A carbon fiber, a preparation method thereof, and a composite material containing the same

Abstract

The present invention belongs to the technical field of composite materials, and specifically relates to a carbon fiber with a phthalonitrile group-terminated polyurethane on its surface, a preparation method thereof, and a resin-based carbon fiber reinforced composite material containing the same. The surface of the carbon fiber has a phthalonitrile group-terminated polyurethane polymer layer. On the one hand, this polymer layer functions as a sizing agent. On the other hand, the polymer layer contains active phthalonitrile functional groups, which can form a thermosetting interface layer with the matrix phthalonitrile resin during the curing process. The interface layer connects the carbon fiber and the resin matrix through covalent bonds and has better interfacial strength than ordinary sizing agents. This interface layer has good thermal stability and can maintain the interfacial layer strength in a high-temperature environment, thereby ensuring the mechanical properties of the composite material in a high-temperature environment.

Description

Technical Field

[0001] The present invention relates to the technical field of composite materials, and particularly to a carbon fiber, a preparation method thereof, and a composite material containing the same. More specifically, it relates to a carbon fiber with a phthalonitrile group-terminated polyurethane on the surface, a preparation method thereof, and a resin-based carbon fiber reinforced composite material containing the same. Background Art

[0002] Compared with traditional lightweight alloy materials, resin-based composite materials have a smaller density, a higher specific strength, and a higher flexible structural designability. With the continuous development of the demand for structural weight reduction, resin-based carbon fiber reinforced composite materials are being increasingly used in fields such as aerospace and high-end automobiles. However, as structural materials, in many cases, there are not only requirements for the mechanical properties of the materials, but also very strict requirements for the heat resistance, ablation resistance, and flame retardancy of the materials. For example, when a spacecraft or a rocket passes through the atmosphere, the intense friction with the air generates a high temperature that can reach several hundred or even over a thousand degrees Celsius, which requires the external fairing material to have good ablation resistance; another example is that the structural materials near a high-power engine are affected by the heat generated by the engine operation, and their working temperature may also reach above 200°C. The heat resistance of resin-based composite materials is their most important performance shortcoming, which restricts their application in high-temperature environments.

[0003] Phthalonitrile is a class of aromatic monomers containing dicyano groups. Phthalonitrile monomers can be cross-linked through cyanide groups under heating conditions to obtain phthalonitrile resins containing triazine rings, isoindole rings, and phthalocyanine ring structures. The cured phthalonitrile resins have excellent mechanical and heat resistance properties, and the glass transition temperature can exceed 400°C, exceeding most types of polyimide resins. Therefore, phthalonitrile / carbon fiber composite materials are composite materials that can be applied to high-temperature environments. However, most of the current commercial carbon fiber sizing agents belong to epoxy and cyanate ester types. These sizing agents have poor heat resistance and low binding force with phthalonitrile resins. Under high-temperature environments, the interfacial strength between carbon fibers and phthalonitrile resins will rapidly decay, resulting in the destruction of the composite material interface layer and ultimately affecting the mechanical properties of the material at high temperatures. Summary of the Invention

[0004] To solve the problems existing in the prior art, the main object of the present invention is to propose a carbon fiber with a phthalonitrile group-terminated polyurethane on the surface, a preparation method thereof, and a resin-based carbon fiber reinforced composite material containing the same.

[0005] To solve the above technical problems, according to one aspect of the present invention, the following technical solutions are provided:

[0006] A carbon fiber with a phthalonitrile group-terminated polyurethane on the surface has the following molecular structure on its surface:

[0007]

[0008] Among them, V is the part of the aminophenol monomer other than the amino group and the phenolic hydroxyl group;

[0009] U is a divalent group, representing the part of the isocyanate-terminated polyurethane other than the terminal -NCO group, having the following structure, where n is an integer greater than or equal to 1:

[0010]

[0011] Among them, X is a divalent group, which is the part of the diol other than the -OH group;

[0012] W is a divalent group, which is the part of the diisocyanate other than the -NCO group.

