High and low temperature cycle stable sizing agent for carbon fiber paving material and preparation method thereof

Abstract

The invention relates to the technical field of fiber sizing agents, in particular to a high and low temperature cycle stable sizing agent for a carbon fiber paving material and a preparation method thereof.The high and low temperature cycle stable sizing agent for the carbon fiber paving material is prepared from, by weight, 0.5-2 parts of sulfonated polyaryletherketone resin, 95-99 parts of deionized water and 0.1-0.5 part of surfactant, and 0.1 to 0.5 part of a modified carbon nanotube. The prepared sizing agent for the carbon fiber paving material has excellent high and low temperature cycle stability, and the preparation method is simple.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of fiber sizing agent, and particularly relates to a high-low temperature cycle stable sizing agent for carbon fiber paving materials and a preparation method thereof. BACKGROUND

[0002] Although carbon fibers have excellent properties such as high specific strength, high specific modulus and high temperature resistance, they are ideal reinforcing materials for high-end composite materials. However, the smooth surface and inert chemical properties of carbon fibers make it difficult to form stable physical and chemical bonds between carbon fibers and resin matrix, which easily leads to poor interfacial properties of composite materials. The sizing agent can form a sizing layer on the surface of carbon fibers, which can not only reduce the hairiness and improve the wear resistance of fibers to protect the carbon fibers, but also introduce polar functional groups to improve the inert environment of the carbon fiber surface, and is a key auxiliary material for improving the bonding strength between carbon fibers and resin matrix.

[0003] In recent years, carbon fiber composites have been increasingly widely used in aerospace, national defense and military, new energy and other frontier fields. For example, the structural parts of hypersonic aircraft will frequently experience drastic temperature changes from low temperature environment to high temperature flight state, and the parts of high-speed trains and ships also need to cope with temperature difference cycles in different regions and seasons. These scenarios not only require excellent overall mechanical properties of carbon fiber composites, but also put forward strict requirements on the interfacial stability of carbon fiber composites. Traditional sizing agents have poor high-low temperature cycle stability, which easily leads to interfacial failure of composite materials, and thus causes the overall structural performance to decrease, which seriously limits the application of carbon fiber composites in high-end fields. Therefore, the development of sizing agents with high-low temperature cycle stability has become a key direction for technological breakthrough in the industry.

[0004] Patent CN117306258B discloses a kind of high temperature resistant thermoplastic carbon fiber water-based composite sizing agent and its preparation method, and the sizing agent includes amino polyether ketone ketone, carboxylated carbon nanotube and deionized water. Compared with the prior art, the sizing agent of the application is a composite water-based sizing agent, which is environmentally friendly and can improve the interfacial bonding strength of carbon fiber reinforced high-performance thermoplastic resin matrix composite materials. However, the intrinsic properties of carbon nanotubes may be damaged during the preparation of carboxylated carbon nanotubes, which affects the high-low temperature cycle stability of the sizing agent.

[0005] Patent CN110820315B discloses a kind of crystalline cross-linkable polyaromatic ether ketone sizing agent modified carbon fiber and its preparation method, the invention utilizes the polymerization of double fluorine monomer and bisphenol monomer containing aniline side group, or the modification of crystalline polyaromatic ether ketone, obtain soluble amorphous polyaromatic ether ketone polymer, then end cap thermally induced cross-linking group to polymer both ends;At the same time, the surface of carbon fiber is electrochemically reduced, and the same cross-linking group as described above is grafted to the surface of carbon fiber;Then the carbon fiber with surface electrochemical reduction treatment is pulled through sizing agent solution for sizing, and the crystallinity of polyaromatic ether ketone sizing agent is recovered by acidification;Finally, the carbon fiber is processed into composite material and then high-temperature heat treatment is carried out to initiate cross-linking reaction and improve the crystallinity of polyaromatic ether ketone polymer, so that the sizing agent has crystalline structure, and chemical bond is formed between the sizing agent and the surface of carbon fiber, the interfacial shear strength is improved, and the sizing agent is resistant to high temperature and corrosion, but the preparation method is relatively complex.

