Polyphenol modified carbon fiber reinforced sulfonated polyetheretherketone composite material and preparation method thereof

Abstract

The invention discloses a polyphenol modified carbon fiber reinforced sulfonated polyetheretherketone composite material and a preparation method thereof, and belongs to the field of polymer composites.The preparation method comprises the steps that a resin matrix and filler are filled into a mold to be sintered, the resin matrix is sulfonated polyetheretherketone, the filler comprises modified carbon fibers and nano-silicon dioxide, and the modified carbon fibers and the nano-silicon dioxide are sintered to obtain the polyphenol modified carbon fiber reinforced sulfonated polyetheretherketone composite material; the modified carbon fiber is prepared by taking carbon fiber, catechol and polyethyleneimine as raw materials in a Tris buffer solution. The hydration lubrication performance of a resin matrix is improved through sulfonated polyetheretherketone, the hydrophilic property is enhanced, a polyphenol coating is formed through self-polymerization reaction on the surfaces of the carbon fibers, the adhesion performance of the surfaces of the fibers is improved through the pi-pi stacking effect, and the interface bonding force between the carbon fibers and the modified resin matrix is enhanced; the nano silicon dioxide is introduced to modify the matrix of the composite material, so that not only is the overall wettability of the material optimized, but also the mechanical property and the wear resistance are effectively improved, and the final composite material has the characteristics of high strength and low friction.

Description

Technical Field

[0001] This invention relates to a polyphenol-modified carbon fiber reinforced sulfonated polyether ether ketone composite material and its preparation method, belonging to the field of polymer composite materials. Background Technology

[0002] Water-lubricated bearings, as an environmentally friendly and energy-saving type of bearing, have been widely used in ships, water pumps, and turbomachinery. Compared with traditional oil-lubricated bearings, water-lubricated bearings not only avoid the environmental pollution problems that lubricating oil may cause, but also significantly reduce operating costs and maintenance requirements, thus becoming a more sustainable choice. In the design of water-lubricated bearings, material selection is one of the key factors determining their performance. Currently, polymer materials occupy an important position in the industrial field due to their excellent comprehensive properties and wide applicability, among which polytetrafluoroethylene (PTFE), nitrile rubber (NBR), and ultra-high molecular weight polyethylene (UHMWPE) are the most typical representatives. However, although these materials perform well under specific conditions, they also have certain limitations and shortcomings.

[0003] Polytetrafluoroethylene (PTFE) is known for its excellent chemical resistance and low coefficient of friction, making it an ideal choice for many harsh working conditions. However, PTFE has relatively low mechanical strength and is prone to severe wear under high loads or high speeds, thus limiting its application range under certain extreme conditions.

[0004] Nitrile butadiene rubber (NBR) is an elastomer material widely used in water-lubricated bearings, especially suitable for applications requiring good sealing performance. It exhibits strong resistance to oil, water, and other liquid media; however, its performance deteriorates significantly at high temperatures, potentially leading to material aging and performance degradation.

[0005] Nitrile rubber has a high coefficient of friction and relatively poor wear resistance, so it may need to be replaced more frequently in high-load or long-term operation applications, which increases maintenance costs.

[0006] Ultra-high molecular weight polyethylene (UHMWPE) possesses excellent wear resistance and self-lubricating properties, making it outstanding in applications requiring low maintenance. However, this material has relatively weak creep resistance and is prone to deformation under sustained high pressure or high temperature conditions, thus affecting bearing stability and service life. Furthermore, UHMWPE has relatively low hardness, which may accelerate wear when exposed to hard particles or other abrasive substances, further reducing bearing reliability.

[0007] In summary, although polymeric materials such as polytetrafluoroethylene (PTFE), nitrile rubber (NBR), and ultra-high molecular weight polyethylene (UHMWPE) have been widely used in water-lubricated bearings, their respective drawbacks cannot be ignored. Therefore, exploring novel composite materials and improving existing water-lubricated bearing material systems to meet diverse needs under different operating conditions has become an important research direction.