[0013] As a preferred embodiment of the carbon fiber with a phthalonitrile group-terminated polyurethane on the surface according to the present invention, wherein: the diol is selected from one or more of the following substances: ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, butanediol, pentanediol, hexanediol, octanediol, heptanediol, nonanediol, decanediol.

[0014] As a preferred embodiment of the carbon fiber with a phthalonitrile group-terminated polyurethane on the surface according to the present invention, wherein: the diisocyanate is selected from one or more of the following substances: 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, m-phenylene diisocyanate, p-phenylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 1,3-diisocyanato-2-methylcyclohexane, 2,4-diisocyanato-1-methylcyclohexane, 1,3-bis(isocyanatomethyl)cyclohexane, 1,4-bis(isocyanatomethyl)cyclohexane, 4,4'-dicyclohexylmethane diisocyanate, hexamethylene diisocyanate.

[0015] To solve the above technical problems, according to another aspect of the present invention, the present invention provides the following technical solutions:

[0016] A preparation method of the carbon fiber with a phthalonitrile group-terminated polyurethane on the surface as described above, comprising the following steps:

[0017] S1. Oxidation of the carbon fiber surface;

[0018] S2. Reduction of the carbon fiber surface;

[0019] S3. Synthesis of isocyanate-terminated polyurethane

[0020] Dissolve the diisocyanate and the catalyst in a solvent, drop the diol solution into the isocyanate solution, and react at 60-80 °C for 2-6 h to obtain solution A;

[0021] S4. First surface treatment of carbon fiber

[0022] Immerse the carbon fiber obtained in step S2 in solution A obtained in step S3, react at 80-100 °C for 5-10 h, fish out the carbon fiber, wash the surface of the carbon fiber with the same solvent as in step S3, and dry it;

[0023] S5. Synthesis of aminophthalonitrile

[0024] Mix 4-nitrophthalonitrile and aminophenol monomers in a solvent, add anhydrous potassium carbonate, and react at 120-150 °C for 3-6 h to obtain solution B;

[0025] S6. Second surface treatment of carbon fiber

[0026] Immerse the carbon fiber obtained in step S4 in solution B obtained in step S5, soak at room temperature for 12-24 h, wash, and dry to obtain carbon fiber with phthalonitrile group-terminated polyurethane on the surface.

[0027] As a preferred embodiment of the preparation method of the carbon fiber with phthalonitrile group-terminated polyurethane on the surface according to the present invention, wherein: in step S3, the solvent is one or more of heptane, toluene, ethyl acetate, butyl acetate, and ethanol dimethyl ether; the catalyst is one or more of dibutyltin dilaurate, N,N-dimethylcyclohexylamine, pentamethyldiethylenetriamine, and bis(dimethylaminoethyl) ether.

[0028] As a preferred embodiment of the preparation method of the carbon fiber with phthalonitrile group-terminated polyurethane on the surface according to the present invention, wherein: in step S3, the diisocyanate monomer is one or more of toluene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), xylylene diisocyanate (XDI), naphthalene diisocyanate (NDI), methylcyclohexyl diisocyanate (HTDI), dicyclohexylmethane diisocyanate (HMDI), hexamethylene diisocyanate (HDI), and isophorone diisocyanate (IPDI); the diol is one or more of ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, butanediol, pentanediol, hexanediol, octanediol, heptanediol, nonanediol, and decanediol.

[0029] As a preferred embodiment of the method for preparing carbon fibers with phthalonitrile group-terminated polyurethane on the surface according to the present invention, in which: in the step S3, the molar ratio of the diisocyanate monomer to the diol monomer is 1.1 to 1.2:1; the mass fraction of the reactants in the solution is 10 to 15 wt%.

[0030] As a preferred embodiment of the method for preparing carbon fibers with phthalonitrile group-terminated polyurethane on the surface according to the present invention, in which: in the step S4, the volume ratio of the solution A to the carbon fibers is 2 to 3:1.