[0006] Therefore, there is an urgent need in the market for a high-temperature and low-temperature cycle stable sizing agent with a simple preparation method. SUMMARY

[0007] In view of the problems in the prior art, the purpose of the present application is to obtain a high-temperature and low-temperature cycle stable sizing agent with excellent heat resistance and a simple preparation method.

[0008] To achieve the above-mentioned purpose, the technical solution adopted by the present application is as follows: In one aspect, the present application provides a high-temperature and low-temperature cycle stable sizing agent for carbon fiber paving material, which comprises the following raw materials in parts by weight: sulfonated polyaromatic ether ketone resin 0.5-2 parts, deionized water 95-99 parts, surfactant 0.1-0.5 parts, and modified carbon nanotube 0.1-0.5 parts.

[0009] The present application obtains a sizing agent with excellent high-temperature and low-temperature cycle stability and a simple preparation method by mixing sulfonated polyaromatic ether ketone resin, modified carbon nanotube, surfactant and deionized water.

[0010] In some embodiments, the sulfonated polyaromatic ether ketone resin is one or more of sulfonated polyether ether ketone, sulfonated polyether ketone, sulfonated polyether ether ketone ketone, and sulfonated polyether ketone ketone.

[0011] Preferably, the sulfonated polyaromatic ether ketone resin is sulfonated polyether ether ketone.

[0012] In some embodiments, the surfactant is polystyrene-poly(N-vinyl pyrrolidone) block copolymer.

[0013] The small molecules such as sodium dodecyl benzene sulfonate and nonylphenol polyoxyethylene ether are often used as the surfactant in the existing sizing agent, and the problem of easy decomposition at high temperature often exists, which reduces the dispersibility of carbon nanotubes in the sizing agent at high temperature. Compared with the conventional surfactant, the polystyrene-poly (N-vinyl pyrrolidone) block copolymer is used as the surfactant in the present application, which has high steric hindrance stability and strong adsorption with poly (aryl ether ketone), and is difficult to degrade, which not only ensures the dispersibility of carbon nanotubes in the sizing agent at high temperature, but also reduces the attack of external degradation products on the resin-fiber interface, and is beneficial to improve the high and low temperature cycle stability and adhesion of the poly (aryl ether ketone) sizing agent.

[0014] In some embodiments, the preparation method of the modified carbon nanotube comprises the following steps: A1, under nitrogen protection, carbon nanotubes are added into dichloromethane, the temperature is reduced to 0-5°C, the rotation speed is adjusted to 500-600 rpm, anhydrous AlCl3 is added, and ultrasonic is performed for 20-40 min to obtain a mixed solution; acyl chloride reagent and acid anhydride reagent are respectively dissolved in dichloromethane, and then added dropwise into the above mixed solution; after the dropwise addition is completed, the temperature is first increased to room temperature, and then heated to 40-60°C, and refluxed for 12-48 h to obtain a mixture; A2, the mixture obtained in step A1 is added dropwise into dilute hydrochloric acid at 0-5°C, stirred for 20-30 min, and then filtered, and washed with dilute hydrochloric acid, deionized water, ethanol and acetone in sequence for multiple times until the filtrate is neutral and no chloride ion is detected, and then dried to obtain pretreated carbon nanotubes; A3, the pretreated carbon nanotubes obtained in step A2 and amino-functionalized POSS are added into N,N-dimethylformamide, the temperature is increased to 40-60°C, an activating agent and a catalyst are added, and reacted for 12-24 h, and then filtered, washed and dried to obtain modified carbon nanotubes.

[0015] Preferably, the concentration of the dilute hydrochloric acid is 1M, and the ratio of the mixture to the dilute hydrochloric acid is 1g: (10-15) ml.

[0016] Preferably, the activating agent is 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride.

[0017] Preferably, the catalyst is 4-dimethylaminopyridine and / or 1-hydroxybenzotriazole.

[0018] Further preferably, the catalyst is 4-dimethylaminopyridine.

[0019] Preferably, the mass ratio of the pretreated carbon nanotubes to N,N-dimethylformamide in step A3 is 1: (10-50) ml.

