Carbon fiber reinforced polyether ether ketone composite, method for producing the same, and elevator hub

Abstract

The application relates to the technical field of high polymer composite materials, and discloses a carbon fiber reinforced polyether ether ketone composite material, a preparation method thereof and an elevator hub, wherein the composite material is mainly made of polyether ether ketone, polyether imide, diphenyl sulfone and pre-coated carbon fiber. The pre-coated carbon fiber is attached with a B-stage solid-state boron-modified thermoplastic phenolic resin on the surface, and when the pre-coated carbon fiber is heated during extrusion, the resin is converted into a C-stage network, topological-level physical entanglement occurs between the resin and the macromolecular chain segments of the matrix, and a semi-interpenetrating polymer network structure is formed in situ at the interface. When the composite material is prepared, the flash phase change of the diphenyl sulfone under specific temperature and pressure generates micro-bubbles, and the micro-bubbles carry water molecules released by interface polycondensation and discharge the high-viscosity melt. The application improves the interface bonding state between the carbon fiber and the matrix, reduces the micro-porosity of the composite material, improves the mechanical strength and the fatigue resistance of the material, and can be used for injection molding of structural parts such as large-load elevator hubs.

Description

Technical Field

[0001] This invention relates to the field of polymer composite materials technology, specifically to carbon fiber reinforced polyetheretherketone composite materials, their preparation methods, and elevator wheel hubs. Background Technology

[0002] Polyetheretherketone (PEEK), a specialty engineering plastic, is often combined with carbon fiber to manufacture load-bearing structural components. Due to the strong chemical inertness of the PEEK molecular chain, it is difficult to form a good interfacial bond with the carbon fiber surface. To improve interfacial compatibility, surface pretreatment such as coating or sizing of the carbon fiber is usually required. However, in actual processing, the extrusion molding temperature of PEEK is typically above 380℃. Conventional epoxy resins or polyurethane interfacial treatment agents are prone to thermal degradation at this processing temperature, not only losing their interfacial bonding effect but also potentially damaging the overall performance of the composite material.

[0003] If a high-temperature resistant condensation-type thermosetting resin is used as the interfacial transition layer, the cross-linking and curing reaction of the resin during the extrusion process with polyetheretherketone (PEEK) will release small molecule byproducts such as water. Because the PEEK melt exhibits high viscosity in the processing state, these small molecules generated at the micro-interface face significant rheological resistance and are difficult to penetrate the polymer melt and exit the system. This trapping phenomenon easily leads to micropores at the fiber-matrix interface after the composite material is molded. The combination of these internal pores and weak interfaces easily becomes a stress concentration source and induces cracks under alternating loads. This reduces the material's mechanical strength and fatigue life to some extent, limiting its application in structural components with high operational stability requirements, such as high-load elevator hubs. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides carbon fiber reinforced polyetheretherketone composite materials, their preparation methods, and elevator hubs. It solves the problem that conventional carbon fibers have relatively weak bonding strength with the polyetheretherketone matrix at high temperatures, and that ordinary surface modification treatments often cannot withstand the high processing temperatures of polyetheretherketone.

[0005] To address the above problems, the present invention provides the following technical solution: In a first aspect, the present invention provides a carbon fiber reinforced polyetheretherketone composite material, which adopts the following technical solution: A carbon fiber reinforced polyetheretherketone composite material, comprising the following components in parts by weight: 56.0–65.0 parts of polyetheretherketone; 3.0–5.0 parts of polyetherimide; 0.1 to 1.0 parts of diphenyl sulfone; 30.0–38.0 parts of pre-coated carbon fiber; The pre-coated carbon fiber includes slurry-free surface-oxidized short-cut carbon fiber and boron-modified thermoplastic phenolic resin in a B-order solid state coated on the surface of the slurry-free surface-oxidized short-cut carbon fiber. The boron-modified thermoplastic phenolic resin in the B-order solid state is heated and transformed into a C-order three-dimensional network during processing and molding. The C-order three-dimensional network undergoes topological physical entanglement with the linear macromolecular segments of polyether ether ketone and polyether imide, forming a semi-interpenetrating polymer network structure in situ at the interface between carbon fiber and polymer matrix.

[0006] By employing the above technical solution, pre-coating the surface of boron-modified thermoplastic phenolic resin in a B-order solid state onto the surface of oxidized short-cut carbon fibers without slurry helps to improve the interfacial bonding strength of the composite material and alleviate porosity defects. The underlying mechanism is mainly reflected in: Firstly, boric acid reacts with phenol and formaldehyde to produce boron-modified thermoplastic phenolic resin. Boron atoms are linked to the molecular backbone of the phenolic resin through BOC chemical bonds. The high bond energy of the BO bonds improves the thermal stability of the resin to a certain extent, enabling it to maintain structural stability in processing environments above 380°C for polyetheretherketone (PEEK).

[0007] Secondly, boron-modified thermoplastic phenolic resin forms a B-stage solid state after initial heat treatment. At this stage, the resin molecules exhibit a large linear or partially branched structure and have not yet formed a fully cross-linked network. It maintains a solid state at room temperature, which is beneficial for maintaining its state during powder mixing and material transportation.

[0008] After entering the extrusion processing stage, the B-order resin coating the carbon fiber surface continues to undergo condensation and crosslinking reactions upon heating, gradually transforming into a C-order three-dimensional network. During this period, the outer polyetheretherketone and polyetherimide are in a molten flow state, and their linear macromolecular segments penetrate into the interior of the crosslinking phenolic resin network. After the C-order network solidifies, the crosslinking nodes physically lock the polymer segments of the matrix in space, forming topological physical entanglements.

[0009] Ultimately, the polar functional groups in the resin form chemical bonds with the oxygen-containing functional groups on the carbon fiber surface. The carbon fiber and polymer matrix, relying on the semi-interpenetrating polymer network structure formed above, can effectively transfer stress, reducing the risk of material fracture or delamination under stress.

[0010] Preferably, it is made from the following components in parts by weight: 62.0 to 64.5 parts of polyetheretherketone; 3.5 to 4.5 parts of polyetherimide; 0.3 to 0.7 parts of diphenyl sulfone; and 31.0 to 32.0 parts of pre-coated carbon fiber; wherein the pre-coated carbon fiber comprises 25.0 to 26.0 parts of slurry-free surface-oxidized short-cut carbon fiber and 6.0 to 7.0 parts of boron-modified thermoplastic phenolic resin.

[0011] By adopting the above technical solution, limiting the specific ratio is beneficial to obtaining a better wetting and dispersion state between the matrix resin and carbon fiber, so that an appropriate amount of phenolic resin participates in the formation of a semi-interpenetrating network at the interface, thereby playing a positive role in improving the interlaminar shear strength of the material.

[0012] Preferably, the boron-modified thermoplastic phenolic resin is a product obtained by polycondensation and dehydration etherification of phenol, formaldehyde aqueous solution and boric acid powder under the action of an acidic catalyst, and its softening point is 90℃~110℃.

[0013] By adopting the above technical solution, the modified resin with a softening point in the range of 90℃ to 110℃ has a better matching melt rheological properties in the early stage of extrusion processing, which is convenient for adhering to the carbon fiber surface to form a film and completing the final network crosslinking in the subsequent high-temperature processing zone.

[0014] Preferably, the surface of the sizing-free surface-oxidized short-cut carbon fibers has been free of commercial sizing agent residues and has oxygen-containing functional groups introduced by the anodizing treatment.

[0015] By adopting the above technical solution, conventional epoxy or polyurethane sizing agents with poor compatibility with polyether ether ketone are removed, and the introduced oxygen-containing polar functional groups are used to promote the chemical bonding of boron-modified thermoplastic phenolic resin on the carbon fiber surface.

[0016] Secondly, the present invention provides a method for preparing carbon fiber reinforced polyetheretherketone composite material, which adopts the following technical solution: A method for preparing a carbon fiber reinforced polyetheretherketone composite material includes the following steps: (1) Pre-sizing treatment of carbon fiber: Boron-modified thermoplastic phenolic resin is dissolved in a solvent to prepare a homogeneous solution. The sizing-free surface-oxidized short carbon fiber is immersed in the homogeneous solution for dip coating treatment. Then, solvent evaporation and initial thermal crosslinking treatment are performed in sequence. After cooling, the pre-coated carbon fiber is obtained. (2) Matrix premixing: Polyether ether ketone, polyether imide and diphenyl sulfone are cold-mixed evenly to obtain a matrix dry mix; (3) Extrusion and gradient devolatilization: The matrix dry mix is ​​added from the main feed port of the twin-screw extruder to shear and melt it, and the pre-coated carbon fiber is fed into the melt through the side feeder in the middle section of the twin-screw extruder for homogeneous dispersion; the material then enters the reaction zone, and the barrel temperature is increased to activate the resin to transform into the C-order network in situ; the material then enters the exhaust zone for multi-stage pressure drop devolatilization treatment, and after extrusion, cooling and curing, pelletizing and drying, carbon fiber reinforced polyether ether ketone composite material is obtained.

[0017] By adopting the above technical solutions, the mid-section side-feeding method helps reduce excessive shearing of carbon fibers in the longer screw section, thus reducing fiber length loss. Heating in the reaction zone facilitates the completion of C-order conversion and interfacial physical entanglement processes. Multi-stage pressure drop devolatilization effectively separates water molecules released from the interfacial crosslinking reaction, thereby reducing the porosity defect rate within the matrix.

[0018] Preferably, in step (1), the mass concentration of the homogeneous solution is 8% to 12%, and the solvent is anhydrous ethanol; the temperature of the volatile solvent is 80°C to 90°C, and the time is 20 to 30 minutes; the temperature of the initial thermal crosslinking treatment is 160°C to 180°C, and the time is 30 to 45 minutes, so as to control the boron-modified thermoplastic phenolic resin to remain in the B-stage state where crosslinking is not complete.

[0019] By adopting the above technical solution, controlling the specific thermo-induced crosslinking temperature and time, the resin undergoes moderate polycondensation, generating a B-stage semi-cured layer that can still soften to a certain extent and continue to crosslink when heated, thus ensuring the relative stability of the processing properties of intermediate materials.

