A high-strength, high-modulus and wear-resistant thermotropic liquid crystal polyarylate composite fiber and its preparation method

Abstract

The present invention relates to a high-strength, high-modulus, and wear-resistant thermotropic liquid crystal polyarylate fiber and a preparation method thereof. Specifically, the fiber utilizes ultra-high molecular weight polyethylene as the coating material and a thermotropic liquid crystal polyarylate fiber as the core material. Modification technology is utilized to effectively enhance the overall wear resistance of the composite fiber while retaining its original high mechanical properties. The resulting thermotropic liquid crystal polyarylate composite fiber exhibits a tensile strength exceeding 24 cN / dtex, a tensile modulus exceeding 800 cN / dtex, and a strength retention rate exceeding 90% after 10,000 friction cycles. Furthermore, the fiber exhibits a low dielectric constant (less than or equal to 2.5) and dielectric loss (less than or equal to 0.005).

Description

Technical Field

[0001] The invention belongs to the technical field of high-performance chemical fibers and relates to a high-performance thermotropic liquid crystal polymer fiber and a preparation method thereof. Background Art

[0002] Thermotropic liquid crystal polyarylate fibers, due to their exceptional mechanical properties and heat resistance, have established a significant position in the high-performance fiber market. These fibers are widely used in automotive, ropes, cables, and slings, and are also demonstrating their unique value in parachutes, particularly those used in spacecraft recovery systems.

[0003] To improve the wear resistance of thermotropic liquid crystal polyarylate fibers, researchers have adopted a variety of chemical modification strategies. First, by adjusting the monomer ratio and the use of catalysts, the molecular structure of the fiber can be optimized, thereby improving its wear resistance. For example, by increasing the molar percentage of 5-aminoindole-2-carboxylic acid, the wear resistance of the fiber can be effectively enhanced. In addition, optimizing the solid-phase polycondensation reaction is also an important means to improve the wear resistance of the fiber. By conducting the reaction under an inert gas atmosphere, fiber products with higher strength and modulus can be produced.

[0004] Surface modification techniques, such as plasma treatment and silane coupling agent treatment, are also effective methods for improving fiber wear resistance. These techniques can introduce reactive groups onto the fiber surface, enhancing adhesion between the fiber and the matrix, thereby improving wear resistance. Furthermore, the addition of inorganic fillers, such as glass fiber and boron nitride fiber, can significantly enhance fiber wear resistance.

[0005] Heat treatment is another key step in improving fiber wear resistance. Relaxation heat setting under a nitrogen atmosphere can improve the fiber's crystallinity and mechanical properties, thereby enhancing wear resistance. Furthermore, the application of UV-irradiation grafting modification technology, by introducing active groups such as acrylic acid onto the fiber surface, can also effectively improve fiber wear resistance.

[0006] The wear resistance of thermotropic liquid crystal polyarylate fibers is particularly important in the parachute industry. Parachutes used in spacecraft recovery systems must withstand extreme mechanical loads and environmental conditions, placing extremely high demands on the material's wear resistance and strength. Through the aforementioned chemical modification method, the performance of thermotropic liquid crystal polyarylate fibers has been significantly improved, enabling them to play a vital role in critical applications such as parachutes (Chinese Patent CN 111038707 B).

[0007] In summary, chemical modification has significantly enhanced the wear resistance of thermotropic liquid crystal polyarylate fibers. This not only enhances their potential for application in traditional fields but also provides a solid foundation for their development in high-end applications such as spacecraft recovery systems. With continued advancements in materials science, the performance of thermotropic liquid crystal polyarylate fibers will be further optimized, and their application range will continue to expand.

