Corrosion-resistant high-strength carbon fiber ETFE composite material and preparation method thereof

Abstract

The application provides a kind of corrosion-resistant high-strength carbon fiber ETFE composite material and its preparation method, belong to the field of engineering plastics.The carbon fiber ETFE composite material is composed of the following raw materials: ETFE resin: 100 parts, amino carbon fiber: 10-30 parts, maleic anhydride grafted polyolefin elastomer: 5-15 parts, PTFE powder: 2-10 parts, epoxy-terminated fluorosilicone oligomer: 1-5 parts, polyethyleneimine non-covalently modified boron nitride nanosheet: 0.5-5 parts, fluorine-containing end anhydride polyimide oligomer: 3-10 parts, fluorinated polyolefin wax: 0.5-2 parts, fluorine-containing leveling agent: 0.1-0.5 parts, nanoscale fumed silica: 0.5-2 parts.The application is designed from the two dimensions of "enhancing mechanical support" and "building corrosion protection barrier", to realize the synchronous improvement of the mechanical properties and corrosion resistance of the composite material.

Description

Technical Field

[0001] This application relates to the field of engineering plastics technology, and in particular to a corrosion-resistant high-strength carbon fiber ETFE composite material and its preparation method. Background Technology

[0002] Ethylene-tetrafluoroethylene copolymer (ETFE), as a high-performance thermoplastic fluoropolymer, has the core advantage of combining the excellent chemical corrosion resistance of polytetrafluoroethylene (PTFE) with the good thermoplastic processing performance of polyethylene (PE). It also has excellent radiation resistance, UV resistance, low coefficient of friction, high impact strength and dimensional stability, and strong resistance to solvents, acids and alkalis. These comprehensive properties make it an ideal material for high-performance fields such as aerospace, chemical industry, and electronics and electrical engineering, and it has irreplaceable application value in the manufacture of components under harsh working conditions.

[0003] However, pure ETFE resin still has significant limitations when used as a structural material: on the one hand, although it has good mechanical properties, its strength, stiffness and creep resistance have not yet met the requirements for load-bearing structural components, making it difficult to meet the high demands of high-end equipment for the mechanical load-bearing capacity of materials; on the other hand, in extreme corrosive environments such as high temperature, strong acid, strong alkali or strong oxidant, the long-term corrosion resistance of pure ETFE materials still has room for improvement, and it cannot fully adapt to application scenarios that are exposed to harsh media for a long time.

[0004] To address the shortcomings of pure ETFE's mechanical properties, existing technologies often employ modification strategies involving the addition of fiber reinforcements or inorganic fillers. Among these, carbon fiber (CF), due to its low specific gravity and high strength and modulus, has become a mainstream reinforcing material, capable of constructing high-performance composites with resin matrices. Existing research has confirmed that carbon fiber-reinforced polytetrafluoroethylene (PTFE) composites can significantly improve the wear resistance and mechanical strength of the matrix, providing a new approach for modifying the mechanical properties of ETFE. However, existing carbon fiber ETFE composite technology still faces three key challenges hindering performance breakthroughs: First, weak interfacial bonding. The smooth surface and high chemical inertness of carbon fibers result in low interfacial bond strength with the ETFE matrix, leading to poor stress transfer efficiency and significantly limiting the potential for improving the composite's mechanical properties. Second, difficulty in balancing performance. Single reinforcement modifications cannot simultaneously address both mechanical and corrosion resistance. While increasing the content of fillers such as carbon fibers can improve mechanical properties, it increases the difficulty of material processing, and more filler-matrix interfaces provide additional penetration paths for corrosive media. Third, decreased corrosion resistance. When the bonding between the reinforcing fiber and the ETFE matrix interface is poor, corrosive media can easily penetrate along interfacial gaps, triggering fiber-matrix interface degradation and leading to premature failure of the composite. Therefore, how to simultaneously improve the mechanical and corrosion resistance properties of carbon fiber ETFE composites is an urgent technical problem to be solved. Summary of the Invention

[0005] This application provides a corrosion-resistant high-strength carbon fiber ETFE composite material and its preparation method to solve the following technical problem: how to simultaneously improve the mechanical properties and corrosion resistance of carbon fiber ETFE composite materials.

[0006] In a first aspect, this application provides a corrosion-resistant, high-strength carbon fiber ETFE composite material, which, by weight, is composed of the following raw materials:

[0007] ETFE resin: 100 parts, aminated carbon fiber: 10-30 parts, maleic anhydride grafted polyolefin elastomer: 5-15 parts, PTFE micro powder: 2-10 parts, epoxy-terminated fluorinated siloxane oligomer: 1-5 parts, polyethyleneimine non-covalently modified boron nitride nanosheets: 0.5-5 parts, fluorinated anhydride-terminated polyimide oligomer: 3-10 parts, fluorinated polyolefin wax: 0.5-2 parts, fluorinated leveling agent: 0.1-0.5 parts, nano-sized fumed silica: 0.5-2 parts;

[0008] Among them, the surface amino groups of the aminated carbon fiber, the surface amino groups of the non-covalently modified boron nitride nanosheets of polyethyleneimine, and the anhydride groups of the maleic anhydride-grafted polyolefin elastomer are reactive components.

[0009] The epoxy groups of the epoxy-terminated fluorinated siloxane oligomer and the anhydride groups of the fluorinated anhydride-terminated polyimide oligomer are bridging components.

[0010] The bridging component and the reactive component undergo covalent bonding through in-situ interfacial reaction, forming a covalently linked network structure.

[0011] Optionally, the preparation method of the aminated carbon fiber includes the following steps:

[0012] S101. Immerse carbon fibers in nitric acid aqueous solution and reflux them at 80-100℃ for 1-3 hours. After post-treatment, carbon fibers with carboxylated surfaces are obtained.

[0013] S102. The surface carboxylated carbon fiber is immersed in an ethanol solution of γ-aminopropyltriethoxysilane and reacted at 60-80°C for 4-8 hours. After post-treatment, the aminated carbon fiber is obtained.

[0014] The mass concentration of the γ-aminopropyltriethoxysilane is 1-3%.

[0015] Optionally, the preparation method of the maleic anhydride-grafted polyolefin elastomer includes the following steps:

[0016] S201. Premix the polyolefin elastomer, maleic anhydride monomer and organic peroxide initiator in a high-speed mixer at 60-80°C for 5-15 minutes to obtain a premix.

[0017] S202. The premixed material is fed into a twin-screw extruder and subjected to a melt grafting reaction at 160-200°C. After extrusion, cooling and pelletizing, the maleic anhydride-grafted polyolefin elastomer is obtained.

[0018] The polyolefin elastomer is a polyethylene octene copolymer elastomer;

[0019] The organic peroxide initiator is dicumyl peroxide;

[0020] The mass of the maleic anhydride monomer is 5-10% of the mass of the polyolefin elastomer;

[0021] The mass of the initiator is 0.1 to 0.5% of the mass of the polyolefin elastomer.

[0022] Optionally, the preparation method of the epoxy-terminated fluorosiloxane oligomer includes the following steps:

[0023] S301. Dissolve hydrogen-containing silicone oil, perfluoroalkyl olefin and allyl glycidyl ether in toluene, add isopropanol solution of chloroplatinic acid under nitrogen protection, and react at 80-90℃ for 6-10 h.

[0024] S302. After the reaction is complete, the solvent is removed by vacuum distillation to obtain the epoxy-terminated fluorinated siloxane oligomer.

[0025] Wherein, the perfluoroalkyl olefin is perfluorooctylethylene;

[0026] The molar ratio of the perfluoroalkyl olefin to the allyl glycidyl ether is 1:(1.5-2.5);

[0027] The mass of the chloroplatinic acid is 0.005 to 0.01% of the total mass of the hydrogen-containing silicone oil, the perfluoroalkyl olefin, and the allyl glycidyl ether;

[0028] The ratio of the molar amount of silicon-hydrogen bonds in the hydrogen-containing silicone oil to the total molar amount of carbon-carbon double bonds in the perfluoroalkyl olefin and the allyl glycidyl ether is 1:(1.0 to 1.2).

[0029] Optionally, the preparation method of the polyethyleneimine non-covalently modified boron nitride nanosheets includes the following steps:

[0030] S401. Add boron nitride powder to N-methylpyrrolidone solvent, perform ultrasonic crushing and exfoliation, and then centrifuge to collect the supernatant to obtain boron nitride nanosheet dispersion.

[0031] S402. Add the polyethyleneimine aqueous solution to the boron nitride nanosheet dispersion, stir and react, centrifuge to collect the precipitate, wash and dry to obtain the polyethyleneimine non-covalently modified boron nitride nanosheets.

[0032] The ultrasonic fragmentation power is 800-1200W, and the time is 4-8h;

[0033] The polyethyleneimine has a hyperbranched structure and a molecular weight of 10,000 to 25,000.

[0034] The mass ratio of the polyethyleneimine to the boron nitride powder is 1:(5-10).

[0035] Optionally, the preparation method of the fluorinated anhydride-terminated polyimide oligomer includes the following steps:

[0036] S501. 4,4'-(hexafluoroisopropylidene) phthalic anhydride and 2,2-bis(trifluoromethyl)benzidine are subjected to a polycondensation reaction in a polar aprotic solvent under nitrogen protection at -10°C to 0°C for 6 to 12 hours to obtain a fluorinated polyamic acid prepolymer solution.

[0037] S502. Add a mixed solution of acetic anhydride and pyridine to the fluorinated polyamic acid prepolymer solution, react at room temperature to 60°C for 8 to 16 hours, and obtain the fluorinated anhydride-terminated polyimide oligomer after post-treatment.

[0038] The molar ratio of the 4,4'-(hexafluoroisopropylidene) phthalic anhydride to the 2,2-bis(trifluoromethyl)benzidine is (1.05-1.15):1;

[0039] The volume ratio of the acetic anhydride to the pyridine is (2-3):1.

[0040] Optionally, the fluorinated polyolefin wax is a polytetrafluoroethylene modified polyethylene wax.

[0041] Optionally, the fluorinated leveling agent is a perfluoropolyether modified polyacrylate.

[0042] Secondly, this application provides a method for preparing the corrosion-resistant high-strength carbon fiber ETFE composite material according to any one of the first aspects, the method comprising the following steps:

[0043] S1. The non-covalently modified boron nitride nanosheets of polyethyleneimine, the epoxy-terminated fluorinated siloxane oligomer, the fluorinated anhydride-terminated polyimide oligomer and a portion of the ETFE resin are premixed in a high-speed mixer to obtain functionalized masterbatch.

[0044] S2. The functionalized masterbatch, the remaining portion of the ETFE resin, the maleic anhydride-grafted polyolefin elastomer, the PTFE micro powder, the fluorinated polyolefin wax, the fluorinated leveling agent, and the nano-sized fumed silica are placed in the main feed port of a twin-screw extruder for melt blending, and the aminated carbon fiber is added to the molten matrix through the side feed port. The mixture is then extruded and granulated to obtain composite granules.

[0045] S3. The composite granules are hot-pressed to obtain the carbon fiber ETFE composite material;

[0046] The mass of a portion of the ETFE resin is 10-30% of the total mass of the ETFE resin.

[0047] Optionally, the processing temperature of the twin-screw extruder is 300-340℃, and the screw speed is 200-400 rpm.