[0020] In some embodiments, the carbon nanotube has a tube diameter of 5-10 nm and an average tube length of 10-30 um.

[0021] In some embodiments, the mass ratio of the carbon nanotube and the anhydrous AlCl3 is 1: (0.01-0.05).

[0022] In some embodiments, the acyl chloride reagent is terephthaloyl chloride or trimesoyl chloride; and the anhydride reagent is one or more of maleic anhydride, 1,4,5,8-naphthalene tetracarboxylic dianhydride, pyromellitic dianhydride, trimesic anhydride, and 3,3',4,4'-biphenyl tetracarboxylic dianhydride.

[0023] The present application can improve the high and low temperature cycle stability of the sizing agent by grafting the acyl chloride reagent and the anhydride reagent containing benzene ring or naphthalene ring to the carbon nanotube, which may be due to: on the one hand, the benzene ring and biphenyl structure on the modified carbon nanotube can produce π-π conjugation with the benzene ring structure on the polyaryletherketone to improve the interaction force between the carbon nanotube and the polyaryletherketone segment, and improve the dispersibility of the carbon nanotube in the sizing agent; on the other hand, the carbon nanotube can be fixed between the polyaryletherketone molecular segments and is not easy to fall off, further improving the high and low temperature cycle stability of the sizing agent. At the same time, the hydrophilic carboxyl structure is introduced on the surface of the carbon nanotube after the reaction of the anhydride reagent and the carbon nanotube, further improving the dispersibility of the modified carbon nanotube in the sizing agent.

[0024] The present application further reacts the carbon nanotube grafted with the acyl chloride reagent and the anhydride reagent with the amino-functionalized POSS, and finds that the high and low temperature cycle stability of the sizing agent is further improved, which may be due to the strong Lewis acid AlCl3 before further modification, which may attack the sp² structure of the carbon tube during the reaction, introducing defects such as vacancies and broken tubes, damaging the thermal conductivity of the carbon nanotube. After further grafting the amino-functionalized POSS on the carbon nanotube, the amino-functionalized POSS molecule can provide up to 8 amino groups, which can be covalently connected to the carboxylated carbon nanotube through amidation reaction, and the polymer chain can be uniformly coated on the carbon nanotube, which can help to solve the problem of uneven functionalization, and the rigid inorganic siloxane cage skeleton has good mechanical properties and heat resistance, further improving the mechanical properties and thermal stability of the sizing agent.

[0025] In some embodiments, the mass ratio of the carbon nanotube and the acyl chloride reagent is 1: (0.4-0.7).

[0026] In some embodiments, the mass ratio of the carbon nanotube and the anhydride reagent is 1: (0.1-0.4).

[0027] Compared with the anhydride reagent, the reaction rate of carbon nanotubes with acyl chloride reagent is faster, and the carbon nanotubes are modified by simultaneously adding acyl chloride reagent and anhydride reagent, and by limiting the ratio of the two reagents to carbon nanotubes, the grafting rate of benzene ring groups can be improved while ensuring the grafting of part of the carboxyl groups on the carbon nanotubes, and the dispersibility of the carbon nanotubes in the sizing agent is further improved.

[0028] In some embodiments, the mass ratio of the pretreated carbon nanotubes and the amino-functionalized POSS is 1: (0.03-0.07).

[0029] In some embodiments, the mass ratio of the 3-methoxypropylamine and the activating agent is 1: (0.03-0.06).

[0030] In some embodiments, the mass ratio of the 3-methoxypropylamine and the catalyst is 1: (0.005-0.01).

[0031] Another aspect of the present application provides a preparation method of a high and low temperature cycle stable sizing agent for carbon fiber paving materials, comprising the following steps: adding sulfonated polyaryletherketone resin and surfactant into deionized water, stirring at 30-40°C for 10-20min, adding modified carbon nanotubes and continuing to stir for 5-10min, and ultrasonicating for 1-3h to obtain the sizing agent.

