Aramid fiber reinforced epoxy soybean oil composite pull rod and preparation method and application thereof

Abstract

This invention relates to the field of composite material modification and molding technology, specifically to an aramid fiber reinforced epoxidized soybean oil composite tie rod, its preparation method, and its application. Raw materials: aramid fiber, a first modification system, a second modification system, a third modification system, and an epoxidized soybean oil matrix; raw materials for the first modification system: metal chlorides, acyl chlorides, and haloalkanes; raw materials for the second modification system: dopamine salt solution; raw materials for the third modification system: solvent and coupling agent; raw materials for the epoxidized soybean oil matrix: epoxidized soybean oil, curing agent, and accelerator. Preparation method: Aramid fiber is sequentially added to the first, second, and third modification systems to obtain modified aramid fiber; the epoxidized soybean oil matrix and the modified aramid fiber are mixed, pultruded, and cut to obtain the aramid fiber reinforced epoxidized soybean oil composite tie rod. This invention solves the problems of poor interfacial compatibility and low bonding strength between aramid fiber and epoxidized soybean oil in the prior art.

Description

Technical Field

[0001] This invention relates to the field of composite material modification and molding technology, specifically to an aramid fiber reinforced epoxy soybean oil composite tie rod, its preparation method, and its application. Background Technology

[0002] Aramid fiber, as a high-performance specialty fiber, is used in composite tie rods made with epoxidized soybean oil matrix. Due to its advantages of being environmentally friendly and having balanced mechanical and insulation properties, it has become the preferred material for insulation structural components in fields such as composite insulators and power equipment. Its application demand in high-end insulation scenarios such as high-voltage power transmission and transformation and high-speed train traction systems continues to rise.

[0003] However, aramid fibers have a regular molecular chain structure, strong surface chemical inertness, and lack active functional groups. This results in poor interfacial compatibility and weak bonding strength with the epoxidized soybean oil matrix, easily forming stress concentration zones at the interface, which becomes a weakness in the mechanical and electrical properties of the composite tie rod. At the same time, epoxidized soybean oil itself has a high degree of molecular chain branching and poor low-temperature fluidity. Insufficient impregnation of aramid fibers during molding can easily lead to defects such as pores and microcracks, further reducing the interfacial bonding effect of the composite material. Consequently, the tensile strength, breakdown voltage, and other key properties of the composite tie rod cannot meet the application requirements of high-end scenarios, thus restricting its large-scale engineering application.

[0004] Current research on interfacial modification of aramid fiber / epoxy composites mainly focuses on single chemical grafting, coupling agent treatment, or simple matrix modification. These modification schemes only focus on improving performance in a single dimension. Either they only activate the aramid fiber surface without simultaneously matching the rheological properties of the epoxy soybean oil matrix, resulting in limited improvement in interfacial bonding strength; or they only toughen the epoxy soybean oil matrix without addressing the interfacial compatibility between the aramid fiber and the resin matrix. The modification methods lack synergy, making it difficult to simultaneously achieve the dual goals of improving the surface activity of the aramid fiber and optimizing the flowability of the epoxy soybean oil matrix. Furthermore, existing composite tie rod performance evaluation systems mostly focus on macroscopic mechanical or electrical indicators, lacking a combined analysis of macroscopic performance and microscopic interfacial parameters. This makes it difficult to accurately select the optimal preparation scheme that balances interfacial reinforcement and process feasibility, and fails to provide scientific guidance for the process optimization of aramid fiber-reinforced epoxy soybean oil composite tie rods. Summary of the Invention

[0005] To address the problems existing in the prior art, the present invention aims to provide an aramid fiber reinforced epoxidized soybean oil composite tie rod, its preparation method, and its application. This invention solves the problems of poor interfacial compatibility and low bonding strength between aramid fiber and epoxidized soybean oil in the prior art. It also solves the problems of insufficient synergy of single modification methods, mismatch between process parameters and modified materials, and lack of macroscopic and microscopic linkage analysis in performance evaluation, which leads to insufficient mechanical and electrical properties of the composite tie rod and poor product consistency.

[0006] The technical solution of the present invention is as follows: This invention provides an aramid fiber reinforced epoxy soybean oil composite tie rod, comprising the following raw materials: Aramid fibers, a first modification system, a second modification system, a third modification system, and an epoxidized soybean oil matrix; The raw materials for the first modified system include: metal chlorides, acyl chlorides, and haloalkanes; The raw materials for the second modified system include: dopamine salt solution; The raw materials for the third modified system include: solvent and coupling agent; The raw materials for the epoxidized soybean oil matrix include: epoxidized soybean oil, curing agent, and accelerator.

[0007] The aramid fiber-reinforced epoxidized soybean oil composite tie rod provided by this invention effectively solves the problems of poor interfacial compatibility and low bonding strength between aramid fibers and epoxidized soybean oil. The specific modification principle is as follows: The aramid fiber surface is activated and pretreated using a first modification system (metal chloride, acyl chloride, haloalkanes) to introduce reactive halogen-containing active functional groups, breaking the surface inertness of the aramid fibers; a second modification system (dopamine salt solution) forms a biomimetic polydopamine layer on the fiber surface, providing abundant catechol and amino active sites; a third modification system (solvent, coupling agent) further grafts silane or titanate coupling agents, significantly improving the surface chemical activity and wettability of the aramid fibers. Through this three-stage progressive interfacial modification, the aramid fiber and epoxidized soybean oil interface is more tightly bonded, the bonding strength is significantly improved, and the stress concentration area is significantly reduced.

[0008] Furthermore, the volume ratio of the aramid fiber, the first modified system, the second modified system, the third modified system, and the epoxidized soybean oil matrix is ​​50~65:3~5:1.5~2.5:1.5~2.5:30~40.

[0009] Furthermore, the volume ratio of the aramid fiber, the first modified system, the second modified system, the third modified system, and the epoxidized soybean oil matrix is ​​62:4:2:2:30.

[0010] Furthermore, the mass ratio of the metal chloride, acyl chloride and haloalkane is 1.7~1.8:1:2.5~3.5.

[0011] Furthermore, the solid-liquid ratio of the first modified system is 1g:15~20mL.

[0012] Furthermore, the concentration of dopamine salt in the dopamine salt solution is 2~3 g / L, and the pH value of the dopamine salt solution is 8.0~8.5.

[0013] Furthermore, in the third modified system, the mass fraction of the coupling agent is 1-2%, and the mass fraction of the solvent is 98-99%.

[0014] Furthermore, the mass ratio of the epoxidized soybean oil, curing agent, and accelerator is 100:70~84:0.3~0.8.

[0015] By optimizing the ratio of epoxidized soybean oil, curing agent, and accelerator, the viscosity of the matrix can be reduced, the low-temperature impregnation fluidity can be improved, and the modified aramid fiber can be fully impregnated during the molding process, significantly reducing porosity and microcrack defects.

[0016] Furthermore, the aramid fiber is selected from one or both of para-aramid fiber and meta-aramid fiber.

[0017] Furthermore, the metal chloride is selected from anhydrous aluminum trichloride, the acyl chloride is selected from chloroacetyl chloride, and the haloalkane is selected from dichloromethane.

[0018] Furthermore, the dopamine salt solution is selected from dopamine hydrochloride solution.

[0019] Furthermore, the dopamine salt is selected from dopamine hydrochloride.

[0020] Furthermore, the solvent is selected from anhydrous ethanol and deionized water, and the volume ratio of anhydrous ethanol to deionized water is 1:1; the coupling agent is selected from γ-glycidoxypropyltrimethoxysilane.

[0021] Furthermore, the curing agent is selected from modified acid anhydride curing agents, and the accelerator is selected from 2-methylimidazole; The modified anhydride curing agent is selected from at least one of hexahydrophthalic anhydride and methyltetrahydrophthalic anhydride; The mass ratio of hexahydrophthalic anhydride to methyltetrahydrophthalic anhydride is 0~4:0~1.

[0022] The present invention also provides a method for preparing the above-mentioned aramid fiber reinforced epoxidized soybean oil composite tie rod, comprising the following steps: sequentially placing the aramid fiber into a first modification system, a second modification system and a third modification system to obtain the modified aramid fiber; The epoxidized soybean oil matrix and the modified aramid fiber are mixed, pultruded, and cut to obtain an aramid fiber reinforced epoxidized soybean oil composite tie rod.

[0023] Through a three-stage modification process involving stepwise grafting and layer-by-layer synergy (first activating and introducing halogen groups, then forming a polydopamine active layer, and finally grafting a coupling agent), a multi-level chemically active interface is constructed on the surface of aramid fibers, significantly enhancing their chemical bonding ability and wettability with the epoxidized soybean oil matrix. Simultaneously, a pultrusion molding process is employed, combining the surface characteristics of the modified fibers with the improved low-viscosity flowability of the matrix, to achieve thorough impregnation and controllable curing, effectively reducing defects such as porosity and microcracks. The result is an aramid fiber-reinforced epoxidized soybean oil composite tie rod with stable interfacial bonding, excellent mechanical and electrical properties, and high batch-to-batch consistency, solving the performance shortcomings caused by insufficient synergy of modification methods and parameter mismatches in traditional processes.