[0008] Ultra-high molecular weight polyethylene (UHMWPE) and its fibers, renowned for their exceptional wear resistance, impact resistance, low coefficient of friction, and good chemical stability, are widely used across multiple industries. UHMWPE fibers boast a specific strength 15 times that of steel, combining ultra-high strength, ultra-high modulus, low density, and excellent chemical resistance, making them ideal for use in bulletproof and stab-resistant security materials, as well as high-performance lightweight composites. UHMWPE fibers excel in wear resistance, outperforming many other materials, including POM (polyacetal), fluororesins, and PA66 nylon. This wear resistance makes them ideal for high-wear applications such as pipes, bushings, shafts, and vessels. UHMWPE's wear resistance increases with molecular weight, making it a suitable metal replacement for applications requiring high wear resistance while also offering lightweighting advantages. Surface modification technologies for UHMWPE fibers are also evolving to enhance their adhesion to the polymer matrix, thereby improving the mechanical properties of the composite. These modification techniques include chemical and physical methods designed to enhance the activity of the fiber surface to promote bonding with the matrix. In specific applications, such as parachute manufacturing, the high strength and low density of UHMWPE fiber make it an ideal material choice. It can be used to manufacture parachute cords and fabrics, providing the required strength and durability while maintaining an overall low weight. In summary, UHMWPE and its fibers perform exceptionally well in terms of wear resistance, thanks to their unique molecular structure and physical properties.

[0009] Therefore, combining thermotropic liquid crystal polyarylate fibers with ultra-high molecular weight polyethylene (UHMWPE) is an effective way to improve the wear resistance of TLCPA fibers. However, there are currently few reports on this. Furthermore, the composite process also presents numerous difficulties, such as poor interfacial adhesion between UHMWPE and TLCPA. These issues require targeted improvements and new process solutions.

[0010] In summary, the existing technology cannot simultaneously meet people's requirements for high strength, high modulus and wear resistance of thermotropic liquid crystal polyarylate fibers. Therefore, it is necessary to develop a thermotropic liquid crystal polyarylate fiber with high strength, high modulus and wear resistance to meet the needs of the downstream application market; and it is very necessary to develop new methods and new processes to fully combine ultra-high molecular weight polyethylene materials with thermotropic liquid crystal polyarylate materials during the development process. Summary of the Invention

[0011] The purpose of the present invention is to break the bottleneck of the existing technical solutions and provide a high-strength, high-modulus and wear-resistant thermotropic liquid crystal polyarylate composite fiber and a preparation method thereof. The present invention can be achieved through the following technical solutions:

[0012] The present invention provides a high-strength, high-modulus, and wear-resistant thermotropic liquid crystal polyarylate composite fiber having a composite structure (fiber cross-section shown in Figure 1). Its main components are thermotropic liquid crystal polyarylate and modified ultra-high molecular weight polyethylene. The composite structure comprises 30-95 parts by weight of the thermotropic liquid crystal polyarylate fiber and 5-80 parts by weight of the modified ultra-high molecular weight polyethylene resin.

[0013] Preferably, the high-strength, high-modulus and wear-resistant thermotropic liquid crystal polyarylate composite fiber, wherein the thermotropic liquid crystal polyarylate fiber used has a tensile strength of 20-40 cN / dtex, a tensile modulus of 500-1000 cN / dtex, and a weight-average molecular weight of the modified ultra-high molecular weight polyethylene of 1 million to 10 million.

[0014] The present invention also provides a method for preparing a high-strength, high-modulus and wear-resistant thermotropic liquid crystal polyarylate composite fiber, which specifically comprises the following steps:

[0015] Step 1: Using dioxane as a solvent, (4-methoxyphenyl)(4-(trifluoromethyl)phenyl)methanone (benzophenone compound 1), thioperoxydicarbonate ([(HS)C(S)]2S2) C,C'-dioctadecyl ester (disulfide compound 2), and phenyl acrylate are mixed in a specific ratio to form a modified solution. Ultra-high molecular weight polyethylene powder is added to the modified solution, and high-purity argon gas is introduced and stirred for a period of time to form a solid-liquid mixture.

[0016] Step 2: Irradiate the solid-liquid mixture from step 2 for a period of time using a 253 nm ultraviolet lamp. During the irradiation process, stirring is continued and high-purity argon gas is continuously introduced. The temperature of the solid-liquid mixture is controlled within a certain range. After stopping the ultraviolet lamp irradiation, the irradiated solid-liquid mixture is filtered, washed with dichloromethane, and then dried in an oven at a certain temperature to obtain a modified ultrahigh molecular weight polyethylene powder.