[0008] Polyetheretherketone (PEEK) is a high-performance engineering plastic with excellent properties, widely used in aerospace, medical devices, automotive, and electronics industries due to its unique physical, chemical, and mechanical characteristics. As a semi-crystalline thermoplastic, PEEK is renowned for its excellent high-temperature resistance, superior mechanical strength, good chemical stability, and self-lubricating properties. In recent years, many researchers have attempted to apply PEEK to water-lubricated bearings, but its tribological properties under water lubrication conditions still need further improvement. Currently, methods to improve the water lubrication performance of PEEK materials mainly include chemical grafting modification and physical filler modification. However, single modification methods often fail to achieve ideal results; when both are used together, the interfacial bonding force between the filler used in physical filler modification and the modified polymer matrix in chemical grafting modification is weak, and the mechanical strength and wear resistance of the composite material often fail to meet the requirements of practical applications. Summary of the Invention

[0009] To overcome the shortcomings of the prior art, the present invention provides a polyphenol-modified carbon fiber reinforced sulfonated polyether ether ketone composite material and its preparation method. The interfacial bonding force between the filler and the modified polyether ether ketone is strong, and the composite material has better mechanical strength and tribological properties.

[0010] The technical solution adopted by this invention to solve its technical problem is: In a first aspect, this application provides a method for preparing polyphenol-modified carbon fiber reinforced sulfonated polyether ether ketone composite material, the steps of which include: filling a composite material powder containing a resin matrix and fillers into a mold and then sintering it, wherein the resin matrix is ​​sulfonated polyether ether ketone, and the fillers include modified carbon fibers and nano-silica, wherein the modified carbon fibers are prepared from carbon fibers, catechol, and polyethyleneimine as raw materials in a tris(hydroxymethyl)aminomethane hydrochloride buffer solution.

[0011] The method for preparing polyphenol-modified carbon fiber reinforced sulfonated polyether ether ketone (PEEK) composites provided in this application uses sulfonated PEEK as the resin matrix. The sulfonation process enhances the hydrophilicity of the PEEK, significantly reducing the coefficient of friction under water lubrication conditions through hydration lubrication, thus improving its performance in water lubrication applications. Modified carbon fibers effectively improve the adhesion properties of the fiber surface through π-π stacking, thereby significantly enhancing the interfacial bonding between the carbon fibers and the modified resin matrix. This makes the overall structure of the composite material more stable, better dispersing stress under external forces and reducing material failure caused by poor interfacial bonding. Nano-silica, with its hydrophilicity, further optimizes the overall wettability of the material and effectively improves its mechanical properties and wear resistance. The combination of these three elements results in a composite material with excellent water lubrication performance, mechanical properties, and structural stability, better meeting the high performance requirements of applications such as water-lubricated bearings.

[0012] Furthermore, the preparation steps of the modified carbon fiber include: Using the tris(hydroxymethyl)aminomethane hydrochloride buffer solution at pH 8.5 as a solvent, the catechol and the polyethyleneimine were dissolved to obtain a modified solution; The carbon fibers that have undergone desizing and drying are immersed in the modified solution and stirred for more than 400 minutes. The solid material was removed, washed, and dried to obtain the modified carbon fiber.

[0013] The buffer solution with this specific pH value provides a stable chemical environment for subsequent reactions, facilitating better dissolution and reaction of catechol and polyethyleneimine. Prolonged stirring and mixing ensures the modified solution fully contacts and reacts with the carbon fibers, guaranteeing that the catechol-grafted polyethyleneimine adheres uniformly and stably to the carbon fiber surface. The modified carbon fibers obtained through this preparation process, when combined with a sulfonated polyether ether ketone matrix, can more effectively enhance interfacial bonding, thereby improving the overall performance of the composite material.

[0014] Furthermore, the molecular weight of the polyethyleneimine is 600 Da.

[0015] When this specification of polyethyleneimine is dissolved in a buffer solution with catechol, it can react with catechol with appropriate reactivity. The amine group attacks the H atoms at the 3 and 6 positions of the catechol, or attacks the H atoms of the phenolic hydroxyl group. This specification of polyethyleneimine is also conducive to adhesion to the surface of carbon fibers.

[0016] Furthermore, the carbon fiber has a single filament diameter of 6μm to 8μm and an aspect ratio of 2 to 8:1.

[0017] This specification of carbon fiber is easy to disperse evenly and is not prone to agglomeration, which is conducive to its full modification by the modification solution; moreover, this specification of carbon fiber ensures that stress can be effectively dispersed in the composite material after modification.

[0018] Furthermore, in the step of dissolving the catechol and the polyethyleneimine, the mass ratio of the catechol to the polyethyleneimine is 1:0.5.