[0024] Furthermore, the preparation method specifically includes the following steps: The aramid fibers are washed and dried to obtain clean aramid fibers; The metal chloride, acyl chloride, and haloalkane are mixed to obtain the first modified system; A dopamine salt solution was prepared to obtain the second modified system; The solvent and coupling agent are mixed to obtain a third modified system; The epoxidized soybean oil, curing agent and accelerator are mixed and stirred for the first time to obtain the epoxidized soybean oil matrix; The clean aramid fiber is placed into the first modification system and subjected to the first modification treatment to obtain the first modified aramid fiber. The first modified aramid fiber is washed and dried, and then placed into the second modification system for a second modification treatment to obtain the second modified aramid fiber. The second modified aramid fiber is washed and dried, and then placed into the third modification system for third modification treatment to obtain the third modified aramid fiber. The modified aramid fiber is dried to obtain the modified aramid fiber. The epoxidized soybean oil matrix and the modified aramid fiber are mixed, pultruded, and cut to obtain an aramid fiber reinforced epoxidized soybean oil composite tie rod.

[0025] This process, through a rigorous step-by-step operation of "cleaning - first modification (halogenation activation) - washing and drying - second modification (polydopamine self-polymerization) - washing and drying - third modification (coupling agent grafting) - drying," achieves multi-layered, controllable, and synergistic chemical modification of the aramid fiber surface. This effectively avoids mutual interference between different modification systems, thereby orderly constructing a composite interface layer with high chemical activity and biomimetic adhesion on the fiber surface, greatly enhancing the chemical bonding and mechanical interlocking ability with the epoxidized soybean oil matrix. Simultaneously, by sequentially mixing and stirring the epoxidized soybean oil, curing agent, and accelerator to obtain a matrix system with low viscosity and good low-temperature impregnation fluidity, combined with the fiber with excellent wettability after the three-step modification, it can be fully impregnated during pultrusion molding, significantly reducing defects such as porosity and microcracks, and improving the density and electrical insulation performance of the composite tie rod. In addition, each step includes washing and drying to remove reaction residues, and the formulation parameters are clearly defined and controllable, ensuring batch consistency of the surface state of the modified fibers. This results in stable performance of the composite tie rod in key properties such as tensile strength and breakdown voltage, solving the technical problems of insufficient synergy of traditional single modification methods and mismatch between process parameters and modified materials. This provides a reliable process path for the large-scale production of composite tie rods with high interface strength and high electrical performance.

[0026] Furthermore, the cleaning and drying specifically includes: placing the aramid fiber in an acetone solution, ultrasonically cleaning for 30-60 minutes, rinsing with anhydrous ethanol 3-5 times, and then drying at a temperature of 80-90℃ for 3-5 hours to obtain clean aramid fiber; the ultrasonic cleaning power is 150-200W.

[0027] Furthermore, the moisture content of the clean aramid fiber is ≤0.5%.

[0028] Furthermore, the first stirring time is 30-45 minutes, and the temperature is 40-50°C.

[0029] Furthermore, the temperature of the first modification treatment is 40~60℃, and the time is 4~6h.

[0030] Furthermore, the temperature of the second modification treatment is 25~30℃, and the time is 6~8h.

[0031] Furthermore, the third modification treatment is carried out at a temperature of 50-60°C for 3-5 hours.

[0032] Furthermore, the drying temperature is 80~100℃, and the time is 3~5h.

[0033] Furthermore, mixing the epoxidized soybean oil matrix and the modified aramid fiber includes: impregnating the modified aramid fiber with the epoxidized soybean oil matrix at a temperature of 30-40°C for 10-15 minutes; the impregnation rate of the modified aramid fiber is ≥95%.

[0034] Furthermore, the pultrusion molding temperature is 80~120℃, and the traction speed is 0.5~2m / min.

[0035] Furthermore, the preparation of the dopamine salt solution includes the following steps: heating the Tris-HCl buffer to 30°C, adding dopamine salt, and stirring until completely dissolved to obtain the dopamine salt solution.

[0036] Furthermore, the preparation method further includes: The tensile strength, flexural strength, fiber exposure ratio, interfacial adhesion coefficient, surface roughness, partial discharge initiation voltage, and breakdown voltage of the aramid fiber reinforced epoxy soybean oil composite tie rod were determined. The interfacial shear strength between the modified aramid fiber and the epoxidized soybean oil matrix was measured. The tensile properties of the aramid fiber-reinforced epoxidized soybean oil composite tie rod were evaluated by tensile strength; the bending properties were evaluated by flexural strength; the degree of encapsulation was evaluated by fiber exposure ratio; the interfacial bonding force between the modified aramid fiber and the epoxidized soybean oil matrix was evaluated by interfacial shear strength; the interfacial adhesion capability was evaluated by interfacial adhesion coefficient; the surface microstructure was evaluated by surface roughness; the partial discharge initiation voltage was evaluated by partial discharge resistance; and the electrical characteristics were evaluated by breakdown voltage. Based on the tensile strength, flexural strength, fiber exposure ratio, interfacial shear strength, interfacial adhesion coefficient, surface roughness, partial discharge initiation voltage, and breakdown voltage, a judgment matrix is ​​constructed, standardized, and a comprehensive evaluation index is calculated. The optimal process is obtained through the comprehensive evaluation indicators.

[0037] This invention simultaneously measures the tensile strength (tensile resistance), flexural strength (flexural resistance), fiber exposure ratio (degree of epoxidized soybean oil coating), interfacial adhesion coefficient (interfacial adhesion ability), surface roughness (surface microstructure), partial discharge initiation voltage (partial discharge resistance), and breakdown voltage (electrical characteristics) of the finished aramid fiber-reinforced epoxidized soybean oil composite tie rod. It also measures the interfacial shear strength (interfacial bonding force between the modified aramid fiber and the epoxidized soybean oil matrix). The results from these eight dimensions are then comprehensively evaluated to obtain the optimal process parameters. The advantages of this method are: it constructs a multi-parameter linkage evaluation system covering macroscopic mechanics (tensile and bending strength), microscopic interfaces (interfacial shear strength, adhesion coefficient, surface roughness, fiber exposure ratio), and electrical properties (partial discharge initiation voltage, breakdown voltage). This system can systematically reveal the influence of different process conditions on fiber-matrix interface bonding, material density, and insulation reliability, providing scientific guidance for optimizing process parameters (such as modification sequence, drying conditions, pultrusion speed, etc.) and avoiding the one-sidedness of single-index evaluation. Therefore, this invention effectively solves the problem in existing technologies where performance evaluation lacks macroscopic and microscopic linkage analysis, leading to insufficient mechanical and electrical properties of composite tie rods and poor product consistency. It provides a scientific basis for accurately selecting the optimal preparation scheme for aramid fiber-reinforced epoxidized soybean oil composite tie rods that balances interface reinforcement effect, electrical reliability, and process feasibility.

[0038] Furthermore, the grading criteria for the comprehensive evaluation indicators are as follows: 0.75 Comprehensive evaluation indicators 1 hour, excellent; 0.5 Comprehensive evaluation indicators At 0.75, the result is good; 0.25 Comprehensive evaluation indicators At 0.5, it's generally acceptable; 0 Comprehensive evaluation indicators At 0.25, the difference is...

[0039] Furthermore, the aramid fiber reinforced epoxy soybean oil composite tie rod has a diameter of 10~50mm, a length of 500~3000mm, a tensile strength ≥350MPa, a bending strength ≥280MPa, a breakdown voltage ≥50kV / mm, and an interfacial shear strength ≥25MPa.

[0040] The present invention also provides the application of the above-mentioned aramid fiber reinforced epoxy soybean oil composite tie rod or the aramid fiber reinforced epoxy soybean oil composite tie rod prepared by the above preparation method in high-voltage power transmission and / or high-speed train traction systems.

[0041] The beneficial effects of this invention are: This invention provides an aramid fiber-reinforced epoxidized soybean oil composite tie rod. The aramid fiber surface is activated and pretreated using a first modification system (metal chloride, acyl chloride, haloalkanes) to introduce reactive halogen groups. A second modification system (dopamine salt solution) forms a biomimetic polydopamine layer on the fiber surface, providing abundant catechol and amino active sites. A third modification system (solvent, coupling agent) further grafts a silane coupling agent. This three-layer synergistic modification significantly enhances the chemical activity and wettability of the aramid fiber surface. Through this multi-system relay modification, the aramid fiber and epoxidized soybean oil interface is more tightly bonded, the adhesion strength is significantly improved, and the stress concentration zone is significantly reduced, solving the problems of poor interfacial compatibility and low adhesion strength between aramid fiber and epoxidized soybean oil.