[0020] Preferably, in step (3), the barrel temperature of the twin-screw extruder in the section from the main feed port to the side feeder is set to 345°C; the barrel temperature in the reaction zone rises sharply to 385°C to 395°C, triggering the cross-linking of the solidified network and locking the polymer melt chain segments.

[0021] By adopting the above technical solution, the basic processing temperature of 345℃ allows polyetheretherketone and polyetherimide to be blended and melted, while avoiding premature deep cross-linking of the B-stage resin. After the carbon fibers are mixed into the melt, the temperature rises sharply to 385℃~395℃ to initiate the C-stage network curing reaction, which effectively balances the timing of fiber dispersion and resin cross-linking in engineering.

[0022] Preferably, in step (3), the multi-stage pressure drop devolatilization treatment specifically includes: The micro-negative pressure exhaust treatment is carried out at the first exhaust port of the twin-screw extruder, with the absolute pressure controlled at 0.05MPa to 0.08MPa to smoothly release melt pressure fluctuations; The high-vacuum phase transformation nucleation-assisted devolatilization process is carried out at the second exhaust port of the twin-screw extruder, with the absolute pressure controlled at 0.001 MPa to 0.01 MPa. Microbubbles are generated by the flash phase transformation from liquid to gas phase under this pressure and temperature node of diphenyl sulfone, which forcibly entrains water molecules generated by condensation at the interface and expels them from the melt.

[0023] By adopting the above technical solution, the degassing effect at the micro-interface of composite materials can be improved. The relevant mechanism is as follows: Within the reaction zone, the hydroxyl groups of the boron-modified thermoplastic phenolic resin undergo deep polycondensation and lose water molecules. Considering the high viscosity of polyetheretherketone melt, the water molecules generated at the micro-interface are subject to significant rheological resistance and are unlikely to migrate to the melt surface on their own.

[0024] Based on this, diphenyl sulfone, whose boiling point is close to the processing temperature of polyether ether ketone, is introduced. Under the conditions of a high vacuum of 0.001 MPa to 0.01 MPa and a melt temperature of 385°C to 395°C provided by the second exhaust port, the diphenyl sulfone dissolved in the polymer melt crosses the phase boundary and undergoes a flash phase transition from the liquid phase to the gas phase.

[0025] The microbubbles generated by the flash evaporation of diphenyl sulfone nucleate in large numbers and expand rapidly inside the polymer melt. The expanded bubble volume provides a gas phase carrier, capturing and entraining water molecules trapped at the surrounding interface. These diphenyl sulfone bubbles carrying water molecules work together to overcome the viscous resistance of the melt, migrate to the melt surface, and break up. This phase transformation nucleation-assisted devolatilization can effectively reduce microscopic porosity defects inside the material.

[0026] Preferably, before step (1), the slurry-free surface-oxidized short-cut carbon fibers and boron-modified thermoplastic phenolic resin are pre-treated as follows: Short-cut carbon fiber precursors are heat-treated at 400℃~420℃ in a nitrogen atmosphere for 60~90 minutes to remove sizing. Then, they are used as anodes in an ammonium bicarbonate aqueous solution with a mass concentration of 5%~10% and subjected to electrolytic anodizing treatment at a current density of 0.01A / cm2~0.02A / cm2 for 10~20 minutes. After washing and drying, the sizing-free surface-oxidized short-cut carbon fibers are obtained. Furthermore, phenol and a 37.0% (w / w) formaldehyde aqueous solution are reacted under oxalic acid catalysis at a constant temperature of 85℃~95℃ for 90~120 minutes to form a linear prepolymer; then the temperature is lowered to 60℃~70℃ and boric acid powder is added; the system is then heated to 120℃~140℃ and kept at that temperature for 120~180 minutes for dehydration reaction, and after cooling, curing, and pulverization, the boron-modified thermoplastic phenolic resin is obtained.

[0027] By adopting the above technical solutions, the heat treatment combined with the weak alkaline electrolyte anodizing process helps to remove organic residues from the surface of carbon fibers and reduces the risk of fiber structure damage caused by the use of strong acids; the segmented temperature-controlled polymerization method promotes a more complete reaction between the boric acid and phenolic system molecular chains, providing a relatively stable basic raw material for subsequent preparation processes.

[0028] Thirdly, the present invention provides an elevator hub, which adopts the following technical solution: An elevator hub, wherein the elevator hub is injection molded from the carbon fiber reinforced polyetheretherketone composite material described in any of the first aspects above.

[0029] This invention provides a carbon fiber reinforced polyetheretherketone composite material, its preparation method, and an elevator hub. It has the following beneficial effects: 1. This invention involves pre-coating the surface of short-cut carbon fibers in a boron-modified thermoplastic phenolic resin (in its B-order state) with a paste-free surface oxidative coating. During the heated process of co-extrusion with polyetheretherketone (PEEK) and polyetherimide, the B-order resin transforms into a C-order three-dimensional network. In this cross-linking and curing stage, the resin network undergoes topological entanglement with the linear macromolecular chains of the molten matrix, constructing a semi-interpenetrating polymer network structure in situ at the micro-interface. This structure improves the interfacial bonding between the carbon fibers and the PEEK matrix, allowing for smoother stress transfer between the two phases under load, thereby enhancing the overall mechanical strength of the composite material.

[0030] 2. This invention utilizes a multi-stage pressure drop devolatilization process combined with the diphenyl sulfone component in the system to alleviate the technical bottleneck of difficult removal of polycondensation byproducts in high-viscosity polymer melts. In the high-vacuum exhaust zone of the extruder, the dissolved diphenyl sulfone undergoes a flash phase transition from liquid to gas at set temperature and pressure points, generating a large number of microbubbles inside the melt. The expanding bubbles act as physical carriers, entraining water molecules generated by interfacial polycondensation, jointly overcoming the viscous resistance of the melt and migrating and breaking down towards the surface. This phase transition nucleation mechanism reduces the internal porosity of the composite material after molding, which has a positive effect on improving the fatigue life of products such as elevator hubs.

[0031] 3. This invention employs boric acid to crosslink and modify thermoplastic phenolic resin, and performs weakly alkaline anodic oxidation on carbon fibers to introduce oxygen-containing functional groups. The introduction of boron enhances the thermal stability of the phenolic resin skeleton, meeting the heat resistance requirements of polyetheretherketone (PEEK) at processing temperatures above 380°C, and preventing thermal degradation of the coating layer. Combined with the chemical bonding between the polar groups on the carbon fiber surface and the resin, this ensures the structural stability of the interface layer under high-temperature shear conditions, providing the necessary conditions for the stable formation of a continuous phase interface in subsequent composite material processing. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the DSC exothermic behavior of the physical mixture of Comparative Example 3 and the B-order coated carbon fiber obtained in Example 1. Detailed Implementation

[0033] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0034] The main raw materials and reagents used in the following examples and comparative examples have the following sources and specifications. Reagents not specifically mentioned are all commercially available analytical grade or higher grade products.

[0035] Polyetheretherketone (PEEK) is a commercially available industrial-grade powdered resin with CAS number 29658-26-2. The molecular formula of this polymer is (C...). 19 H 12 O3)n, its macromolecular backbone structure consists of benzene rings linked by alternating ether bonds and carbonyl groups, and the chemical name of the repeating unit is poly(oxy-1,4-phenylene-oxy-1,4-phenylene-carbonyl-1,4-phenylene). The selected polyether ether ketone has a crystallinity range of 30% to 35%, a weight-average molecular weight (Mw) of 90,000 g / mol to 110,000 g / mol, a polydispersity index (PDI) of 2.0 to 2.5, and a density of 1.30 g / cm³. 3 The glass transition temperature Tg is 143℃, the melting point Tm is 343℃, and the melt index under 380℃ and 5kg load conditions is 10g / 10min~20g / 10min.

[0036] Polyetherimide is a commercially available amorphous polymer powder, CAS number 61128-46-9. The polymer's main molecular chain structure contains aromatic imide rings and ether bonds, with its repeating units formed by the condensation reaction of 2,2-bis[4-(3,4-dicarboxyphenoxy)phenyl]propane dianhydride with m-phenylenediamine. The selected polyetherimide has a weight-average molecular weight (Mw) of 30,000 g / mol to 45,000 g / mol and a density of 1.27 g / cm³. 3 The glass transition temperature (Tg) is 215℃, and the melt flow index under conditions of 337℃ and 6.6kg load is 9g / 10min~12g / 10min.

[0037] The chopped carbon fiber precursor is commercially available polyacrylonitrile-based carbon fiber, CAS number 7440-44-0. The carbon fiber surface is coated with a commercially available polyurethane sizing agent. The carbon fiber monofilament diameter is 6μm–8μm, the cut length is between 3.0mm and 6.0mm, and the density is 1.76g / cm³. 3 ~1.78g / cm 3 The monofilament tensile strength is >4900MPa, the tensile modulus of elasticity is >230GPa, and the carbon content is >95%.

[0038] Diphenyl sulfone is a commercially available industrial-grade solid powder with CAS number 127-63-9. The molecular formula of this compound is C2. 12 H 10 O2S, chemically known as 1,1'-sulfonyl diphenyl, is a white to slightly yellow crystalline powder at room temperature with a purity ≥99.0%, a melting point of 127℃~129℃, and a boiling point of 379℃ at normal pressure.

[0039] The conventional chemical raw materials used in the preparation examples of this invention, including phenol (CAS No. 108-95-2), formaldehyde aqueous solution (mass concentration 37.0%, CAS No. 50-00-0), oxalic acid (CAS No. 144-62-7), boric acid (CAS No. 10043-35-3), anhydrous ethanol (CAS No. 64-17-5), and ammonium bicarbonate (CAS No. 1066-33-7), are all commercially available analytical grade conventional reagents.

[0040] Preparation Example 1: Preparation of Slurry-Free Surface-Oxidized Short-Cut Carbon Fibers This preparation example provides a method for preparing slurry-free surface-oxidized short-cut carbon fibers, which includes the following steps: (1) Desizing treatment: Take short-cut carbon fiber filaments and place them in a tube muffle furnace at a temperature of 400℃. Heat treat them for 60 minutes under a nitrogen atmosphere to remove the commercial sizing agent on the surface by thermal decomposition. (2) Anodizing treatment: The desized carbon fiber is used as the anode and the graphite plate is used as the cathode. The mixture is placed in an electrolytic cell with a mass concentration of 5% ammonium bicarbonate (NH4HCO3) aqueous solution and the current density is 0.01A / cm. 2 Under these conditions, electrolytic anodizing treatment was performed for 10 minutes; (3) Cleaning and drying: Take out the oxidized carbon fiber, wash it with deionized water until the pH value of the washing solution is 6.5, and then place it in a vacuum drying oven at 110℃ for 4 hours to obtain slurry-free surface oxidized short carbon fiber for later use.