[0031] As a preferred embodiment of the method for preparing carbon fibers with phthalonitrile group-terminated polyurethane on the surface according to the present invention, in which: in the step S5, the solvent is one or more of N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, N-methylpyrrolidone;

[0032] As a preferred embodiment of the method for preparing carbon fibers with phthalonitrile group-terminated polyurethane on the surface according to the present invention, in which: in the step S5, the aminophenol monomers include but are not limited to 4-amino-4'-hydroxydiphenyl sulfone, 2,4-diaminophenol, 3-amino-4-methylphenol, 2-amino-4-methylphenol, 6-amino-2,4-dimethylphenol, 4-amino-2,5-dimethylphenol, etc.

[0033] As a preferred embodiment of the method for preparing carbon fibers with phthalonitrile group-terminated polyurethane on the surface according to the present invention, in which: in the step S6, the volume ratio of the solution B to the carbon fibers is 2 to 3:1.

[0034] To solve the above technical problems, according to another aspect of the present invention, the present invention provides the following technical solutions:

[0035] A resin-based carbon fiber reinforced composite material, comprising the above-mentioned carbon fibers with phthalonitrile group-terminated polyurethane on the surface.

[0036] As a preferred embodiment of the resin-based carbon fiber reinforced composite material according to the present invention, in which: it is a phthalonitrile resin-based carbon fiber reinforced composite material, comprising the above-mentioned carbon fibers with phthalonitrile group-terminated polyurethane on the surface and a phthalonitrile resin matrix.

[0037] The beneficial effects of the present invention are as follows:

[0038] The present invention provides a carbon fiber with a phthalonitrile group - terminated polyurethane on its surface, a preparation method thereof, and a resin - based carbon fiber - reinforced composite material containing the same. The surface of the carbon fiber has a phthalonitrile group - terminated polyurethane polymer layer. On the one hand, this polymer layer functions as a sizing agent. On the other hand, the polymer layer contains active phthalonitrile functional groups, which can form a thermosetting interface layer with the matrix phthalonitrile resin during the curing process. The interface layer connects the carbon fiber and the resin matrix through covalent bonds and has better interfacial strength than ordinary sizing agents. This interface layer has good thermal stability and can maintain the interfacial layer strength in a high - temperature environment, thereby ensuring the mechanical properties of the composite material in a high - temperature environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the following - described drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on the structures shown in these drawings.

[0040] Figure 1 It is the surface infrared spectrogram of the carbon fibers of Example 1 and Comparative Example 1 of the present invention;

[0041] Figure 2 It is the scanning electron microscope image of the surface morphology of the carbon fibers of Example 1 and Comparative Example 1 of the present invention;

[0042] Figure 3 It is the comparison chart of the tensile strength and interlaminar shear strength of the composite materials containing the carbon fibers of Example 1 and Comparative Example 1 of the present invention at 200 °C.

[0043] The realization, functional features, and advantages of the objectives of the present invention will be further described in conjunction with the embodiments and with reference to the drawings. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0044] The following will clearly and completely describe the technical solutions in the embodiments. Obviously, the described embodiments are only some of the embodiments of the present invention, rather than all of them. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0045] The present invention provides a carbon fiber with a phthalonitrile group-terminated polyurethane on its surface, a preparation method thereof, and a resin matrix carbon fiber-reinforced composite material containing the same. The carbon fiber provided has phthalonitrile functional groups on its surface, and during the process of forming a composite material with a phthalonitrile resin matrix, a polyphthalonitrile composite interface layer can be formed, thereby significantly improving the interface strength and mechanical properties of the composite material in a high-temperature environment.

[0046] Based on the first aspect of the present invention, the present invention first provides a carbon fiber with a phthalonitrile group-terminated polyurethane on its surface. On the one hand, the polyurethane polymer on the surface of the carbon fiber acts as a sizing agent, endowing the carbon fiber with good processability and compatibility with the matrix resin; on the other hand, the polymer end group contains phthalonitrile functional groups, which can participate in the cross-linking reaction of the matrix phthalonitrile resin during the curing process, thereby covalently bonding the carbon fiber and the matrix resin to form a strong interface layer, and the interface layer has the characteristics of good heat resistance of the phthalonitrile resin, thus ensuring that the carbon fiber / phthalonitrile composite material has good interface strength and mechanical properties at high temperatures.