[0048] The technical solutions provided in this application have the following advantages compared with the prior art:

[0049] This application provides a corrosion-resistant, high-strength carbon fiber ETFE composite material. By precisely selecting functional components and constructing a covalently bonded network structure, it achieves a simultaneous improvement in the mechanical properties and corrosion resistance of the composite material through a synergistic design from two dimensions: "enhanced mechanical support" and "construction of an anti-corrosion barrier." The specific mechanism is as follows:

[0050] In terms of improving mechanical properties, the core is achieved through a combination of "strong load-bearing skeleton + rigid cross-linked network + toughness supplementation". First, aminated carbon fiber, as the main load-bearing skeleton, has high modulus and high strength due to its graphitized crystal structure. Furthermore, the surface amino groups (reactive components) can undergo in-situ covalent reactions with bridging components (the anhydride groups of fluorinated anhydride-terminated polyimide and the epoxy groups of epoxy-terminated fluorinated siloxanes) to form imide bonds and CN bonds, firmly fixing the carbon fiber in the matrix. This ensures that external stress can be efficiently transferred from the matrix to the carbon fiber, preventing fiber-matrix interface slippage and significantly improving the overall load-bearing capacity of the material. Second, the rigid aromatic imide backbone of the fluorinated anhydride-terminated polyimide oligomer acts like "molecular steel bars," enhancing the rigidity of the matrix itself and cross-linking with other components through the anhydride groups to construct a three-dimensional rigid network penetrating the matrix and reinforcement, further strengthening structural stability. Meanwhile, the anhydride groups (reactive components) of maleic anhydride-grafted polyolefin elastomers can react with the bridging components. The elastomer's "soft phase" can absorb impact energy through molecular chain entanglement and conformational changes, inducing crazes and shear bands, thus preventing brittle fracture under impact and achieving a balance of high strength and toughness, thus balancing mechanical properties. Furthermore, non-covalently modified boron nitride nanosheets (two-dimensional structure) of polyethyleneimine can be uniformly dispersed in the matrix, aiding in stress dispersion and further enhancing the mechanical reinforcement effect.

[0051] In terms of improving corrosion resistance, the core is achieved through a combination of "continuous fluorine barrier + dense structure + two-dimensional barrier". First, ETFE resin itself contains high-energy CF bonds, forming a primary corrosion barrier. PTFE micropowder (perfluorinated structure) and the CF segments of ETFE are compatible and symbiotic through fluorine-fluorine interactions, filling the molecular gaps in the amorphous region of ETFE and forming a "fluorine-rich region", significantly reducing the penetration rate of corrosive media. The fluorinated segments of epoxy-terminated fluorinated siloxane oligomers can be integrated into this fluorine-rich region, while their epoxy groups combine with other components through covalent reactions, avoiding the generation of interfacial voids and ensuring a continuous and defect-free fluorine barrier. Second, the covalent bond network formed by bridging components and reactive components makes the overall structure of the material denser, reducing porosity and microcracks, and blocking the penetration channels of corrosive media from a macroscopic structural perspective. In addition, the non-covalently modified boron nitride nanosheets of polyethyleneimine have a two-dimensional layered structure, which can form a "maze-like" physical barrier inside the material, forcing the corrosive media to diffuse around the layers, significantly extending its penetration path, and further improving corrosion resistance. All fluorinated components (ETFE, PTFE, fluorinated siloxanes, and fluorinated polyimides) work synergistically to construct a continuous anti-corrosion system from the molecular to the microstructure, effectively resisting the erosion of corrosive media.

[0052] Crucially, the covalently bonded network structure is the core link for the synergistic enhancement of both components: this network ensures a tight bond between the reinforcement (carbon fiber, boron nitride nanosheets) and the matrix to strengthen mechanical properties, while preventing interfacial voids to ensure the continuity of the corrosion barrier. The fluorinated components, while participating in the construction of the corrosion barrier, also ensure uniform dispersion of the mechanical reinforcement components due to their compatibility with other components (e.g., fluorinated siloxanes and fluorinated polyimides are compatible with ETFE through fluorine-fluorine interactions), thus avoiding shortcomings in mechanical or corrosion resistance caused by component agglomeration. Ultimately, through complementary component functions and structural synergy, the mechanical properties and corrosion resistance of the composite material are simultaneously optimized. Attached Figure Description

[0053] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0054] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0055] Figure 1 This is a schematic flowchart illustrating a method for preparing a corrosion-resistant, high-strength carbon fiber ETFE composite material, as provided in an embodiment of this application. Detailed Implementation

[0056] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0057] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this application can be purchased from the market or prepared by existing methods.

[0058] This application provides a corrosion-resistant, high-strength carbon fiber ETFE composite material, which, by weight, is composed of the following raw materials:

[0059] ETFE resin: 100 parts, aminated carbon fiber: 10-30 parts, maleic anhydride grafted polyolefin elastomer: 5-15 parts, PTFE micro powder: 2-10 parts, epoxy-terminated fluorinated siloxane oligomer: 1-5 parts, polyethyleneimine non-covalently modified boron nitride nanosheets: 0.5-5 parts, fluorinated anhydride-terminated polyimide oligomer: 3-10 parts, fluorinated polyolefin wax: 0.5-2 parts, fluorinated leveling agent: 0.1-0.5 parts, nano-sized fumed silica: 0.5-2 parts;

[0060] Among them, the surface amino groups of aminated carbon fibers, the surface amino groups of non-covalently modified boron nitride nanosheets of polyethyleneimine, and the anhydride groups of maleic anhydride-grafted polyolefin elastomers are reactive components.

[0061] The epoxy groups of the epoxy-terminated fluorinated siloxane oligomers and the terminal anhydride groups of the fluorinated anhydride-terminated polyimide oligomers serve as bridging components.

[0062] The bridging component and the reactive component undergo covalent bonding through in-situ interfacial reactions, forming a covalently linked network structure.

[0063] It should be noted that in the non-covalently modified boron nitride nanosheets of polyethyleneimine, polyethyleneimine (PEI) is adsorbed onto the surface of the boron nitride nanosheets through non-covalent interactions such as hydrogen bonding and van der Waals forces to achieve stable dispersion. However, a large number of primary and secondary amine groups in the PEI molecule that did not participate in adsorption can act as 'reactive components' and undergo covalent bonding reactions with 'bridging components' such as epoxy groups and acid anhydride groups during the melt processing of the composite material, thereby integrating the nanosheets into a three-dimensional network. 'In-situ interfacial reaction' refers to the chemical reaction that occurs at the interface under the action of heat and shear force during the melt blending and molding of the composite material, involving the active groups carried by each component.

[0064] In the corrosion-resistant high-strength carbon fiber ETFE composite material of this application, each component, through clear functional division and molecular-level synergy, jointly constructs a material system that combines excellent mechanical properties and corrosion resistance, as detailed below:

[0065] As a structural matrix, ETFE resin has high bond energy (approximately 485 kJ / mol) and low electron cloud density in its CF bonds, which can effectively resist the chemical attack of corrosive media and form a primary molecular barrier for corrosion resistance. At the same time, the ethylene segments in the molecular chain provide flexibility through single bond rotation, reduce intermolecular forces during melt processing, endow the material with processability, and lay the molecular basis for the overall mechanical framework.

[0066] Aminated carbon fiber serves as the main load-bearing skeleton. Its graphitized crystal structure forms a high-strength molecular skeleton through interlayer π-π conjugation forces, which can efficiently bear external stress. The surface-modified amino groups, as highly polar functional groups, can form chemical bonds with the active groups of other components, becoming molecular anchors connecting the reinforcement and the matrix, directly determining the high strength molecular transfer efficiency of the material.

[0067] Maleic anhydride-grafted polyolefin elastomers act as phase harmonizers. The anhydride groups (-CO-O-CO-) in the molecular chain are highly reactive sites that can undergo nucleophilic addition reactions with amino and epoxy groups, achieving molecular-level bonding with other components. At the same time, the long chain segments of the elastomer, through molecular chain entanglement and conformational changes, induce crazes and shear bands upon impact, absorbing energy through molecular motion, preventing crack propagation, and providing additional toughness to the material.

[0068] As a cornerstone of corrosion resistance, PTFE micro powder has a strong fluorine-fluorine interaction (electron cloud repulsion effect) between its perfluorinated molecular chain structure and the CF segment of ETFE. This intermolecular force promotes the compatibility and symbiosis of the two, which can fill the molecular gaps in the amorphous region of ETFE and form a "fluorine enrichment zone". This significantly increases the penetration resistance of corrosive media at the molecular level and enhances corrosion resistance.

[0069] Epoxy-terminated fluorinated siloxane oligomers serve as molecular-level bridges, with their fluorinated segments achieving molecular compatibility with ETFE and PTFE through fluorine-fluorine interactions. The flexible siloxane backbone (-Si-O-Si-) releases intramolecular stress at the interface through bond angle rotation. The terminal epoxy group (-COC-) forms covalent bonds with amino and anhydride groups through ring-opening reactions, establishing molecular-level connections between different components and optimizing interfacial stress transfer.

[0070] Boron nitride nanosheets (BNNS) with non-covalent modification of polyethyleneimine (PEI) serve as two-dimensional nanoguardians. The two-dimensional layered structure of BNNS forms a "physical barrier" at the molecular scale, requiring corrosive media to diffuse around the layers. The amine groups (-NH-, -NH2) in the PEI molecule are tightly adsorbed onto the surface of BNNS through hydrogen bonds and van der Waals forces, which not only prevents BNNS aggregation but also allows the amine groups to participate in covalent reactions, achieving a molecular synergy of "barrier-enhancement" dual functions.

[0071] Fluorinated anhydride-terminated polyimide oligomers act as dynamic network architects. Their rigid aromatic imide backbone (-CO-NH-CO-) forms a strong molecular skeleton through conjugation, acting like "molecular steel bars" to enhance the rigidity of the matrix. The fluorinated side chains are compatible with the matrix through fluorine-fluorine interactions. The terminal anhydride groups (-CO-O-CO-) form a cross-linked network through reactions with amino and epoxy groups, thereby strengthening the mechanical stability and heat resistance of the material at the molecular level.

[0072] Fluorinated polyolefin wax, fluorinated leveling agent, and nano-sized fumed silica are used as processing optimizers. Fluorinated polyolefin wax improves melt flow by reducing intermolecular friction; fluorinated leveling agent reduces interfacial tension and improves product smoothness by migrating molecules to the surface; fumed silica forms a three-dimensional hydrogen bond network through surface hydroxyl groups, controlling the rheology of the system. All three ensure that the functional components maintain a uniform molecular distribution during processing through physical molecular interactions.

[0073] Furthermore, the composite material in this application is not a simple physical mixture, but rather a "multi-level, multi-dimensional synergistic network" constructed through molecular design, ultimately achieving a balance between corrosion resistance and high strength.

[0074] Covalent bonds construct a "rigid stress transfer network." During processing, in-situ molecular reactions occur between bridging components (the anhydride groups of fluorinated anhydride-terminated polyimide and the epoxy groups of fluorinated siloxane) and reactive components (the amino groups of aminated carbon fibers, the amino groups on the surface of BNNS, and the anhydride groups of the elastomer): the anhydride groups and amino groups form imide / amide bonds through nucleophilic addition; the epoxy groups and amino groups form CN bonds through ring-opening reactions; and the anhydride groups and epoxy groups form ester bonds through esterification. These covalent bonds firmly connect the reinforcement (carbon fibers, BNNS), the matrix (ETFE), and other components, constructing a three-dimensional molecular network. Under stress, stress can be efficiently transferred to the high-strength carbon fiber and polyimide backbone through covalent bonds, preventing intermolecular slippage and ensuring the high strength performance of the material at the molecular level.

[0075] Fluorine-fluorine interactions and a two-dimensional barrier form a corrosion-resistant molecular barrier. In ETFE, PTFE, fluorinated siloxanes, and fluorinated polyimides, the high electronegativity of fluorine atoms generates a strong fluorine-fluorine electron cloud repulsion effect between the fluorinated segments. This intermolecular force forces the fluorinated components to be tightly packed within the material, forming a dense "fluorine molecular protective layer" that resists the molecular penetration of corrosive media such as water, acids, and alkalis. Simultaneously, the two-dimensional layered structure of BNNS, interwoven with carbon fibers at the nano- to micro-scale, together with the dense fluorine molecular layer, constructs a "multi-scale maze." Corrosive media must bypass multiple barriers at the molecular level, significantly extending the diffusion path and further enhancing corrosion resistance.