[0041] Preparation Example 2: This preparation example provides a method for preparing slurry-free surface-oxidized short-cut carbon fibers, which includes the following steps: (1) Desizing treatment: Take short-cut carbon fiber filaments and place them in a tube muffle furnace at a temperature of 410℃. Heat treat them for 75 minutes under a nitrogen atmosphere to remove the commercial sizing agent on the surface by thermal decomposition. (2) Anodizing treatment: The desized carbon fiber is used as the anode and the graphite plate is used as the cathode. The mixture is placed in an electrolytic cell with an 8% ammonium bicarbonate (NH4HCO3) aqueous solution and the current density is 0.015 A / cm. 2 Under these conditions, electrolytic anodizing treatment was performed for 15 minutes; (3) Cleaning and drying: Take out the oxidized carbon fiber, wash it with deionized water until the pH value of the washing solution is 7.0, and then place it in a vacuum drying oven at 115℃ for 5 hours to obtain slurry-free surface oxidized short carbon fiber for later use.

[0042] Preparation Example 3: This preparation example provides a method for preparing slurry-free surface-oxidized short-cut carbon fibers, which includes the following steps: (1) Desizing treatment: Take short-cut carbon fiber filaments and place them in a tube muffle furnace at a temperature of 420℃. Heat treat them for 90 minutes under a nitrogen atmosphere to remove the commercial sizing agent on the surface by thermal decomposition. (2) Anodizing treatment: The desized carbon fiber is used as the anode and the graphite plate is used as the cathode. The mixture is placed in an electrolytic cell with a mass concentration of 10% ammonium bicarbonate (NH4HCO3) aqueous solution and the current density is 0.02A / cm. 2 Under these conditions, electrolytic anodizing treatment was performed for 20 minutes; (3) Cleaning and drying: Take out the oxidized carbon fiber, wash it with deionized water until the pH value of the washing solution is 7.5, and then place it in a vacuum drying oven at 120℃ for 6 hours to obtain slurry-free surface oxidized short carbon fiber for later use.

[0043] Preparation Example 4: This preparation example provides a method for preparing boron-modified thermoplastic phenolic resin, which includes the following steps: (1) Feeding of reaction materials: In a reactor equipped with a reflux condenser, thermometer and mechanical stirrer, add 100 parts by mass of phenol and 60 parts by mass of formaldehyde aqueous solution (mass concentration 37.0%), then add 1.0 parts by mass of oxalic acid as an acidic catalyst and adjust the pH of the system to 2.0; (2) Primary polycondensation: Turn on the stirrer, heat the reaction system to 85°C, and reflux at a constant temperature for 90 minutes to form a linear thermoplastic phenolic resin prepolymer; (3) Boration modification: Reduce the system temperature to 60°C and slowly add 15 parts by mass of boric acid powder; (4) High-temperature dehydration and etherification: Remove the reflux condenser and replace it with a distillation condenser. Proceed to 120°C and maintain the temperature for 120 minutes for the dehydration reaction. (5) Discharge: Pour the liquid resin into a cooling pan while it is still hot, cool and solidify at room temperature, and then crush it to obtain boron-modified thermoplastic phenolic resin powder with a softening point of 90℃ for later use.

[0044] Preparation Example 5: This preparation example provides a method for preparing boron-modified thermoplastic phenolic resin, which includes the following steps: (1) Feeding of reaction materials: In a reactor equipped with a reflux condenser, thermometer and mechanical stirrer, add 100 parts by mass of phenol and 68 parts by mass of formaldehyde aqueous solution (mass concentration 37.0%), then add 1.5 parts by mass of oxalic acid as an acidic catalyst and adjust the pH of the system to 2.5; (2) Primary polycondensation: Turn on the stirrer, heat the reaction system to 90°C, and reflux at a constant temperature for 105 minutes to form a linear thermoplastic phenolic resin prepolymer. (3) Boration modification: Reduce the system temperature to 65°C and slowly add 20 parts by mass of boric acid powder; (4) High-temperature dehydration and etherification: Remove the reflux condenser and replace it with a distillation condenser. Proceed to 130°C and maintain the temperature for 150 minutes for the dehydration reaction. (5) Discharge: Pour the liquid resin into a cooling pan while it is still hot, cool and solidify at room temperature, and then crush it to obtain boron-modified thermoplastic phenolic resin powder with a softening point of 100℃ for later use.

[0045] Preparation Example 6: This preparation example provides a method for preparing boron-modified thermoplastic phenolic resin, which includes the following steps: (1) Feeding of reaction materials: In a reactor equipped with a reflux condenser, thermometer and mechanical stirrer, add 100 parts by mass of phenol and 75 parts by mass of formaldehyde aqueous solution (mass concentration 37.0%), then add 2.0 parts by mass of oxalic acid as an acidic catalyst and adjust the pH of the system to 3.0; (2) Primary polycondensation: Turn on the stirrer, heat the reaction system to 95°C, and reflux at a constant temperature for 120 minutes to form a linear thermoplastic phenolic resin prepolymer. (3) Boration modification: Reduce the system temperature to 70°C and slowly add 25 parts by mass of boric acid powder; (4) High-temperature dehydration and etherification: Remove the reflux condenser and replace it with a distillation condenser. Proceed to 140°C and maintain the temperature for 180 minutes for the dehydration reaction. (5) Discharge: Pour the liquid resin into a cooling pan while it is still hot, cool and solidify at room temperature, and then crush it to obtain boron-modified thermoplastic phenolic resin powder with a softening point of 110℃ for later use.

[0046] Example 1: This example provides a method for preparing carbon fiber reinforced polyetheretherketone composite material, which includes the following steps: (1) Pre-sizing treatment of carbon fibers: 6.5 parts by weight of boron-modified thermoplastic phenolic resin prepared in Preparation Example 5 were dissolved in anhydrous ethanol to prepare a homogeneous solution with a mass concentration of 10%. 25.0 parts by weight of sizing-free surface-oxidized short-cut carbon fibers prepared in Preparation Example 2 were immersed in the above solution and treated for 20 minutes at a stirring rate of 250 rpm. The coated carbon fibers were filtered out and sent to a multi-temperature zone tunnel hot air oven. The carbon fibers were held at 85°C in the first temperature zone for 25 minutes to evaporate the ethanol, and then held at 170°C in the second temperature zone for 40 minutes to perform initial thermal crosslinking. After cooling, carbon fibers with a B-stage solid coating layer were obtained. (2) Matrix premix: 64.0 parts by weight of polyether ether ketone powder, 4.0 parts by weight of polyether imide powder and 0.5 parts by weight of diphenyl sulfone powder are added to a high-speed mixer and cold-mixed at 600 rpm for 12 minutes to obtain a matrix dry mix; (3) Twin-screw extrusion and gradient devolatilization: The matrix dry mix is ​​fed into the main feed port of a co-rotating twin-screw extruder with an aspect ratio of 48, and the screw speed is set to 300 rpm. The barrel temperature of the first and second stages of the extruder is set to 345°C. Under the shearing action of the screw, the polyether ether ketone is fully melted and forms a molten mixture with polyether imide. In the third and fourth stages, the carbon fibers with the B-stage coating are fed into the melt through a side feeder. The temperature in this section is controlled at 345°C to achieve homogeneous dispersion of carbon fibers in the molten matrix while avoiding premature deep crosslinking of the B-stage coating. When the material enters the fifth reaction zone, the barrel temperature rises sharply to 390°C to activate the conversion of the B-stage resin to the C-stage network. The material enters the sixth and seventh exhaust zones, maintaining a temperature of 390℃. In the sixth zone, a first exhaust port is installed, and the absolute pressure is controlled at 0.06 MPa for micro-negative pressure exhaust. In the seventh zone, a second exhaust port is installed, and the absolute pressure is controlled at 0.005 MPa for high-vacuum phase transformation and nucleation-assisted devolatilization. The melt is extruded into thin strips through a die head at 375℃, cooled and solidified in a 50℃ water bath, air-dried, and pelletized. The pellets are then dried at 150℃ for 5 hours to obtain composite material particles. (4) Elevator hub molding: The composite material particles are added to the injection molding machine, and the feeding section temperature is set to 365℃, the plasticizing section temperature to 380℃, and the nozzle temperature to 385℃. The mold is preheated to 190℃. The blank is injection molded under the conditions of injection pressure of 125MPa, holding pressure of 90MPa, and holding time of 20 seconds. The blank is removed and placed in a forced convection oven, heated to 210℃ at 2℃ / min and held for 5 hours, and then cooled to room temperature in the oven at 1℃ / min to obtain the elevator hub.

