carbon fiber to the mixed solution prepared in Step 2, and soak at room temperature for 24 hours. The carbon fiber is then removed and cleaned. Dry the cleaned carbon fibers to obtain amine-functionalized carbon fibers;

Step 4: Immerse the amine-functionalized carbon fiber prepared in Step 3 into a mixed solution consisting of anhydrous chloroform, sodium carbonate, and pyridine in a mass ratio of 100:40:1, and dropwise add 3,5-dichloromethane. Dilute acid chloride and anhydrous chloroform were prepared into a solution with a mass fraction of 40%, which was heated to 50° C. and the reaction continued for 10 hours. After the reaction, the carbon fibers are taken out and cleaned, and then heated and dried to obtain the carbon fibers of the grafted diene;

Step 5: Put the carbon fiber grafted with diene in step 4 into a reaction kettle containing a 20% mass fraction of 1,4-pentadiene n-hexane solution, heat to 60° C. and stir for 6 hours. The carbon fiber is taken out, washed with n-hexane, and then heated and dried to obtain the carbon fiber grafted with dienophile;

Step 6: Mix 2,4-pentadien-1-amine and epoxy resin according to the mass ratio of 21:100, and stir evenly;

Step 7: The carbon fiber grafted with dienophile prepared in step 5 is compounded with the resin mixture prepared in step 6, and then pre-cured at 60 ° C for 8 hours, and then cured according to the resin curing process. Carbon fiber reinforced epoxy resin composites with interface self-healing properties can be obtained.

The self-healing of the carbon fiber reinforced epoxy resin composite material with interface self-healing properties prepared in this example is performed according to the following steps: firstly, the prepared composite material is heated at 110° C. for 3 hours, and then heated at 60° C. for 3 hours.

Example 4

The preparation method of carbon fiber reinforced epoxy resin composite material with interface self-healing performance is specifically prepared according to the following steps:

Step 1: Prepare a borax solution with a mass fraction of 1.2‰, and use boric acid to adjust the pH to 9.5;

Step 2: mixing dopamine, polyethyleneimine with a number-average molecular weight of 10,000 and the solution with a pH of 9.5 prepared in step 1 according to a mass ratio of 1:4:600 to obtain a mixed solution;

Step 3: Add carbon fiber to the mixed solution prepared in Step 2, and soak at room temperature for 30 hours. The carbon fiber is then removed and cleaned. Dry the cleaned carbon fibers to obtain amine-functionalized carbon fibers;

Step 4: Immerse the amine-functionalized carbon fiber prepared in Step 3 into a mixed solution consisting of anhydrous carbon dichloride, sodium hydroxide, and pyridine in a mass ratio of 100:50:1, and dropwise add 4 , 6-didilute acid chloride and anhydrous carbon dichloride were prepared into a solution with a mass fraction of 50%, and heated to 60° C. to make the reaction continue for 12 hours. After the reaction, the carbon fibers are taken out and cleaned, and then heated and dried to obtain the carbon fibers of the grafted diene;

Step 5: The carbon fiber grafted with diene in Step 4 is placed in a reaction kettle containing 40% 1,5-hexadiene in n-hexane solution, heated to 70° C. and stirred for 8 hours. The carbon fiber is taken out, washed with n-hexane, and then heated and dried to obtain the carbon fiber grafted with dienophile;

Step 6: Mix the glycidyl furfuryl ether and the epoxy resin according to the mass ratio of 30:100, and stir evenly;

Step 7: The carbon fiber grafted with dienophile prepared in step 5 is compounded with the resin mixture prepared in step 6, and then pre-cured at 70 ° C for 8 hours, and then cured according to the resin curing process. Carbon fiber reinforced epoxy resin composites with interface self-healing properties can be obtained.

The self-healing of the carbon fiber reinforced epoxy resin composite material with interface self-healing properties prepared in this example is carried out according to the following steps: firstly, the prepared composite material is heated at 120° C. for 3 hours, and then heated at 70° C. for 3 hours.