[0076] Hydrogen bonds, combined with the synergistic effect of rigidity and flexibility, can balance toughness and performance stability. Numerous hydrogen bonds exist between the PEI-modified layer and the BNNS surface, as well as between PEI and other polar components. These weak molecular interactions form an "energy dissipation network": when the material is impacted, hydrogen bonds preferentially break to absorb energy, preventing the covalent backbone from being destroyed, thus achieving a toughening effect. Simultaneously, the rigid phase formed by fluorinated polyimide and carbon fiber (molecular conjugated backbone), and the flexible phase formed by maleic anhydride-grafted elastomer and siloxane segments (molecular chain entanglement), achieve microscopic phase separation yet tight bonding through covalent bonds and fluorine-fluorine interactions. The rigid phase ensures load-bearing strength, while the flexible phase buffers impact energy. This overcomes the contradiction of traditional materials being either "strong and brittle" or "tough and soft" at the molecular phase structure level, ensuring a balance between high strength and high toughness without weakening the corrosion resistance of the fluorine molecular barrier.

[0077] In some embodiments, the preparation method of aminated carbon fiber includes the following steps:

[0078] S101. Immerse carbon fibers in nitric acid aqueous solution and reflux them at 80-100℃ for 1-3 hours. After post-treatment, carbon fibers with carboxylated surfaces are obtained.

[0079] S102. The surface carboxylated carbon fibers are immersed in an ethanol solution of γ-aminopropyltriethoxysilane and reacted at 60-80°C for 4-8 hours. After post-treatment, amino-modified carbon fibers are obtained.

[0080] The mass concentration of γ-aminopropyltriethoxysilane is 1–3%.

[0081] It should be noted that the preparation of aminated carbon fibers involves a two-step process of "oxidative modification-silane coupling," precisely constructing surface active sites. In the nitric acid aqueous solution oxidation treatment in step S101, the reflux temperature of 80–100°C ensures that the nitric acid maintains sufficient oxidative activity, uniformly generating a sufficient amount of carboxyl groups (-COOH) on the carbon fiber surface. These carboxyl groups are the core sites for subsequent reactions with the silane coupling agent. The reflux time of 1–3 hours ensures a moderate oxidation depth, achieving the required functional group density on the carbon fiber surface without damaging the graphitized crystal structure of the fiber itself, thus guaranteeing its mechanical load-bearing capacity. The strong oxidizing properties of the nitric acid aqueous solution can precisely act on the carbon fiber lattice edges, directionally introducing oxygen-containing functional groups, laying the foundation for subsequent silane grafting.

[0082] In the silane coupling treatment of step S102, γ-aminopropyltriethoxysilane with a mass concentration of 1-3% can achieve monolayer coverage of silane on the carbon fiber surface, which not only avoids the degradation of interfacial properties caused by multilayer adsorption, but also allows the alkoxy groups of silane to be fully hydrolyzed into silanols (-Si-OH). The reaction temperature of 60-80℃ can accelerate the condensation reaction between silanols and carboxyl groups to form stable Si-OC covalent bonds. The reaction time of 4-8h ensures complete reaction, so that the amino groups at the silane ends are uniformly oriented towards the outside of the fiber, providing sufficient active sites for covalent bonding with other components in the composite material.

[0083] In some embodiments, the preparation method of maleic anhydride-grafted polyolefin elastomer includes the following steps:

[0084] S201. Premix the polyolefin elastomer, maleic anhydride monomer and organic peroxide initiator in a high-speed mixer at 60-80°C for 5-15 minutes to obtain a premix.

[0085] S202. The premixed material is fed into a twin-screw extruder and subjected to a melt grafting reaction at 160-200°C. After extrusion, cooling and pelletizing, maleic anhydride grafted polyolefin elastomer is obtained.

[0086] Among them, the polyolefin elastomer is a polyethylene octene copolymer elastomer;

[0087] The organic peroxide initiator is dicumyl peroxide;

[0088] The mass of maleic anhydride monomer is 5-10% of the mass of polyolefin elastomer;

[0089] The mass of the initiator is 0.1 to 0.5% of the mass of the polyolefin elastomer.

[0090] It should be noted that maleic anhydride-grafted polyolefin elastomers achieve efficient grafting through a "premix-melt grafting" process. In the premixing stage of step S201, a temperature of 60–80°C allows the maleic anhydride monomer to partially melt, ensuring thorough mixing with the polyethylene octene copolymer elastomer and dicumyl peroxide initiator, thus preventing monomer agglomeration during subsequent melt grafting. A premixing time of 5–15 minutes ensures uniform mixing while avoiding energy waste. The maleic anhydride monomer accounts for 5–10% of the polyolefin elastomer's mass. This amount ensures sufficient density of anhydride groups grafted onto the elastomer molecular chain, providing ample active sites for subsequent interfacial covalent reactions. 0.1–0.5% of the initiator generates appropriate free radicals, precisely driving the grafting reaction while balancing grafting efficiency and the integrity of the elastomer molecular chain.

[0091] In the melt grafting stage of step S202, the twin-screw extrusion temperature of 160-200°C allows the polyolefin elastomer to fully melt and maintain good fluidity, while also ensuring that the half-life of the initiator is matched with the extrusion process, continuously generating free radicals to drive the grafting reaction. The extrusion, cooling, and pelletizing process can make the grafted elastomer into granules, which is convenient for subsequent mixing and processing with other components, while ensuring the uniformity of the product shape.

[0092] In some embodiments, the preparation method of epoxy-terminated fluorosiloxane oligomers includes the following steps:

[0093] S301. Dissolve hydrogen-containing silicone oil, perfluoroalkyl olefin and allyl glycidyl ether in toluene, add isopropanol solution of chloroplatinic acid under nitrogen protection, and react at 80-90℃ for 6-10 h.

[0094] S302. After the reaction is complete, the solvent is removed by vacuum distillation to obtain epoxy-terminated fluorinated siloxane oligomers.

[0095] Among them, the perfluoroalkyl olefin is perfluorooctylethylene;

[0096] The molar ratio of perfluoroalkyl olefin to allyl glycidyl ether is 1:(1.5–2.5);

[0097] The mass of chloroplatinic acid is 0.005–0.01% of the total mass of hydrogen-containing silicone oil, perfluoroalkyl olefins, and allyl glycidyl ether.

[0098] The ratio of the molar amount of silane-hydrogen bonds in hydrogen-containing silicone oil to the total molar amount of carbon-carbon double bonds in perfluoroalkyl olefins and allyl glycidyl ethers is 1:(1.0~1.2).

[0099] It should be noted that the epoxy-terminated fluorosiloxane oligomers are synthesized via a hydrosilylation reaction. In step S301, 0.005–0.01% by mass of chloroplatinic acid (Karstedt catalyst) precisely catalyzes the reaction between the hydroxyl bonds (≡Si-H) of the hydrosilicone oil and the carbon-carbon double bonds of perfluorooctylethylene and allyl glycidyl ether, ensuring a stable reaction rate and no significant side reactions. The molar ratio of perfluoroalkyl olefin to allyl glycidyl ether is 1:(1.5–2.5), with an excess of allyl glycidyl ether, ensuring that epoxy groups are preferentially grafted onto the ends of the hydrosilicone oil molecular chains, ultimately forming an epoxy-terminated structure that meets the subsequent functional requirement of serving as a "molecular bridge." The total molar ratio of hydroxyl bonds to carbon-carbon double bonds in the hydrosilicone oil is 1:(1.0–1.2), a ratio that allows for the complete consumption of hydroxyl bonds, avoiding residual hydroxyl bonds from affecting the subsequent stability of the oligomer. A reaction temperature of 80–90°C promotes the full progress of the hydrosilylation reaction, and a reaction time of 6–10 hours ensures the complete reaction and the formation of oligomers with uniform structure. Nitrogen protection can prevent the raw materials from being oxidized during the reaction and ensure the purity of the product.

[0100] The vacuum distillation in step S302 can completely remove the reaction solvent toluene, yielding pure epoxy-terminated fluorosiloxane oligomers, thus avoiding solvent residue from interfering with the interfacial bonding and properties of subsequent composite materials.

[0101] In some embodiments, the preparation method of non-covalently modified boron nitride nanosheets with polyethyleneimine includes the following steps:

[0102] S401. Add boron nitride powder to N-methylpyrrolidone solvent, perform ultrasonic crushing and exfoliation, and then centrifuge to collect the supernatant to obtain boron nitride nanosheet dispersion.

[0103] S402. Add the polyethyleneimine aqueous solution to the boron nitride nanosheet dispersion, stir the reaction, centrifuge to collect the precipitate, wash and dry it to obtain non-covalently modified boron nitride nanosheets with polyethyleneimine.

[0104] The power of ultrasonic fragmentation is 800-1200W, and the time is 4-8 hours;

[0105] Polyethyleneimine has a hyperbranched structure and a molecular weight of 10,000–25,000.

[0106] The mass ratio of polyethyleneimine to boron nitride powder is 1:(5-10).

[0107] It should be noted that the non-covalently modified boron nitride nanosheets with polyethyleneimine were prepared via an "ultrasonic exfoliation-non-covalent modification" process. In step S401, the ultrasonic exfoliation stage, with an ultrasonic power of 800–1200 W, provided sufficient energy to overcome the van der Waals forces between boron nitride powder particles, achieving effective exfoliation and yielding few-layer boron nitride nanosheets (BNNS). An ultrasonic time of 4–8 hours ensured sufficient exfoliation while avoiding excessive ultrasonication that could damage the two-dimensional layered structure of the BNNS, thus maintaining its barrier function. The surface energy of the N-methylpyrrolidone solvent matched that of boron nitride, efficiently dispersing the exfoliated BNNS, preventing nanosheet aggregation, and ensuring uniform subsequent modification.

[0108] In the non-covalent modification stage of step S402, hyperbranched polyethyleneimine (PEI) with a molecular weight of 10,000–25,000 is selected. Its highly branched structure provides a large number of amine groups, which are firmly adsorbed onto the BNNS surface through hydrogen bonding (interacting with BN bonds on the BNNS surface) and electrostatic interactions (attracting protonated amine groups to the negative charge on the BNNS surface). This ensures modification stability without affecting the two-dimensional structure of BNNS. The mass ratio of PEI to boron nitride powder is 1:(5–10). This ratio allows PEI to completely cover the BNNS surface while avoiding excessive PEI that could lead to nanosheet agglomeration, ensuring that the modified BNNS is uniformly dispersed in the composite material. After stirring and reacting, the mixture is collected by centrifugation, washed, and dried to separate pure modified BNNS and remove unadsorbed free PEI, ensuring product purity.

[0109] In some embodiments, the preparation method of fluorinated anhydride-terminated polyimide oligomers includes the following steps:

[0110] S501. 4,4'-(hexafluoroisopropylidene) phthalic anhydride and 2,2-bis(trifluoromethyl)benzidine are subjected to a polycondensation reaction in a polar aprotic solvent under nitrogen protection at -10°C to 0°C for 6 to 12 hours to obtain a fluorinated polyamic acid prepolymer solution.

[0111] S502. Add a mixed solution of acetic anhydride and pyridine to the fluorinated polyamic acid prepolymer solution, react at room temperature to 60°C for 8 to 16 hours, and obtain fluorinated anhydride-terminated polyimide oligomers after post-treatment.

[0112] The molar ratio of 4,4'-(hexafluoroisopropylidene)phthalic anhydride to 2,2-bis(trifluoromethyl)benzidine is (1.05–1.15):1;

[0113] The volume ratio of acetic anhydride to pyridine is (2-3):1.