[0047] Example 2: This example provides a method for preparing carbon fiber reinforced polyetheretherketone composite material, which includes the following steps: (1) Pre-sizing treatment of carbon fibers: 5.0 parts by weight of boron-modified thermoplastic phenolic resin prepared in Preparation Example 4 were dissolved in anhydrous ethanol to prepare a homogeneous solution with a mass concentration of 8%. 26.9 parts by weight of sizing-free surface-oxidized short-cut carbon fibers prepared in Preparation Example 1 were immersed in the above solution and treated for 15 minutes at a stirring rate of 200 rpm. The coated carbon fibers were filtered out and sent to a multi-temperature zone tunnel hot air oven. The carbon fibers were held at 80°C in the first temperature zone for 20 minutes to evaporate the ethanol, and then held at 160°C in the second temperature zone for 30 minutes to perform initial thermal crosslinking. After cooling, carbon fibers with a B-stage solid coating layer were obtained. (2) Matrix premix: 65.0 parts by weight of polyether ether ketone powder, 3.0 parts by weight of polyether imide powder and 0.1 parts by weight of diphenyl sulfone powder are added to a high-speed mixer and cold-mixed at 500 rpm for 10 minutes to obtain a dry matrix mixture; (3) Twin-screw extrusion and gradient devolatilization: The matrix dry mix is ​​fed into the main feed port of a co-rotating twin-screw extruder with an aspect ratio of 48, and the screw speed is set to 250 rpm. The barrel temperature of the first and second stages of the extruder is set to 345°C. Under the shearing action of the screw, the polyether ether ketone is fully melted and forms a molten mixture with the polyether imide. In the third and fourth stages, the carbon fibers with the B-stage coating are fed into the melt through a side feeder. The temperature in this section is controlled at 345°C to achieve homogeneous dispersion of carbon fibers in the molten matrix while avoiding premature deep crosslinking of the B-stage coating. When the material enters the fifth reaction zone, the barrel temperature rises sharply to 385°C to activate the conversion of the B-stage resin to the C-stage network. The material enters the sixth and seventh exhaust zones, maintaining a temperature of 385℃. A first exhaust port is set in the sixth zone, and the absolute pressure is controlled at 0.08MPa for micro-negative pressure exhaust. A second exhaust port is set in the seventh zone, and the absolute pressure is controlled at 0.01MPa for high-vacuum phase transformation and nucleation-assisted devolatilization. The melt is extruded into thin strips through a die head at 370℃, cooled and solidified in a 40℃ water bath, air-dried, and pelletized. The pellets are then dried at 150℃ for 4 hours to obtain composite material particles. (4) Elevator hub molding: The composite material particles are added to the injection molding machine, and the feeding section temperature is set to 360℃, the plasticizing section temperature to 375℃, and the nozzle temperature to 380℃. The mold is preheated to 180℃. The blank is injection molded under the conditions of injection pressure of 110MPa, holding pressure of 80MPa, and holding time of 15 seconds. The blank is removed and placed in a forced convection oven, heated to 200℃ at 2℃ / min and held for 4 hours, and then cooled to room temperature in the oven at 1℃ / min to obtain the elevator hub.

[0048] Example 3: This example provides a method for preparing carbon fiber reinforced polyetheretherketone composite material, which includes the following steps: (1) Pre-sizing treatment of carbon fibers: 8.0 parts by weight of boron-modified thermoplastic phenolic resin prepared in Preparation Example 6 were dissolved in anhydrous ethanol to prepare a homogeneous solution with a mass concentration of 12%. 30.0 parts by weight of sizing-free surface-oxidized short-cut carbon fibers prepared in Preparation Example 3 were immersed in the above solution and treated at a stirring rate of 300 rpm for 30 minutes. The coated carbon fibers were filtered out and sent to a multi-temperature zone tunnel hot air oven. The carbon fibers were held at 90°C in the first temperature zone for 30 minutes to evaporate the ethanol, and then held at 180°C in the second temperature zone for 45 minutes to perform initial thermo-crosslinking. After cooling, carbon fibers with a B-stage solid coating layer were obtained. (2) Matrix premix: 56.0 parts by weight of polyether ether ketone powder, 5.0 parts by weight of polyether imide powder and 1.0 parts by weight of diphenyl sulfone powder are added to a high-speed mixer and cold-mixed at 800 rpm for 15 minutes to obtain a matrix dry mix; (3) Twin-screw extrusion and gradient devolatilization: The matrix dry mix is ​​fed into the main feed port of a co-rotating twin-screw extruder with an aspect ratio of 48, and the screw speed is set to 350 rpm. The barrel temperature of the first and second stages of the extruder is set to 345°C. Under the shearing action of the screw, the polyether ether ketone is fully melted and forms a molten mixture with the polyether imide. In the third and fourth stages, the carbon fibers with the B-stage coating are fed into the melt through a side feeder. The temperature in this section is controlled at 345°C to achieve homogeneous dispersion of the carbon fibers in the molten matrix while avoiding premature deep crosslinking of the B-stage coating. When the material enters the fifth reaction zone, the barrel temperature rises sharply to 395°C to activate the conversion of the B-stage resin to the C-stage network. The material enters the sixth and seventh exhaust zones, maintaining a temperature of 395℃. In the sixth zone, a first exhaust port is set up, and the absolute pressure is controlled at 0.05MPa for micro-negative pressure exhaust. In the seventh zone, a second exhaust port is set up, and the absolute pressure is controlled at 0.001MPa for high-vacuum phase transformation and nucleation-assisted devolatilization. The melt is extruded into thin strips through a die head at 380℃, cooled and solidified in a 60℃ water bath, air-dried, and pelletized. The pellets are then dried at 150℃ for 6 hours to obtain composite material particles. (4) Elevator hub molding: The composite material particles are added to the injection molding machine, and the feeding section temperature is set to 370℃, the plasticizing section temperature to 385℃, and the nozzle temperature to 390℃. The mold is preheated to 200℃. The blank is injection molded under the conditions of injection pressure of 140MPa, holding pressure of 100MPa, and holding time of 30 seconds. The blank is removed and placed in a forced convection oven, heated to 220℃ at 2℃ / min and held for 6 hours, and then cooled to room temperature in the oven at 1℃ / min to obtain the elevator hub.

[0049] Example 4: This example provides a method for preparing carbon fiber reinforced polyetheretherketone composite material, which includes the following steps: (1) Pre-sizing treatment of carbon fibers: 6.0 parts by weight of boron-modified thermoplastic phenolic resin prepared in Preparation Example 6 were dissolved in anhydrous ethanol to prepare a homogeneous solution with a mass concentration of 10%. 25.0 parts by weight of sizing-free surface-oxidized short-cut carbon fibers prepared in Preparation Example 1 were immersed in the above solution and treated for 25 minutes at a stirring rate of 250 rpm. The coated carbon fibers were filtered out and sent to a multi-temperature zone tunnel hot air oven. The carbon fibers were held at 85°C in the first temperature zone for 25 minutes to evaporate the ethanol, and then held at 170°C in the second temperature zone for 40 minutes to perform initial thermal crosslinking. After cooling, carbon fibers with a B-stage solid coating layer were obtained. (2) Matrix premix: 64.0 parts by weight of polyether ether ketone powder, 4.5 parts by weight of polyether imide powder and 0.5 parts by weight of diphenyl sulfone powder are added to a high-speed mixer and cold-mixed at 600 rpm for 12 minutes to obtain a dry matrix mixture; (3) Twin-screw extrusion and gradient devolatilization: The matrix dry mix is ​​fed into the main feed port of a co-rotating twin-screw extruder with an aspect ratio of 48, and the screw speed is set to 300 rpm. The barrel temperature of the first and second stages of the extruder is set to 345°C. Under the shearing action of the screw, the polyether ether ketone is fully melted and forms a molten mixture with polyether imide. In the third and fourth stages, the carbon fibers with the B-stage coating are fed into the melt through a side feeder. The temperature in this section is controlled at 345°C to achieve homogeneous dispersion of carbon fibers in the molten matrix while avoiding premature deep crosslinking of the B-stage coating. When the material enters the fifth reaction zone, the barrel temperature rises sharply to 390°C to activate the conversion of the B-stage resin to the C-stage network. The material enters the sixth and seventh exhaust zones, maintaining a temperature of 390℃. In the sixth zone, a first exhaust port is installed, and the absolute pressure is controlled at 0.06 MPa for micro-negative pressure exhaust. In the seventh zone, a second exhaust port is installed, and the absolute pressure is controlled at 0.005 MPa for high-vacuum phase transformation and nucleation-assisted devolatilization. The melt is extruded into thin strips through a die head at 375℃, cooled and solidified in a 50℃ water bath, air-dried, and pelletized. The pellets are then dried at 150℃ for 5 hours to obtain composite material particles. (4) Elevator hub molding: The composite material particles are added to the injection molding machine, and the feeding section temperature is set to 365℃, the plasticizing section temperature to 380℃, and the nozzle temperature to 385℃. The mold is preheated to 190℃. The blank is injection molded under the conditions of injection pressure of 125MPa, holding pressure of 90MPa, and holding time of 20 seconds. The blank is removed and placed in a forced convection oven, heated to 210℃ at 2℃ / min and held for 5 hours, and then cooled to room temperature in the oven at 1℃ / min to obtain the elevator hub.

[0050] Example 5: This example provides a method for preparing carbon fiber reinforced polyetheretherketone composite material, which includes the following steps: (1) Pre-sizing treatment of carbon fibers: 6.5 parts by weight of boron-modified thermoplastic phenolic resin prepared in Preparation Example 5 were dissolved in anhydrous ethanol to prepare a homogeneous solution with a mass concentration of 10%. 25.0 parts by weight of sizing-free surface-oxidized short-cut carbon fibers prepared in Preparation Example 2 were immersed in the above solution and treated for 20 minutes at a stirring rate of 250 rpm. The coated carbon fibers were filtered out and sent to a multi-temperature zone tunnel hot air oven. The carbon fibers were held at 85°C in the first temperature zone for 25 minutes to evaporate the ethanol, and then held at 160°C in the second temperature zone for 45 minutes to perform initial thermal crosslinking. After cooling, carbon fibers with a B-stage solid coating layer were obtained. (2) Matrix premix: 64.0 parts by weight of polyether ether ketone powder, 4.0 parts by weight of polyether imide powder and 0.5 parts by weight of diphenyl sulfone powder are added to a high-speed mixer and cold-mixed at 600 rpm for 12 minutes to obtain a matrix dry mix; (3) Twin-screw extrusion and gradient devolatilization: The matrix dry mix is ​​fed into the main feed port of a co-rotating twin-screw extruder with an aspect ratio of 48, and the screw speed is set to 300 rpm. The barrel temperature of the first and second stages of the extruder is set to 345°C. Under the shearing action of the screw, the polyether ether ketone is fully melted and forms a molten mixture with polyether imide. In the third and fourth stages, the carbon fibers with the B-stage coating are fed into the melt through a side feeder. The temperature in this section is controlled at 345°C to achieve homogeneous dispersion of carbon fibers in the molten matrix while avoiding premature deep crosslinking of the B-stage coating. When the material enters the fifth reaction zone, the barrel temperature rises sharply to 395°C to activate the conversion of the B-stage resin to the C-stage network. The material enters the sixth and seventh exhaust zones, maintaining a temperature of 395℃. A first exhaust port is set in the sixth zone, and the absolute pressure is controlled at 0.05MPa for micro-negative pressure exhaust. A second exhaust port is set in the seventh zone, and the absolute pressure is controlled at 0.001MPa for high-vacuum phase transformation and nucleation-assisted devolatilization. The melt is extruded into thin strips through a die head at 375℃, cooled and solidified in a 50℃ water bath, air-dried, and pelletized. The pellets are then dried at 150℃ for 5 hours to obtain composite material particles. (4) Elevator hub molding: The composite material particles are added to the injection molding machine, and the feeding section temperature is set to 365℃, the plasticizing section temperature to 380℃, and the nozzle temperature to 385℃. The mold is preheated to 190℃. The blank is injection molded under the conditions of injection pressure of 125MPa, holding pressure of 90MPa, and holding time of 20 seconds. The blank is removed and placed in a forced convection oven, heated to 210℃ at 2℃ / min and held for 5 hours, and then cooled to room temperature in the oven at 1℃ / min to obtain the elevator hub.