[0032] Compared with the prior art, the present application has the following beneficial effects: (1) The present application has excellent high and low temperature cycle stability and simple preparation method by mixing sulfonated polyaryletherketone resin, modified carbon nanotubes, surfactant and deionized water to obtain the sizing agent.

[0033] (2) The present application has high steric hindrance stability and strong adsorption effect with polyaryletherketone by using the preferred polystyrene-poly (N-vinylpyrrolidone) block copolymer as a surfactant, and it is difficult to degrade itself, which not only ensures the dispersibility of carbon nanotubes in the sizing agent at high temperature, but also reduces the attack of external degradation products on the resin-fiber interface, which is beneficial to improve the high and low temperature cycle stability and adhesion of the polyaryletherketone sizing agent.

[0034] (3) The benzene ring and biphenyl structure on the modified carbon nanotubes prepared by the present application can produce π-π conjugation with the benzene ring structure on the polyaryletherketone to improve the interaction force between the carbon nanotubes and the polyaryletherketone segments, and improve the dispersibility of the carbon nanotubes in the sizing agent.

[0035] (4) The amino functionalized POSS is grafted on the carbon nanotube, and the polymer chain is uniformly coated on the carbon nanotube through the amidation reaction and the multi-point covalent connection of the carboxylated carbon nanotube, which helps to solve the problem of uneven functionalization and further improves the high and low temperature cycle stability of the sizing agent. DETAILED DESCRIPTION

[0036] The application will be described in detail below with reference to specific embodiments. It should be noted that the following examples are examples of the application and are only used to illustrate the application, but not to limit the application. Other combinations and various modifications within the concept of the application can be made without departing from the spirit or scope of the application.

[0037] In the following examples and comparative examples, the compounds and related reagents used except for the modified carbon nanotube can be purchased from the market, wherein the sulfonation degree of sulfonated polyether ether ketone is 80%, purchased from Dongguan Tianhong Plastic Co., Ltd.; the tube diameter of the carbon nanotube is 5-10 nm, and the average tube length is 30 um, purchased from Shanghai Maoguo Nanometer Technology Co., Ltd.; the number average molecular weight of polystyrene-poly(N-vinyl pyrrolidone) block copolymer is 5000, purchased from Hangzhou Xinjiao Biological Technology Co., Ltd.; the amino functionalized POSS is octa-phenylamine propyl cage polysilsesquioxane, purchased from Hubei Maidaihe Biological Technology Co., Ltd.

[0038] Preparation Example 1 The preparation method of the modified carbon nanotube-1 comprises the following steps: A1, 10 g of carbon nanotubes were added to 250 ml of dichloromethane under nitrogen protection, cooled to 3°C, the rotation speed was adjusted to 550 rpm, 0.3 g of anhydrous AlCl3 was added, and ultrasonic treatment was performed for 30 min to obtain a mixed solution; 5 g of trimesoyl chloride and 2.5 g of trimesic anhydride were dissolved in 50 ml of dichloromethane respectively, and then added dropwise to the above mixed solution at a dropwise speed of 2 drops / s; after the dropwise addition was completed, the temperature was first increased to room temperature, and then heated to 50°C, and refluxed for 24 h to obtain a mixture; A2, 50 g of the mixture obtained in step A1 was added dropwise to 600 ml of 1M dilute hydrochloric acid at 3°C at a dropwise speed of 2 drops / s, stirred for 25 min, and then filtered and washed with 1M dilute hydrochloric acid, deionized water, anhydrous ethanol, and anhydrous acetone in sequence for multiple times until the filtrate was neutral and no chloride ion was detected, and then dried to obtain the pretreated carbon nanotube; A3, 10 g of the pretreated carbon nanotubes obtained in step A2 and 0.5 g of the amino-functionalized POSS were added to 350 ml of N,N-dimethylformamide, and the temperature was raised to 50°C. 0.45 g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and 0.07 g of 4-dimethylaminopyridine were added, and the reaction was carried out for 18 h. After filtration, the product was washed with N,N-dimethylformamide, 80 wt% ethanol-water mixture, and deionized water, and dried to obtain modified carbon nanotubes-1.