[0019] In the reaction process, the ratio of catechol to polyethyleneimine is used to control the degree of grafting of catechol onto polyethyleneimine, which is beneficial for the subsequent formation of a stable and uniform polyphenol coating on the carbon fiber surface. The amount of reaction substrate not only affects the degree of grafting but also influences whether the amino groups attack the H atoms at positions 3 and 6 of the catechol or the H atoms of the phenolic hydroxyl group. This feed ratio is conducive to the formation of a uniform coating, which, when combined with the sulfonated polyether ether ketone matrix, enhances the interfacial bonding force between the two. This allows the stress to be uniformly transferred between the fiber and the matrix when the composite material is under load, improving the mechanical properties of the composite material. For example, in water-lubricated bearing applications, it can improve its load-bearing capacity and fatigue resistance.

[0020] Furthermore, in the modified solution, the concentration of catechol is 1 mg / ml, and the concentration of polyethyleneimine is 0.5 mg / ml.

[0021] A suitable concentration allows for appropriate intermolecular spacing and reactivity between catechol and polyethyleneimine in the buffer solution, enabling them to react fully and adhere uniformly to the carbon fiber surface. By controlling the feed mass ratio and concentration, the reaction is guided to occur primarily at the 3 and 6 positions of catechol, allowing for the attachment of more hydroxyl groups to the polyethyleneimine. This not only facilitates hydrogen bonding to the sulfonated polyether ether ketone (and possibly some covalent bonds, which were macroscopically verified in this application but not microscopically characterized), but also contributes to a stronger hydrophilicity in the final composite material. A uniform modified coating enhances the interfacial bonding between the carbon fiber and the sulfonated polyether ether ketone matrix. Furthermore, in the composite material, it contributes to the overall stability of the material's properties, such as ensuring consistent performance across different parts during the operation of water-lubricated bearings, thus improving its reliability.

[0022] Furthermore, in the step of immersing the carbon fibers that have undergone desizing and drying (ultrasonic cleaning in DMF solvent for 60 minutes, followed by repeated rinsing and drying at 80°C) into the modified solution, 2g to 3g of the carbon fibers are soaked in each 100ml of solution.

[0023] This ratio ensures that the carbon fiber is fully impregnated, guaranteeing that the catechol-grafted polyethyleneimine in the solution fully contacts and adheres to the carbon fiber, thus fully modifying the carbon fiber surface. This improves the mechanical properties and stability of the composite material, enabling it to better withstand forces under various working conditions and extend its service life in water-lubricated bearing applications.

[0024] Furthermore, in the composite material powder, the mass ratio of the sulfonated polyether ether ketone, the nano-silica, and the modified carbon fiber is 44:1:5.

[0025] Based on the specially modified carbon fiber produced in this application, the filler mixing ratio enables the three components to exert synergistic advantages.

[0026] Furthermore, the sintering is carried out in a vacuum hot press furnace, and the sintering procedure is as follows: the temperature is increased to 230°C at 5°C / min while the pressure is increased to 50MPa, and then held for 3 hours; then the temperature is decreased to 200°C at 1°C / min while the pressure is increased to 100MPa, and held for 60 minutes; the pressure is maintained, and the temperature is decreased to 25°C at 2°C / min, and the pressure is released and the mold is demolded.

[0027] This sintering process, through precise control of temperature and pressure, enables the composite material to possess excellent molding quality, mechanical properties, and dimensional stability. In water-lubricated bearing applications, it can better adapt to the working environment and ensure stable operation.

[0028] In a second aspect, this application provides a polyphenol-modified carbon fiber reinforced sulfonated polyether ether ketone composite material, which is prepared by the method for preparing the polyphenol-modified carbon fiber reinforced sulfonated polyether ether ketone composite material described in the first aspect.

[0029] Sulfonated polyether ether ketone has stronger hydrophilicity and can significantly reduce the coefficient of friction under water lubrication conditions through hydration; after surface modification, the inert carbon fiber has stronger interfacial bonding with the matrix; combined with nano-silica, the mechanical strength and tribological properties of the composite material are further improved.

[0030] The beneficial effects of this invention are as follows: Firstly, by sulfonating polyether ether ketone, the hydration and lubrication properties of the resin matrix are improved, while its hydrophilicity is significantly enhanced. Secondly, by carrying out a self-polymerization reaction on the carbon fiber surface to form a polyphenol coating, the adhesion properties of the fiber surface are effectively improved by utilizing the π-π stacking effect, thereby significantly enhancing the interfacial bonding force between the carbon fiber and the modified resin matrix. In addition, by introducing hydrophilic nano-silica to further modify the composite matrix, not only is the overall wettability of the material optimized, but its mechanical properties and wear resistance are also effectively improved. The final composite material has both high strength and low friction characteristics.