[0047] A carbon fiber with a phthalonitrile group-terminated polyurethane on its surface has the following molecular structure on its surface:

[0048]

[0049] Among them, V is the part of the aminophenol monomer other than the amino group and the phenolic hydroxyl group, and the aminophenol monomer has the following molecular structure:

[0050]

[0051] U is a divalent group, representing the part of the isocyanate-terminated polyurethane other than the end group -NCO, and has the following structure, where n is an integer greater than or equal to 1:

[0052]

[0053] Among them, X is a divalent group, which is the part of the diol other than the -OH group;

[0054] W is a divalent group, which is the part of the diisocyanate other than the -NCO group.

[0055] Preferably, the diol is selected from one or more of the following substances: ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, butanediol, pentanediol, hexanediol, octanediol, heptanediol, nonanediol, decanediol.

[0056] Preferably, the diisocyanate is selected from one or more of the following substances: 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, m-xylene diisocyanate, p-xylene diisocyanate, 4,4'-diisocyanatodiphenylmethane, 1,3-diisocyanato-2-methylcyclohexane, 2,4-diisocyanato-1-methylcyclohexane, 1,3-bis(isocyanatomethyl)cyclohexane, 1,4-bis(isocyanatomethyl)cyclohexane, 4,4'-diisocyanatodicyclohexylmethane, hexamethylene diisocyanate.

[0057] Based on the second aspect of the present invention, a method for preparing the carbon fiber with the surface phthalonitrile group-capped polyurethane polymer is also provided. In this method, the carbon fiber is first surface-treated by a solution redox method to generate active reaction sites on the surface of the carbon fiber; then, the phthalonitrile functional group is grafted onto the surface of the carbon fiber through the nucleophilic addition reaction between the isocyanate group-capped polyurethane oligomer and amino phthalonitrile. This method has the advantages of simple process, little environmental pollution, low energy consumption and low cost.

[0058] A method for preparing the carbon fiber with the surface phthalonitrile group-capped polyurethane as described above includes the following steps:

[0059] S1. Oxidation of the carbon fiber surface;

[0060] S2. Reduction of the carbon fiber surface;

[0061] S3. Synthesis of the isocyanate group-capped polyurethane

[0062] Dissolve the diisocyanate and the catalyst in a solvent, drop the diol solution into the isocyanate solution, and react at 60-80 °C for 2-6 h to obtain solution A;

[0063] S4. First surface treatment of the carbon fiber

[0064] Immerse the carbon fiber obtained in step S2 in the solution A obtained in step S3, react at 80-100 °C for 5-10 h, take out the carbon fiber, wash the surface of the carbon fiber with the same solvent as in step S3, and dry it;

[0065] S5. Synthesis of amino phthalonitrile

[0066] Mix 4-nitrophthalonitrile and amino phenol monomers in a solvent, add anhydrous potassium carbonate, and react at 120-150 °C for 3-6 h to obtain solution B;

[0067] S6. Second surface treatment of the carbon fiber

[0068] Soak the carbon fiber obtained in step S4 in solution B obtained in step S5, soak for 12 - 24 h at room temperature, wash, and dry to obtain carbon fiber with phthalonitrile group-terminated polyurethane on the surface.

[0069] The preparation method can be as follows:

[0070]

[0071]

[0072] Preferably, before step S1, it further includes

[0073] S0. Desizing of carbon fiber

[0074] Immerse the carbon fiber cloth in acetone, then reflux at 80 °C for 24 h to complete the desizing of the carbon fiber cloth.

[0075] Preferably, in step S1, dissolve silver nitrate and potassium persulfate in water, heat the solution to 50 - 70 °C, immerse the carbon fiber in the solution for 3 - 5 h, take out the carbon fiber, and wash.

[0076] Preferably, in step S2, dissolve sodium borohydride in water, immerse the carbon fiber treated in step S1 in the solution, treat under heating and reflux conditions for 1 - 3 h, take out the carbon fiber, wash with water, and dry.