[0042] This invention utilizes a multi-dimensional approach to measure and evaluate aramid fiber-reinforced epoxidized soybean oil composite tie rods, incorporating tensile strength, flexural strength, fiber exposure ratio, interfacial shear strength, interfacial adhesion coefficient, surface roughness, partial discharge initiation voltage, and breakdown voltage. This yields optimal process parameters (such as the modified system ratio, modification time, drying temperature, pultrusion speed, and curing temperature). It overcomes the limitations of traditional methods that focus solely on macroscopic mechanical or electrical indicators, establishing a multi-parameter linkage analysis method encompassing macroscopic mechanics (tensile and flexural strength), microscopic interfaces (interfacial shear strength, adhesion coefficient, surface roughness, and fiber exposure ratio), and electrical properties (partial discharge initiation voltage and breakdown voltage). This system can accurately screen for the optimal preparation scheme that balances interfacial reinforcement, process feasibility, and electrical reliability. It effectively solves the problem in existing technologies where performance evaluation lacks macroscopic and microscopic linkage analysis, leading to insufficient mechanical and electrical properties and poor product consistency in composite tie rods. This provides a scientific basis for the refined control of process parameters and the stable control of product performance.

[0043] This invention provides a method for preparing aramid fiber-reinforced epoxidized soybean oil composite tie rods. It employs a multi-step synergistic strategy of Bock chemical modification, dopamine physical modification, and coupling agent interface modification to regulate the surface structure and chemical properties of aramid fibers. A modified anhydride curing agent is used to optimize the epoxidized soybean oil matrix system, improving its low-temperature fluidity and impregnation effect. Simultaneously, an adaptive pultrusion molding process is proposed to precisely control key molding parameters. This invention significantly enhances the interfacial bonding strength between aramid fibers and the epoxidized soybean oil matrix, increasing the tensile strength of the composite tie rod by over 40% and the breakdown voltage by over 35%. Furthermore, the process exhibits strong stability and can be mass-produced. It can be used in composite insulator core rods and in high-end insulation applications such as power equipment support and transmission, demonstrating broad application prospects. Attached Figure Description

[0044] Figure 1A process flow diagram of the interfacial reinforcement modification of aramid fiber in the preparation method of aramid fiber reinforced epoxidized soybean oil composite tie rod; Detailed Implementation

[0045] The present invention will be further described in detail below through embodiments, but in no way is the invention limited.

[0046] Example 1 (Process 5)

[0047] like Figure 1 As shown, a method for preparing an aramid fiber reinforced epoxy soybean oil composite tie rod includes the following steps: S1. Place the para-aramid fiber in an acetone aqueous solution and ultrasonically clean it for 60 minutes at an ultrasonic cleaning power of 150W to remove surface oil and impurities. Then rinse it three times with anhydrous ethanol and dry it for 5 hours at a temperature of 80℃ to make the moisture content of the para-aramid fiber ≤0.5% and obtain clean para-aramid fiber. S2. Anhydrous aluminum trichloride, chloroacetyl chloride and dichloromethane are mixed in a mass ratio of 1.8:1:3 to obtain the first modification system for interfacial modification and reinforcement of para-aramid fibers. S3. Place the clean para-aramid fiber into the first modification system and magnetically stir it at 40°C for 6 hours while continuously purging with nitrogen for protection to perform the first modification process (Bock chemical modification) to obtain the first modified para-aramid fiber; take out the first modified para-aramid fiber and wash it repeatedly with deionized water, collect the water flowing down during the washing process (i.e., filtrate), and wash until the filtrate is neutral. The first modified para-aramid fiber after washing was dried at 80°C for 5 hours to obtain the dried first modified para-aramid fiber. S4. Dissolve 6.057 g of Tris base (tris(hydroxymethyl)aminomethane) in 800 mL of deionized water, and adjust the pH to 8.0 with 1 mol / L HCl solution at 25 °C to obtain a Tris-HCl buffer solution with a Tris base concentration of 0.05 mol / L and a pH of 8.0. Then heat the Tris-HCl buffer solution to 30 °C, add dopamine hydrochloride, and stir until completely dissolved to prepare a dopamine hydrochloride solution with a dopamine hydrochloride concentration of 2 g / L and a pH of 8.0. This is the second modification system for interfacial modification and reinforcement of para-aramid fibers. S5. The dried first modified para-aramid fiber is placed into the second modification system and stirred at 25°C for 8 hours to perform the second modification process (dopamine physical modification) to obtain the second modified para-aramid fiber. Take out the second modified para-aramid fiber and wash it repeatedly with deionized water. Collect the water (i.e., filtrate) that flows down during the washing process and wash until the filtrate is neutral. The washed second modified para-aramid fiber was dried at 80℃ for 5 hours to obtain the dried second modified para-aramid fiber. S6. Mix anhydrous ethanol and deionized water at a volume ratio of 1:1 to obtain a solvent, and then add coupling agent γ-glycidyl etheroxypropyltrimethoxysilane (KH560) to obtain a third modification system for interfacial modification and reinforcement of para-aramid fibers. In the third modified system, the mass fraction of the coupling agent is 2%, and the mass fraction of the solvent is 98%. S7. The dried para-aramid fiber after the second modification is placed into the third modification system and reacted in a water bath at 50°C for 5 hours to perform the third modification process (coupling agent interface modification) to obtain the para-aramid fiber after the third modification. The modified para-aramid fiber was dried at 80℃ for 5 hours to obtain the modified para-aramid fiber. S8. Mix epoxidized soybean oil, modified acid anhydride curing agent, and accelerator (2-methylimidazole) at a mass ratio of 100:70:0.3, stir at 40°C for 45 minutes until the system is uniform and transparent to obtain the epoxidized soybean oil matrix. Among them, the modified anhydride curing agent is composed of hexahydrophthalic anhydride and methyltetrahydrophthalic anhydride in a mass ratio of 4:1; S9. The modified para-aramid fiber is introduced into the impregnation tank through the wire feeding frame. The temperature of the impregnation tank is controlled at 30℃, and the impregnation time is 15min, so that the modified para-aramid fiber is fully impregnated in the epoxy soybean oil matrix, ensuring that the impregnation rate of para-aramid fiber is ≥95%. Then, it is put into the pultrusion die for molding. The temperature of the pultrusion die is controlled at 80~120℃ (the temperature of the pultrusion die is controlled in stages: 80~90℃ in the inlet section, 90~100℃ in the middle section, and 100~120℃ in the outlet section), and the traction speed is 0.5m / min. After continuous heat curing for 8min, it is cut to obtain the aramid fiber reinforced epoxy soybean oil composite tie rod. The volume ratio of the epoxy soybean oil matrix in the aramid fiber reinforced epoxy soybean oil composite tie rod is 30%.

[0048] In this embodiment, the volume ratio of para-aramid fiber, the first modified system, the second modified system, the third modified system, and the epoxidized soybean oil matrix is ​​62:4:2:2:30.