[0031] Other features and advantages of this application will be set forth in the following description and will be apparent in part from the description or may be learned by practicing the application. The objectives and other advantages of this application may be realized and obtained by means of the structures particularly pointed out in the written description and the accompanying drawings. Attached Figure Description

[0032] Figure 1 This is a schematic diagram illustrating the principle of preparing modified carbon fibers.

[0033] Figure 2 This is a schematic diagram of the composition used to prepare the composite powder.

[0034] Figure 3 This is a schematic diagram of the sintering process. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of the embodiments of this disclosure clearer, the technical solutions of the embodiments of this disclosure are described clearly and completely below. Obviously, the described embodiments are only some, not all, of the embodiments of this disclosure. All other embodiments obtained by those skilled in the art based on the described embodiments of this disclosure without creative effort are within the scope of protection of this invention.

[0036] It should be understood that, without conflict, any and all embodiments of the present invention can be combined with technical features of any other embodiment or multiple other embodiments to obtain other embodiments. The present invention includes such combinations to obtain other embodiments.

[0037] In this specification, groups and their substituents may be selected by those skilled in the art to provide stable structural moieties and compounds. When a substituent is described by a conventional chemical formula written from left to right, the substituent also includes chemically equivalent substituents obtained when the structural formula is written from right to left.

[0038] Unless otherwise specified, all technical and scientific terms used herein have the standard meaning in the field to which the claimed subject matter pertains. Where multiple definitions exist for a term, the definition herein shall prevail.

[0039] Single modification methods often fail to achieve ideal results, thus requiring a combination of chemical grafting modification and physical filler modification to achieve synergistic effects. However, this approach also faces certain challenges: chemical grafting modification typically enhances the hydration capacity of PEEK by introducing ionic groups, while commonly used physically modified fillers (such as carbon fiber, graphite, and molybdenum disulfide) have relatively inert surfaces, resulting in weak interfacial bonding with the chemically grafted PEEK matrix. This mismatch can lead to a decrease in the mechanical strength and wear resistance of the composite material, thereby affecting its overall performance. To address this issue, surface modification of the filler is usually necessary to improve its interfacial compatibility with the PEEK matrix. For example, functionalizing or surface coating the filler can significantly improve the bonding strength between the filler and the PEEK matrix, thereby effectively enhancing the mechanical properties and wear resistance of the composite material. Therefore, comprehensively considering chemical grafting modification and filler surface modification is a key strategy for achieving high-performance applications of PEEK materials under water-lubricated conditions.

[0040] To improve the water lubrication performance of polyetheretherketone (PEEK) to meet the application requirements of water-lubricated bearings, this invention provides a method for preparing polyphenol-modified carbon fiber reinforced sulfonated PEEK composite material. Specifically, the method involves using polyphenol-modified carbon fiber and nano-silica to jointly reinforce the sulfonated PEEK composite material.

[0041] Polyphenol-modified carbon fibers are prepared by carbon fibers, catechol and polyethyleneimine in tris(hydroxymethyl)aminomethane hydrochloride buffer solution (Tris buffer solution).

[0042] Sulfonated PEEK resin is prepared from bisphenol A, 4,4'-difluorobenzophenone, potassium 2,5-dihydroxybenzenesulfonate, potassium carbonate catalyst, toluene dehydrating agent, and DMSO solvent.

[0043] The raw material carbon fiber monofilaments have a diameter of approximately 7 μm and an aspect ratio of 2–8:1. If the carbon fiber diameter is too large, the surface roughness of the sample after doping will increase significantly, affecting the frictional properties and reducing the surface quality of the material; if the diameter is too small, the reinforcing effect will be limited, making it difficult to exert the strengthening effect of the carbon fiber. When the composite material is subjected to external forces, carbon fibers within this aspect ratio range, after modification and participation as part of the composite material, can be uniformly dispersed in the sulfonated polyether ether ketone matrix like a skeleton, enhancing the overall strength and toughness of the material. This allows it to better withstand various forces during the operation of water-lubricated bearings, improving their reliability and stability.

[0044] PEI (polyethyleneimine) has a molecular weight of 600 Da. If the molecular weight is too large, the molecular chains may be too long, affecting the diffusion rate in solution and making it difficult to react uniformly with catechol and adhere to the carbon fiber surface. If the molecular weight is too small, it may not be able to effectively modify the carbon fiber. When combined with a sulfonated polyether ether ketone matrix, PEI of this molecular weight can form a good interfacial bond with the matrix after modification, which helps to effectively transfer stress within the composite material. For example, in water-lubricated bearings subjected to high pressure, this good stress transfer can prevent material damage caused by stress concentration and improve the overall mechanical properties of the composite material.