[0077] Preferably, in step S3, the solvent is one or more of heptane, toluene, ethyl acetate, butyl acetate, ethanol dimethyl ether; the catalyst is one or more of dibutyltin dilaurate, N,N-dimethylcyclohexylamine, pentamethyldiethylenetriamine, bis(dimethylaminoethyl) ether.

[0078] Preferably, in step S3, the diisocyanate monomer is one or more of toluene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), xylylene diisocyanate (XDI), naphthalene diisocyanate (NDI), methylcyclohexyl diisocyanate (HTDI), dicyclohexylmethane diisocyanate (HMDI), hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI); the diol is one or more of ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, butanediol, pentanediol, hexanediol, octanediol, heptanediol, nonanediol, decanediol.

[0079] Preferably, in step S3, the molar ratio of the diisocyanate monomer to the diol monomer is 1.1 - 1.2:1; the mass fraction of the reactants in the solution is 10 - 15 wt%.

[0080] Preferably, in the step S4, the volume ratio of the solution A to the carbon fiber is 2-3:1.

[0081] Preferably, in the step S5, the solvent is one or more of N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, and N-methylpyrrolidone;

[0082] Preferably, in the step S5, the aminophenol monomers include but are not limited to 4-amino-4'-hydroxydiphenyl sulfone, 2,4-diaminophenol, 3-amino-4-methylphenol, 2-amino-4-methylphenol, 6-amino-2,4-dimethylphenol, 4-amino-2,5-dimethylphenol, etc. The aminophenol monomers have the following structures:

[0083]

[0084] Preferably, in the step S6, the volume ratio of the solution B to the carbon fiber is 2-3:1.

[0085] Based on the third aspect of the present invention, a phthalonitrile resin-based carbon fiber reinforced composite material is proposed, which includes the above-mentioned carbon fiber with a phthalonitrile group-terminated polyurethane polymer on the surface and a phthalonitrile resin matrix. Compared with the carbon fiber / phthalonitrile composite material without surface treatment, the interlaminar shear strength of this composite material is significantly improved at room temperature and high temperature (250 °C), and it has significant advantages in mechanical properties at high temperature.

[0086] A resin-based carbon fiber reinforced composite material includes the above-mentioned carbon fiber with a phthalonitrile group-terminated polyurethane on the surface.

[0087] Preferably, the resin-based carbon fiber reinforced composite material is a phthalonitrile resin-based carbon fiber reinforced composite material, which includes the above-mentioned carbon fiber with a phthalonitrile group-terminated polyurethane on the surface and a phthalonitrile resin matrix.

[0088] The technical solution of the present invention will be further described below in conjunction with specific embodiments.

[0089] Example 1

[0090] A preparation method of a carbon fiber with a phthalonitrile group-terminated polyurethane on the surface. In this example, the type of carbon fiber used is Toray T700SC-12000-50C, and the fiber uses a general epoxy sizing agent, including the following steps:

[0091] S0. Carbon fiber desizing

[0092] To surface-treat carbon fibers using the method of the present invention, the commercial carbon fibers are first desized. First, the carbon fiber cloth is immersed in acetone and then refluxed at 80 °C for 24 h to complete the desizing of the carbon fiber cloth;

[0093] S1. Oxidation of the carbon fiber surface

[0094] Silver nitrate and potassium persulfate are dissolved in water, the solution is heated to 60 °C, the carbon fibers are immersed in the solution for 4 h, and then the carbon fibers are taken out and washed.

[0095] S2. Reduction of the carbon fiber surface

[0096] Sodium borohydride is dissolved in water, the carbon fibers treated in step S1 are immersed in the solution, and the treatment is carried out under heating and reflux conditions for 2 h. Then the carbon fibers are taken out, washed with water and dried.