[0051] Comparative Example 1: Compared with Example 1, the difference is that step (1) is omitted, and boron-modified thermoplastic phenolic resin and diphenyl sulfone powder are not added in steps (2) and (3). Commercially available untreated short-cut carbon fiber filaments containing commercial polyurethane sizing agent are directly used for extrusion granulation. All other steps are the same.

[0052] Comparative Example 2: Compared with Example 1, the difference is that in step (1), short-cut carbon fibers that have only undergone muffle furnace heat treatment to remove sizing but have not undergone anodizing are directly used for pre-sizing, while the rest are the same.

[0053] Comparative Example 3: Compared with Example 1, the difference is that step (1) is omitted. In step (3), carbon fibers with B-level coating are not used. Instead, untreated slurry-free surface-oxidized short carbon fibers and boron-modified thermoplastic phenolic resin powder are fed directly into the extruder from the side feeder at the same time. All other aspects are the same.

[0054] Comparative Example 4: The difference from Example 1 is that diphenyl sulfone powder is not added in step (2), but all other steps are the same.

[0055] Comparative Example 5: Compared with Example 1, the difference is that the two-stage gradient devolatilization is cancelled in step (3), and a single-stage exhaust port is set only in the sixth stage, and the absolute pressure is directly controlled at 0.005MPa for single-stage high vacuum exhaust. The rest are the same.

[0056] Comparative Example 6: Compared with Example 1, the difference is that in step (1), ordinary commercially available thermoplastic phenolic resin without boron modification is used instead of boron-modified thermoplastic phenolic resin for pre-sizing treatment, while the rest are the same.

[0057] Test Example 1: This test example is used to evaluate the effect of anodizing treatment on the content of oxygen-containing functional groups on the surface of chopped carbon fibers. The specific test procedure is as follows: (1) Sample preparation: Unanodized desizing short-cut carbon fiber precursors and sizing-free surface-oxidized short-cut carbon fibers prepared by Preparation Example 1, Preparation Example 2 and Preparation Example 3 were used as test objects. Each group of carbon fiber samples was placed in an 80℃ vacuum drying oven for 12 hours to reduce the influence of surface-adsorbed moisture on the test results.

[0058] (2) Fourier Transform Infrared Spectroscopy: The functional groups on the surface of each group of carbon fiber samples were characterized using a Fourier Transform Infrared Spectrometer. The dried carbon fibers were cut into small pieces and mixed with dried potassium bromide powder at a mass ratio of 1:100, then ground and pressed into transparent thin sheets. The spectral scanning range was set to 4000 cm⁻¹. -1 Up to 400cm -1 The resolution is 4cm. -1 The infrared transmission spectrum was recorded 32 times.

[0059] (3) X-ray photoelectron spectroscopy (XPS): The elemental composition and chemical environment of carbon on the surface of each group of carbon fiber samples were analyzed using an XPS. Monochromatic AlKα was used as the X-ray source during the test, and the basic vacuum level in the analysis chamber was better than 1.0 × 10⁻⁶. -9mbar. First, a wide-range full-spectrum scan was performed to obtain the relative atomic ratio of oxygen atoms to carbon atoms on the sample surface, i.e., the O / C ratio. Then, a high-resolution narrow-spectrum C1s scan was performed within the binding energy range of 280 eV to 295 eV, and the C1s spectrum was fitted using nonlinear least squares peak decomposition. The binding energy calibration reference was the C=C single bond peak of the exogenous contaminant carbon, with a calibration position of 284.6 eV. Based on the fitting results, the relative percentage content of the peak areas corresponding to CO bonds, C=O bonds, and OC=O bonds was calculated, where the CO bond binding energy is approximately 286.1 eV, the C=O bond binding energy is approximately 287.5 eV, and the OC=O bond binding energy is approximately 289.0 eV.

[0060] Table 1. Chemical composition and X-ray photoelectron spectroscopy analysis results of carbon fiber surfaces in each group: Unoxidized desizing raw silk 0.038 1.15 0.32 0.17 Preparation Example 1 0.152 6.71 3.58 1.84 Preparation Example 2 0.231 10.42 6.13 3.06 Preparation Example 3 0.287 12.83 7.95 4.81 As shown in Table 1, the O / C ratio of the unoxidized desizing precursor fiber was 0.038, and the relative contents of CO bonds, C=O bonds, and OC=O bonds were 1.15%, 0.32%, and 0.17%, respectively. After anodizing treatment with ammonium bicarbonate aqueous solution, the O / C ratios of the carbon fibers obtained in Preparation Examples 1 to 3 were 0.152, 0.231, and 0.287, respectively, showing a gradually increasing trend; at the same time, the relative contents of CO bonds, C=O bonds, and OC=O bonds also increased accordingly.

[0061] The above results indicate that under the test conditions, anodic oxidation treatment can increase the relative content of oxygen elements on the carbon fiber surface and increase the proportion of oxygen-containing structures such as CO, C=O, and OC=O. With increasing ammonium bicarbonate aqueous solution concentration, current density, and treatment time, the degree of oxidation on the carbon fiber surface shows an increasing trend. These changes in surface chemical composition are beneficial for improving the polarity and wettability of the carbon fiber surface and can provide more possible interfacial interaction sites for subsequent pre-sizing and coating with boron-modified thermoplastic phenolic resin.

[0062] Test Example 2: This test example is used to evaluate the effect of boron modification on the chemical structure and thermal stability of thermoplastic phenolic resin. The specific test procedure is as follows: (1) Sample preparation: Ordinary commercially available thermoplastic phenolic resin without boron modification and boron-modified thermoplastic phenolic resin prepared by Preparation Example 4, Preparation Example 5 and Preparation Example 6 were selected as test objects. The resin samples of each group were ground into fine powder in a mortar and placed in a vacuum drying oven at 60°C for 24 hours to reduce the influence of residual moisture in the samples on the test results.

[0063] (2) Fourier Transform Infrared Spectroscopy: The chemical bond structure of each group of resin samples was characterized using a Fourier Transform Infrared Spectrometer. 2 mg of dried resin powder was mixed and ground with 200 mg of thoroughly dried potassium bromide powder, and then pressed into transparent test specimens using a tablet press at a pressure of 10 MPa. The wavenumber scanning range of the infrared spectrometer was set to 4000 cm⁻¹. -1 Up to 400cm -1 The resolution is set to 4cm. -1 Both the background and sample were scanned 32 times, with a focus on the 1340cm² area. -1 Up to 1380cm -1 Does the interval contain characteristic absorption peaks related to the BOC bond?

[0064] (3) Thermogravimetric analysis (TGA) test: The mass retention of each group of resin samples under high temperature conditions was tested using a thermogravimetric analyzer. 5.0 mg to 8.0 mg of resin powder samples were weighed and placed in an alumina crucible, which was then placed in the heating furnace of the thermogravimetric analyzer. The test atmosphere was high-purity nitrogen, and the gas flow rate was set to 50 mL / min. The test temperature program was as follows: after holding at 30℃ for 5 minutes, the temperature was continuously increased to 800℃ at a rate of 10℃ / min, and the curve of sample mass change with temperature was recorded. Based on the test results, the temperature T5% corresponding to 5% thermal weight loss was extracted, and the mass retention rates at 390℃ and 500℃ were also extracted, where 390℃ corresponds to the temperature of the reaction zone after extrusion processing in some embodiments of this invention.

[0065] Table 2. Infrared characteristic peaks and thermogravimetric analysis results of phenolic resins in each group: Ordinary thermoplastic phenolic resin Not detected 281.6 68.3 54.1 Preparation Example 4 1344.2 358.4 87.5 74.2 Preparation Example 5 1353.8 386.7 93.1 82.6 Preparation Example 6 1362.5 405.2 96.4 86.3 As shown in Table 2, ordinary thermoplastic phenolic resin at 1340cm -1 Up to 1380cm -1 No obvious characteristic absorption peaks of BOC bonds were detected within the range. Its T5% was 281.6℃, and its mass retention rate was 68.3% at 390℃ and 54.1% at 500℃. Compared with ordinary thermoplastic phenolic resins, the boron-modified thermoplastic phenolic resins obtained in Preparation Examples 4 to 6 showed a higher T5% at 1344.2 cm⁻¹. -1 Up to 1362.5cm -1 The presence of characteristic absorption peaks within the range indicates that a structure related to BOC bonds may have formed in the resin system after borylation modification.

[0066] Thermogravimetric analysis results showed that the T5% of the boron-modified thermoplastic phenolic resins obtained in Preparation Examples 4 to 6 were 358.4℃, 386.7℃, and 405.2℃, respectively, all higher than that of ordinary thermoplastic phenolic resins; the mass retention rates at 390℃ were 87.5%, 93.1%, and 96.4%, respectively, and the mass retention rates at 500℃ were 74.2%, 82.6%, and 86.3%, respectively. These results indicate that under the test conditions, with the increase of boric acid dosage and dehydration etherification reaction conditions, the obtained boron-modified thermoplastic phenolic resins exhibited higher high-temperature mass retention capabilities.

[0067] The results of infrared spectroscopy and thermogravimetric analysis show that boronization modification may induce a certain degree of condensation reaction between the phenolic hydroxyl and hydroxymethyl groups in the phenolic resin molecules and boric acid, forming a boron-containing structure and improving the resin's thermal stability under an inert atmosphere. This type of resin maintains a high mass retention rate in the high-temperature range of 385℃ to 395℃, thus facilitating its further transformation as a surface coating layer for carbon fibers during the later stages of polyetheretherketone (PEEK) melt processing. These results provide experimental basis for the subsequent formation of local crosslinked or topologically entangled structures at the carbon fiber / PEEK matrix interface.