[0039] Preparation Example 2 The preparation method of modified carbon nanotubes-2 was the same as that of Preparation Example 1, except that the amount of anhydrous AlCl3 added was 0.07 g.

[0040] Preparation Example 3 The preparation method of modified carbon nanotubes-3 was the same as that of Preparation Example 1, except that the amount of trimesic anhydride added was 5 g.

[0041] Preparation Example 4 The preparation method of modified carbon nanotubes-4 was the same as that of Preparation Example 1, except that the amount of amino-functionalized POSS added was 0.9 g.

[0042] Preparation Example 5 The preparation method of modified carbon nanotubes-1 included the following steps: A1, 10 g of carbon nanotubes were added to 250 ml of dichloromethane under nitrogen protection, and the temperature was lowered to 3°C. The rotation speed was adjusted to 550 rpm, and 0.3 g of anhydrous AlCl3 was added. Ultrasonic treatment was carried out for 30 min to obtain a mixed solution. 5 g of trimesoyl chloride and 2.5 g of trimesic anhydride were dissolved in 50 ml of dichloromethane, respectively, and added dropwise to the above mixed solution at a dropwise adding speed of 2 drops / s. After the dropwise adding was completed, the temperature was first raised to room temperature, and then heated to 50°C. The reaction was carried out under reflux for 24 h to obtain a mixture; A2, 50 g of the mixture obtained in step A1 was added dropwise to 600 ml of 1M dilute hydrochloric acid at 3°C at a dropwise adding speed of 2 drops / s. After stirring for 25 min, the product was filtered and washed with 1M dilute hydrochloric acid, deionized water, anhydrous ethanol, and anhydrous acetone for several times until the filtrate was neutral and no chloride ion was detected. The product was dried to obtain modified carbon nanotubes-5.

[0043] Example 1 A high-temperature and low-temperature cycle stable sizing agent for carbon fiber paving materials, which comprises the following raw materials in parts by weight: 1 part of sulfonated polyether ether ketone, 97 parts of deionized water, 0.3 parts of polystyrene-poly(N-vinyl pyrrolidone) block copolymer, and 0.3 parts of modified carbon nanotubes-1.

[0044] The preparation method of the high and low temperature cycle stable sizing agent for carbon fiber laminates comprises the following steps: sulfonated polyether ether ketone, polystyrene-poly (N-vinyl pyrrolidone) block copolymer are added to deionized water, stirred at 35°C for 15min, modified carbon nanotube-1 is added and stirred for 7min, ultrasonic for 2h, to obtain the sizing agent.

[0045] Example 2 A high and low temperature cycle stable sizing agent for carbon fiber laminates comprises the following raw materials in parts by weight: sulfonated polyether ether ketone 0.5 parts, deionized water 95 parts, polystyrene-poly (N-vinyl pyrrolidone) block copolymer 0.1 parts, modified carbon nanotube-1 0.1 parts.

[0046] The preparation method of the high and low temperature cycle stable sizing agent for carbon fiber laminates comprises the following steps: sulfonated polyether ether ketone, polystyrene-poly (N-vinyl pyrrolidone) block copolymer are added to deionized water, stirred at 30°C for 20min, modified carbon nanotube-1 is added and stirred for 5min, ultrasonic for 1h, to obtain the sizing agent.

[0047] Example 3 A high and low temperature cycle stable sizing agent for carbon fiber laminates comprises the following raw materials in parts by weight: sulfonated polyether ether ketone 2 parts, deionized water 99 parts, polystyrene-poly (N-vinyl pyrrolidone) block copolymer 0.5 parts, modified carbon nanotube-1 0.5 parts.

[0048] The preparation method of the high and low temperature cycle stable sizing agent for carbon fiber laminates comprises the following steps: sulfonated polyether ether ketone, polystyrene-poly (N-vinyl pyrrolidone) block copolymer are added to deionized water, stirred at 40°C for 10min, modified carbon nanotube-1 is added and stirred for 10min, ultrasonic for 3h, to obtain the sizing agent.