[0017] Step 3: Mix the modified ultra-high molecular weight polyethylene powder with decalin, and mechanically stir the mixture at a certain temperature for a period of time to fully dissolve the modified ultra-high molecular weight polyethylene, thereby obtaining a modified ultra-high molecular weight polyethylene / decalin solution with a certain mass fraction concentration.

[0018] Step 4: preheating the thermotropic liquid crystal polyarylate fibers (including thermotropic liquid crystal polyarylate monofilaments and thermotropic liquid crystal polyarylate multifilaments) in air at a certain temperature, and then coating the modified ultra-high molecular weight polyethylene / decalin solution in step 3 on the surface of the thermotropic liquid crystal polyarylate fibers using a screw extruder at a certain temperature, and then passing the fibers through a high-temperature oven to evaporate the decalin, thereby obtaining thermotropic liquid crystal polyarylate composite fibers.

[0019] Preferably, in step 1, the chemical structures of (4-methoxyphenyl)(4-(trifluoromethyl)phenyl)methanone (referred to as benzophenone compound 1) and thioperoxydicarbonate ([(HS)C(S)]2S2) C,C'-dioctadecyl ester (referred to as disulfide compound 2) are shown in Figure 2, and the molar ratio of benzophenone compound 1, disulfide compound 2, and phenyl acrylate is 1:1:(100-300); the weight-average molecular weight of the ultra-high molecular weight polyethylene powder in step 1 is between 1 million and 8 million; the purity of argon is greater than 99.999%; the argon gas flow rate is 10-2000 ml / min; the mass ratio of ultra-high molecular weight polyethylene to phenyl acrylate is 1:(0.1-50), and the stirring and nitrogen flow times are the same, 5-60 minutes.

[0020] Preferably, in step 2, the argon gas flow rate is 10-2000 ml / min; the temperature of the solid-liquid mixture is controlled within the range of 10 to 60 degrees Celsius, and the UV lamp irradiation time is 3 to 48 hours. During the drying process, the oven temperature is 40-80 degrees Celsius, and the drying time is 2-10 hours.

[0021] Preferably, in step 3, the temperature of the modified ultra-high molecular weight polyethylene powder and decalin is controlled at 60-150 degrees Celsius when they are mixed, and the mechanical stirring is 1 to 5 hours. The mass fraction concentration of the modified ultra-high molecular weight polyethylene in the obtained modified ultra-high molecular weight polyethylene / decalin solution is 0.5% to 10%.

[0022] Preferably, in step 4, the thermotropic liquid crystal polyarylate fibers (including thermotropic liquid crystal polyarylate monofilaments and thermotropic liquid crystal polyarylate multifilaments) are preheated in air at 100-150 degrees Celsius. The screw extruder is set at a temperature of 60-200 degrees Celsius, and the high-temperature oven is set at a temperature of 100-250 degrees Celsius.

[0023] The thermotropic liquid crystal polyarylate composite fiber obtained through steps 1 to 4 of the present invention has a tensile strength higher than 24 cN / dtex, a tensile modulus higher than 800 cN / dtex, and a strength retention rate higher than 90% after rubbing 10,000 times.

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows: using ultra-high molecular weight polyethylene as a coating material and thermotropic liquid crystal polyarylate fiber as a core material, the wear resistance of the composite fiber as a whole can be effectively improved while retaining the original high mechanical properties; At the same time, the present invention also adopts a modification technology, chemically modifying the ultra-high molecular weight polyethylene before coating, on the ultra-high molecular weight polyethylene molecular chain, under the action of benzophenone compounds and disulfide compounds, forming a reaction site, initiating the polymerization of a monomer such as phenyl acrylate, and successfully grafting polyphenyl acrylate. The ultra-high molecular weight polyethylene grafted with polyphenyl acrylate molecular chain has a similar chemical structure to the main component polyarylate of thermotropic liquid crystal polyarylate fiber, compared with unmodified ultra-high molecular weight polyethylene material, the method provided by the present invention can effectively improve the bonding force between ultra-high molecular weight polyethylene and thermotropic liquid crystal polyarylate fiber, and is shown in performance as having more excellent overall mechanical properties and wear resistance, and the composite fiber has a lower dielectric constant (less than or equal to 2.5) and dielectric loss (less than or equal to 0.005).