Comparative Example 1

The preparation method of Comparative Example 1 is as follows:

The carbon fibers used in Comparative Example 1 are carbon fibers that have not been modified by the modification methods in steps 1 to 5 in the examples. The carbon fiber is compounded with a resin mixture of 2-furan methylamine and epoxy resin in a mass ratio of 5:100, then pre-cured at 50° C. for 5 hours, and then cured according to the resin curing process.

The self-healing of the carbon fiber reinforced epoxy resin composite material prepared in Comparative Example 1 was carried out according to the following steps: firstly, the prepared composite material was heated at 100° C. for 1 hour, and then heated at 50° C. for 1 hour.

The surface elements of the carbon fibers grafted with maleimide rings prepared in Example 1 and the carbon fibers of Comparative Example 1 were analyzed by using the 1/AXIS UltraDLD X-ray photoelectron spectrometer of Shimadzu-Kratos Company, and the results are shown in the figure. 1 and Table 1. The interfacial shear strength of the carbon fiber reinforced epoxy resin composite materials with self-healing properties of the interface of Examples 1 to 4 and the carbon fiber reinforced epoxy resin composite material of Comparative Example 1 were measured by the microdrop method, and the testing instrument was Beijing Fumar. The results are shown in Table 2, and the load-displacement curves of Example 1 and Comparative Example 1 are shown in Figure 2. The interface repair efficiency is defined as the ratio of the repaired interface shear strength to the initial interface shear strength multiplied by 100%, and the repair efficiency is shown in Table 2.

Tables 1 and 2 are described below.

Table 1 Carbon fiber prepared in Example 1 and carbon fiber surface element and functional group content of the comparative example

Table 2 Interface shear strength and self-healing efficiency of examples and comparative examples

As can be seen from Figure 1 and Table 1, the carbon fiber grafted with maleimide rings in Example 1 has more nitrogen elements on the surface than the unmodified carbon fiber in Comparative Example 1, and the oxygen-containing functional group C= The O content increased significantly, indicating that the maleimide ring was successfully grafted onto the carbon fiber surface. It can be seen from Figure 2 and Table 2 at the same time that the carbon fiber reinforced epoxy resin composites with interface self-healing properties prepared in Examples 1 to 4 still have strong interfacial shear strength after repair, showing high efficiency self-healing performance with multiple self-healing behaviors. Compared with Comparative Example 1, the initial interfacial shear strength of the carbon fiber reinforced epoxy resin composites with interface self-healing properties prepared in Examples 1 to 4 is increased by about 51%, indicating that the preparation method provided by the present invention can effectively improve the carbon fiber reinforced ring. Interfacial adhesion properties of oxy-resin composites.

The above description of the embodiments is for the convenience of those of ordinary skill in the art to understand and apply the present application. It will be apparent to those skilled in the art that various modifications to these embodiments can be readily made, and the generic principles described herein can be applied to other embodiments without inventive step. Therefore, the present application is not limited to the embodiments herein, and those skilled in the art can make improvements and modifications without departing from the scope and spirit of the present application based on the content disclosed in the present application, all within the scope of the present application.

Claims (10)