[0068] Test Example 3: (1) Take the physical mixture of untreated, slurry-free, surface-oxidized short carbon fibers and boron-modified thermoplastic phenolic resin from Comparative Example 3, as well as the carbon fibers with B-stage solid coatings obtained in step (1) of Examples 1, 2 and 3, as test samples. Place each sample in a desiccator at room temperature for 24 hours to eliminate static electricity and residual moisture.

[0069] (2) The non-isothermal curing reaction thermodynamic characteristics of the sample were tested using a differential scanning calorimeter. Approximately 6.5 mg to 8.5 mg of the test sample was accurately weighed, spread and compacted in a standard aluminum crucible, and covered and pressed. An empty aluminum crucible of the same specification was prepared as a reference end.

[0070] (3) The test environment atmosphere was set to high-purity nitrogen, and the gas purging flow rate was controlled at 50 mL / min. The test temperature program was set as follows: first, the temperature was kept constant at 30℃ for 3 minutes, and then the temperature was linearly increased to 450℃ at a heating rate of 15℃ / min. The heat flow rate between the sample and the reference end was recorded and output as a function of temperature in real time. The onset temperature (T_onset, extrapolation onset point method), peak temperature (T_peak), and normalized enthalpy change of curing reaction (ΔH) of the curing exothermic peak of each sample were extracted using data analysis software.

[0071] Table 3. Differential Scanning Calorimetry (DSC) Curing Exothermic Characteristics Data for Each Group of Test Samples: Comparative Example 3 Mixture 148.3 192.7 115.4 559.4 Example 1 Step (1) Product 362.1 393.5 34.6 34.6 Example 2 Step (1) Product 351.4 382.9 41.2 262.9 Example 3 Step (1) Product 368.5 404.2 28.9 173.3 According to Table 3 and the appendix Figure 1 The data shows that the physical mixture of Comparative Example 3 exhibits different exothermic characteristics compared to the B-stage coated carbon fibers obtained in Examples 1 to 3 during DSC temperature rise testing. The curing exothermic onset temperature of the mixture of Comparative Example 3 was 148.3℃, the peak temperature was 192.7℃, the curing enthalpy change based on the total mass of the sample was 115.4 J / g, and the residual curing enthalpy normalized to resin mass was 559.4 J / g-resin. This result indicates that the physical blending of boron-modified thermoplastic phenolic resin without pretreatment with carbon fiber still exhibits high exothermic reactivity in the lower temperature range. During extrusion processing, if such materials are directly introduced into the high-temperature mixing zone, concentrated condensation or cross-linking reactions may occur before the resin is fully dispersed, thereby increasing the risk of melt viscosity fluctuations and increased equipment load.

[0072] The curing exothermic onset temperatures of the samples obtained in step (1) of Examples 1 to 3 were 362.1℃, 351.4℃, and 368.5℃, respectively, and the peak temperatures were 393.5℃, 382.9℃, and 404.2℃, respectively. The residual curing reaction enthalpies after normalization according to resin mass were 167.7 J / g-resin, 262.9 J / g-resin, and 137.3 J / g-resin, respectively. Compared with Comparative Example 3, no obvious curing exothermic peak was observed in the sample of Examples 1 to 300℃, indicating that after pretreatment in a multi-temperature tunnel oven, some low-temperature reactive groups in the coating layer had already reacted or been consumed in the pretreatment stage, and the resulting coating layer exhibited lower exothermic activity in the lower temperature range.

[0073] The above results indicate that the B-stage coating treatment shifts the main residual exothermic zone of the resin coating layer to a higher temperature, making it closer to the temperature range of the reaction zone in the later stage of the extruder. Therefore, under the condition of a mixing temperature of approximately 340°C to 345°C in the early and middle stages of the extruder, the B-stage coating layer is less prone to significant concentrated exothermic reactions, which is beneficial for the dispersion of carbon fibers in the polyether ether ketone matrix. When the material enters the later high-temperature zone of approximately 385°C to 395°C, the residual reactive groups in the coating layer can further participate in condensation or cross-linking reactions, promoting the structural transformation of the interfacial coating layer towards a higher degree of cross-linking. These test results, from a thermal analysis perspective, support the process design of this scheme, which matches the main reaction stage of the resin coating layer with different functional sections in the extrusion process through pretreatment and temperature gradient control.

[0074] Test Example 4: (1) The mixtures prepared in Examples 1 to 5, as well as the mixtures in Comparative Examples 3 and 5, were selected as test objects. A co-rotating twin-screw extruder with a length-to-diameter ratio of 48 was used, and the equipment was preheated and the parameters were set according to the temperature gradient, screw speed and exhaust pressure conditions in the corresponding examples or comparative examples.

[0075] (2) Start the feeding system. After the extruder head discharges continuously and the equipment operating parameters are basically stable, start recording the extrusion operation data. Using the extruder's built-in PLC data acquisition system, continuously record the percentage of the main engine torque to the rated torque over 60 minutes at a sampling frequency of 1Hz. Calculate the average main engine torque during this time period based on the recorded data, and calculate the torque fluctuation rate according to the following formula: Torque fluctuation rate = (peak torque - average main engine torque) / average main engine torque × 100%.

[0076] The torque ripple rate is used to characterize the change in melt load during extrusion and serves as a reference indicator for evaluating the rheological stability of the extrusion process.

[0077] (3) Industrial cameras were installed above the sixth and seventh exhaust ports of the twin-screw extruder to synchronously observe the material state at the exhaust ports. For the comparative group where no exhaust port was set, only the exhaust ports that were actually set were observed and marked as "not set" in the data table. Within the above 60-minute data recording window, the number of times the melt surged up with the airflow and rushed out of the exhaust port was counted and converted into the spray frequency per unit time.

[0078] Table 4. Data on the stability of extrusion processing for each group of samples: Example 1 62.4 3.8 0 0 Example 2 59.8 3.1 0 0 Example 3 68.2 4.6 0 0 Example 4 64.1 3.5 0 0 Example 5 63.7 4.2 0 0 Comparative Example 3 85.6 31.4 3 2 Comparative Example 5 61.9 4.0 Not set 18 Note: "0" in the table indicates that no recordable material spraying or overflowing was observed within a continuous 60-minute test window.

[0079] As shown in Table 4, the average main engine torque in Examples 1 to 5 ranged from 59.8% to 68.2%, with a torque fluctuation rate of 3.1% to 4.6%. Under these test conditions, the main engine load variation was small, and no recordable material ejection or overflow was observed at either exhaust port. In contrast, the average main engine torque in Comparative Example 3 was 85.6%, with a torque fluctuation rate of 31.4%, and material ejection frequencies of 3 times / hour and 2 times / hour were recorded at the first and second exhaust ports, respectively. These results indicate that when untreated resin components are directly introduced into the high-temperature melt mixing zone, the viscosity change and torque fluctuation of the material system may increase, and the stability of the extrusion process may be relatively reduced.

[0080] In the example group, the pre-formed B-stage coating layer on the carbon fiber surface maintains a relatively stable dispersion state during the early and middle stages of mixing, making it less prone to significant load surges before entering the higher-temperature zone in the later stages. This result corresponds to the lower torque fluctuation rate in the example group, indicating that the pretreatment method is beneficial in reducing load fluctuations caused by changes in the material reaction state during extrusion.

[0081] Regarding the exhaust process, Comparative Example 5 used a single-stage high-vacuum exhaust, and its average host torque and torque fluctuation rate were similar to those of the Example Group. However, the ejection frequency at the second exhaust port reached 18 times / hour. This phenomenon indicates that, under the test conditions, although single-stage high-vacuum exhaust did not significantly increase the average load of the host, it may lead to concentrated escape of volatiles and melt entrainment at the exhaust port, thus affecting the stability of the continuous exhaust process. Examples 1 to 5 adopted a gradient devolatilization method combining a first-stage micro-negative pressure exhaust and a second-stage high-vacuum exhaust. No ejection phenomenon was observed within a continuous 60-minute test window, indicating that this exhaust pressure distribution method is beneficial for mitigating the gas release process at the exhaust port and improving the operational stability of the extrusion devolatilization process.

[0082] Test Example 5: (1) Elevator hub blanks after injection molding in Examples 1 to 5 and Comparative Examples 4 and 5 were selected as test objects. Solid samples with a size of approximately 10mm × 10mm × 3mm were cut from different parts of each blank, and 8 parallel samples were prepared for each test group. The cut samples were dried in a vacuum oven at 120℃ for 6 hours, and then cooled to 23℃ in a desiccator containing color-changing silica gel for later use.

[0083] (2) The actual density of the sample was determined using an electronic density balance with an accuracy of 0.1 mg. The test medium was deionized water that had undergone degassing treatment, and the test environment temperature was 23℃. First, the dry mass M1 of the sample in air was weighed. Then, the sample was completely immersed in deionized water, and air bubbles adhering to the surface of the sample were removed. The suspended mass M2 of the sample in water was weighed. The actual density of each sample was calculated according to M1 / (M1-M2)×density of deionized water.

[0084] (3) Summarize the mass fractions of polyetheretherketone, carbon fiber, polyetherimide, thermoplastic phenolic resin, and diphenyl sulfone in each group. Diphenyl sulfone, as a high-boiling-point phase change auxiliary devolatilization agent, may partially volatilize during the extrusion devolatilization process and be discharged with small molecule volatiles. Therefore, the theoretical density in this test is estimated by normalizing the actual composition of each group. The standard theoretical density values ​​of each single component at room temperature are consulted and set. Based on the multi-component mixing rule, i.e., the mass fraction of each component divided by the reciprocal of the sum of its own densities, the apparent theoretical density of the composite material in each group is calculated. The obtained apparent volumetric porosity is used for relative comparison between different process groups.

[0085] (4) Compare the average actual density obtained from the test with the apparent theoretical density of the corresponding group, calculate the apparent volume porosity of each sample block according to the formula (1-actual density / apparent theoretical density)×100%, and calculate the standard deviation of the porosity calculation results of 8 parallel samples to evaluate the degree of dispersion of porosity test results between different samples.