[0114] It should be noted that the fluorinated anhydride-terminated polyimide oligomer is synthesized through a "low-temperature polycondensation-chemical imidization" process. In step S501, the low-temperature polycondensation stage, with a reaction temperature ranging from -10°C to 0°C, allows for precise control of the polycondensation rate, preventing localized overheating that could lead to an excessively wide molecular weight distribution in the polyamic acid prepolymer and ensuring a uniform prepolymer structure. A reaction time of 6–12 hours ensures sufficient reaction between 4,4'-(hexafluoroisopropylidene)phthalic anhydride and 2,2-bis(trifluoromethyl)benzidine to generate a sufficient amount of prepolymer. The monomer molar ratio is (1.05–1.15):1, with excess dianhydride ensuring that the ends of the prepolymer molecular chains are all anhydride groups, providing sufficient active sites for subsequent crosslinking reactions. The polar aprotic solvent effectively dissolves the monomers and prepolymer, and nitrogen protection prevents oxidation of the raw materials or products during the reaction, ensuring the purity of the prepolymer.

[0115] In the chemical imidization stage of step S502, the volume ratio of acetic anhydride to pyridine is (2-3):1. Acetic anhydride acts as a dehydrating agent to promote the cyclization of polyamic acid to form imide bonds. Pyridine acts as a catalyst to accelerate the cyclization reaction and absorbs the acid generated in the reaction to maintain the stability of the reaction system. The gradient temperature increase from room temperature to 60°C can gradually advance the imidization reaction and avoid the molecular chain breakage caused by a sudden temperature rise. The reaction time of 8-16 hours ensures complete imidization and generates structurally stable fluorinated anhydride-terminated polyimide oligomers. The post-treatment process can remove reaction byproducts and obtain pure oligomers, laying the foundation for the subsequent construction of cross-linked networks.

[0116] In some embodiments, the fluorinated polyolefin wax is a polytetrafluoroethylene modified polyethylene wax.

[0117] It should be noted that the fluorinated polyolefin wax is made of polytetrafluoroethylene modified polyethylene wax. The fluorinated segments in its molecular structure have excellent compatibility with ETFE and PTFE. They can reduce the viscosity of the composite melt and improve processing fluidity through molecular chain entanglement. At the same time, the fluorinated segments will migrate directionally to the material surface during processing, further optimizing the fluidity during the molding process and ensuring uniform product molding.

[0118] In some embodiments, the fluorinated leveling agent is a perfluoropolyether modified polyacrylate.

[0119] It should be noted that the fluorinated leveling agent is a perfluoropolyether modified polyacrylate. The perfluoropolyether segments can significantly reduce the surface tension of the material, effectively avoiding surface defects such as shrinkage cavities and orange peel during the molding process. The acrylate segments have good compatibility with the polymer resin matrix, which can ensure that the leveling agent is uniformly dispersed in the system, ensuring a long-lasting leveling effect without affecting the overall mechanical properties and corrosion resistance of the composite material.

[0120] Figure 1This is a schematic flowchart illustrating a method for preparing a corrosion-resistant, high-strength carbon fiber ETFE composite material, as provided in an embodiment of this application.

[0121] Based on a general inventive concept, such as Figure 1 As shown, this application provides a method for preparing a corrosion-resistant high-strength carbon fiber ETFE composite material according to any one of the above-mentioned methods, the method comprising the following steps:

[0122] S1. Boron nitride nanosheets non-covalently modified with polyethyleneimine, epoxy-terminated fluorinated siloxane oligomers, fluorinated anhydride-terminated polyimide oligomers and a portion of ETFE resin are premixed in a high-speed mixer to obtain functionalized masterbatch.

[0123] S2. The functionalized masterbatch, the remaining ETFE resin, maleic anhydride grafted polyolefin elastomer, PTFE micro powder, fluorinated polyolefin wax, fluorinated leveling agent, and nano-sized fumed silica are placed in the main feed port of a twin-screw extruder for melt blending, and the aminated carbon fiber is added to the melted matrix through the side feed port. The two parts are then extruded and granulated together to obtain composite granules.

[0124] S3. The composite granules are hot-pressed to obtain carbon fiber ETFE composite material.

[0125] The mass of some ETFE resin is 10-30% of the total mass of ETFE resin.

[0126] In some embodiments, the twin-screw extruder operates at a processing temperature of 300–340°C and a screw speed of 200–400 rpm.

[0127] In some embodiments, the hot pressing temperature is 260–290°C, the pressure is 13–16 MPa, and the constant temperature and pressure time is 5–12 min.

[0128] It should be noted that step S1 is the preparation of functionalized masterbatch. The core of this step is to achieve efficient dispersion of key functional components through premixing, laying a foundation for uniformity in subsequent processing. Specifically, non-covalently modified boron nitride nanosheets (BNNS), epoxy-terminated fluorinated siloxane oligomers, fluorinated anhydride-terminated polyimide oligomers, and a portion of ETFE resin accounting for 10-30% of the total mass of ETFE resin are premixed in a high-speed mixer to form functionalized masterbatch.

[0129] The ETFE content ranges from 10% to 30%. A 10% content ensures sufficient resin to encapsulate the functional components, forming a structurally stable masterbatch and preventing the functional components from scattering due to lack of a carrier. The upper limit of 30% prevents the ETFE resin from excessively diluting the functional components, ensuring the concentration of reactive groups such as epoxy groups and terminal anhydride groups, as well as BNNS, in the masterbatch, thus ensuring their full effectiveness in subsequent processing. This step, through pre-dispersion, pre-fixes easily agglomerated nano-components (such as BNNS) and highly reactive components in the resin carrier, effectively preventing them from re-agglomerating during subsequent melt blending, while ensuring the uniform distribution of reactive components, thus guaranteeing the structural uniformity of the final composite material.

[0130] Step S2 is melt blending and granulation, which is the key to achieving full integration and reaction of the components. It consists of two parts: the main feed port process and the side feed port process.

[0131] The main feed port is primarily responsible for melt blending the functionalized masterbatch with the remaining ETFE resin, maleic anhydride-grafted polyolefin elastomer, PTFE micropowder, fluorinated polyolefin wax, fluorinated leveling agent, and nano-sized fumed silica. The twin-screw extruder's processing temperature of 300–340°C ensures complete melting of the ETFE resin and various additives to form a continuous phase, while maintaining good melt flowability, facilitating thorough contact and mixing of the components. The screw speed of 200–400 rpm plays a role through appropriate shear force: lower speeds (around 200 rpm) provide gentle shear, suitable for protecting the molecular chain integrity of sensitive components such as maleic anhydride-grafted polyolefin elastomers; higher speeds (around 400 rpm) generate strong shear force, effectively breaking down the micro-agglomerates of PTFE micropowder and nano-sized fumed silica, promoting their uniform dispersion in the matrix.

[0132] Meanwhile, at a processing temperature of 300–340°C in a twin-screw extruder, the anhydride groups of maleic anhydride-grafted polyolefin elastomers, the amino groups on the surface of aminated carbon fibers and non-covalently modified boron nitride nanosheets of polyethyleneimine can undergo ring-opening reactions with the epoxy groups of epoxy-terminated fluorinated siloxane oligomers to form covalent bonds, or they can undergo condensation reactions with the terminal anhydride groups of fluorinated anhydride-terminated polyimide oligomers to form imide bonds or amide bonds. These in-situ interfacial reactions together constitute a three-dimensional network structure linked by covalent bonds.

[0133] The side feed port is used to add aminated carbon fibers after the matrix has melted. The molten matrix has good fluidity, which can quickly wet the carbon fiber surface and improve the interfacial bonding between the fiber and the matrix. At the same time, it avoids direct friction between the carbon fiber and solid particles during the main feeding stage, reducing fiber breakage and maximizing the retention of its aspect ratio. The aspect ratio is the core of carbon fiber's role as the "main load-bearing skeleton" and can significantly improve the material's mechanical strength. In addition, the molten environment can also promote the in-situ interfacial reaction between the amino groups on the carbon fiber surface and the epoxy groups and terminal anhydride groups in the matrix, further strengthening the bonding force between the fiber and the matrix. Finally, uniform composite granules are obtained through co-extrusion granulation.

[0134] Step S3 is hot pressing, which is the shaping stage that transforms composite granules into the final composite material product. The core is to achieve material densification and performance optimization through the synergistic effect of heat and pressure.

[0135] Temperature control slightly below the melting point of ETFE softens the composite granules to conform to the mold shape while preventing shape loss due to excessive resin melting, ensuring dimensional stability of the product. Staged pressure application gradually extrudes micro-bubbles generated during granule melting, eliminating internal pores and increasing material density. This densified structure not only enhances mechanical properties but also reduces channels for corrosive media penetration, strengthening corrosion resistance. Controlling the cooling rate optimizes the crystallinity of ETFE resin, ensuring a uniform crystalline structure. This avoids internal stress caused by rapid cooling and balances the rigidity and toughness of the material through appropriate crystallinity, ultimately guaranteeing stable and compliant mechanical properties and corrosion resistance of the product.

[0136] In summary, this application overcomes the technical challenges of traditional composite materials, such as the difficulty in balancing high strength and high corrosion resistance, the tendency of nano-components to agglomerate, and the difficulty in balancing fiber reinforcement and interfacial bonding, through an integrated solution of "precise component design - molecular-level synergy - process innovation." This results in multi-dimensional core advantages, as detailed below:

[0137] From a component design perspective, this application achieves "precise matching of functional components and full-chain interface optimization." Using ETFE resin as the matrix, functional components such as aminated carbon fiber (main load-bearing), PEI-modified BNNS (two-dimensional barrier), and PTFE micropowder (fluorine enrichment reinforcement) are selectively introduced. Each component has a clear functional division and is highly compatible. For example, aminated carbon fiber constructs covalent bond anchors through surface amino groups; PEI-modified BNNS serves both as a barrier and reinforcement; and PTFE and ETFE form a dense fluorine-fluorine interaction layer. Simultaneously, epoxy-based fluorinated siloxanes and fluorinated anhydride-terminated polyimides act as "molecular bridges," completely resolving the interfacial compatibility issues between inorganic functional components and the organic matrix. This avoids performance degradation caused by interfacial defects in traditional materials, laying a structural foundation for high strength and corrosion resistance. Furthermore, the selection of additives is highly compatible with the matrix characteristics. For instance, fluorinated polyolefin waxes and perfluoropolyether leveling agents are both fluorine-modified, improving processing fluidity without damaging the fluorine molecular barrier, ensuring synergistic performance without conflict.

[0138] From the perspective of molecular-level collaborative mechanisms, this application constructs a "multi-level network" to achieve a performance breakthrough. On the one hand, through the in-situ covalent reaction of bridging components (epoxy groups, terminal anhydride groups) and reactive components (amino groups, acid anhydride groups), a three-dimensional rigid network is formed that runs through the reinforcement (carbon fiber, BNNS) and the matrix. Stress can be efficiently transferred to the carbon fiber and polyimide backbone, avoiding intermolecular slippage and significantly improving mechanical strength. On the other hand, the fluorinated segments of ETFE, PTFE, fluorinated siloxanes, and fluorinated polyimides are tightly arranged through fluorine-fluorine interactions. Combined with the two-dimensional layered structure of BNNS and the micron-level interlacing of carbon fibers, a "multi-scale fluorine molecule-physical barrier" is constructed, which greatly extends the diffusion path of corrosive media and achieves excellent corrosion resistance. At the same time, the hydrogen bonds between PEI and BNNS form an "energy dissipation network". With the flexible segments of maleic anhydride-grafted elastomer, a "rigid phase (carbon fiber + polyimide) - flexible phase (elastomer + siloxane)" balanced system is constructed to overcome the contradiction of traditional materials being "strong and brittle" or "tough and soft", and to take into account excellent impact resistance on the basis of high strength.