[0025] The thermotropic liquid crystal polyarylate composite fiber of the present invention can be processed and compounded with various additives, such as antioxidants, antistatic agents, flame retardants, pigments, glass fibers, and inorganic powders, depending on the product's properties. Suitable applications include fishing lines, ropes, arresting cables, parachutes, and more. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] FIG1 is a schematic diagram of the cross-sectional structure of a melt-spun polyethylene melt-coated thermotropic liquid crystal polyarylate fiber composite yarn.

[0027] FIG2 is the chemical structural formula of benzophenone compound 1 and disulfide compound 2. DETAILED DESCRIPTION

[0028] Below in conjunction with specific embodiment, further set forth the present invention.Should be understood that these embodiments are only used to illustrate the present invention and are not used in limiting the scope of the present invention.In addition, should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall equally within the scope limited by the appended claims of the application.

[0029] Example 1

[0030] Step 1: Using dioxane as a solvent, (4-methoxyphenyl)(4-(trifluoromethyl)phenyl)methanone (hereinafter referred to as benzophenone compound 1), thioperoxydicarbonate ([(HS)C(S)]2S2) C,C'-dioctadecyl ester (hereinafter referred to as disulfide compound 2), and phenyl acrylate were mixed in a molar ratio of 1:1:100 to obtain a modified solution. Ultra-high molecular weight polyethylene powder with a weight-average molecular weight of 2,000,000 was added to the modified solution, with a mass ratio of ultra-high molecular weight polyethylene to phenyl acrylate of 1:10. Argon gas with a purity greater than 99.999% was introduced at a rate of 200 ml / min, and stirred for 30 minutes to obtain a solid-liquid mixture.

[0031] Step 2: Irradiate the solid-liquid mixture from step 2 with an ultraviolet lamp having a wavelength of 253 nm for 12 hours. During the irradiation process, stirring is continued and high-purity argon gas is continuously introduced at a rate of 200 ml / min. The temperature of the solid-liquid mixture is controlled at 20°C. After stopping the ultraviolet lamp irradiation, the irradiated solid-liquid mixture is filtered and washed with dichloromethane, followed by drying in an oven at 60°C for 3 hours to obtain a modified ultrahigh molecular weight polyethylene powder.

[0032] Step 3: Mix the modified ultra-high molecular weight polyethylene powder with decalin, and mechanically stir at 80 degrees Celsius for 2 hours to fully dissolve the modified ultra-high molecular weight polyethylene, thereby obtaining a modified ultra-high molecular weight polyethylene / decalin solution with a mass concentration of 2%.

[0033] Step 4: Preheat the thermotropic liquid crystal polyarylate fiber in air at a certain temperature of 110 degrees Celsius, then use a screw extruder to coat the modified ultra-high molecular weight polyethylene / decalin solution in step 3 on the surface of the thermotropic liquid crystal polyarylate fiber at 110 degrees Celsius, and then pass through a high-temperature oven at 150 degrees to evaporate the decalin to obtain a thermotropic liquid crystal polyarylate composite fiber.

[0034] The prepared composite fiber contains 78 parts by weight of thermotropic liquid crystal polyarylate and 22 parts by weight of modified ultra-high molecular weight polyethylene resin.

[0035] Example 2

[0036] Step 1: Using dioxane as a solvent, (4-methoxyphenyl)(4-(trifluoromethyl)phenyl)methanone (hereinafter referred to as benzophenone compound 1), thioperoxydicarbonate ([(HS)C(S)]2S2) C,C'-dioctadecyl ester (hereinafter referred to as disulfide compound 2), and phenyl acrylate were mixed in a molar ratio of 1:1:150 to obtain a modified solution. Ultra-high molecular weight polyethylene powder with a weight-average molecular weight of 2.5 million was added to the modified solution, with a mass ratio of ultra-high molecular weight polyethylene to phenyl acrylate of 1:50. Argon gas with a purity greater than 99.999% was introduced at a rate of 500 ml / min, and stirred for 40 minutes to obtain a solid-liquid mixture.