[0049] Example 4 A high and low temperature cycle stable sizing agent for carbon fiber laminates and its preparation method, the specific implementation is the same as example 1, the difference is that the functional modified carbon nanotube-1 is replaced by modified carbon nanotube-2 in equal amount.

[0050] Example 5 A high and low temperature cycle stable sizing agent for carbon fiber laminates and its preparation method, the specific implementation is the same as example 1, the difference is that the modified carbon nanotube-1 is replaced by modified carbon nanotube-3 in equal amount.

[0051] Example 6 A high and low temperature cycle stable sizing agent for carbon fiber laminates and its preparation method, the specific implementation is the same as example 1, the difference is that the modified carbon nanotube-1 is replaced by modified carbon nanotube-4 in equal amount.

[0052] Example 7 A high and low temperature cycle stable sizing agent for carbon fiber prepreg and a preparation method thereof, the specific implementation is the same as example 1, the difference is that the modified carbon nanotube-1 is replaced by the same amount of modified carbon nanotube-5.

[0053] Comparative example 1 A high and low temperature cycle stable sizing agent and a preparation method thereof, the specific implementation is the same as example 1, the difference is that the modified carbon nanotube-1 is replaced by the same amount of carbon nanotube.

[0054] Performance test The high and low temperature cycle stable sizing agent obtained by each of the above examples and comparative examples is tested: Sample preparation: use each sizing agent to perform preliminary sizing treatment on carbon fiber yarn (purchased from Shanghai Xidong New Material Co., Ltd., with a thickness of 48K), the fiber pulling rate is 100mm / min, to obtain carbon fiber with surface modification sizing agent.

[0055] (1) The above carbon fiber with surface modification sizing agent is dried at 230℃ in a resistance wire evaporator, then introduced into a hydrolysis tank, and treated with 0.1mol / L dilute sulfuric acid for 2h, then taken out and dried at 150℃, to obtain carbon fiber modified by each sizing agent.

[0056] (2) Performance test: the initial interlaminar shear strength of carbon fiber modified by each sizing agent is tested according to the test method of ASTM 2344, then each sample is placed at-100℃ and 200℃ respectively for 30min, and the interlaminar shear strength after high and low temperature cycle is tested after 50 cycles, to evaluate the high and low temperature cycle stability.

[0057] The test results are shown in Table 1: Table 1 From the data in Table 1, the carbon fibers in Examples 1-3 of the present application have high interlaminar shear strength, and the modified carbon nanotubes have good dispersibility and heat resistance, and are not prone to thermal decomposition during use, and are not prone to cause the formation of pores and defects in the composite material, so that the sizing agent modified carbon fibers have excellent interlaminar strength, and the sizing agent modified carbon fibers in Examples 1-3 still have good interlaminar shear strength after high-low temperature cycle test, indicating that the sizing agent has excellent high-low temperature cycle stability. From the comparison of Example 4 and Example 1, it can be seen that changing the ratio of carbon nanotubes and anhydrous AlCl3 or the ratio of carbon nanotubes and trimesic anhydride will exacerbate the electrophilic addition or Friedel-Crafts alkylation / acylation reaction of the acid anhydride reagent on the carbon nanotubes itself, which may destroy the conjugated structure of the carbon nanotubes, cause excessive defects in the tube wall, and even break, ultimately damage its intrinsic properties, and cause the high-low temperature cycle stability of the sizing agent to decrease; From the comparison of Example 6 and Example 1, it can be seen that changing the ratio of pretreated carbon nanotubes and amino-functionalized POSS may cause excessive amino POSS to self-polymerize or have a side reaction with other components in the system, resulting in a decrease in the high-low temperature cycle stability of the sizing agent; From the comparison of Example 7 and Example 1, it can be seen that when the pretreated carbon nanotubes are not modified with amino-functionalized POSS, the high-low temperature cycle stability of the sizing agent decreases; From the comparison of Comparative Example 1 and Example 1, it can be seen that when the carbon nanotubes are not modified, the high-low temperature cycle stability of the sizing agent is poor.