[0139] From the perspective of the preparation process, this application innovates the "graded dispersion-precise temperature control-fiber protection" process system to ensure stable performance. Through the "functionalized masterbatch pre-dispersion" process, easily agglomerated BNNS, highly reactive components (epoxysiloxane, anhydride-terminated polyimide) are premixed with 10-30% ETFE, solving the problem of nano-component agglomeration from the source. The twin-screw extrusion adopts the "main feed melting-side feed plus carbon fiber" design, which ensures that the matrix and additives are fully melted and mixed, and avoids the breakage caused by the friction between carbon fibers and solid particles, maximizing the preservation of fiber aspect ratio and mechanical reinforcement effect. Hot pressing molding achieves material densification and optimizes crystallinity while avoiding internal stress and pore defects through "temperature control slightly below the melting point-stage pressurization-controlled cooling rate", further enhancing mechanical properties and corrosion resistance stability. In addition, the preparation processes of each key component have been optimized with parameters (such as the two-step method of "nitric acid oxidation-silane coupling" for aminated carbon fibers and the "low-temperature polycondensation-gradient imidization" for fluorinated anhydride-terminated polyimide) to ensure sufficient active sites and uniform structure, thus providing a guarantee for subsequent synergistic reactions.

[0140] In terms of performance, this application achieves a comprehensive balance of "high strength, high corrosion resistance, high toughness, and easy processing." Regarding mechanical properties, the synergistic effect of the three-dimensional covalent network and carbon fiber reinforcement ensures high modulus and high strength. For corrosion resistance, the dense fluorine molecular layer and the two-dimensional barrier of BNNS resist the penetration of corrosive media such as acids, alkalis, and solvents. In terms of toughness, hydrogen bond dissipation and flexibility work together to prevent brittle fracture under impact. Regarding processability, functionalized masterbatch and fluorine-based additives improve melt flowability, making it compatible with conventional processes such as twin-screw extrusion and hot pressing, and enabling the stable preparation of products in various shapes. Compared to traditional composite materials, this application does not sacrifice one property to improve another, truly achieving "comprehensive performance balance optimization." It can be widely adapted to high-end equipment shells, chemical corrosion-resistant components, electronic equipment protection, and other scenarios with high requirements for "strength, corrosion resistance, and toughness," possessing significant technical value and application prospects.

[0141] The present application is further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the application. Experimental methods in the following embodiments that do not specify specific conditions are generally determined according to industry standards. If there is no corresponding industry standard, then common international standards, conventional conditions, or conditions recommended by the manufacturer are followed.

[0142] Example 1

[0143] This embodiment provides a corrosion-resistant, high-strength carbon fiber ETFE composite material, which, by mass parts, is composed of the following chemical raw materials:

[0144] ETFE resin (purchased from Asahi Glass Co., Ltd., grade F-40, CAS No. 25038-71-5): 100 parts; Aminated carbon fiber: 20 parts; Maleic anhydride-grafted polyolefin elastomer: 10 parts; PTFE micropowder (purchased from DuPont, grade Teflon 6C, CAS No. 9002-84-0): 6 parts; Epoxy-terminated fluorosiloxane oligomer: 3 parts; Non-covalently modified boron nitride nanosheets with polyethyleneimine: 2.5 parts Fluorinated anhydride-terminated polyimide oligomer: 6.5 parts; Fluorinated polyolefin wax (PTFE-modified polyethylene wax, purchased from Klein Company, CAS No. 68442-62-6): 1.2 parts; Fluorinated leveling agent (perfluoropolyether-modified polyacrylate, purchased from Asahi Glass Co., Ltd., brand name CF-32): 0.3 parts; Nanoscale fumed silica (purchased from Degussa Company, brand name AEROSIL200, particle size approximately 12 nm, surface area approximately 200 m²) 2 / g): 1.2 parts.

[0145] The preparation method of aminated carbon fiber includes the following steps:

[0146] S101. The substrate carbon fiber (Toray T700) was immersed in a 65% nitric acid aqueous solution and refluxed at 90°C for 2 hours. After the reaction, it was repeatedly washed with deionized water until the pH of the washing solution was neutral. Then it was vacuum dried at 80°C for 6 hours to obtain surface carboxylated carbon fiber.

[0147] S102. The surface carboxylated carbon fiber is immersed in a 2% (w / w) γ-aminopropyltriethoxysilane (KH-550) ethanol solution and reacted at 70°C for 6 hours. After the reaction, the carbon fiber is taken out and washed with ethanol three times to remove unreacted silane reagent. Finally, it is vacuum dried at 60°C for 4 hours to obtain aminated carbon fiber.

[0148] The preparation method of maleic anhydride-grafted polyolefin elastomer includes the following steps:

[0149] S201. Polyethylene octene copolymer elastomer (purchased from Mitsui Chemicals, DF740), maleic anhydride monomer (CAS No. 108-31-6), and organic peroxide initiator (dicumyl peroxide, CAS No. 80-43-3) are premixed in a high-speed mixer at 70°C for 10 min to obtain a premix; wherein the mass of maleic anhydride monomer is 7.5% of the mass of polyethylene octene copolymer elastomer, and the mass of dicumyl peroxide is 0.3% of the mass of polyethylene octene copolymer elastomer;

[0150] S202. The premixed material is fed into a twin-screw extruder and subjected to a melt grafting reaction at 180°C. After the extrudate is cooled by water, it is cut into particles with a particle size of 2-3 mm by a pelletizer to obtain maleic anhydride grafted polyolefin elastomer.

[0151] The preparation method of epoxy-terminated fluorosiloxane oligomers includes the following steps:

[0152] S301. Hydrogen-containing silicone oil (CAS No. 68937-54-2, hydrogen content 0.18%), perfluorooctylethylene (CAS No. 21652-58-4), and allyl glycidyl ether (CAS No. 106-92-3) are dissolved in toluene. Under nitrogen protection, an isopropanol solution of chloroplatinic acid (chloroplatinic acid mass concentration 0.1%) is added, and the reaction is carried out at 85℃ for 8 hours. The molar ratio of perfluorooctylethylene to allyl glycidyl ether is 1:2, the molar ratio of silicon-hydrogen bonds in the hydrogen-containing silicone oil to the total molar ratio of carbon-carbon double bonds in perfluorooctylethylene and allyl glycidyl ether is 1:1.1, and the mass of chloroplatinic acid is 0.0075% of the total mass of the hydrogen-containing silicone oil, perfluorooctylethylene, and allyl glycidyl ether.

[0153] S302. After the reaction is complete, the reaction system is placed in a rotary evaporator and distilled under reduced pressure at 80℃ and -0.09MPa for 2 hours to remove the toluene solvent, thereby obtaining epoxy-terminated fluorosiloxane oligomers.

[0154] The preparation method of non-covalently modified boron nitride nanosheets with polyethyleneimine includes the following steps:

[0155] S401. Boron nitride powder (CAS No. 10043-11-5, average particle size 1μm) was added to N-methylpyrrolidone to prepare a dispersion with a mass concentration of 5%. The dispersion was ultrasonically broken up and exfoliated at 1000W power for 6 hours using an ultrasonic crusher. Then, it was centrifuged at 8000rpm for 15 minutes, and the supernatant was taken to obtain a boron nitride nanosheet dispersion.

[0156] S402. Hyperbranched polyethyleneimine (CAS No. 9002-98-6, average molecular weight 17500) was dissolved in deionized water to prepare a 10% (w / w) aqueous solution. The aqueous solution was added to the boron nitride nanosheet dispersion at a mass ratio of polyethyleneimine to boron nitride powder of 1:7.5. The mixture was stirred at 500 rpm for 4 h. After the reaction, the mixture was centrifuged at 10000 rpm for 20 min, the precipitate was collected, washed three times with deionized water, and then vacuum dried at 70 °C for 8 h to obtain non-covalently modified boron nitride nanosheets with polyethyleneimine.

[0157] The preparation method of fluorinated anhydride-terminated polyimide oligomers includes the following steps:

[0158] S501. 4,4'-(hexafluoroisopropylidene) phthalic anhydride (CAS No. 1107-00-2) and 2,2-bis(trifluoromethyl)benzidine (CAS No. 341-58-2) are mixed in N,N-dimethylformamide (a polar aprotic solvent) and subjected to a polycondensation reaction at -5°C for 9 hours under nitrogen protection to obtain a fluorinated polyamic acid prepolymer solution; wherein the molar ratio of 4,4'-(hexafluoroisopropylidene) phthalic anhydride to 2,2-bis(trifluoromethyl)benzidine is 1.1:1;

[0159] S502. Add a mixed solution of acetic anhydride and pyridine (volume ratio 2.5:1) to the fluorinated polyamic acid prepolymer solution, raise the system temperature to 30℃, and react at a constant temperature for 12h. After the reaction is completed, drop the reaction solution into deionized water to precipitate the precipitate, filter and collect the precipitate, wash it twice with ethanol, and then dry it under vacuum at 120℃ for 6h to obtain the fluorinated anhydride-terminated polyimide oligomer.

[0160] Based on the chemical composition of the above-mentioned carbon fiber ETFE composite material, this embodiment also provides a method for preparing a corrosion-resistant high-strength carbon fiber ETFE composite material, including the following steps:

[0161] S1. According to the formula, add the non-covalently modified boron nitride nanosheets of polyethyleneimine, epoxy-terminated fluorinated siloxane oligomer, fluorinated anhydride-terminated polyimide oligomer and 20% by mass of ETFE resin (i.e., 20 parts) into a high-speed mixer, set the stirring speed to 1500 rpm and the mixing temperature to 80℃, mix for 30 min and then discharge the material to obtain functionalized masterbatch;

[0162] S2. The functionalized masterbatch, the remaining 80% by mass of ETFE resin (i.e., 80 parts), maleic anhydride-grafted polyolefin elastomer, PTFE micro powder, fluorinated polyolefin wax, fluorinated leveling agent, and nano-sized fumed silica are placed in the main feed port of a twin-screw extruder. The twin-screw extruder is set to a processing temperature of 320℃ (temperatures of each section: feeding section 300℃, compression section 310℃, melting section 320℃, homogenization section 320℃, and die head 315℃) and a screw speed of 300 rpm for melt blending. After the material is completely melted in the barrel, aminated carbon fiber is added through the side feed port. After blending for another 10 minutes, the mixture is extruded from the die head, cooled by water, and pelletized by a pelletizer to obtain composite granules with a particle size of 2-3 mm.

[0163] S3. Add the composite granules into the mold of the hot press molding machine, set the hot pressing temperature to 280℃ and the pressure to 15MPa, maintain the constant temperature and pressure for 10 minutes, and then let it cool naturally to room temperature. After demolding, the corrosion-resistant high-strength carbon fiber ETFE composite material is obtained.

[0164] Example 2

[0165] This embodiment provides a corrosion-resistant, high-strength carbon fiber ETFE composite material, which, by mass parts, is composed of the following chemical raw materials:

[0166] ETFE resin: 100 parts; Aminated carbon fiber: 15 parts; Maleic anhydride-grafted polyolefin elastomer: 8 parts; PTFE micro powder: 4 parts; Epoxy-terminated fluorinated siloxane oligomer: 2 parts; Polyethyleneimine non-covalently modified boron nitride nanosheets: 1.8 parts; Fluorinated anhydride-terminated polyimide oligomer: 5 parts; Fluorinated polyolefin wax (PTFE-modified polyethylene wax): 1.0 part; Fluorinated leveling agent (perfluoropolyether-modified polyacrylate): 0.2 parts; Nanoscale fumed silica (particle size approximately 10 nm, surface area approximately 180 m²) 2 / g): 1.0 part.

[0167] The preparation method of aminated carbon fiber includes the following steps:

[0168] S101. The substrate carbon fiber is immersed in a 60% nitric acid aqueous solution and refluxed at 85°C for 1.5 hours. After the reaction, it is repeatedly washed with deionized water until the pH of the washing solution is neutral. Then it is vacuum dried at 75°C for 5 hours to obtain surface carboxylated carbon fiber.