[0045] During the operation of water-lubricated bearings, the low-friction properties of sulfonated polyether ether ketone can reduce wear between components. Modified carbon fiber and nano-silica jointly improve mechanical properties and wear resistance. Among them, the interfacial bonding force enhanced by the interpenetration of modified carbon fiber ensures that the overall structure of the material is not easy to loosen under stress, which can extend the service life of the material.

[0046] In the following examples, carbon fiber was provided by Shengli (Nanjing) Technology Co., Ltd.; catechol, polyethyleneimine, and tris(hydroxymethyl)aminomethane hydrochloride buffer solution, and nano-silica (hydrophilic) were provided by Shanghai Maclean Biochemical Technology Co., Ltd.; bisphenol A, 4,4'-difluorobenzophenone, potassium 2,5-dihydroxybenzenesulfonate, potassium carbonate, toluene, and dimethyl sulfoxide were provided by Anhui Zesheng Technology Co., Ltd.; and polyetheretherketone (PEEK) was provided by Jilin Zhongyan Polymer Materials Co., Ltd., model 330UPF.

[0047] Example 1 ① Preparation of polyphenol-modified carbon fiber like Figure 1 (The rod-shaped object represents carbon fiber; the color change of the rod indicates surface adhesion.) First, catechol and polyethyleneimine in a mass ratio of 1:0.5 were thoroughly dissolved in a tris(hydroxymethyl)aminomethane hydrochloride buffer solution with a pH of 8.5. Then, carbon fibers that had undergone desizing and drying (commercially available carbon fibers come with slurry protection at the factory) were immersed in the prepared catechol-polyethyleneimine mixed solution and stirred continuously at room temperature for 400 minutes to ensure complete reaction. After the reaction, the carbon fibers were removed from the solution, thoroughly washed with deionized water, and then dried in an oven at 80°C for 15 hours, finally obtaining a surface-modified carbon fiber sample, labeled 1:0.5@CF.

[0048] The concentration of catechol was set at 1 mg / mL, and the concentration of polyethyleneimine (PEI) was 0.5 mg / mL. This ratio helps to form a uniform coating on the carbon fiber surface, thereby enhancing its interfacial bonding with the matrix material. In practical applications, such as in water-lubricated bearings, this good interfacial bonding ensures that the carbon fiber will not easily detach from the matrix during long-term operation and stress, maintaining the structural stability of the composite material and improving its load-bearing capacity and service life.

[0049] ② Preparation of sulfonated polyether ether ketone In a single-layer glass reactor, bisphenol A, 4,4'-difluorobenzophenone, potassium 2,5-dihydroxybenzenesulfonate, potassium carbonate, and solvents toluene and DMSO were added sequentially. Under nitrogen protection, the system was heated to 150°C and maintained for 2 hours, followed by further heating to 180°C. During this process, toluene was distilled off when the water level in the separator stopped increasing. The reaction was considered complete when no more obvious toluene reflux vapor was observed in the system. At this point, the product was quickly poured into ice water to precipitate a solid, yielding a white, strip-shaped polymer. Subsequently, the crude product was crushed into powder using a high-speed blender and washed 10 times each with ethanol and water at 50°C to thoroughly remove residual solvent, unreacted monomers, and inorganic salt impurities. Finally, the treated product was dried in a 100°C forced-air drying oven for 120 hours to obtain sulfonated polyether ether ketone (SPEEK).

[0050] The molar ratio of bisphenol A, 4,4'-difluorobenzophenone, potassium 2,5-dihydroxybenzenesulfonate, and potassium carbonate is 98:100:2:250.

[0051] ③ Preparation of composite material powders containing resin matrix and filler Reference Figure 2 First, 88g of PEEK powder, 2g of nano-silica, and 10g of modified carbon fiber (1:0.5@CF) were added to a clean ball mill jar. Then, ceramic balls were added to the jar, and the mixture was ball-milled at 60Hz for 30 minutes. After milling, the resulting composite powder was dried in an oven at 80℃ for 3 hours.