[0037] Step 2: Irradiate the solid-liquid mixture from step 2 using a 253 nm UV lamp for 18 hours. During the irradiation process, stirring was continued and high-purity argon gas was continuously introduced at a rate of 500 ml / min. The temperature of the solid-liquid mixture was maintained at 25°C. After stopping the UV lamp irradiation, the irradiated solid-liquid mixture was filtered, washed with dichloromethane, and then dried in an oven at 70°C for 5 hours to obtain a modified ultrahigh molecular weight polyethylene powder.

[0038] Step 3: Mix the modified ultra-high molecular weight polyethylene powder with decalin, and mechanically stir at 90 degrees Celsius for 2.5 hours to fully dissolve the modified ultra-high molecular weight polyethylene, thereby obtaining a modified ultra-high molecular weight polyethylene / decalin solution with a mass concentration of 3%.

[0039] Step 4: Preheat the thermotropic liquid crystal polyarylate fiber in air at a certain temperature of 115 degrees Celsius, then use a screw extruder to coat the modified ultra-high molecular weight polyethylene / decalin solution in step 3 on the surface of the thermotropic liquid crystal polyarylate fiber at 120 degrees Celsius, and then pass through a high-temperature oven at 155 degrees to evaporate the decalin to obtain a thermotropic liquid crystal polyarylate composite fiber.

[0040] The prepared composite fiber contains 82 parts by weight of thermotropic liquid crystal polyarylate and 18 parts by weight of modified ultra-high molecular weight polyethylene resin.

[0041] Example 3

[0042] Step 1: Using dioxane as a solvent, (4-methoxyphenyl)(4-(trifluoromethyl)phenyl)methanone (hereinafter referred to as benzophenone compound 1), thioperoxydicarbonate ([(HS)C(S)]2S2) C,C'-dioctadecyl ester (hereinafter referred to as disulfide compound 2), and phenyl acrylate were mixed in a molar ratio of 1:1:200 to form a modified solution. Ultra-high molecular weight polyethylene powder with a weight-average molecular weight of 3,000,000 was added to the modified solution, with a mass ratio of ultra-high molecular weight polyethylene to phenyl acrylate of 1:80. Argon gas with a purity greater than 99.999% was introduced at a rate of 200 ml / min, and stirred for 30 minutes to form a solid-liquid mixture.

[0043] Step 2: Irradiate the solid-liquid mixture from step 2 with an ultraviolet lamp having a wavelength of 253 nm for 12 hours. During the irradiation process, stirring was continued and high-purity argon gas was continuously introduced at a rate of 700 ml / min. The temperature of the solid-liquid mixture was controlled at 20°C. After stopping the ultraviolet lamp irradiation, the irradiated solid-liquid mixture was filtered and washed with dichloromethane, followed by drying in an oven at 80°C for 3 hours to obtain a modified ultrahigh molecular weight polyethylene powder.

[0044] Step 3: Mix the modified ultra-high molecular weight polyethylene powder with decalin, and mechanically stir at 100 degrees Celsius for 3 hours to fully dissolve the modified ultra-high molecular weight polyethylene, thereby obtaining a modified ultra-high molecular weight polyethylene / decalin solution with a mass concentration of 2.5%.

[0045] Step 4: Preheat the thermotropic liquid crystal polyarylate fiber in air at a certain temperature of 115 degrees Celsius, then use a screw extruder to coat the modified ultra-high molecular weight polyethylene / decalin solution in step 3 on the surface of the thermotropic liquid crystal polyarylate fiber at 125 degrees Celsius, and then pass through a high-temperature oven at 160 degrees to evaporate the decalin to obtain a thermotropic liquid crystal polyarylate composite fiber.

[0046] The prepared composite fiber contains 85 parts by weight of thermotropic liquid crystal polyarylate and 15 parts by weight of modified ultra-high molecular weight polyethylene resin.