[0169] S102. The surface carboxylated carbon fiber is immersed in a 1.5% (w / w) γ-aminopropyltriethoxysilane ethanol solution and reacted at 65°C for 5 hours. After the reaction, the carbon fiber is taken out and washed three times with ethanol to remove unreacted silane reagent. Finally, it is vacuum dried at 55°C for 3.5 hours to obtain aminated carbon fiber.

[0170] The preparation method of maleic anhydride-grafted polyolefin elastomer includes the following steps:

[0171] S201. Polyethylene octene copolymer elastomer, maleic anhydride monomer, and organic peroxide initiator (dicumyl peroxide) are premixed in a high-speed mixer at 65°C for 8 minutes to obtain a premix; wherein the mass of maleic anhydride monomer is 6% of the mass of polyethylene octene copolymer elastomer, and the mass of dicumyl peroxide is 0.25% of the mass of polyethylene octene copolymer elastomer;

[0172] S202. The premixed material is fed into a twin-screw extruder and subjected to a melt grafting reaction at 170°C. After the extrudate is cooled by water, it is cut into particles with a particle size of 2-3 mm by a pelletizer to obtain maleic anhydride grafted polyolefin elastomer.

[0173] The preparation method of epoxy-terminated fluorosiloxane oligomers includes the following steps:

[0174] S301. Hydrogen-containing silicone oil (hydrogen content 0.16%), perfluorooctylethylene, and allyl glycidyl ether are dissolved in toluene. Under nitrogen protection, an isopropanol solution of chloroplatinic acid (chloroplatinic acid mass concentration 0.1%) is added, and the reaction is carried out at 80°C for 7 hours. The molar ratio of perfluorooctylethylene to allyl glycidyl ether is 1:1.8, the molar ratio of silicon-hydrogen bonds in the hydrogen-containing silicone oil to the total molar ratio of carbon-carbon double bonds in the perfluorooctylethylene and allyl glycidyl ether is 1:1.05, and the mass of chloroplatinic acid is 0.006% of the total mass of the hydrogen-containing silicone oil, perfluorooctylethylene, and allyl glycidyl ether.

[0175] S302. After the reaction is complete, the reaction system is placed in a rotary evaporator and distilled under reduced pressure at 75℃ and -0.085MPa for 1.5h to remove the toluene solvent, and epoxy-terminated fluorosiloxane oligomers are obtained.

[0176] The preparation method of non-covalently modified boron nitride nanosheets with polyethyleneimine includes the following steps:

[0177] S401. Add boron nitride powder (average particle size 1.2 μm) to N-methylpyrrolidone to prepare a dispersion with a mass concentration of 4%. Use an ultrasonic crusher to ultrasonically crush and peel the particles at a power of 900W for 5 hours. Then centrifuge at a speed of 7500rpm for 12 minutes and take the supernatant to obtain a boron nitride nanosheet dispersion.

[0178] S402. Hyperbranched polyethyleneimine (average molecular weight 15000) was dissolved in deionized water to prepare an 8% (w / w) aqueous solution. The aqueous solution was added to the boron nitride nanosheet dispersion at a mass ratio of 1:6 (w / w) of polyethyleneimine to boron nitride powder. The mixture was stirred at 450 rpm for 3.5 h. After the reaction, the mixture was centrifuged at 9000 rpm for 18 min, the precipitate was collected, washed three times with deionized water, and then dried under vacuum at 65 °C for 7 h to obtain non-covalently modified boron nitride nanosheets with polyethyleneimine.

[0179] The preparation method of fluorinated anhydride-terminated polyimide oligomers includes the following steps:

[0180] S501. 4,4'-(hexafluoroisopropylidene) phthalic anhydride and 2,2-bis(trifluoromethyl)benzidine are mixed in N,N-dimethylformamide (a polar aprotic solvent) and subjected to a polycondensation reaction at -8°C for 8 hours under nitrogen protection to obtain a fluorinated polyamic acid prepolymer solution; wherein the molar ratio of 4,4'-(hexafluoroisopropylidene) phthalic anhydride to 2,2-bis(trifluoromethyl)benzidine is 1.08:1;

[0181] S502. Add a mixed solution of acetic anhydride and pyridine (volume ratio 2:1) to the fluorinated polyamic acid prepolymer solution, raise the system temperature to 25℃, and react at a constant temperature for 10h. After the reaction is completed, drop the reaction solution into deionized water to precipitate the precipitate, filter and collect the precipitate, wash it twice with ethanol, and then dry it under vacuum at 110℃ for 5h to obtain the fluorinated anhydride-terminated polyimide oligomer.

[0182] Based on the chemical composition of the above-mentioned carbon fiber ETFE composite material, this embodiment also provides a method for preparing a corrosion-resistant high-strength carbon fiber ETFE composite material, including the following steps:

[0183] S1. According to the formula, add non-covalently modified boron nitride nanosheets of polyethyleneimine, epoxy-terminated fluorinated siloxane oligomer, fluorinated anhydride-terminated polyimide oligomer and 15% by mass of ETFE resin (i.e., 15 parts) into a high-speed mixer, set the stirring speed to 1400 rpm and the mixing temperature to 75℃, mix for 25 min and then discharge the material to obtain functionalized masterbatch;

[0184] S2. The functionalized masterbatch, the remaining 85% by mass of ETFE resin (i.e., 85 parts), maleic anhydride-grafted polyolefin elastomer, PTFE micro powder, fluorinated polyolefin wax, fluorinated leveling agent, and nano-sized fumed silica are placed in the main feed port of a twin-screw extruder. The twin-screw extruder is set to a processing temperature of 310℃ (temperatures of each section: feeding section 290℃, compression section 300℃, melting section 310℃, homogenization section 310℃, and die head 305℃) and a screw speed of 280 rpm for melt blending. After the material is completely melted in the barrel, aminated carbon fiber is added through the side feed port. After blending for another 8 minutes, the mixture is extruded from the die head, cooled by water, and pelletized by a pelletizer to obtain composite granules with a particle size of 2-3 mm.

[0185] S3. Add the composite granules into the mold of the hot press molding machine, set the hot pressing temperature to 270℃ and the pressure to 14MPa, maintain the constant temperature and pressure for 8 minutes, and then let it cool naturally to room temperature. After demolding, the corrosion-resistant high-strength carbon fiber ETFE composite material is obtained.

[0186] Example 3

[0187] This embodiment provides a corrosion-resistant, high-strength carbon fiber ETFE composite material, which, by mass parts, is composed of the following chemical raw materials:

[0188] ETFE resin: 100 parts; Aminated carbon fiber: 25 parts; Maleic anhydride-grafted polyolefin elastomer: 12 parts; PTFE micro powder: 8 parts; Epoxy-terminated fluorinated siloxane oligomer: 4 parts; Polyethyleneimine non-covalently modified boron nitride nanosheets: 4 parts; Fluorinated anhydride-terminated polyimide oligomer: 8.5 parts; Fluorinated polyolefin wax (PTFE-modified polyethylene wax): 1.8 parts; Fluorinated leveling agent (perfluoropolyether-modified polyacrylate): 0.4 parts; Nanoscale fumed silica (particle size approximately 15 nm, surface area approximately 220 m²) 2 / g): 1.8 parts.

[0189] The preparation method of aminated carbon fiber includes the following steps:

[0190] S101. The substrate carbon fiber is immersed in a 70% nitric acid aqueous solution and refluxed at 95°C for 2.5 hours. After the reaction, it is repeatedly washed with deionized water until the pH of the washing solution is neutral. Then it is vacuum dried at 85°C for 7 hours to obtain surface carboxylated carbon fiber.

[0191] S102. The surface carboxylated carbon fiber is immersed in a 2.5% (w / w) γ-aminopropyltriethoxysilane ethanol solution and reacted at 75°C for 7 hours. After the reaction, the carbon fiber is taken out and washed three times with ethanol to remove unreacted silane reagent. Finally, it is vacuum dried at 65°C for 4.5 hours to obtain aminated carbon fiber.

[0192] The preparation method of maleic anhydride-grafted polyolefin elastomer includes the following steps:

[0193] S201. Polyethylene octene copolymer elastomer, maleic anhydride monomer, and organic peroxide initiator (dicumyl peroxide) are premixed in a high-speed mixer at 75°C for 12 min to obtain a premix; wherein, the mass of maleic anhydride monomer is 9% of the mass of polyethylene octene copolymer elastomer, and the mass of dicumyl peroxide is 0.4% of the mass of polyethylene octene copolymer elastomer;

[0194] S202. The premixed material is fed into a twin-screw extruder and subjected to a melt grafting reaction at 190°C. After the extrudate is cooled by water, it is cut into particles with a particle size of 2-3 mm by a pelletizer to obtain maleic anhydride grafted polyolefin elastomer.

[0195] The preparation method of epoxy-terminated fluorosiloxane oligomers includes the following steps:

[0196] S301. Hydrogen-containing silicone oil (hydrogen content 0.20%), perfluorooctylethylene, and allyl glycidyl ether are dissolved in toluene. Under nitrogen protection, an isopropanol solution of chloroplatinic acid (chloroplatinic acid mass concentration 0.1%) is added, and the reaction is carried out at 90℃ for 9 hours. The molar ratio of perfluorooctylethylene to allyl glycidyl ether is 1:2.2, the molar ratio of silicon-hydrogen bonds in the hydrogen-containing silicone oil to the total molar ratio of carbon-carbon double bonds in the perfluorooctylethylene and allyl glycidyl ether is 1:1.15, and the mass of chloroplatinic acid is 0.009% of the total mass of the hydrogen-containing silicone oil, perfluorooctylethylene, and allyl glycidyl ether.

[0197] S302. After the reaction is complete, the reaction system is placed in a rotary evaporator and distilled under reduced pressure at 85℃ and -0.095MPa for 2.5h to remove the toluene solvent, and epoxy-terminated fluorosiloxane oligomers are obtained.

[0198] The preparation method of non-covalently modified boron nitride nanosheets with polyethyleneimine includes the following steps:

[0199] S401. Add boron nitride powder (average particle size 0.8 μm) to N-methylpyrrolidone to prepare a dispersion with a mass concentration of 6%. Use an ultrasonic crusher to ultrasonically crush and peel the particles at a power of 1100W for 7 hours. Then centrifuge at a speed of 8500rpm for 18 minutes and take the supernatant to obtain a boron nitride nanosheet dispersion.

[0200] S402. Hyperbranched polyethyleneimine (average molecular weight of 20,000) was dissolved in deionized water to prepare a 12% (w / w) aqueous solution. The aqueous solution was added to the boron nitride nanosheet dispersion at a mass ratio of 1:9 (w / w) of polyethyleneimine to boron nitride powder. The mixture was stirred at 550 rpm for 4.5 h. After the reaction, the mixture was centrifuged at 11,000 rpm for 22 min, the precipitate was collected, washed three times with deionized water, and then vacuum dried at 75 °C for 9 h to obtain non-covalently modified boron nitride nanosheets with polyethyleneimine.

[0201] The preparation method of fluorinated anhydride-terminated polyimide oligomers includes the following steps:

[0202] S501. 4,4'-(hexafluoroisopropylidene) phthalic anhydride and 2,2-bis(trifluoromethyl)benzidine are mixed in N,N-dimethylformamide (a polar aprotic solvent) and subjected to a polycondensation reaction at -2°C for 10 h under nitrogen protection to obtain a fluorinated polyamic acid prepolymer solution; wherein the molar ratio of 4,4'-(hexafluoroisopropylidene) phthalic anhydride to 2,2-bis(trifluoromethyl)benzidine is 1.12:1;

[0203] S502. Add a mixed solution of acetic anhydride and pyridine (volume ratio 2.8:1) to the fluorinated polyamic acid prepolymer solution, raise the system temperature to 35℃, and react at a constant temperature for 14h. After the reaction is completed, drop the reaction solution into deionized water to precipitate the precipitate, filter and collect the precipitate, wash it twice with ethanol, and then dry it under vacuum at 130℃ for 7h to obtain the fluorinated anhydride-terminated polyimide oligomer.