[0049] Example 2

[0050] A method for preparing an aramid fiber reinforced epoxy soybean oil composite tie rod includes the following steps: S1. Place the meta-aramid fiber in an acetone aqueous solution and ultrasonically clean it for 45 minutes at an ultrasonic cleaning power of 175W to remove surface oil and impurities. Then rinse it 4 times with anhydrous ethanol and dry it at a temperature of 85℃ for 4 hours to make the moisture content of the meta-aramid fiber ≤0.5% and obtain clean meta-aramid fiber. S2. Anhydrous aluminum trichloride, chloroacetyl chloride and dichloromethane are mixed in a mass ratio of 1.7:1:3.5 to obtain the first modification system for interfacial modification and reinforcement of meta-aramid fibers. S3. Place the clean meta-aramid fiber into the first modification system and magnetically stir it at 50°C for 5 hours while continuously purging with nitrogen for protection to perform the first modification process (Bock chemical modification) to obtain the first modified meta-aramid fiber; take out the first modified meta-aramid fiber and wash it repeatedly with deionized water, collect the water flowing down during the washing process (i.e., filtrate), and wash until the filtrate is neutral. The first modified meta-aramid fiber after washing was dried at 90℃ for 4 hours to obtain the dried first modified meta-aramid fiber. S4. Dissolve 6.057 g of Tris base (tris(hydroxymethyl)aminomethane) in 800 mL of deionized water, and adjust the pH to 8.0 with 1 mol / L HCl solution at 25 °C to obtain a Tris-HCl buffer solution with a Tris base concentration of 0.05 mol / L and a pH of 8.0. Then heat the Tris-HCl buffer solution to 30 °C, add dopamine hydrochloride, and stir until completely dissolved to prepare a dopamine hydrochloride solution with a dopamine hydrochloride concentration of 2.5 g / L and a pH of 8.3. This is the second modification system for the interface modification and reinforcement of meta-aramid fibers. S5. The dried first modified meta-aramid fiber is placed into the second modification system and stirred at 27°C for 7 hours to perform the second modification process (dopamine physical modification) to obtain the second modified meta-aramid fiber. Take out the second modified meta-aramid fiber and wash it repeatedly with deionized water. Collect the water (i.e., filtrate) that flows down during the washing process and wash until the filtrate is neutral. The washed second modified meta-aramid fiber was dried at 90℃ for 4 hours to obtain the dried second modified meta-aramid fiber. S6. Mix anhydrous ethanol and deionized water at a volume ratio of 1:1 to obtain a solvent, and then add the coupling agent γ-glycidyl etheroxypropyltrimethoxysilane (KH560) to obtain a third modification system for the interface modification and reinforcement of meta-aramid fibers. In the third modified system, the mass fraction of the coupling agent is 1%, and the mass fraction of the solvent is 99%. S7. The dried meta-aramid fiber after the second modification is placed into the third modification system and reacted in a water bath at 55°C for 4 hours to perform the third modification process (coupling agent interface modification) to obtain the meta-aramid fiber after the third modification. The modified meta-aramid fiber was dried at 90℃ for 4 hours to obtain the modified meta-aramid fiber. S8. Mix epoxidized soybean oil, modified acid anhydride curing agent, and accelerator (2-methylimidazole) at a mass ratio of 100:74:0.5, stir at 40~50℃ for 40 minutes until the system is uniform and transparent to obtain epoxidized soybean oil matrix. Among them, the modified anhydride curing agent is composed of hexahydrophthalic anhydride and methyltetrahydrophthalic anhydride in a mass ratio of 4:1; S9. The modified meta-aramid fiber is introduced into the impregnation tank through the feeder. The temperature of the impregnation tank is controlled at 35℃, and the impregnation time is 12min, so that the modified meta-aramid fiber is fully impregnated in the epoxidized soybean oil matrix, ensuring that the impregnation rate of the meta-aramid fiber is ≥95%. Then, it is put into the pultrusion die for molding. The temperature of the pultrusion die is controlled at 80~120℃ (the temperature of the pultrusion die is controlled in stages: 80~90℃ in the inlet section, 90~100℃ in the middle section, and 100~120℃ in the outlet section), and the traction speed is 1.25m / min. After continuous heat curing for 7min, it is cut to obtain the aramid fiber reinforced epoxidized soybean oil composite tie rod. The volume ratio of the epoxidized soybean oil matrix in the aramid fiber reinforced epoxidized soybean oil composite tie rod is 35%.

[0051] In this embodiment, the volume ratio of meta-aramid fiber, the first modified system, the second modified system, the third modified system, and the epoxidized soybean oil matrix is ​​57:4.5:1.75:1.75:35.

[0052] Example 3

[0053] A method for preparing an aramid fiber reinforced epoxy soybean oil composite tie rod includes the following steps: S1. Place the meta-aramid fiber in an acetone aqueous solution and ultrasonically clean it for 30 minutes at an ultrasonic cleaning power of 200W to remove surface oil and impurities. Then rinse it 5 times with anhydrous ethanol and dry it at a temperature of 90℃ for 3 hours to make the moisture content of the meta-aramid fiber ≤0.5% and obtain clean meta-aramid fiber. S2. Anhydrous aluminum trichloride, chloroacetyl chloride and dichloromethane are mixed at a mass ratio of 1.8:1:2.5 to obtain the first modification system for interfacial modification and reinforcement of meta-aramid fibers. S3. Place the clean meta-aramid fiber into the first modification system and magnetically stir it at 60°C for 4 hours while continuously purging with nitrogen for protection to perform the first modification process (Bock chemical modification) to obtain the first modified meta-aramid fiber; take out the first modified meta-aramid fiber and wash it repeatedly with deionized water, collect the water flowing down during the washing process (i.e., filtrate), and wash until the filtrate is neutral. The first modified meta-aramid fiber after washing was dried at 100℃ for 3 hours to obtain the dried first modified meta-aramid fiber. S4. Dissolve 6.057 g of Tris base (tris(hydroxymethyl)aminomethane) in 800 mL of deionized water, and adjust the pH to 8.0 with 1 mol / L HCl solution at 25 °C to obtain a Tris-HCl buffer solution with a Tris base concentration of 0.05 mol / L and a pH of 8.0. Then heat the Tris-HCl buffer solution to 30 °C, add dopamine hydrochloride, and stir until completely dissolved to prepare a dopamine hydrochloride solution with a dopamine hydrochloride concentration of 3 g / L and a pH of 8.5. This is the second modification system for the interfacial modification and reinforcement of meta-aramid fibers. S5. The dried first modified meta-aramid fiber is placed into the second modification system and stirred at 30°C for 6 hours to perform the second modification process (dopamine physical modification) to obtain the second modified meta-aramid fiber. Take out the second modified meta-aramid fiber and wash it repeatedly with deionized water. Collect the water (i.e., filtrate) that flows down during the washing process and wash until the filtrate is neutral. The washed second modified meta-aramid fiber was dried at 100℃ for 3 hours to obtain the dried second modified meta-aramid fiber. S6. Mix anhydrous ethanol and deionized water at a volume ratio of 1:1 to obtain a solvent, and then add the coupling agent γ-glycidyl etheroxypropyltrimethoxysilane (KH560) to obtain a third modification system for the interface modification and reinforcement of meta-aramid fibers. In the third modified system, the mass fraction of the coupling agent is 1%, and the mass fraction of the solvent is 99%. S7. The dried meta-aramid fiber after the second modification is placed into the third modification system and reacted in a water bath at 60°C for 3 hours to perform the third modification process (coupling agent interface modification) to obtain the meta-aramid fiber after the third modification. The modified meta-aramid fiber was dried at 100℃ for 3 hours to obtain the modified meta-aramid fiber. S8. Mix epoxidized soybean oil, modified acid anhydride curing agent, and accelerator (2-methylimidazole) at a mass ratio of 100:78:0.8, stir at 50°C for 30 minutes until the system is uniform and transparent to obtain the epoxidized soybean oil matrix. Among them, the modified anhydride curing agent is composed of hexahydrophthalic anhydride and methyltetrahydrophthalic anhydride in a mass ratio of 4:1; S9. The modified meta-aramid fiber is introduced into the impregnation tank through the wire feeding frame. The temperature of the impregnation tank is controlled at 40℃ and the impregnation time is 10min, so that the modified meta-aramid fiber is fully impregnated in the epoxidized soybean oil matrix, ensuring that the impregnation rate of the meta-aramid fiber is ≥95%. Then, it is put into the pultrusion die for molding. The temperature of the pultrusion die is controlled at 80~120℃ (the temperature of the pultrusion die is controlled in stages: 80~90℃ in the inlet section, 90~100℃ in the middle section, and 100~120℃ in the outlet section), and the traction speed is 2m / min. After continuous heat curing for 5min, it is cut to obtain the aramid fiber reinforced epoxidized soybean oil composite tie rod. The volume ratio of the epoxidized soybean oil matrix in the aramid fiber reinforced epoxidized soybean oil composite tie rod is 40%.

[0054] In this embodiment, the volume ratio of meta-aramid fiber, the first modified system, the second modified system, the third modified system, and the epoxidized soybean oil matrix is ​​52:3.75:2:2.25:40.

[0055] Comparative Example 1 (Process 1) The preparation method of unmodified aramid fiber reinforced epoxy soybean oil composite tie rod includes the following steps: S1. Place the para-aramid fiber in an acetone aqueous solution and ultrasonically clean it for 60 minutes at an ultrasonic cleaning power of 150W to remove surface oil and impurities. Then rinse it three times with anhydrous ethanol and dry it for 5 hours at a temperature of 80℃ to make the moisture content of the para-aramid fiber ≤0.5% and obtain clean para-aramid fiber. S2. Mix epoxidized soybean oil, modified acid anhydride curing agent, and accelerator (2-methylimidazole) in a mass ratio of 100:70:0.3, stir at 40°C for 45 minutes until the system is uniform and transparent to obtain the epoxidized soybean oil matrix. Among them, the modified anhydride curing agent is composed of hexahydrophthalic anhydride and methyltetrahydrophthalic anhydride in a mass ratio of 4:1; S3. Clean para-aramid fibers are introduced into the impregnation tank through a feeder. The temperature of the impregnation tank is controlled at 30℃, and the impregnation time is 15 minutes, so that the clean para-aramid fibers are fully impregnated in the epoxy soybean oil matrix, ensuring that the impregnation rate of para-aramid fibers is ≥95%. Then, the fibers are put into a pultrusion die for molding. The temperature of the pultrusion die is controlled at 80~120℃ (the temperature of the pultrusion die is controlled in stages: 80~90℃ at the inlet, 90~100℃ in the middle, and 100~120℃ at the outlet), and the traction speed is 0.5m / min. After continuous heat curing for 8 minutes, the fibers are cut to obtain aramid fiber reinforced epoxy soybean oil composite tie rods. The volume ratio of the epoxy soybean oil matrix in the aramid fiber reinforced epoxy soybean oil composite tie rods is 30%.