[0058] The above embodiments are only for illustrating the technical concept and characteristics of the present application, and the purpose is to enable those skilled in the art to understand the content of the present application and implement it, and cannot limit the protection scope of the present application, and any equivalent changes or modifications made according to the spirit and essence of the present application should be covered within the protection scope of the present application.

Claims

1. A high- and low-temperature cycling stabilized sizing agent for carbon fiber layup materials, characterized in that, By weight, it includes the following raw materials: 0.5-2 parts of sulfonated polyarylether ketone resin, 95-99 parts of deionized water, 0.1-0.5 parts of surfactant, and 0.1-0.5 parts of modified carbon nanotubes.

2. The high and low temperature cycling stabilized sizing agent for carbon fiber layup according to claim 1, characterized in that, The sulfonated polyarylether ketone resin is one or more of sulfonated polyether ether ketone, sulfonated polyether ketone, sulfonated polyether ether ketone ketone, and sulfonated polyether ketone ketone.

3. The high and low temperature cycling stabilized sizing agent for carbon fiber layup according to claim 1, characterized in that, The surfactant is a polystyrene-poly(N-vinylpyrrolidone) block copolymer.

4. The high and low temperature cycling stabilized sizing agent for carbon fiber layup according to claim 1, characterized in that, The method for preparing the modified carbon nanotubes includes the following steps: A1. Under nitrogen protection, carbon nanotubes are added to dichloromethane, cooled to 0-5°C, and the rotation speed is adjusted to 500-600 rpm. Anhydrous AlCl3 is added, and the mixture is sonicated for 20-40 min to obtain a mixed solution. Acyl chloride reagent and acid anhydride reagent are dissolved in dichloromethane respectively and added dropwise to the above mixed solution. After the addition is complete, the temperature is first raised to room temperature, then heated to 40-60°C, and refluxed for 12-48 h to obtain a mixture. A2. Add the mixture obtained in step A1 dropwise to dilute hydrochloric acid at 0-5℃, stir for 20-30 minutes, filter, and wash repeatedly with dilute hydrochloric acid, deionized water, ethanol, and acetone until the filtrate is neutral and no chloride ions are detected. Dry to obtain pretreated carbon nanotubes. A3. Add the pretreated carbon nanotubes and amino-functionalized POSS obtained in step A2 to N,N-dimethylformamide, heat to 40-60℃, add activator and catalyst, react for 12-24h, filter, wash and dry to obtain modified carbon nanotubes.

5. The high and low temperature cycling stabilized sizing agent for carbon fiber layup according to claim 4, characterized in that, The mass ratio of the carbon nanotubes to anhydrous AlCl3 is 1:(0.01-0.05).

6. The high and low temperature cycling stabilized sizing agent for carbon fiber layup according to claim 4, characterized in that, The acyl chloride reagent is terephthaloyl chloride or trimesoyl chloride; the acid anhydride reagent is one or more of maleic anhydride, 1,4,5,8-naphthoic tetracarboxylic dianhydride, trimesoyl dianhydride, and 3,3',4,4'-biphenyltetracarboxylic dianhydride.

7. The high and low temperature cycling stabilized sizing agent for carbon fiber layup according to claim 4, characterized in that, The mass ratio of the carbon nanotubes to the acyl chloride reagent is 1:(0.4-0.7).

8. The high and low temperature cycling stabilized sizing agent for carbon fiber layup according to claim 4, characterized in that, The mass ratio of the carbon nanotubes to the acid anhydride reagent is 1:(0.1-0.4).

9. The high and low temperature cycling stabilized sizing agent for carbon fiber layup according to claim 4, characterized in that, The mass ratio of the pretreated carbon nanotubes to amino-functionalized POSS is 1:(0.03-0.07).

10. A method for preparing a high- and low-temperature cycling-stabilized sizing agent for carbon fiber layup as described in any one of claims 1-9, characterized in that, The process includes the following steps: adding sulfonated polyarylether ketone resin and surfactant to deionized water, stirring at 30-40°C for 10-20 minutes, adding modified carbon nanotubes and continuing to stir for 5-10 minutes, and sonicating for 1-3 hours to obtain a sizing agent.

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