[0086] Table 5. Test data of composite material density and porosity for each group: Example 1 1.392 1.381 0.79 0.12 Example 2 1.396 1.383 0.93 0.15 Example 3 1.405 1.396 0.64 0.09 Example 4 1.392 1.382 0.72 0.11 Example 5 1.392 1.379 0.93 0.14 Comparative Example 4 1.392 1.332 4.31 0.68 Comparative Example 5 1.392 1.346 3.30 0.82 According to the data in Table 5, the apparent volumetric porosity of Examples 1 to 5 ranged from 0.64% to 0.93%, with standard deviations of porosity ranging from 0.09 to 0.15; the apparent volumetric porosity of Comparative Examples 4 and 5 were 4.31% and 3.30%, respectively, with standard deviations of porosity of 0.68 and 0.82, respectively. Therefore, under the test conditions, the sample from the examples using diphenyl sulfone in conjunction with a two-stage gradient devolatilization process exhibited lower apparent volumetric porosity and smaller porosity dispersion.

[0087] Comparative Example 4, which did not include diphenyl sulfone powder in the matrix, exhibited higher apparent volumetric porosity and porosity standard deviation than the Example group. This result may be related to the lack of high-boiling-point phase change-aiding devolatilization components in the system. During high-temperature extrusion, the further condensation of boron-modified phenolic resin at the interface may be accompanied by the release of small molecules. Under conditions of high melt viscosity in polyetheretherketone (PEEK), the lack of devolatilization-aiding components that facilitate the nucleation and migration of volatiles may increase the difficulty of volatiles being discharged from the melt and interface regions, resulting in a higher proportion of residual microporous defects in the molded sample.

[0088] Comparative Example 5, employing a single-stage high-vacuum exhaust process, exhibited a lower porosity than Comparative Example 4, but still significantly higher than the Example Group, with a larger standard deviation. This result indicates that, in the presence of diphenyl sulfone, if a single-stage high-vacuum exhaust process is directly used, the release of volatiles may concentrate in a single low-pressure zone, easily leading to excessively rapid local gas release rates, material overflow from the exhaust port, or uneven migration of volatiles. This, in turn, affects the stability of the devolatilization process and the uniformity of the pore distribution within the product.

[0089] Examples 1 to 5 employ a two-stage gradient devolatilization method combining micro-negative pressure venting and high-vacuum venting. The micro-negative pressure stage releases some of the gases and low-molecular-weight volatiles entrained during the initial mixing process, reducing the instantaneous venting load in the subsequent high-vacuum stage. In the high-vacuum stage, residual diphenyl sulfone and small molecules generated by interfacial polycondensation can further volatilize or undergo phase transitions under high temperature and low pressure conditions, forming more dispersed gas-phase migration paths, thus facilitating the removal of volatiles from the high-viscosity melt. The above results indicate that under the described process conditions, the combined use of diphenyl sulfone and the two-stage gradient devolatilization process helps reduce the apparent volumetric porosity of the molded composite material and improves the uniformity of porosity test results between samples.

[0090] Test Example 6: (1) The composite material blanks obtained by injection molding of Examples 1 to 5, and Comparative Examples 1, 2 and 6 were selected and prepared into standard-sized specimens conforming to the testing specifications of the International Organization for Standardization (ISO) by machining. All specimens were placed in a constant temperature and humidity environment of 23°C and 50% for 48 hours to eliminate the internal stress of processing.

[0091] (2) The tensile strength of the material was determined using a universal testing machine. A type I dumbbell-shaped specimen was selected, with a gauge length of 50 mm. The two ends of the specimen were clamped in the upper and lower fixtures of the testing machine, and the crosshead tensile movement rate was set to 5 mm / min. The system automatically recorded the load-displacement data, extracted the maximum load at which the specimen fractured, and calculated the tensile strength value. The average value of 6 valid samples was calculated for each test group.

[0092] (3) The apparent interlaminar shear strength, also known as the short beam shear strength, is determined using a universal testing machine combined with a three-point bending fixture. A rectangular specimen with dimensions of 20mm × 10mm × 2mm is tested using the short beam method, with a test span of 10mm. The indenter applying the load moves downward at a rate of 1mm / min, compressing the middle of the specimen until interlaminar shear failure occurs. The critical load at failure is recorded, and the interlaminar shear strength of this group is obtained through relevant calculation formulas.

[0093] (4) The impact strength of the cantilever beam notch was determined using a pendulum impact testing machine. A type A notch with a depth of 2 mm was pre-made in the middle of a rectangular specimen with dimensions of 80 mm × 10 mm × 4 mm. The specimen was vertically fixed on the clamp, and a pendulum with a nominal energy of 5.5 J was released to impact the back side of the notch. The impact absorption energy displayed by the instrument was read and divided by the remaining cross-sectional area at the notch to obtain the impact strength value.

[0094] Table 6. Test data of tensile strength, apparent interlaminar shear strength and impact strength of composite materials: Example 1 242.3 91.5 12.8 Example 2 238.1 88.6 12.1 Example 3 245.7 92.4 11.5 Example 4 239.5 89.2 12.5 Example 5 241.6 90.7 13.1 Comparative Example 1 168.4 49.3 6.2 Comparative Example 2 193.5 63.8 7.8 Comparative Example 6 175.2 55.4 6.9 According to the test results in Table 6, the tensile strength, apparent interlaminar shear strength, and cantilever beam notched impact strength of the composite materials obtained in Examples 1 to 5 are all higher than those in Comparative Examples 1, 2, and 6. The tensile strength of the example groups ranges from 238.1 MPa to 245.7 MPa, the apparent interlaminar shear strength ranges from 88.6 MPa to 92.4 MPa, and the cantilever beam notched impact strength ranges from 11.5 kJ / m². 2 Up to 13.1 kJ / m 2 The results indicate that the overall mechanical properties of the composite material are improved after pre-coating with surface-oxidized short-cut carbon fibers and boron-modified thermoplastic phenolic resin.

[0095] Comparative Example 1 directly used short-cut carbon fiber precursors containing commercially available polyurethane sizing agents. Under the high-temperature processing conditions of the polyetheretherketone (PEEK) system, the heat resistance of this type of sizing agent may be insufficient, easily adversely affecting the interfacial bonding between the carbon fiber and the matrix, thus reducing the efficiency of load transfer from the matrix to the carbon fiber. Therefore, the tensile strength and apparent interlaminar shear strength of Comparative Example 1 were 168.4 MPa and 49.3 MPa, respectively, which were lower than those of the Example Group.

[0096] Comparative Example 6 used unmodified ordinary thermoplastic phenolic resin for pre-coating. Compared with boron-modified thermoplastic phenolic resin, ordinary thermoplastic phenolic resin has relatively weaker structural stability in the high-temperature processing range, which may lead to a decrease in the continuity and stability of the interfacial coating layer, thereby affecting the bonding effect between carbon fiber and polyetheretherketone matrix. Accordingly, the tensile strength, apparent interlaminar shear strength, and cantilever beam notched impact strength of Comparative Example 6 were all lower than those of the Example Group.

[0097] Although Comparative Example 2 used boron-modified thermoplastic phenolic resin for pre-coating, the desized carbon fibers were not anodized. Due to the relatively small number of oxygen-containing functional groups on the carbon fiber surface, the interaction between the resin coating and the fiber surface was relatively insufficient, potentially affecting the stability of the coating under melt mixing and shearing. Therefore, while the mechanical properties of Comparative Example 2 were higher than those of Comparative Example 1 and Comparative Example 6, they were still lower than those of the Example Group.

[0098] In Examples 1 to 5, anodizing facilitates the introduction of oxygen-containing functional groups onto the carbon fiber surface, allowing the boron-modified thermoplastic phenolic resin pre-coating layer to adhere stably to the carbon fiber surface. During subsequent high-temperature extrusion, the pre-coating layer undergoes further thermal action and forms an interfacial transition region with the polyetheretherketone / polyetherimide matrix. This interfacial transition region may include localized interpenetration, entanglement, or intercalation between the resin coating layer and matrix segments, thereby contributing to improved interfacial compatibility and load transfer capacity between the carbon fiber and the polymer matrix. The above results demonstrate that the carbon fiber surface oxidation, boron-modified resin pre-coating, and high-temperature interface construction processes employed in this invention have a positive effect on improving the tensile, interlaminar shear, and notched impact properties of the composite material.

[0099] Test Example 7: (1) The injection molded samples of Examples 1 to 5 and Comparative Examples 1 to 6 were used as experimental subjects. Each group of injection molded parts was machined into cuboid pin-shaped friction specimens with dimensions of 4mm×4mm×15mm by machining. The surface of the specimens was cleaned with acetone in an ultrasonic bath for 5 minutes and dried in a vacuum oven at 80°C for 4 hours. After cooling, the initial mass was weighed using an analytical balance with an accuracy of 0.1mg.

[0100] (2) Dry sliding friction tests were conducted using a pin-disc friction and wear testing machine. A GCr15 bearing steel disc with a surface roughness Ra of 0.2 μm was selected for the wear part. The normal contact load was set to 150 N, the sliding linear velocity to 1.2 m / s, the ambient temperature to 25℃, the relative humidity to 45%, and the continuous friction test time to 120 minutes. The system sensor collected and recorded the friction coefficient curve in real time. After the test, the wear debris on the sample surface was cleaned, and the residual mass was weighed again. The volumetric wear rate of the sample was calculated based on the mass difference, material density, applied load, and total sliding distance. Five samples were tested in each group, and the average value was calculated.

[0101] (3) The elevator hub solid parts of each embodiment and comparative example, which were injection molded using special molds, were taken as fatigue test objects. The hubs were clamped on the customized tooling frame of the electro-hydraulic servo fatigue testing machine to simulate the actual stress state of the hubs on the elevator traction machine.

[0102] (4) The test mode was set to radial compression-compression alternating fatigue. The loading waveform was a sine wave with a loading frequency of 10 Hz. The maximum radial load was set to 12.5 kN and the minimum radial load was set to 1.2 kN. The testing machine ran continuously, and the wheel hub deformation was observed in real time through displacement sensors and a visual monitoring system. When a macroscopically visible through-crack appeared on the wheel hub or the stiffness decreased by more than 15% of the initial value, the component was judged to have failed, the machine was automatically stopped, and the total number of cycles when the failure state was reached was recorded. Three wheel hubs were tested in each group, and the average number of cycles was taken.