[0056] In this comparative example, the volume ratio of para-aramid fiber to epoxidized soybean oil matrix is ​​70:30.

[0057] Comparative Example 2 (Process 2) The preparation method of aramid fiber reinforced epoxidized soybean oil composite tie rod treated only by the second modification system (dopamine system) includes the following steps: S1. Place the para-aramid fiber in an acetone aqueous solution and ultrasonically clean it for 60 minutes at an ultrasonic cleaning power of 150W to remove surface oil and impurities. Then rinse it three times with anhydrous ethanol and dry it for 5 hours at a temperature of 80℃ to make the moisture content of the para-aramid fiber ≤0.5% and obtain clean para-aramid fiber. S2. Dissolve 6.057 g of Tris base (tris(hydroxymethyl)aminomethane) in 800 mL of deionized water, and adjust the pH to 8.0 with 1 mol / L HCl solution at 25 °C to obtain a Tris-HCl buffer solution with a Tris base concentration of 0.05 mol / L and a pH of 8.0. Then heat the Tris-HCl buffer solution to 30 °C, add dopamine hydrochloride, and stir until completely dissolved to prepare a dopamine hydrochloride solution with a dopamine hydrochloride concentration of 2 g / L and a pH of 8.0. This is the second modification system for interfacial modification and reinforcement of para-aramid fibers. S3. Place the clean para-aramid fiber into the second modification system and stir at 25°C for 8 hours to perform the second modification process (dopamine physical modification) to obtain the second modified para-aramid fiber. Take out the second modified para-aramid fiber and wash it repeatedly with deionized water. Collect the water (i.e., filtrate) that flows down during the washing process and wash until the filtrate is neutral. The washed second modified para-aramid fiber was dried at 80℃ for 5 hours to obtain the dried second modified para-aramid fiber. S4. Mix epoxidized soybean oil, modified acid anhydride curing agent, and accelerator (2-methylimidazole) at a mass ratio of 100:70:0.3, stir at 40°C for 45 minutes until the system is uniform and transparent to obtain the epoxidized soybean oil matrix. Among them, the modified anhydride curing agent is composed of hexahydrophthalic anhydride and methyltetrahydrophthalic anhydride in a mass ratio of 4:1; S5. The dried second modified para-aramid fiber is introduced into the impregnation tank through the feeding frame. The temperature of the impregnation tank is controlled at 30℃, and the impregnation time is 15min, so that the dried second modified para-aramid fiber is fully impregnated in the epoxy soybean oil matrix, ensuring that the impregnation rate of para-aramid fiber is ≥95%. Then, it is put into the pultrusion die for molding. The temperature of the pultrusion die is controlled at 80~120℃ (the temperature of the pultrusion die is controlled in stages: 80~90℃ in the inlet section, 90~100℃ in the middle section, and 100~120℃ in the outlet section), and the traction speed is 0.5m / min. After continuous heat curing for 8min, it is cut to obtain the aramid fiber reinforced epoxy soybean oil composite tie rod; the volume ratio of the epoxy soybean oil matrix in the aramid fiber reinforced epoxy soybean oil composite tie rod is 30%.

[0058] In this comparative example, the volume ratio of para-aramid fiber, the second modified system, and the epoxidized soybean oil matrix is ​​68:2:30.

[0059] Comparative Example 3 (Process 3) The preparation method of aramid fiber reinforced epoxy soybean oil composite tie rod treated with the first modification system + the second modification system includes the following steps: S1. Place the para-aramid fiber in an acetone aqueous solution and ultrasonically clean it for 60 minutes at an ultrasonic cleaning power of 150W to remove surface oil and impurities. Then rinse it three times with anhydrous ethanol and dry it for 5 hours at a temperature of 80℃ to make the moisture content of the para-aramid fiber ≤0.5% and obtain clean para-aramid fiber. S2. Anhydrous aluminum trichloride, chloroacetyl chloride and dichloromethane are mixed in a mass ratio of 1.8:1:3 to obtain the first modification system for interfacial modification and reinforcement of para-aramid fibers. S3. Place the clean para-aramid fiber into the first modification system and magnetically stir it at 40°C for 6 hours while continuously purging with nitrogen for protection to perform the first modification process (Bock chemical modification) to obtain the first modified para-aramid fiber; take out the first modified para-aramid fiber and wash it repeatedly with deionized water, collect the water flowing down during the washing process (i.e., filtrate), and wash until the filtrate is neutral. The first modified para-aramid fiber after washing was dried at 80°C for 5 hours to obtain the dried first modified para-aramid fiber. S4. Dissolve 6.057 g of Tris base (tris(hydroxymethyl)aminomethane) in 800 mL of deionized water, and adjust the pH to 8.0 with 1 mol / L HCl solution at 25 °C to obtain a Tris-HCl buffer solution with a Tris base concentration of 0.05 mol / L and a pH of 8.0. Then heat the Tris-HCl buffer solution to 30 °C, add dopamine hydrochloride, and stir until completely dissolved to prepare a dopamine hydrochloride solution with a dopamine hydrochloride concentration of 2 g / L and a pH of 8.0. This is the second modification system for interfacial modification and reinforcement of para-aramid fibers. S5. The dried first modified para-aramid fiber is placed into the second modification system and stirred at 25°C for 8 hours to perform the second modification process (dopamine physical modification) to obtain the second modified para-aramid fiber. Take out the second modified para-aramid fiber and wash it repeatedly with deionized water. Collect the water (i.e., filtrate) that flows down during the washing process and wash until the filtrate is neutral. The washed second modified para-aramid fiber was dried at 80℃ for 5 hours to obtain the dried second modified para-aramid fiber. S6. Mix epoxidized soybean oil, modified acid anhydride curing agent, and accelerator (2-methylimidazole) in a mass ratio of 100:70:0.3, stir at 40°C for 45 minutes until the system is uniform and transparent to obtain the epoxidized soybean oil matrix. Among them, the modified anhydride curing agent is composed of hexahydrophthalic anhydride and methyltetrahydrophthalic anhydride in a mass ratio of 4:1; S7. The dried second modified para-aramid fiber is introduced into the impregnation tank through the wire feeding frame. The temperature of the impregnation tank is controlled at 30℃, and the impregnation time is 15min, so that the dried second modified para-aramid fiber is fully impregnated in the epoxy soybean oil matrix, ensuring that the impregnation rate of para-aramid fiber is ≥95%. Then, it is put into the pultrusion die for molding. The temperature of the pultrusion die is controlled at 80~120℃ (the temperature of the pultrusion die is controlled in stages: 80~90℃ in the inlet section, 90~100℃ in the middle section, and 100~120℃ in the outlet section), and the traction speed is 0.5m / min. After continuous heat curing for 8min, it is cut to obtain the aramid fiber reinforced epoxy soybean oil composite tie rod; the volume ratio of the epoxy soybean oil matrix in the aramid fiber reinforced epoxy soybean oil composite tie rod is 30%.

[0060] In this comparative example, the volume ratio of para-aramid fiber, the first modified system, the second modified system, and the epoxidized soybean oil matrix is ​​64:4:2:30.

[0061] Comparative Example 4 (Process 4) Preparation method of aramid fiber reinforced epoxy soybean oil composite tie rod treated with the first modification system + the third modification system: S1. Place the para-aramid fiber in an acetone aqueous solution and ultrasonically clean it for 60 minutes at an ultrasonic cleaning power of 150W to remove surface oil and impurities. Then rinse it three times with anhydrous ethanol and dry it for 5 hours at a temperature of 80℃ to make the moisture content of the para-aramid fiber ≤0.5% and obtain clean para-aramid fiber. S2. Anhydrous aluminum trichloride, chloroacetyl chloride and dichloromethane are mixed in a mass ratio of 1.8:1:3 to obtain the first modification system for interfacial modification and reinforcement of para-aramid fibers. S3. Place the clean para-aramid fiber into the first modification system and magnetically stir it at 40°C for 6 hours while continuously purging with nitrogen for protection to perform the first modification process (Bock chemical modification) to obtain the first modified para-aramid fiber; take out the first modified para-aramid fiber and wash it repeatedly with deionized water, collect the water flowing down during the washing process (i.e., filtrate), and wash until the filtrate is neutral. The first modified para-aramid fiber after washing was dried at 80°C for 5 hours to obtain the dried first modified para-aramid fiber. S4. Mix anhydrous ethanol and deionized water at a volume ratio of 1:1 to obtain a solvent, and then add the coupling agent γ-glycidyl etheroxypropyltrimethoxysilane (KH560) to obtain the third modification system for the interface modification and reinforcement of para-aramid fibers. In the third modified system, the mass fraction of the coupling agent is 2%, and the mass fraction of the solvent is 98%. S5. The dried para-aramid fiber after the first modification is placed into the third modification system and reacted in a water bath at 50°C for 5 hours to perform the third modification process (coupling agent interface modification) to obtain the para-aramid fiber after the third modification. The modified para-aramid fiber was dried at 80℃ for 5 hours to obtain the modified para-aramid fiber. S6. Mix epoxidized soybean oil, modified acid anhydride curing agent, and accelerator (2-methylimidazole) in a mass ratio of 100:70:0.3, stir at 40°C for 45 minutes until the system is uniform and transparent to obtain the epoxidized soybean oil matrix. Among them, the modified anhydride curing agent is composed of hexahydrophthalic anhydride and methyltetrahydrophthalic anhydride in a mass ratio of 4:1; S7. The modified para-aramid fiber is introduced into the impregnation tank through the wire feeding frame. The temperature of the impregnation tank is controlled at 30℃, and the impregnation time is 15min, so that the modified para-aramid fiber is fully impregnated in the epoxy soybean oil matrix, ensuring that the impregnation rate of para-aramid fiber is ≥95%. Then, it is put into the pultrusion die for molding. The temperature of the pultrusion die is controlled at 80~120℃ (the temperature of the pultrusion die is controlled in stages: 80~90℃ in the inlet section, 90~100℃ in the middle section, and 100~120℃ in the outlet section), and the traction speed is 0.5m / min. After continuous heat curing for 8min, it is cut to obtain the aramid fiber reinforced epoxy soybean oil composite tie rod; the volume ratio of the epoxy soybean oil matrix in the aramid fiber reinforced epoxy soybean oil composite tie rod is 30%.