[0097] S3. Synthesis of isocyanate-terminated polyurethane

[0098] 4,4`-Diphenylmethane diisocyanate and dibutyltin dilaurate are dissolved in a solvent, and the diglycol solution is dropped into the isocyanate solution, and the reaction is carried out at 80 °C for 5 h to obtain solution A;

[0099] S4. First surface treatment of carbon fibers

[0100] The carbon fibers obtained in step S2 are immersed in solution A obtained in step S3, and the reaction is carried out at 80 °C for 8 h. Then the carbon fibers are taken out, and the surface of the carbon fibers is washed with the same solvent as in step S3 and dried;

[0101] S5. Synthesis of aminophthalonitrile

[0102] 4-Nitrophthalonitrile and 3-amino-4-methylphenol are mixed in a solvent, anhydrous potassium carbonate is added, and the reaction is carried out at 130 °C for 4 h to obtain solution B;

[0103] S6. Second surface treatment of carbon fibers

[0104] The carbon fibers obtained in step S4 are immersed in solution B obtained in step S5, soaked at room temperature for 20 h, washed, and dried to obtain carbon fibers with phthalonitrile group-terminated polyurethane on the surface.

[0105] A resin-based carbon fiber reinforced composite material, which is a phthalonitrile resin-based carbon fiber reinforced composite material, is cured from carbon fibers with phthalonitrile group-terminated polyurethane on the surface prepared in this example and a phthalonitrile resin matrix. The resin matrix is bisphenol A type phthalonitrile, and the resin content is 40-45 wt%. The curing process is: heat preservation at 240 °C for 2 h, heat preservation at 280 °C for 2 h, heat preservation at 320 °C for 2 h, and heat preservation at 350 °C for 2 h.

[0106] Comparative Example 1

[0107] It is different from Example 1 in that

[0108] The type of carbon fiber used in this comparative example is Toray T700SC-12000-50C and it is not treated.

[0109] Infrared spectroscopy analysis was carried out on the carbon fibers prepared in Example 1 and the carbon fibers in Comparative Example 1. The results are as Figure 1 shown. Compared with the untreated carbon fibers in Comparative Example 1, the infrared absorption peaks on the surface of the carbon fibers treated in Example 1 are more complex. An absorption peak attributed to the carbonyl group in polyurethane appears at 1720 cm -1 and an obvious absorption peak attributed to the cyano group in phthalonitrile appears at 2232 cm -1 . Thus, it can be seen that the carbon fiber surface has a polyurethane structure and phthalonitrile functional groups.

[0110] Scanning electron microscopy morphology observation was carried out on the carbon fibers prepared in Example 1 and the carbon fibers in Comparative Example 1. The results are as Figure 2 shown. As can be seen from Figure 2 a in it, the surface roughness of the untreated carbon fibers in Comparative Example 1 is relatively large and the gully-like morphology is obvious. As can be seen from Figure 2 b in it, for the carbon fibers treated in Example 1, since a polyurethane-based phthalonitrile layer is formed on the carbon fiber surface, the surface becomes significantly flatter and the gullies become shallower.

[0111] The interlaminar shear strength of the composite material was tested using GB / T 1450.1-2005 "Test Method for Interlaminar Shear Strength of Fiber Reinforced Plastics"; the tensile properties of the composite material were tested using GB / T 1447-2005 "Test Method for Tensile Properties of Fiber Reinforced Plastics". The mechanical properties at high temperature were tested through an environmental test chamber equipped with a mechanical testing machine. The results are as Figure 3 shown. From the test results, it can be seen that after the surface of the carbon fiber is treated by the method described in Example 1 of the present invention, the high-temperature mechanical interface strength of its phthalonitrile-based composite material is significantly improved. Compared with the carbon fiber composite material untreated in Comparative Example 1, the interface shear strength is increased by 196%. Thanks to the improvement of the interface strength, the tensile strength of the composite material in the 0° direction is also increased by 40%.

[0112] The carbon fiber surface of the present invention contains a phthalonitrile group-terminated polyurethane polymer layer. On the one hand, this polymer layer functions as a sizing agent. On the other hand, the polymer layer contains active phthalonitrile functional groups, which can form a thermosetting interface layer with the matrix phthalonitrile resin during the curing process. The interface layer connects the carbon fiber and the resin matrix through covalent bonds, and has better interfacial strength than ordinary sizing agents. This interface layer has good thermal stability and can maintain the interfacial strength in a high-temperature environment, thereby ensuring the mechanical properties of the composite material in a high-temperature environment.