[0052] Sulfonated polyetheretherketone (PEEK) serves as the matrix, providing basic structural support and water lubrication properties for the composite material. Although the amount of nano-silica added is small, it effectively improves the material's mechanical properties and wear resistance, while optimizing wettability. Modified carbon fibers enhance the interfacial bonding with the matrix and further improve the material's strength. A suitable mass ratio allows the three components to work synergistically. For example, nano-silica can fill the voids between the PEEK matrix and the modified carbon fibers, enhancing the material's density, while the good interfacial bonding between the modified carbon fibers and the matrix helps in the effective transfer of stress throughout the composite material. In water-lubricated bearing applications, this synergistic effect allows the material to withstand certain pressure and friction while maintaining good water lubrication performance, improving its overall performance and service life.

[0053] ④ Sintering process of composite materials Reference Figure 3 5g of composite material powder was filled into a metal mold, which was then placed in a vacuum hot press furnace. The temperature was raised to 230℃ at a heating rate of 5℃ / min, while the pressure (referring to the axial pressure on the columnar material, such as...) was applied. Figure 3 As shown, the material was radially confined and pressurized (upper and lower ends were pressurized) to 50 MPa and held at this temperature and pressure for 3 hours to ensure complete melting of the composite powder and full bonding between the matrix and filler. Subsequently, the temperature was lowered to 200°C at a cooling rate of 1°C / min, and the pressure was increased to 100 MPa and held for 60 minutes to further reduce the internal porosity of the composite material. Finally, the temperature was lowered to 25°C at a cooling rate of 2°C / min before demolding to obtain the target part.

[0054] A heating rate of 5℃ / min prevents excessively rapid heating, which could cause uneven heat transfer within the material, leading to thermal stress or localized overheating and affecting the final molding quality. 230℃ falls within the suitable processing temperature range for the sulfonated PEEK synthesized in Example 1, ensuring sufficient melting while avoiding thermal degradation caused by excessive temperature. A pressure of 50MPa effectively removes air bubbles from the material, improving its density while preventing overflow or structural damage due to excessive pressure, thus enhancing the composite's mechanical properties. A cooling rate of 1℃ / min then promotes more complete entanglement of polymer molecular chains, reducing internal stress accumulation, improving the uniformity of the material's microstructure, and enhancing dimensional stability and mechanical properties. Increasing the pressure to 100MPa further reduces the porosity of the composite, improving molding quality and mechanical properties. Finally, maintaining the pressure, the temperature is reduced to 25℃ at a rate of 2℃ / min, followed by pressure release and demolding. The precise control of temperature and pressure throughout the sintering process ensures the composite material possesses excellent molding quality, mechanical properties, and dimensional stability, enabling it to better adapt to the working environment and ensure stable operation in water-lubricated bearing applications.

[0055] Comparative Example 1 The difference from Example 1 is that no filler is added during ball milling, i.e., only SPEEK powder is sintered in step ④. The rest of the operation is the same as in Example 1.

[0056] Comparative Example 2 The difference from Example 1 is that in ③, 95g of SPEEK powder and 5g of modified carbon fiber (1:0.5@CF) were ball-milled, while in ④, only the mixture of SPEEK powder and modified carbon fiber (1:0.5@CF) was sintered. The rest of the operation is the same as in Example 1.

[0057] Comparative Example 3 The difference from Example 1 is that in ③, 90g of SPEEK powder and 10g of modified carbon fiber (1:0.5@CF) were ball-milled, while in ④, only the mixture of SPEEK powder and modified carbon fiber (1:0.5@CF) was sintered. The rest of the operation is the same as in Example 1.

[0058] Example 2 The difference from Example 1 is that in ③, 89g of SPEEK powder, 1g of nano-silica, and 10g of modified carbon fiber (1:0.5@CF) were ball-milled. The rest of the operation was the same as in Example 1.

[0059] Example 3 The difference from Example 1 is that in ③, 87g of SPEEK powder, 3g of nano-silica, and 10g of modified carbon fiber (1:0.5@CF) were ball-milled. The rest of the operation was the same as in Example 1.

[0060] Example 4 The difference from Example 1 is that in ③, 85g of SPEEK powder, 5g of nano-silica, and 10g of modified carbon fiber (1:0.5@CF) were ball-milled. The rest of the operation was the same as in Example 1.

[0061] Comparative Example 4 First, add 100g of commercially available polyetheretherketone (PEEK, 330UPF) to a clean ball mill jar. Then, add ceramic balls to the ball mill jar and ball mill at a frequency of 60Hz for 30 minutes. After ball milling, place the resulting powder in an oven at 80℃ and dry for 3 hours.