[0047] Example 4

[0048] Step 1: Using dioxane as a solvent, (4-methoxyphenyl)(4-(trifluoromethyl)phenyl)methanone (hereinafter referred to as benzophenone compound 1), thioperoxydicarbonate ([(HS)C(S)]2S2) C,C'-dioctadecyl ester (hereinafter referred to as disulfide compound 2), and phenyl acrylate were mixed in a molar ratio of 1:1:100 to obtain a modified solution. Ultra-high molecular weight polyethylene powder with a weight-average molecular weight of 5,000,000 was added to the modified solution, with a mass ratio of ultra-high molecular weight polyethylene to phenyl acrylate of 1:150. Argon gas with a purity greater than 99.999% was introduced at a rate of 500 ml / min, and stirred for 55 minutes to obtain a solid-liquid mixture.

[0049] Step 2: Irradiate the solid-liquid mixture from step 2 with an ultraviolet lamp having a wavelength of 253 nm for 20 hours. During the irradiation process, stirring is continued and high-purity argon gas is continuously introduced at a rate of 1000 ml / min. The temperature of the solid-liquid mixture is controlled at 23°C. After stopping the ultraviolet lamp irradiation, the irradiated solid-liquid mixture is filtered, washed with dichloromethane, and then dried in an oven at 65°C for 6 hours to obtain a modified ultrahigh molecular weight polyethylene powder.

[0050] Step 3: Mix the modified ultra-high molecular weight polyethylene powder with decalin, and mechanically stir at 110 degrees Celsius for 3 hours to fully dissolve the modified ultra-high molecular weight polyethylene, thereby obtaining a modified ultra-high molecular weight polyethylene / decalin solution with a mass concentration of 3%.

[0051] Step 4: Preheat the thermotropic liquid crystal polyarylate fiber in air at a certain temperature of 110 degrees Celsius, then use a screw extruder to coat the modified ultra-high molecular weight polyethylene / decalin solution in step 3 on the surface of the thermotropic liquid crystal polyarylate fiber at 115 degrees Celsius, and then pass through a high-temperature oven at 150 degrees to evaporate the decalin to obtain a thermotropic liquid crystal polyarylate composite fiber.

[0052] The prepared composite fiber contains 89 parts by weight of thermotropic liquid crystal polyarylate and 11 parts by weight of modified ultra-high molecular weight polyethylene resin.

[0053] Comparative Example 1

[0054] Step 1: Mix ultra-high molecular weight polyethylene powder with a weight average molecular weight of 2 million with decalin, and mechanically stir at 80 degrees Celsius for 2 hours to fully dissolve the ultra-high molecular weight polyethylene to obtain an ultra-high molecular weight polyethylene / decalin solution with a mass concentration of 2%.

[0055] Step 2: Preheat the thermotropic liquid crystal polyarylate fiber in air at 110 degrees Celsius, then use a screw extruder to coat the modified ultra-high molecular weight polyethylene / decalin solution in step 3 on the surface of the thermotropic liquid crystal polyarylate fiber at 110 degrees Celsius, and then pass through a high-temperature oven at 150 degrees to evaporate the decalin to obtain a thermotropic liquid crystal polyarylate composite fiber.

[0056] The prepared composite fiber contains 85 parts by weight of thermotropic liquid crystal polyarylate and 15 parts by weight of ultra-high molecular weight polyethylene resin.

[0057] Comparative Example 2

[0058] Step 1: Mix ultra-high molecular weight polyethylene powder with a weight average molecular weight of 5 million with decalin, and mechanically stir at 110 degrees Celsius for 3 hours to fully dissolve the ultra-high molecular weight polyethylene to obtain an ultra-high molecular weight polyethylene / decalin solution with a mass concentration of 3%.

[0059] Step 2: Preheat the thermotropic liquid crystal polyarylate fiber in air at 110 degrees Celsius, then use a screw extruder to coat the modified ultra-high molecular weight polyethylene / decalin solution in step 3 on the surface of the thermotropic liquid crystal polyarylate fiber at 115 degrees Celsius, and then pass through a high-temperature oven at 150 degrees to evaporate the decalin to obtain a thermotropic liquid crystal polyarylate composite fiber.