[0113] The above are only the preferred embodiments of the present invention, and do not limit the patent scope of the present invention accordingly. Any equivalent structural transformation made by using the content of the specification of the present invention under the inventive concept of the present invention, or any direct / indirect application in other related technical fields is included in the patent protection scope of the present invention.

Claims

1. A resin-based carbon fiber reinforced composite material, characterized in that, The resin-based carbon fiber reinforced composite material described is a phthalonitrile resin-based carbon fiber reinforced composite material, including carbon fibers with phthalonitrile group-terminated polyurethane on the surface and a phthalonitrile resin matrix; The surface of the carbon fiber with phthalonitrile group-terminated polyurethane on the surface has the following molecular structure: Among them, V is the part of the aminophenol monomer other than the amino group and the phenolic hydroxyl group; U is a divalent group, representing the part of the isocyanate-terminated polyurethane other than the terminal -NCO group, and has the following structure, where n is an integer greater than or equal to 1: Among them, X is a divalent group, which is the part of the diol other than the -OH group; W is a divalent group, which is the part of the diisocyanate other than the -NCO group.

2. The resin-based carbon fiber reinforced composite material according to claim 1, wherein The preparation method of the carbon fiber with phthalonitrile group-terminated polyurethane on the surface includes the following steps: S1. Oxidation of the carbon fiber surface; S2. Reduction of the carbon fiber surface; S3. Synthesis of isocyanate-terminated polyurethane Dissolve the diisocyanate and the catalyst in a solvent, drop the diol solution into the isocyanate solution, and react at 60 - 80 °C for 2 - 6 h to obtain solution A; S4. First surface treatment of the carbon fiber Immerse the carbon fiber obtained in step S2 in solution A obtained in step S3, react at 80 - 100 °C for 5 - 10 h, fish out the carbon fiber, wash the carbon fiber surface with the same solvent as in step S3, and dry it; S5. Synthesis of amino phthalonitrile Mix 4-nitro phthalonitrile and aminophenol monomer in a solvent, add anhydrous potassium carbonate, and react at 120 - 150 °C for 3 - 6 h to obtain solution B; S6. Second surface treatment of the carbon fiber Immerse the carbon fiber obtained in step S4 in solution B obtained in step S5, soak at room temperature for 12 - 24 h, wash, and dry to obtain the carbon fiber with phthalonitrile group-terminated polyurethane on the surface.

3. The resin-based carbon fiber reinforced composite material according to claim 2, wherein, In step S3, the catalyst is one or more of dibutyltin dilaurate, N,N-dimethylcyclohexylamine, pentamethyldiethylenetriamine, and bis(dimethylaminoethyl) ether.

4. The resin-based carbon fiber reinforced composite material according to claim 2, characterized in that In step S3, the diisocyanate monomer is one or more of toluene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), xylylene diisocyanate (XDI), naphthalene diisocyanate (NDI), methylcyclohexyl diisocyanate (HTDI), dicyclohexylmethane diisocyanate (HMDI), hexamethylene diisocyanate (HDI), and isophorone diisocyanate (IPDI); the diol is one or more of ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, butanediol, pentanediol, hexanediol, octanediol, heptanediol, nonanediol, and decanediol.

5. The resin-based carbon fiber reinforced composite material according to claim 2, wherein In step S3, the molar ratio of the diisocyanate monomer to the diol monomer is 1.1 - 1.2:1; the mass fraction of the reactants in the solution is 10 - 15 wt%.

6. The resin matrix carbon fiber reinforced composite material according to claim 2, wherein In step S4, the volume ratio of solution A to the carbon fiber is 2 - 3:

1.

7. The resin-based carbon fiber reinforced composite material according to claim 2, wherein, In the step S5, the aminophenol monomer is 4-amino-4'-hydroxydiphenyl sulfone, 2,4-diaminophenol, 3-amino-4-methylphenol, 2-amino-4-methylphenol, 6-amino-2,4-xylenol, or 4-amino-2,5-xylenol.

8. The resin-based carbon fiber reinforced composite material according to claim 2, wherein In the step S6, the volume ratio of solution B to carbon fiber is 2~3:1.

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