[0204] Based on the chemical composition of the above-mentioned carbon fiber ETFE composite material, this embodiment also provides a method for preparing a corrosion-resistant high-strength carbon fiber ETFE composite material, including the following steps:

[0205] S1. According to the formula, add non-covalently modified boron nitride nanosheets of polyethyleneimine, epoxy-terminated fluorinated siloxane oligomer, fluorinated anhydride-terminated polyimide oligomer and 25% by mass of ETFE resin (i.e., 25 parts) into a high-speed mixer, set the stirring speed to 1600 rpm and the mixing temperature to 85℃, mix for 35 min and then discharge the material to obtain functionalized masterbatch;

[0206] S2. The functionalized masterbatch, the remaining 75% by mass of ETFE resin (i.e., 75 parts), maleic anhydride-grafted polyolefin elastomer, PTFE micro powder, fluorinated polyolefin wax, fluorinated leveling agent, and nano-grade fumed silica are placed in the main feed port of a twin-screw extruder. The twin-screw extruder is set to a processing temperature of 330℃ (temperatures of each section: feeding section 310℃, compression section 320℃, melting section 330℃, homogenization section 330℃, and die head 325℃) and a screw speed of 320 rpm for melt blending. After the material is completely melted in the barrel, aminated carbon fiber is added through the side feed port. After blending for another 12 minutes, the mixture is extruded from the die head, cooled by water, and pelletized by a pelletizer to obtain composite granules with a particle size of 2-3 mm.

[0207] S3. Add the composite granules into the mold of the hot press molding machine, set the hot pressing temperature to 290℃ and the pressure to 16MPa, maintain the constant temperature and pressure for 12 minutes, and then let it cool naturally to room temperature. After demolding, the corrosion-resistant high-strength carbon fiber ETFE composite material is obtained.

[0208] Example 4

[0209] This embodiment provides a corrosion-resistant, high-strength carbon fiber ETFE composite material, which, by mass parts, is composed of the following chemical raw materials:

[0210] ETFE resin: 100 parts; Aminated carbon fiber: 10 parts; Maleic anhydride-grafted polyolefin elastomer: 5 parts; PTFE micro powder: 2 parts; Epoxy-terminated fluorinated siloxane oligomer: 1 part; Polyethyleneimine non-covalently modified boron nitride nanosheets: 0.5 parts; Fluorinated anhydride-terminated polyimide oligomer: 3 parts; Fluorinated polyolefin wax (PTFE-modified polyethylene wax): 0.5 parts; Fluorinated leveling agent (perfluoropolyether-modified polyacrylate): 0.1 parts; Nanoscale fumed silica (particle size approximately 8 nm, surface area approximately 160 m²) 2 / g): 0.5 parts.

[0211] The preparation method of aminated carbon fiber includes the following steps:

[0212] S101. The substrate carbon fiber is immersed in a 55% nitric acid aqueous solution and refluxed at 80°C for 1 hour. After the reaction, it is repeatedly washed with deionized water until the pH of the washing solution is neutral. Then it is vacuum dried at 70°C for 4 hours to obtain surface carboxylated carbon fiber.

[0213] S102. The surface carboxylated carbon fiber is immersed in a 1% (w / w) γ-aminopropyltriethoxysilane ethanol solution and reacted at 60°C for 4 hours. After the reaction, the carbon fiber is taken out and washed three times with ethanol to remove unreacted silane reagent. Finally, it is vacuum dried at 50°C for 3 hours to obtain aminated carbon fiber.

[0214] The preparation method of maleic anhydride-grafted polyolefin elastomer includes the following steps:

[0215] S201. Polyethylene octene copolymer elastomer, maleic anhydride monomer, and organic peroxide initiator (dicumyl peroxide) are premixed in a high-speed mixer at 60°C for 5 min to obtain a premix; wherein, the mass of maleic anhydride monomer is 5% of the mass of polyethylene octene copolymer elastomer, and the mass of dicumyl peroxide is 0.1% of the mass of polyethylene octene copolymer elastomer;

[0216] S202. The premixed material is fed into a twin-screw extruder and subjected to a melt grafting reaction at 160°C. After the extrudate is cooled by water, it is cut into particles with a particle size of 2-3 mm by a pelletizer to obtain maleic anhydride grafted polyolefin elastomer.

[0217] The preparation method of epoxy-terminated fluorosiloxane oligomers includes the following steps:

[0218] S301. Hydrogen-containing silicone oil (hydrogen content 0.15%), perfluorooctylethylene, and allyl glycidyl ether are dissolved in toluene. Under nitrogen protection, an isopropanol solution of chloroplatinic acid (chloroplatinic acid mass concentration 0.1%) is added, and the reaction is carried out at 75°C for 6 hours. The molar ratio of perfluorooctylethylene to allyl glycidyl ether is 1:1.5, the molar ratio of silicon-hydrogen bonds in the hydrogen-containing silicone oil to the total molar ratio of carbon-carbon double bonds in the perfluorooctylethylene and allyl glycidyl ether is 1:1.0, and the mass of chloroplatinic acid is 0.005% of the total mass of the hydrogen-containing silicone oil, perfluorooctylethylene, and allyl glycidyl ether.

[0219] S302. After the reaction is complete, the reaction system is placed in a rotary evaporator and distilled under reduced pressure at 70℃ and -0.08MPa for 1h to remove the toluene solvent, thereby obtaining epoxy-terminated fluorosiloxane oligomers.

[0220] The preparation method of non-covalently modified boron nitride nanosheets with polyethyleneimine includes the following steps:

[0221] S401. Add boron nitride powder (average particle size 1.5 μm) to N-methylpyrrolidone to prepare a dispersion with a mass concentration of 3%. Use an ultrasonic crusher to ultrasonically crush and peel the particles at a power of 800W for 4 hours. Then centrifuge at a speed of 7000rpm for 10 minutes and take the supernatant to obtain a boron nitride nanosheet dispersion.

[0222] S402. Hyperbranched polyethyleneimine (average molecular weight 12000) was dissolved in deionized water to prepare a 5% (w / w) aqueous solution. The aqueous solution was added to the boron nitride nanosheet dispersion at a mass ratio of 1:5 (w / w) of polyethyleneimine to boron nitride powder. The mixture was stirred at 400 rpm for 3 h. After the reaction, the mixture was centrifuged at 8000 rpm for 15 min, the precipitate was collected, washed three times with deionized water, and then vacuum dried at 60 °C for 6 h to obtain non-covalently modified boron nitride nanosheets with polyethyleneimine.

[0223] The preparation method of fluorinated anhydride-terminated polyimide oligomers includes the following steps:

[0224] S501. 4,4'-(hexafluoroisopropylidene) phthalic anhydride and 2,2-bis(trifluoromethyl)benzidine are mixed in N,N-dimethylformamide (a polar aprotic solvent) and subjected to a polycondensation reaction at -10°C for 6 hours under nitrogen protection to obtain a fluorinated polyamic acid prepolymer solution; wherein the molar ratio of 4,4'-(hexafluoroisopropylidene) phthalic anhydride to 2,2-bis(trifluoromethyl)benzidine is 1.05:1;

[0225] S502. Add a mixed solution of acetic anhydride and pyridine (volume ratio 2:1) to the fluorinated polyamic acid prepolymer solution, raise the system temperature to 20℃, and react at a constant temperature for 8 hours. After the reaction is completed, drop the reaction solution into deionized water to precipitate the precipitate, filter and collect the precipitate, wash it twice with ethanol, and then dry it under vacuum at 100℃ for 4 hours to obtain the fluorinated anhydride-terminated polyimide oligomer.

[0226] Based on the chemical composition of the above-mentioned carbon fiber ETFE composite material, this embodiment also provides a method for preparing a corrosion-resistant high-strength carbon fiber ETFE composite material, including the following steps:

[0227] S1. According to the formula, add non-covalently modified boron nitride nanosheets of polyethyleneimine, epoxy-terminated fluorinated siloxane oligomer, fluorinated anhydride-terminated polyimide oligomer and 10% by mass of ETFE resin (i.e., 10 parts) into a high-speed mixer, set the stirring speed to 1300 rpm and the mixing temperature to 70℃, mix for 20 min and then discharge the material to obtain functionalized masterbatch;

[0228] S2. The functionalized masterbatch, the remaining 90% by mass of ETFE resin (i.e., 90 parts), maleic anhydride-grafted polyolefin elastomer, PTFE micro powder, fluorinated polyolefin wax, fluorinated leveling agent, and nano-grade fumed silica are placed in the main feed port of a twin-screw extruder. The twin-screw extruder is set to a processing temperature of 300℃ (temperatures of each section: feeding section 280℃, compression section 290℃, melting section 300℃, homogenization section 300℃, and die head 295℃) and a screw speed of 200 rpm for melt blending. After the material is completely melted in the barrel, aminated carbon fiber is added through the side feed port. After blending for another 5 minutes, the mixture is extruded through the die head, cooled by water, and pelletized by a pelletizer to obtain composite granules with a particle size of 2-3 mm.

[0229] S3. Add the composite granules into the mold of the hot press molding machine, set the hot pressing temperature to 260℃ and the pressure to 13MPa, maintain the constant temperature and pressure for 5 minutes, and then let it cool naturally to room temperature. After demolding, the corrosion-resistant high-strength carbon fiber ETFE composite material is obtained.

[0230] Comparative Example 1

[0231] This comparative example provides a carbon fiber ETFE composite material, which, by mass parts, is composed of the following chemical raw materials: ETFE resin: 100 parts; carbon fiber: 20 parts.

[0232] Comparative Example 2

[0233] This comparative example is modified from the one disclosed in Example 1 as follows:

[0234] The chemical raw materials of carbon fiber ETFE composite materials do not contain maleic anhydride-grafted polyolefin elastomers.

[0235] Comparative Example 3

[0236] This comparative example is modified from the one disclosed in Example 1 as follows:

[0237] The chemical raw materials of carbon fiber ETFE composite materials do not contain PTFE micro powder.

[0238] Comparative Example 4

[0239] This comparative example is modified from the one disclosed in Example 1 as follows:

[0240] The chemical raw materials of carbon fiber ETFE composites do not contain epoxy-terminated fluorinated siloxane oligomers.

[0241] Comparative Example 5

[0242] This comparative example is modified from the one disclosed in Example 1 as follows:

[0243] The chemical raw materials of carbon fiber ETFE composites do not contain non-covalently modified boron nitride nanosheets of polyethyleneimine.

[0244] Comparative Example 6

[0245] This comparative example is modified from the one disclosed in Example 1 as follows:

[0246] The chemical raw materials of carbon fiber ETFE composites do not contain fluorinated anhydride-terminated polyimide oligomers.

[0247] The corrosion-resistant high-strength carbon fiber ETFE composite materials obtained in Examples 1-4 and Comparative Examples 1-6 were subjected to performance testing, and the results are shown in Tables 1 and 2. The performance testing methods are as follows:

[0248] (1) Mechanical properties

[0249] Tensile strength: Refer to GB / T 1040.2-2006, using a universal testing machine.

[0250] Bending strength: Refer to GB / T 9341-2008.

[0251] Impact strength: Refer to GB / T 1043.1-2008 (simply supported beam without notch).

[0252] (2) Corrosion resistance

[0253] Salt spray 96h attenuation rate: Refer to GB / T 10125-2021, the attenuation rate of tensile strength after 96 hours in 5% NaCl spray.

[0254] Acid / alkali resistance: Refer to GB / T 11547-2008, immerse the sample in 5% H2SO4 or 5% NaOH solution (room temperature, 24h), and measure the rate of mass change.