[0062] 5g of ball-milled powder was loaded into a metal mold, which was then placed in a vacuum autoclave. The temperature was increased to 230℃ at a heating rate of 5℃ / min, while the pressure was increased to 50MPa, and maintained at this temperature and pressure for 3 hours to ensure complete melting of the composite powder and full bonding between the matrix and filler. Subsequently, the temperature was reduced to 200℃ at a cooling rate of 1℃ / min, and the pressure was increased to 100MPa and maintained for 60 minutes to further reduce the internal porosity of the composite material. Finally, the temperature was reduced to 25℃ at a cooling rate of 2℃ / min before demolding to obtain the target part.

[0063] Comparative Example 5 The difference from Example 1 is that commercially available polyetheretherketone (PEEK) was used instead of sulfonated polyetheretherketone (SPEEK) during ball milling. All other operations were the same as in Example 1.

[0064] Comparative Example 6 The difference from Example 1 is that the modified carbon fiber was directly replaced with commercially available unmodified carbon fiber (CF) during ball milling. The rest of the operation was the same as in Example 1.

[0065] The compressive strength, coefficient of friction, and wear rate of Examples 1 to 4 and Comparative Examples 1 to 6 were tested, and the results are shown in Table 1 below.

[0066] Table 1

[0067] Analysis of the data from Comparative Examples 1 to 3 shows that the introduction of modified carbon fiber (1:0.5@CF) significantly improved the compressive strength of the composite material while effectively reducing the coefficient of friction and wear rate. The reinforcing effect was most significant when the amount of modified carbon fiber added was 10%. Comparison of the data from Examples 1 to 4 shows that adding an appropriate amount of hydrophilic nano-silica can further improve the compressive and tribological properties of the composite material; however, excessive addition can easily lead to the aggregation of nanoparticles in the matrix, resulting in a decrease in material properties. Experiments show that an addition of 2% hydrophilic nano-silica can achieve the optimal performance of the composite material. When commercially available PEEK is used instead of SPEEK as the matrix material, the compressive strength of the composite material is improved, mainly due to the crystalline properties of PEEK. However, because PEEK is significantly less hydrophilic than SPEEK, its coefficient of friction and wear rate increase significantly under water lubrication conditions (in the UMT ball-and-disc test mode, using seawater as the lubricating medium, with a load of 50 N and a linear velocity of 0.1 m / s) (see Comparative Examples 4 and 5). Furthermore, when ordinary carbon fiber (CF) is used instead of modified carbon fiber (1:0.5@CF), the compressive strength and tribological properties of the composite material decrease significantly. This is because the interfacial bonding strength between ordinary carbon fiber and the matrix is ​​low, thus affecting the overall performance of the material (see Comparative Example 6).

[0068] Comparative Example 7 The difference from Comparative Example 6 is that 90g of SPEEK powder and 10g of carbon fiber (CF) were ball-milled. The rest of the operation was the same as Comparative Example 6.

[0069] Comparative Example 8 The difference from Comparative Example 3 is as follows: In ①, catechol and polyethyleneimine at a mass ratio of 1:0.1 were first fully dissolved in a tris(hydroxymethyl)aminomethane hydrochloride buffer solution with a pH of 8.5. The resulting surface-modified carbon fiber sample was labeled 1:0.1@CF. The remaining procedures were the same as in Comparative Example 3.

[0070] Comparative Example 9 The difference from Comparative Example 3 is as follows: In ①, catechol and polyethyleneimine at a mass ratio of 1:0.25 were first fully dissolved in a tris(hydroxymethyl)aminomethane hydrochloride buffer solution with a pH of 8.5. The resulting surface-modified carbon fiber sample was labeled 1:0.25@CF. The remaining procedures were the same as in Comparative Example 3.

[0071] Comparative Example 10 The difference from Comparative Example 3 is as follows: In ①, catechol and polyethyleneimine at a mass ratio of 1:1 were first fully dissolved in a tris(hydroxymethyl)aminomethane hydrochloride buffer solution with a pH of 8.5. The resulting surface-modified carbon fiber sample was labeled 1:1@CF. The remaining procedures were the same as in Comparative Example 3.

[0072] Comparative Example 11 The difference from Comparative Example 3 is as follows: In ①, catechol and polyethyleneimine at a mass ratio of 1:2 were first fully dissolved in a tris(hydroxymethyl)aminomethane hydrochloride buffer solution with a pH of 8.5. The resulting surface-modified carbon fiber sample was labeled 1:2@CF. The remaining procedures were the same as in Comparative Example 3.