1. a method for preparing modified carbon fiber, is characterized in that, described method comprises the following steps: S1: soak the carbon fibers in a first mixed solution at room temperature for 18-30 hours, and obtain amine-functionalized carbon fibers after drying, wherein the first mixed solution is obtained by mixing a buffer solution, dopamine and polyethyleneimine; S2: soak the amine functionalized carbon fibers in the second mixed solution in advance, and then dropwise add the anhydrous solution of the diene body containing acid chloride groups to the second mixed solution, and continue at a temperature of 30-60° C. The reaction is carried out for 6-12 hours, and after drying, the carbon fiber of the grafted diene body is obtained, wherein the second mixed solution is obtained by mixing an anhydrous solvent, an acid binding agent and a catalyst; S3: The carbon fiber of the grafted diene body and the solution of the dienophile containing two double bonds in a good solvent are stirred and reacted at a temperature of 50-70° C. for 4-8 hours to obtain the grafted dienephile Body modified carbon fiber. 2. The method according to claim 1, wherein, in step S1, the pH value of the buffer solution is 7.5-9.5, preferably the pH value is 8.5; The buffer solution is prepared from tris(hydroxymethyl)aminomethane-hydrochloric acid buffer pair, glycine-sodium hydroxide buffer pair, borax-sodium hydroxide buffer pair or boric acid-borax buffer pair; The number-average molecular weight of the polyethyleneimine is 600-10000; The mass ratio of the dopamine, polyethyleneimine and buffer solution is 1:(0.25-4):(400-600). 3. The method according to claim 1, characterized in that, in step S2, the anhydrous solvent should be a good solvent for diene bodies containing acid chloride groups, preferably anhydrous dichloromethane, anhydrous A mixed solution of one or more of dichloroethane, anhydrous chloroform and anhydrous carbon dichloride; The acid binding agent is one or more of triethylamine, sodium bicarbonate, sodium carbonate, sodium hydroxide, carbonate, phosphate, acetate, etc.; Described catalyzer is a kind of in N,N'-dimethylformamide or pyridine; The diene body containing an acid chloride group is one or more mixtures of furoyl chloride or an acid chloride containing a butadiene structure, and the furoyl chloride is preferably 2-furoyl chloride or 2-furan acetyl chloride; the The acid chloride containing butadiene structure is preferably 3,5-dialenyl chloride or 4,6-dialenyl chloride; The mixed mass ratio of the anhydrous solvent, acid binding agent and catalyst is preferably 100:(30-50):(0.5-1). 4. method as claimed in claim 1 is characterized in that, the described dienophile that contains two double bonds is the mixture of one or more in bismaleimides or unsaturated double bond compounds , bismaleimides are preferably 1,2-bismaleimidoethane, 1,4-bismaleimidobutane, 1,6-bismaleimidoyl Iminohexane, or N,N'-(4,4-methylenediphenyl)bismaleimide; the unsaturated double bond compound is preferably 1,4-pentadiene or 1,5 -hexadiene; the mass fraction of dienophiles containing two double bonds in the solution is 20% to 40%. 5. A grafted dienophile modified fiber prepared by the method of any one of claims 1-4. 6. A method for preparing a modified carbon fiber reinforced epoxy resin composite material, wherein the method comprises the following steps: (1) mixing the amine group-containing diene body or the epoxy group-containing diene body and the epoxy resin according to a mass ratio of (5-30):100 to obtain an epoxy resin mixed solution; (2) pre-curing the modified fiber grafted with dienophile as claimed in claim 5 and the epoxy resin mixed solution obtained in step (1), and then curing to obtain modified carbon fiber reinforced epoxy resin resin composite. 7. method as claimed in claim 6, is characterized in that, in step (1), described diene body containing amine group is 2-furan methylamine, 2-furan ethylamine, 2-furan propylamine, One or more of 2,4-pentadien-1-amine and 1,3-butadiene-1-amine; The epoxy-containing diene body is one or more of glycidyl furfuryl ether and 2-epoxymethylfuran. 8. The method of claim 6, wherein the pre-curing temperature is 50-70°C, and the pre-curing time is 4-8 hours. 9. A modified carbon fiber reinforced epoxy resin composite material prepared by the method according to any one of claims 6-8. 10. The modified carbon fiber reinforced epoxy resin composite material according to claim 9, wherein the modified carbon fiber reinforced epoxy resin composite material has interface self-healing performance, and the self-healing method is carried out as follows: first The prepared modified carbon fiber reinforced epoxy resin composite material is heated at 100-120° C. for 1-3 hours, and then heated at 50-70° C. for 1-3 hours.

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