[0062] In this comparative example, the volume ratio of para-aramid fiber, the first modified system, the third modified system, and the epoxidized soybean oil matrix is ​​64:4:2:30.

[0063] Detection and Analysis The specific steps for evaluating and screening the interface modification and preparation process of aramid fiber-reinforced epoxidized soybean oil composite tension bars are as follows: Five aramid fiber reinforced epoxy soybean oil composite tie rod samples were prepared using five different preparation methods (Example 1, Comparative Example 1, Comparative Example 2, Comparative Example 3, and Comparative Example 4), and named as follows: The aramid fiber reinforced epoxy soybean oil composite tie rod prepared in Comparative Example 1 is named Sample 1; the aramid fiber reinforced epoxy soybean oil composite tie rod prepared in Comparative Example 2 is named Sample 2; the aramid fiber reinforced epoxy soybean oil composite tie rod prepared in Comparative Example 3 is named Sample 3; the aramid fiber reinforced epoxy soybean oil composite tie rod prepared in Comparative Example 4 is named Sample 4; and the aramid fiber reinforced epoxy soybean oil composite tie rod prepared in Example 1 is named Sample 5. Samples 1, 2, 3, 4, and 5 are collectively referred to as Samples.

[0064] The above samples were subjected to tensile strength, flexural strength, fiber exposure ratio, interfacial adhesion coefficient, surface roughness, interfacial shear strength, partial discharge initiation voltage, and breakdown voltage tests. These multiple parameters were integrated into a comprehensive evaluation index C*. The overall performance of the aramid fiber-reinforced epoxidized soybean oil composite tie rod was judged by the C* value; a higher C* value indicates better overall performance. The specific steps are as follows: 1. Measurement of tensile strength: Apply a static tensile load uniformly along the axial direction of the specimen until the specimen breaks to obtain the maximum failure load. Then, combine the width and thickness of the specimen to calculate the tensile strength using formula (I).

[0065] The tensile strength was used to characterize the maximum normal stress that prevents the aramid fiber reinforced epoxy soybean oil composite tie rod from breaking under tensile load.

[0066] The formula for calculating tensile strength is shown in equation (I): (I); in formula (I), 1 represents tensile strength, with units of MPa; F m The maximum destructive load is represented in Newtons (N), m represents one of specimens 1 to 5, b represents the width of the specimen in mm, and d represents the thickness of the specimen in mm.

[0067] 2. Measurement of bending strength: The three-point bending compression method is used to apply a static bending load at a constant speed along the radial direction of the specimen until the specimen breaks to obtain the maximum failure load. The bending strength is then calculated by formula (II) in combination with the span, width and thickness of the specimen.

[0068] The bending strength is used to characterize the maximum normal stress that prevents the aramid fiber-reinforced epoxidized soybean oil composite tie rod from failing under bending load.

[0069] The formula for calculating bending strength is shown in equation (II): (II); In formula (II), 2 represents bending strength, with units of MPa; P m The maximum destructive load is represented by Newtons (N), m represents one of specimens 1 to 5, L represents the span in mm, b represents the width of the specimen in mm, and h represents the thickness of the specimen in mm.

[0070] 3. Measurement of interfacial shear strength: The interfacial shear strength between the modified aramid fiber and the epoxidized soybean oil matrix is ​​measured. This can be used to characterize the interfacial bonding force between the modified aramid fiber and the epoxidized soybean oil matrix, thereby indirectly evaluating the degree of aramid fiber modification in the aramid fiber reinforced epoxidized soybean oil composite tie rod. Interfacial shear strength measurement method: A small amount of epoxidized soybean oil matrix was prepared into epoxidized soybean oil droplets using a dropper. Modified aramid fibers were embedded in the epoxidized soybean oil droplets. After the matrix was completely cured, the epoxidized soybean oil droplets were fixed in place using a clamp (using two rigid carrier plates with holes, so that the cured epoxidized soybean oil droplets were completely clamped between the two carrier plates, allowing only the modified aramid fibers to protrude from the upper hole, ensuring that the epoxidized soybean oil droplets were completely free of displacement during the test). The modified aramid fibers were pulled upward at a constant rate until they were completely pulled out of the epoxidized soybean oil droplets. The maximum pull-out force during the pull-out process of the modified aramid fibers was recorded. The diameter of the modified aramid fibers was measured using a micrometer under an optical microscope. The length of the modified aramid fibers embedded in the epoxidized soybean oil droplets was obtained by measuring the vertical distance between the top and bottom of the fiber embedded using a vernier caliper. The interfacial shear strength was calculated using Equation (III) by combining the maximum pull-out force during the pull-out process of the modified aramid fiber, the diameter of the modified aramid fiber, and the length of the modified aramid fiber embedded in the epoxidized soybean oil droplet.

[0071] The formula for calculating the interfacial shear strength is shown in equation (III): (III), in equation (III), P represents the interfacial shear strength, F max The maximum pull-out force is represented by Newtons (N); d represents the diameter of the modified aramid fiber in mm; L represents the length of the modified aramid fiber embedded in the epoxidized soybean oil droplet in mm. 4. Measure the fiber exposure ratio: Acquire images of the sample surface, count the area of ​​the exposed modified aramid fibers and the total area of ​​the sample, and calculate the fiber exposure ratio using formula (IV). The fiber exposure ratio is the ratio of the area of ​​the exposed modified aramid fibers in the sample to the total area of ​​the sample.

[0072] The degree of epoxy soybean oil coating in aramid fiber reinforced epoxy soybean oil composite tie rods was determined by measuring the fiber exposure ratio, which can be used to characterize the epoxy soybean oil coating on the surface of the sample.

[0073] The formula for calculating the fiber exposure ratio is shown in equation (IV): (IV), in equation (IV), S e S represents the fiber exposure ratio, S represents the area of ​​the exposed modified aramid fiber, and S0 represents the total area of ​​the sample.

[0074] 5. Measurement of interfacial adhesion coefficient: The sample and the epoxidized soybean oil matrix material were subjected to DMA tests respectively, and the relative damping of the sample was obtained. Relative damping of epoxidized soybean oil materials Furthermore, considering the volume fraction V of modified aramid fiber in the aramid fiber-reinforced epoxidized soybean oil composite tie rod... f The interfacial adhesion coefficient is then obtained through the calculation formula shown in Equation (V), which characterizes the interfacial bonding strength between the modified aramid fiber and epoxidized soybean oil.

[0075] The formula for calculating the interfacial adhesion coefficient is shown in equation (V): In equation (V), A represents the interfacial adhesion coefficient, and V... f This represents the volume fraction of modified aramid fibers in the aramid fiber-reinforced epoxy soybean oil composite tie rod. Relative damping of the aramid fiber reinforced epoxy soybean oil composite tie rod. Represents the relative damping of the epoxidized soybean oil matrix material.

[0076] 6. Surface Roughness Measurement: W points are uniformly selected on the sample for SEM testing to obtain surface morphology images of each point. The roughness at each of the w points is calculated and the average value is taken. The surface morphology image is modeled in MATLAB. Two adjacent edges are selected at the edge of the surface morphology image as the X and Y axes, and a Z-axis is established in the direction perpendicular to this plane. The grayscale value of the pixels in the surface morphology image is used as the Z-axis value. Discrete points are sampled on the X and Y axes, with M and N points respectively. Let the average grayscale value of the absolute value of the offset be μ. The formula for calculating μ is shown in equation (VI): (VI); In equation (VI), μ represents the average gray value, i ranges from 1 to M, j ranges from 1 to N, M represents the number of discrete sampling points along the X-axis, and N represents the number of discrete sampling points along the Y-axis. It is a double summation symbol that iterates through all pixels in the image (from 1 to M in the X direction and from 1 to N in the Y direction). Representing coordinates The gray value corresponding to the pixel is the height of that pixel on the Z-axis.