[0103] Table 7. Test data on friction and wear properties of materials and fatigue life of wheel hub components for each group: Example 1 0.162 2.58 158.4 Example 2 0.171 2.84 149.2 Example 3 0.158 2.41 162.7 Example 4 0.165 2.63 154.5 Example 5 0.169 2.75 152.1 Comparative Example 1 0.384 18.72 16.3 Comparative Example 2 0.245 8.95 68.4 Comparative Example 3 0.287 11.41 35.8 Comparative Example 4 0.201 5.36 41.2 Comparative Example 5 0.218 6.84 52.6 Comparative Example 6 0.315 14.62 22.7 According to the data in Table 7, under the same test conditions, the steady-state average friction coefficients of Examples 1 to 5 were 0.158–0.171, and the specific wear rate was 2.41 × 10⁻⁶. -6 mm 3 / (N·m)~2.84×10 -6 mm 3 / (N·m), the average number of cycles for fatigue failure is 149.2×10 4 ~162.7×10 4 Compared with the comparative examples, the example group showed lower friction and wear levels and higher fatigue cycle counts in terms of both friction and wear performance and wheel hub component fatigue life.

[0104] Comparative Examples 1 and 6 exhibited relatively high steady-state average friction coefficients and specific wear rates. Specifically, Comparative Example 1 had a steady-state average friction coefficient of 0.384 and a specific wear rate of 18.72 × 10⁻⁶. -6 mm 3 / (N·m). Based on the differences in carbon fiber surface treatment and resin coating methods, it is speculated that insufficient interfacial bonding between carbon fiber and polyether ether ketone matrix may make short carbon fibers at the contact surface more prone to pull-out, breakage or partial detachment under frictional shearing. After the detached fibers and wear debris enter the friction pair interface, they may increase the wear of third-body abrasive particles, thereby increasing the friction coefficient and specific wear rate.

[0105] The average number of fatigue failure cycles for Comparative Examples 4 and 5 were 41.2 × 10⁻⁶, respectively. 4 The sum of the two is 52.6 × 10⁻⁶. 4 The density and porosity results were lower than those of the example group. Based on the aforementioned density and porosity test results, it is speculated that insufficient devolatilization or inadequate stability of the devolatilization process may result in the retention of more micropores or local defects inside the part. Under radial compression-compression alternating loads, these defects may become local stress concentration areas and promote the initiation and propagation of cracks around the pores or near the fiber / matrix interface, thereby reducing the fatigue life of the wheel hub solid part.

[0106] In Examples 1 to 5, the combination of carbon fiber surface oxidation treatment, boron-modified thermoplastic phenolic resin pre-coating treatment, and gradient venting process may help improve the interfacial bonding between carbon fiber and polyetheretherketone matrix, and reduce the internal porosity of the part. Under dry sliding friction conditions, a more stable interfacial bonding helps reduce the shedding of carbon fiber from the matrix and allows the carbon fiber to bear part of the load in the friction contact area; at the same time, the graphite microcrystalline structure of the carbon fiber itself may have a certain friction-reducing effect on the friction process. Therefore, the example group exhibits a low and relatively close steady-state average coefficient of friction and specific wear rate.

[0107] In fatigue testing, lower porosity and a more stable interfacial bonding state facilitate load transfer between the matrix and reinforcing fibers, and may reduce stress concentration caused by local defects, thereby delaying the initiation and propagation of fatigue cracks. As shown in Table 7, the average number of fatigue cycles for the solid wheel hub components in Examples 1 to 5 all exceeded 140 × 10⁻⁶ cycles. 4 This paper explains that the interface control process and phase transformation nucleation-assisted devolatilization process of the present invention have a certain positive effect on improving the service stability of carbon fiber reinforced polyether ether ketone composite wheel hub parts under dynamic load conditions.

[0108] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A carbon fiber reinforced polyetheretherketone composite material, characterized in that, It is made from the following components in parts by weight: 56.0–65.0 parts of polyetheretherketone; 3.0–5.0 parts of polyetherimide; 0.1 to 1.0 parts of diphenyl sulfone; 30.0–38.0 parts of pre-coated carbon fiber; The pre-coated carbon fiber includes slurry-free surface-oxidized short-cut carbon fiber and boron-modified thermoplastic phenolic resin in a B-order solid state coated on the surface of the slurry-free surface-oxidized short-cut carbon fiber. The boron-modified thermoplastic phenolic resin in the B-order solid state is heated and transformed into a C-order three-dimensional network during processing and molding. The C-order three-dimensional network undergoes topological physical entanglement with the linear macromolecular segments of polyether ether ketone and polyether imide, forming a semi-interpenetrating polymer network structure in situ at the interface between carbon fiber and polymer matrix.

2. The carbon fiber reinforced polyetheretherketone composite material according to claim 1, characterized in that, It is made from the following components in parts by weight: Polyetheretherketone (PEEK) 62.0–64.5 parts; 3.5–4.5 parts of polyetherimide; 0.3 to 0.7 parts of diphenyl sulfone; 31.0–32.0 parts of pre-coated carbon fiber; The pre-coated carbon fiber contains 25.0 to 26.0 parts of slurry-free surface-oxidized short-cut carbon fiber and 6.0 to 7.0 parts of boron-modified thermoplastic phenolic resin.

3. The carbon fiber reinforced polyetheretherketone composite material according to claim 1, characterized in that, The boron-modified thermoplastic phenolic resin is a product obtained by polycondensation and dehydration etherification of phenol, formaldehyde aqueous solution and boric acid powder under the action of an acidic catalyst, and its softening point is 90℃~110℃.

4. The carbon fiber reinforced polyetheretherketone composite material according to claim 1, characterized in that, The surface of the sizing-free surface-oxidized short-cut carbon fibers has been free of commercial sizing agent residues and has oxygen-containing functional groups introduced through anodizing treatment.

5. An elevator hub, characterized in that, The elevator hub is manufactured by injection molding using carbon fiber reinforced polyetheretherketone composite material as described in any one of claims 1-4.

6. A method for preparing a carbon fiber reinforced polyetheretherketone composite material as described in any one of claims 1-4, characterized in that, Includes the following steps: (1) Pre-sizing treatment of carbon fiber: Boron-modified thermoplastic phenolic resin is dissolved in a solvent to prepare a homogeneous solution. The sizing-free surface-oxidized short carbon fiber is immersed in the homogeneous solution for dip coating treatment. Then, solvent evaporation and initial thermal crosslinking treatment are performed in sequence. After cooling, the pre-coated carbon fiber is obtained. (2) Matrix premixing: Polyether ether ketone, polyether imide and diphenyl sulfone are cold-mixed evenly to obtain a matrix dry mix; (3) Extrusion and gradient devolatilization: The matrix dry mix is ​​added from the main feed port of the twin-screw extruder to shear and melt it, and the pre-coated carbon fiber is fed into the melt through the side feeder in the middle section of the twin-screw extruder for homogeneous dispersion; the material then enters the reaction zone, and the barrel temperature is increased to activate the resin to transform into a C-order network in situ. The material then enters the exhaust zone for multi-stage pressure drop devolatilization treatment. After extrusion, cooling and curing, pelletizing and drying, carbon fiber reinforced polyether ether ketone composite material is obtained.

7. The method for preparing carbon fiber reinforced polyetheretherketone composite material according to claim 6, characterized in that, In step (1), the mass concentration of the homogeneous solution is 8% to 12%, and the solvent is anhydrous ethanol; the temperature of the volatile solvent is 80°C to 90°C, and the time is 20 to 30 minutes; the temperature of the initial thermal crosslinking treatment is 160°C to 180°C, and the time is 30 to 45 minutes, so as to control the boron-modified thermoplastic phenolic resin to remain in the B-stage state where crosslinking is not complete.

8. The preparation method of the carbon fiber reinforced polyetheretherketone composite material and the elevator hub according to claim 6, characterized in that, In step (3), the barrel temperature of the twin-screw extruder in the section from the main feed port to the side feeder is set to 345°C; the barrel temperature in the reaction zone rises sharply to 385°C to 395°C, triggering the cross-linking of the solidified network and locking the polymer melt chain segments.

9. The carbon fiber reinforced polyetheretherketone composite material according to claim 1, its preparation method, and the elevator hub, characterized in that, In step (3), the multi-stage pressure drop devolatilization process specifically includes: The micro-negative pressure exhaust treatment is carried out at the first exhaust port of the twin-screw extruder, with the absolute pressure controlled at 0.05MPa to 0.08MPa to smoothly release melt pressure fluctuations; The high-vacuum phase transformation nucleation-assisted devolatilization process is carried out at the second exhaust port of the twin-screw extruder, with the absolute pressure controlled at 0.001 MPa to 0.01 MPa. Microbubbles are generated by the flash phase transformation from liquid to gas phase under this pressure and temperature node of diphenyl sulfone, which forcibly entrains water molecules generated by condensation at the interface and expels them from the melt.

10. The method for preparing carbon fiber reinforced polyetheretherketone composite material according to claim 6, characterized in that, Before step (1), the slurry-free surface-oxidized short-cut carbon fibers and boron-modified thermoplastic phenolic resin were pre-treated as follows: Short-cut carbon fiber precursors were heat-treated at 400℃~420℃ under a nitrogen atmosphere for 60~90 minutes to remove sizing. Subsequently, they were used as anodes in a 5%~10% ammonium bicarbonate aqueous solution at 0.01A / cm². 2 ~0.02A / cm 2 Electrolytic anodizing treatment was performed at a current density for 10–20 minutes, followed by washing and drying to obtain the pulp-free surface-oxidized short-cut carbon fibers. Furthermore, phenol and a 37.0% (w / w) formaldehyde aqueous solution are reacted under oxalic acid catalysis at a constant temperature of 85℃~95℃ for 90~120 minutes to form a linear prepolymer; then the temperature is lowered to 60℃~70℃ and boric acid powder is added; the system is then heated to 120℃~140℃ and kept at that temperature for 120~180 minutes for dehydration reaction, and after cooling, curing, and pulverization, the boron-modified thermoplastic phenolic resin is obtained.

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