[0073] The compressive strength of Comparative Examples 7 to 11 was compared with that of Comparative Example 3, and the results are shown in Table 2 below.

[0074] Table 2

[0075] It is evident that under different PEI concentrations (1:0@CF, 1:0.1@CF, 1:0.25@CF, 1:0.5@CF), the interfacial bonding strength between the modified carbon fiber and sulfonated PEEK increases with increasing PEI concentration, and the compressive strength of the samples also improves. However, when the PEI concentration is further increased to 1:1@CF and 1:2@CF, both the interfacial bonding strength and compressive strength show a decreasing trend. This may be due to the local aggregation of the copolymer on the fiber surface, leading to a decrease in interfacial adhesion performance, hindering the effective transfer of stress, and thus affecting the overall mechanical properties of the composite material. Therefore, the selection of PEI concentration must balance the interfacial reinforcement effect with the structural stability of the material.

[0076] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0077] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A method for preparing a polyphenol-modified carbon fiber reinforced sulfonated polyether ether ketone composite material, comprising the following steps: The composite material powder containing a resin matrix and fillers is filled into a mold and then sintered. The resin matrix is ​​sulfonated polyether ether ketone, and the filler includes modified carbon fiber and nano silica. The modified carbon fiber is prepared by using carbon fiber, catechol, and polyethyleneimine as raw materials in a tris(hydroxymethyl)aminomethane hydrochloride buffer solution.

2. The method for preparing polyphenol-modified carbon fiber reinforced sulfonated polyetheretherketone composite material according to claim 1, characterized in that, The preparation steps of the modified carbon fiber include: Using the tris(hydroxymethyl)aminomethane hydrochloride buffer solution at pH 8.5 as a solvent, the catechol and the polyethyleneimine were dissolved to obtain a modified solution; The carbon fibers that have undergone desizing and drying are immersed in the modified solution and stirred for more than 400 minutes. The solid material was removed, washed, and dried to obtain the modified carbon fiber.

3. The method for preparing polyphenol-modified carbon fiber reinforced sulfonated polyetheretherketone composite material according to claim 2, characterized in that, The molecular weight of the polyethyleneimine is 600 Da.

4. The method for preparing polyphenol-modified carbon fiber reinforced sulfonated polyetheretherketone composite material according to claim 2, characterized in that, The carbon fiber has a single filament diameter of 6μm to 8μm and an aspect ratio of 2 to 8:

1.

5. The method for preparing polyphenol-modified carbon fiber reinforced sulfonated polyetheretherketone composite material according to claim 2, characterized in that, In the step of dissolving the catechol and the polyethyleneimine, the mass ratio of the catechol to the polyethyleneimine is 1:0.

5.

6. The method for preparing polyphenol-modified carbon fiber reinforced sulfonated polyetheretherketone composite material according to claim 5, characterized in that, In the modified solution, the concentration of catechol is 1 mg / ml, and the concentration of polyethyleneimine is 0.5 mg / ml.

7. The method for preparing polyphenol-modified carbon fiber reinforced sulfonated polyetheretherketone composite material according to claim 6, characterized in that, In the step of immersing the carbon fibers that have undergone desizing and drying into the modified solution, 2g to 3g of the carbon fibers are soaked in every 100ml of solution.

8. The method for preparing polyphenol-modified carbon fiber reinforced sulfonated polyetheretherketone composite material according to claim 1, characterized in that, In the composite material powder, the mass ratio of the sulfonated polyether ether ketone, the nano-silica, and the modified carbon fiber is 44:1:

5.

9. The method for preparing polyphenol-modified carbon fiber reinforced sulfonated polyetheretherketone composite material according to claim 1, characterized in that, The sintering is carried out in a vacuum hot press furnace. The sintering procedure is as follows: the temperature is increased to 230°C at 5°C / min while the pressure is increased to 50MPa, and then held for 3 hours; the temperature is then decreased to 200°C at 1°C / min while the pressure is increased to 100MPa, and held for 60 minutes; the pressure is maintained, and the temperature is decreased to 25°C at 2°C / min, and the pressure is released and the mold is demolded.

10. A polyphenol-modified carbon fiber reinforced sulfonated polyetheretherketone composite material, characterized in that, It is prepared by the method for preparing polyphenol-modified carbon fiber reinforced sulfonated polyether ether ketone composite material according to any one of claims 1 to 9.

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