[0077] The surface roughness of the sample is measured by the three-dimensional arithmetic mean deviation S. a This is represented as shown in equation (VII): (VII); In equation (VII), S a The value of i represents the surface roughness of the sample, and the value of j represents the value of 1 to M. M represents the number of discrete sampling points in the X-axis direction, and N represents the number of discrete sampling points in the Y-axis direction. It is a double summation symbol that iterates through all pixels in the image (from 1 to M in the X direction and from 1 to N in the Y direction). Representing coordinates The gray value corresponding to the pixel is the height of the pixel on the Z-axis; μ is the average gray value obtained by equation (VI); Coordinates are The absolute value of the difference between the gray value of a pixel and the average gray value.

[0078] The roughness at W points is S. a1 S a2 S a3 ,...S aw The average roughness is , The calculation formula is shown in equation (VIII): (VIII).

[0079] In equation (VIII), Represents the average roughness; i ranges from 1 to W; S a1 S a2 S a3 ,...S aw This represents the roughness at W points; It is a summation symbol, which means adding up the roughness values ​​of W points.

[0080] 7. Measurement of Partial Discharge Initiation Voltage: The partial discharge characteristics of the aramid fiber reinforced epoxidized soybean oil composite tie rod are characterized using the partial discharge initiation voltage. The voltage is increased using a step-up method while observing the partial discharge monitor. If a single discharge exceeds 10 pC and continues until the next voltage increase, the current voltage is defined as the partial discharge initiation voltage u1.

[0081] 8. Measurement of breakdown voltage: The breakdown characteristics of the aramid fiber reinforced epoxidized soybean oil composite tie rod were characterized using breakdown voltage. The voltage was increased systematically using the step-up method until the sample was observed to break down. The voltage at which the sample broke down was defined as the breakdown voltage u2.

[0082] Based on the aforementioned mechanical and electrical properties, these serve as criteria for judging the correlation between each parameter and the material's modification and reinforcement effect. This facilitates the subsequent weighting of each evaluation parameter to screen for the optimal preparation process. When establishing an evaluation model for interface modification and reinforcement and the optimal preparation process using the aforementioned macroscopic and microscopic parameters, tensile strength is used as the primary parameter. 1. Bending strength 2. Interfacial adhesion coefficient A, interfacial shear strength P, and average surface roughness Partial discharge initiation voltage u1 and breakdown voltage u2 are positive evaluation indicators, and fiber exposure ratio S e The negative evaluation index is used. There are m aramid fiber reinforced epoxidized soybean oil composite tension bar samples prepared by m different manufacturing methods. Each sample has eight evaluation indexes, and a judgment matrix is ​​constructed.

[0083] (IX) In Equation (IX), N represents the judgment matrix, with rows representing different samples and columns representing different evaluation indicators; m represents the number of samples, with a value of 1 to 5. This represents the tensile strength of sample 1. arrive And so on; Represents the bending strength of sample 1. arrive And so on; A1 represents the interfacial adhesion coefficient of sample 1, A2 to A... m And so on; P1 represents the interfacial shear strength of sample 1, P2 to P...m And so on; This represents the average surface roughness of sample 1. arrive And so on; u 11 The partial discharge initiation voltage, u, represents sample 1. 12 to u 1m And so on; u 21 u represents the breakdown voltage of sample 1. 22 to u 2m And so on; S e1 S represents the fiber exposure ratio of sample 1. e2 To S em And so on; To determine the element in the i-th row and j-th column of the matrix, we need to identify the measured value of the i-th sample on the j-th evaluation index.

[0084] By normalizing and aligning matrix N, the order of magnitude and dimensions of different indicators are eliminated, resulting in a normalized judgment matrix P.

[0085] Therefore, the weights of each indicator are calculated. .

[0086] (X) In equation (X), i takes values ​​from 1 to m, and j takes values ​​from 1 to 8. Information entropy representing each evaluation indicator. This represents each element in the normalized judgment matrix P. Represents the weight of each indicator. The coefficient representing the difference between each evaluation indicator. (Through...) The objective weight matrix Z is obtained.

[0087] (XI) In equation (XI), Z represents the objective weight matrix; ~ The weights of tensile strength, flexural strength, interfacial adhesion coefficient, interfacial shear strength, average surface roughness, partial discharge initiation voltage, breakdown voltage, and fiber bareness ratio are represented in that order; m represents the number of samples, with a value of 1 to 5. This represents the tensile strength of sample 1. arrive And so on; Represents the bending strength of sample 1. arrive And so on; A1 represents the interfacial adhesion coefficient of sample 1, A2 to A... m And so on; P1 represents the interfacial shear strength of sample 1, P2 to P... m And so on; This represents the average surface roughness of sample 1. arrive And so on; u 11 The partial discharge initiation voltage, u, represents sample 1. 12 to u 1m And so on; u 21 u represents the breakdown voltage of sample 1. 22 to u 2m And so on; S e1 S represents the fiber exposure ratio of sample 1. e2 To S em And so on; The element in the i-th row and j-th column of the objective weight matrix Z represents the weighted value of the j-th index of the i-th sample, where i ranges from 1 to m and j ranges from 1 to 8.

[0088] Formula (XI) selects the optimal elements in each column of Z, namely the maximum value of the positive evaluation index and the minimum value of the negative evaluation index, to form a positive ideal solution; and selects the worst values ​​in each column of Z, namely the minimum value of the positive evaluation index and the maximum value of the negative evaluation index, to form a negative ideal solution.

[0089] (XII) In formula (XII), Represents the ideal solution. Represents the negative ideal solution; Represents a set of positive evaluation indicators, This represents a set of negative evaluation indicators; The element in the i-th row and j-th column of the objective weight matrix Z represents the weighted value of the j-th index of the i-th sample; i ranges from 1 to m, and j ranges from 1 to 8. This means that for all samples, the maximum value of the j-th positive index is taken as the value of that index in the positive ideal solution; This means that for all samples, the minimum value of the j-th negative index is taken as the value of that index in the positive ideal solution; This means that for all samples, the minimum value of the j-th positive index is taken as the value of that index in the negative ideal solution; This means that for all samples, the maximum value of the j-th negative index is taken as the value of that index in the negative ideal solution.

[0090] The formula for calculating the distance of the comprehensive evaluation index is shown in equation (XIII): (XIII) In equation (XIII), the value of i is 1 to m, and the value of j is 1 to 8; This represents the distance from sample i to the positive ideal solution. This represents the distance from sample i to the negative ideal solution; The element in the i-th row and j-th column of the objective weight matrix Z represents the weighted value of the j-th index of the i-th sample. This represents the optimal value of the j-th index in the positive ideal solution (positive indices take the maximum value, and negative indices take the minimum value). This represents the worst value of the j-th index in the negative ideal solution (the positive index takes the minimum value, and the negative index takes the maximum value).

[0091] The aramid fiber reinforced epoxidized soybean oil composite tie rod samples prepared under different manufacturing methods were evaluated by measuring the distances between each sample and the positive ideal solution and the negative ideal solution. The smaller the positive ideal solution distance and the larger the negative ideal solution distance of the sample, the higher the quality of the aramid fiber reinforced epoxidized soybean oil composite tie rod sample and the better the corresponding sample preparation process.

[0092] With a dimensionless quantity (Comprehensive evaluation indicators) The advantages and disadvantages of the interfacial modification and reinforcement preparation process of aramid fiber reinforced epoxidized soybean oil composite tension rods are characterized as shown in formula (XIV): (XIV) In formula (XIV), Represents comprehensive evaluation indicators, This represents the distance from sample i to the negative ideal solution. This represents the distance from sample i to the positive ideal solution.

[0093] Results and Analysis: The manufacturing method of the unmodified composite tie rod is designated as process 1; the manufacturing method treated only by the second modification system (dopamine system) is designated as process 2; the manufacturing method treated by the first modification system + the second modification system is designated as process 3; the manufacturing method treated by the first modification system + the third modification system is designated as process 4; and the manufacturing method treated by the first modification system + the second modification system + the third modification system is designated as process 5.

[0094] The original experimental data are shown in Table 1: Table 1. Experimental raw data on the performance of aramid fiber reinforced epoxidized soybean oil composite tie rods prepared by different processes. The weights calculated using formula (X) are ω1=0.1166, ω2=0.1206, ω3=0.1180, ω4=0.1152, ω5=0.1168, ω6=0.1173, ω7=0.1191, and ω8=0.1162, where ω1 represents... The weight of 1, ω2 represents 2 represents the weight, ω3 represents the weight of A, ω4 represents the weight of P, and ω5 represents... The weights are ω6, ω7, and ω8 respectively. e The weight.