[0060] The prepared composite fiber contains 89 parts by weight of thermotropic liquid crystal polyarylate and 11 parts by weight of ultra-high molecular weight polyethylene resin.

[0061] The relevant material properties of Examples 1 to 4 and Comparative Examples 1 to 2 are shown in Table 1.

[0062] Table 1

[0063]

[0064] Note: The tensile strength, tensile modulus and dielectric constant in the table are the average values ​​of 20 samples measured under the same processing technology.

[0065] As can be seen from the above table, the tensile strength, tensile modulus and wear resistance of the high-strength, high-modulus and wear-resistant thermotropic liquid crystal polyarylate composite fiber prepared by the present invention are significantly improved compared with the products obtained by the conventional method, especially the wear resistance index is significantly improved, indicating that the method of the present invention can effectively improve the performance of the fiber.

Claims

1. A high-strength, high-modulus and wear-resistant thermotropic liquid crystal polyarylate composite fiber, characterized in that: The fiber comprises thermotropic liquid crystal polyarylate and modified ultra-high molecular weight polyethylene, wherein the thermotropic liquid crystal polyarylate fiber accounts for 30-95 parts by weight and the modified ultra-high molecular weight polyethylene accounts for 5-80 parts by weight; The method for preparing a high-strength, high-modulus and wear-resistant thermotropic liquid crystal polyarylate composite fiber comprises the following steps: (1) pre-mixing a benzophenone compound, a disulfide compound and phenyl acrylate to obtain a modified solution, and then mixing the solution with ultra-high molecular weight polyethylene powder; (2) modifying the solution in argon gas under ultraviolet light irradiation to obtain a modified ultra-high molecular weight polyethylene; (3) dissolving the modified ultra-high molecular weight polyethylene in decahydronaphthalene to obtain a modified ultra-high molecular weight polyethylene / decahydronaphthalene solution; and (4) using a screw extruder to compound the solution with the preheated thermotropic liquid crystal polyarylate fiber, and then heating the solution in an oven to obtain a high-strength, high-modulus and wear-resistant thermotropic liquid crystal polyarylate composite fiber.

2. The high-strength, high-modulus and wear-resistant thermotropic liquid crystal polyarylate composite fiber according to claim 1, characterized in that: In step (1), the molar ratio of the benzophenone compound, the disulfide compound and phenyl acrylate is 1:1:(100-300), the mass ratio of the ultra-high molecular weight polyethylene to phenyl acrylate is 1:(0.1-50), and the weight average molecular weight of the ultra-high molecular weight polyethylene powder is between 1 million and 8 million.

3. The high-strength, high-modulus and wear-resistant thermotropic liquid crystal polyarylate composite fiber according to claim 1, characterized in that: The UV lamp irradiation time in step (2) is 3 to 48 hours.

4. The high-strength, high-modulus and wear-resistant thermotropic liquid crystal polyarylate composite fiber according to claim 1, characterized in that: In the step (3), the mass fraction concentration of the modified ultra-high molecular weight polyethylene is 0.5% to 10%.

5. The high-strength, high-modulus and wear-resistant thermotropic liquid crystal polyarylate composite fiber according to claim 1, characterized in that: The thermotropic liquid crystal polyarylate fibers described in step (4) include thermotropic liquid crystal polyarylate monofilaments and thermotropic liquid crystal polyarylate multifilaments, which are preheated in air at 100-150 degrees Celsius, the screw extruder is set at a temperature of 60-200 degrees Celsius, and the oven temperature is 100-250 degrees Celsius.

6. The high-strength, high-modulus and wear-resistant thermotropic liquid crystal polyarylate composite fiber according to claim 1, characterized in that: The obtained high-strength, high-modulus and wear-resistant thermotropic liquid crystal polyarylate composite fiber has a tensile strength higher than 24 cN / dtex, a tensile modulus higher than 800 cN / dtex, a strength retention rate higher than 90% after 10,000 friction times, a dielectric constant less than or equal to 2.5, and a dielectric loss less than or equal to 0.005.

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