[0095] The objective weight matrix Z is obtained by formula (XI): Further calculations using formulas (XII) and (XIII) yielded distances S1 and S2 respectively for the positive ideal solution. + =21.1724, S2 + =15.5796, S3 + =10.9133, S4 + =13.2601, S5 + =0.0000; the distances to the negative ideal solutions are S1 - =0.0000, S2 - =5.6131, S3 - =10.2964, S4 - =7.9493, S5 - =21.1724.

[0096] Finally, the comprehensive evaluation index was calculated using formula (XIV), as shown in Table 2: Table 2 Comprehensive evaluation indicators for different processes From Table 2, the comprehensive evaluation index C * It can be seen that the aramid fiber reinforced epoxy soybean oil composite tie rod produced by three modifications in this invention corresponds to process 5, C. * Reaching a maximum value of 1.0000, C in process 1 * The minimum value is 0.0000, and the C values ​​for the remaining processes are... * All values ​​are between 0 and 1, and all are less than 0.5, indicating that the performance does not meet the good standard.

[0097] This result shows that the three-stage modification process in Example 1 can effectively synergistically improve the various properties of the aramid fiber reinforced epoxidized soybean oil composite tie rod, enabling the product to achieve optimal balance in multiple dimensions. Its comprehensive performance is significantly better than the other four processes, such as unmodified and single-stage modification, thus verifying the superiority of the three-stage modification process proposed in this invention.

[0098] The principles and implementation methods of the present invention are described with reference to specific embodiments only. The description of the embodiments above is only for the purpose of helping to understand the method and its core principles. For those skilled in the art, based on the technical concept of the present invention, corresponding modifications and adjustments can be made to the specific implementation methods and application scope.

Claims

1. An aramid fiber reinforced epoxy soybean oil composite pull rod, characterized in that, Including the following raw materials: Aramid fibers, a first modification system, a second modification system, a third modification system, and an epoxidized soybean oil matrix; The raw materials for the first modified system include: metal chlorides, acyl chlorides, and haloalkanes; The raw materials for the second modified system include: dopamine salt solution; The raw materials for the third modified system include: solvent and coupling agent; The raw materials for the epoxidized soybean oil matrix include: epoxidized soybean oil, curing agent, and accelerator.

2. The aramid fiber reinforced epoxy soybean oil composite pull rod of claim 1, wherein, The volume ratio of the aramid fiber, the first modified system, the second modified system, the third modified system, and the epoxidized soybean oil matrix is ​​50~65:3~5:1.5~2.5:1.5~2.5:30~40; And / or, the mass ratio of the metal chloride, acyl chloride and haloalkane is 1.7~1.8:1:2.5~3.5; And / or, the concentration of dopamine salt in the dopamine salt solution is 2~3 g / L, and the pH value of the dopamine salt solution is 8.0~8.5; And / or, in the third modified system, the mass fraction of the coupling agent is 1-2%, and the mass fraction of the solvent is 98-99%; And / or, the mass ratio of the epoxidized soybean oil, curing agent and accelerator is 100:70~84:0.3~0.

8.

3. The aramid fiber reinforced epoxy soybean oil composite pull rod of claim 1, wherein, The aramid fiber is selected from one or two of para-aramid fiber and meta-aramid fiber; And / or, the metal chloride is selected from anhydrous aluminum trichloride, the acyl chloride is selected from chloroacetyl chloride, and the haloalkane is selected from dichloromethane; And / or, the dopamine salt solution is selected from dopamine hydrochloride solution; And / or, the solvent is selected from anhydrous ethanol and deionized water, wherein the volume ratio of anhydrous ethanol to deionized water is 1:1; the coupling agent is selected from γ-glycidoxypropyltrimethoxysilane. And / or, the curing agent is selected from modified acid anhydride curing agents, and the accelerator is selected from 2-methylimidazole; The modified anhydride curing agent is selected from at least one of hexahydrophthalic anhydride and methyltetrahydrophthalic anhydride; The mass ratio of hexahydrophthalic anhydride to methyltetrahydrophthalic anhydride is 0~4:0~1.

4. The preparation method of the aramid fiber reinforced epoxy soybean oil composite tie rod according to any one of claims 1 to 3, characterized in that, The process includes the following steps: sequentially placing the aramid fiber into a first modification system, a second modification system, and a third modification system to obtain the modified aramid fiber; The epoxidized soybean oil matrix and the modified aramid fiber are mixed, pultruded, and cut to obtain an aramid fiber reinforced epoxidized soybean oil composite tie rod.

5. The preparation method according to claim 4, characterized in that, The preparation method specifically includes the following steps: The aramid fibers are washed and dried to obtain clean aramid fibers; The metal chloride, acyl chloride, and haloalkane are mixed to obtain the first modified system; A dopamine salt solution was prepared to obtain the second modified system; The solvent and coupling agent are mixed to obtain a third modified system; The epoxidized soybean oil, curing agent and accelerator are mixed and stirred for the first time to obtain the epoxidized soybean oil matrix; The clean aramid fiber is placed in the first modification system and subjected to the first modification treatment to obtain the first modified aramid fiber. The first modified aramid fiber is washed and dried, and then placed into the second modification system for a second modification treatment to obtain the second modified aramid fiber. The second modified aramid fiber is washed and dried, and then placed into the third modification system for third modification treatment to obtain the third modified aramid fiber. The modified aramid fiber is dried to obtain the modified aramid fiber. The epoxidized soybean oil matrix and the modified aramid fiber are mixed, pultruded, and cut to obtain an aramid fiber reinforced epoxidized soybean oil composite tie rod.

6. The preparation method according to claim 5, characterized in that, The cleaning and drying process specifically includes: placing the aramid fiber in an acetone solution, ultrasonically cleaning for 30-60 minutes, rinsing with anhydrous ethanol 3-5 times, and then drying at a temperature of 80-90℃ for 3-5 hours to obtain clean aramid fiber; the ultrasonic cleaning power is 150-200W. And / or, the moisture content of the clean aramid fiber is ≤0.5%; And / or, the first stirring time is 30~45 min, and the temperature is 40~50℃; And / or, the temperature of the first modification treatment is 40~60℃ and the time is 4~6h; And / or, the temperature of the second modification treatment is 25~30℃, and the time is 6~8h; And / or, the third modification treatment is performed at a temperature of 50~60℃ for 3~5 hours; And / or, the drying temperature is 80~100℃, and the time is 3~5h; And / or, mixing the epoxidized soybean oil matrix and the modified aramid fiber, comprising: impregnating the modified aramid fiber with the epoxidized soybean oil matrix at a temperature of 30-40°C for 10-15 minutes; wherein the impregnation rate of the modified aramid fiber is ≥95%; And / or, the pultrusion temperature is 80~120℃, and the traction speed is 0.5~2m / min; And / or, the preparation of the dopamine salt solution includes the following steps: heating the Tris-HCl buffer to 30°C, adding dopamine salt, and stirring until completely dissolved to obtain the dopamine salt solution.

7. The preparation method according to claim 5, characterized in that, The preparation method further includes: The tensile strength, flexural strength, fiber exposure ratio, interfacial adhesion coefficient, surface roughness, partial discharge initiation voltage, and breakdown voltage of the aramid fiber reinforced epoxy soybean oil composite tie rod were determined. The interfacial shear strength between the modified aramid fiber and the epoxidized soybean oil matrix was measured. Based on the tensile strength, flexural strength, fiber exposure ratio, interfacial shear strength, interfacial adhesion coefficient, surface roughness, partial discharge initiation voltage, and breakdown voltage, a judgment matrix is ​​constructed, standardized, and a comprehensive evaluation index is calculated. The optimal process is obtained through the comprehensive evaluation indicators.

8. The preparation method according to claim 7, characterized in that, The grading criteria for the comprehensive evaluation indicators are as follows: 0.75 Overall evaluation index 1 is excellent; 0.5 Comprehensive evaluation index At 0.75, the result is good; 0.25 Comprehensive evaluation index 0.5, generally; 0 Comprehensive evaluation indicators At 0.25, the difference is...

9. The preparation method according to claim 4, characterized in that, The aramid fiber reinforced epoxy soybean oil composite tie rod has a diameter of 10~50mm, a length of 500~3000mm, a tensile strength ≥350MPa, a bending strength ≥280MPa, a breakdown voltage ≥50kV / mm, and an interfacial shear strength ≥25MPa.

10. The application of the aramid fiber reinforced epoxy soybean oil composite tie rod according to any one of claims 1 to 3 or the aramid fiber reinforced epoxy soybean oil composite tie rod prepared by the preparation method according to any one of claims 4 to 9 in high-voltage power transmission and / or high-speed train traction systems.

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