[0255] (3) Heat distortion temperature: Refer to GB / T 1634.2-2004 (load 1.8 MPa).

[0256] Table 1. Properties of corrosion-resistant high-strength carbon fiber ETFE composites in Examples 1-4

[0257] Group Tensile strength (MPa) Bending strength (MPa) <![CDATA[Impact strength (kJ / m 2 )]]> Salt spray 96h attenuation rate (%) <![CDATA[Mass change rate of 5% H2SO4 (%)]]> 5% NaOH mass change rate (%) Heat distortion temperature (°C) Example 1 104.7 154.3 44.5 4.5 0.35 0.62 132 Example 2 93.8 142.5 40.1 5.2 0.44 0.74 128 Example 3 112.9 171.1 48.3 3.8 0.28 0.51 135 Example 4 94.6 142.3 39.6 5.1 0.45 0.73 129

[0258] As shown in Table 1, the carbon fiber ETFE composite materials of Examples 1-4 exhibit outstanding comprehensive performance, achieving a synergistic unity of high strength, good toughness, excellent corrosion resistance, and stable heat resistance: tensile strength ranges from 93.8 to 112.9 MPa, and flexural strength ranges from 142.3 to 171.1 MPa, demonstrating strong structural load-bearing capacity; impact strength reaches 39.6 to 48.3 kJ / m², with good toughness, effectively resisting external impacts; corrosion resistance is particularly excellent, with a salt spray decay rate of only 3.8% to 5.2% after 96 hours, a 5% H₂SO₄ mass change rate of 0.28% to 0.45%, and a 5% NaOH mass change rate of 0.51% to 0.74%, effectively resisting acid, alkali, and salt spray erosion; the heat distortion temperature is stable at 128 to 135℃, exhibiting good heat resistance stability, and the overall performance is suitable for applications with high requirements for material mechanics and corrosion resistance.

[0259] Table 2. Properties of corrosion-resistant high-strength carbon fiber ETFE composites from Comparative Examples 1–6

[0260] Group Tensile strength (MPa) Bending strength (MPa) <![CDATA[Impact strength (kJ / m 2 )]]> Salt spray 96h attenuation rate (%) <![CDATA[Mass change rate of 5% H2SO4 (%)]]> 5% NaOH mass change rate (%) Heat distortion temperature (°C) Comparative Example 1 48.4 74.2 25.4 12.6 1.51 1.81 118 Comparative Example 2 90.1 130.1 18.1 5.1 0.42 0.72 126 Comparative Example 3 102.3 148.4 42.2 5.8 0.61 0.94 131 Comparative Example 4 82.3 121.2 38.4 7.4 0.55 0.85 125 Comparative Example 5 98.4 146.7 41.6 5.5 0.52 0.82 129 Comparative Example 6 92.2 133.1 39.3 6.2 0.48 0.78 122

[0261] As shown in Table 2, Comparative Example 1, containing only ETFE resin and ordinary carbon fiber without any interface modification or functional components, resulted in significantly inferior performance: the interface between ordinary carbon fiber and ETFE was weak, stress could not be effectively transferred, and the tensile strength (48.4 MPa) and flexural strength (74.2 MPa) were only about half of those in Example 1; lacking toughening components, the impact strength (25.4 kJ / m) was also significantly lower. 2 The corrosion resistance is significantly lower than that of the example; without anti-corrosion auxiliary components (such as PTFE, BNNS), the 96-hour salt spray decay rate (12.6%) and acid-base mass change rate (1.51%~1.81%) are far higher than those of the example, and the corrosion resistance is greatly reduced; at the same time, due to the absence of rigid cross-linking components, the heat distortion temperature (118°C) is also lower than that of the example.

[0262] Comparative Example 2, which lacks maleic anhydride-grafted polyolefin elastomer, suffers from a critical problem: a sharp drop in impact strength (18.1 kJ / m). 2(Only about 40% of that in Example 1): This elastomer, as a "soft phase", can absorb impact energy and inhibit crack propagation. Its absence increases the brittleness of the material. Although its mechanical strength (tensile strength 90.1 MPa, bending strength 130.1 MPa) and corrosion resistance (salt spray 5.1%) are better than those of Comparative Example 1, its overall performance is unbalanced due to the loss of toughness.

[0263] Comparative Example 3, lacking PTFE micropowder, suffers from poor corrosion resistance as its main weakness. PTFE can form a dense fluorine barrier with ETFE, reducing the penetration of corrosive media. However, without PTFE, the 96-hour salt spray decay rate (5.8%), the 5% H2SO4 mass change rate (0.61%), and the 5% NaOH mass change rate (0.94%) are all higher than in Example 1. Furthermore, due to the incomplete fluorine barrier, corrosive media can penetrate more easily. However, PTFE does not directly participate in mechanical reinforcement, therefore its tensile (102.3 MPa), flexural (148.4 MPa), and impact (42.2 kJ / m) resistances are significantly lower. 2 The mechanical properties are similar to those of Example 1.

[0264] Comparative Example 4: Fluorosiloxane oligomers lacking epoxy-terminated groups. This component acts as a "molecular bridge" to strengthen interfacial bonding. Its absence worsens the interfacial adhesion between carbon fibers and the ETFE matrix, resulting in a significant decrease in tensile strength (82.3 MPa) and flexural strength (121.2 MPa) compared to Example 1. Simultaneously, the increased interfacial defects create channels for corrosive media penetration, leading to an increased salt spray decay rate (7.4%) and weakened corrosion resistance. Impact strength (38.4 kJ / m²) also decreased. 2 The value was also slightly reduced due to poor interfacial stress transmission.

[0265] Compared to Example 5, which lacks non-covalent modification of polyethyleneimine (BNNS), the two-dimensional barrier and nano-reinforcing effects of BNNS disappear: the material density decreases, the salt spray decay rate (5.5%) and acid-base mass change rate (0.52%–0.82%) are slightly higher than in Example 1, and the corrosion resistance declines slightly; at the same time, the stress-dispersing effect of BNNS is lost, and the tensile (98.4 MPa) and flexural (146.7 MPa) strengths are slightly lower than in Example 1, with only the impact performance (41.6 kJ / m) decreasing. 2 It is less affected.

[0266] Comparative Example 6 lacks fluorinated anhydride-terminated polyimide oligomers, which are the core components for constructing the rigid crosslinked network. After its absence, the three-dimensional reinforcing network is incomplete, and the tensile (92.2 MPa) and flexural (133.1 MPa) strengths decrease. Furthermore, the rigid imide structure is reduced, the thermal stability of the molecular chain decreases, and the heat distortion temperature (122°C) is significantly lower than that of Example 1 (132°C). At the same time, due to insufficient crosslinking, the interfacial sealing performance decreases, and the salt spray decay rate (6.2%) also increases slightly.

[0267] Various embodiments of this application may exist in the form of a range; it should be understood that the description in the form of a range is merely for convenience and brevity and should not be construed as a hard limitation on the scope of this application; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical values ​​within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single numbers within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. Furthermore, whenever a numerical range is referred to herein, it means including any referenced number (fraction or integer) within the referred range.

[0268] Furthermore, in the description of this application, the terms "comprising," "including," etc., mean "including but not limited to." In this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations.

[0269] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A corrosion-resistant, high-strength carbon fiber ETFE composite material, characterized in that, The carbon fiber ETFE composite material is composed of the following raw materials in parts by weight: ETFE resin: 100 parts, aminated carbon fiber: 10-30 parts, maleic anhydride grafted polyolefin elastomer: 5-15 parts, PTFE micro powder: 2-10 parts, epoxy-terminated fluorinated siloxane oligomer: 1-5 parts, polyethyleneimine non-covalently modified boron nitride nanosheets: 0.5-5 parts, fluorinated anhydride-terminated polyimide oligomer: 3-10 parts, fluorinated polyolefin wax: 0.5-2 parts, fluorinated leveling agent: 0.1-0.5 parts, nano-sized fumed silica: 0.5-2 parts; Among them, the surface amino groups of the aminated carbon fiber, the surface amino groups of the non-covalently modified boron nitride nanosheets of polyethyleneimine, and the anhydride groups of the maleic anhydride-grafted polyolefin elastomer are reactive components. The epoxy groups of the epoxy-terminated fluorinated siloxane oligomer and the anhydride groups of the fluorinated anhydride-terminated polyimide oligomer are bridging components. The bridging component and the reactive component undergo covalent bonding through in-situ interfacial reaction, forming a covalently connected network structure. The preparation method of the epoxy-terminated fluorinated siloxane oligomer includes the following steps: S301. Dissolve hydrogen-containing silicone oil, perfluoroalkyl olefin and allyl glycidyl ether in toluene, add isopropanol solution of chloroplatinic acid under nitrogen protection, and react at 80-90℃ for 6-10 h. S302. After the reaction is complete, the solvent is removed by vacuum distillation to obtain the epoxy-terminated fluorinated siloxane oligomer. Wherein, the perfluoroalkyl olefin is perfluorooctylethylene; The molar ratio of the perfluoroalkyl olefin to the allyl glycidyl ether is 1:(1.5-2.5); The mass of the chloroplatinic acid is 0.005 to 0.01% of the total mass of the hydrogen-containing silicone oil, the perfluoroalkyl olefin, and the allyl glycidyl ether; The ratio of the molar amount of silicon-hydrogen bonds in the hydrogen-containing silicone oil to the total molar amount of carbon-carbon double bonds in the perfluoroalkyl olefin and the allyl glycidyl ether is 1:(1.0~1.2). The preparation method of the fluorinated anhydride-terminated polyimide oligomer includes the following steps: S501. 4,4'-(hexafluoroisopropylidene) phthalic anhydride and 2,2-bis(trifluoromethyl)benzidine are subjected to a polycondensation reaction in a polar aprotic solvent under nitrogen protection at -10°C to 0°C for 6 to 12 hours to obtain a fluorinated polyamic acid prepolymer solution. S502. Add a mixed solution of acetic anhydride and pyridine to the fluorinated polyamic acid prepolymer solution, react at room temperature to 60°C for 8 to 16 hours, and obtain the fluorinated anhydride-terminated polyimide oligomer after post-treatment. The molar ratio of the 4,4'-(hexafluoroisopropylidene) phthalic anhydride to the 2,2-bis(trifluoromethyl)benzidine is (1.05-1.15):1; The volume ratio of the acetic anhydride to the pyridine is (2-3):

1.

2. The corrosion-resistant high-strength carbon fiber ETFE composite material according to claim 1, characterized in that, The preparation method of the aminated carbon fiber includes the following steps: S101. Immerse carbon fibers in nitric acid aqueous solution and reflux them at 80-100℃ for 1-3 hours. After post-treatment, carbon fibers with carboxylated surfaces are obtained. S102. The surface carboxylated carbon fiber is immersed in an ethanol solution of γ-aminopropyltriethoxysilane and reacted at 60-80°C for 4-8 hours. After post-treatment, the aminated carbon fiber is obtained. The mass concentration of the γ-aminopropyltriethoxysilane is 1-3%.

3. The corrosion-resistant high-strength carbon fiber ETFE composite material according to claim 1, characterized in that, The preparation method of the maleic anhydride-grafted polyolefin elastomer includes the following steps: S201. Premix the polyolefin elastomer, maleic anhydride monomer and organic peroxide initiator in a high-speed mixer at 60-80°C for 5-15 minutes to obtain a premix. S202. The premixed material is fed into a twin-screw extruder and subjected to a melt grafting reaction at 160-200°C. After extrusion, cooling and pelletizing, the maleic anhydride-grafted polyolefin elastomer is obtained. The polyolefin elastomer is a polyethylene octene copolymer elastomer; The organic peroxide initiator is dicumyl peroxide; The mass of the maleic anhydride monomer is 5-10% of the mass of the polyolefin elastomer; The mass of the initiator is 0.1 to 0.5% of the mass of the polyolefin elastomer.

4. The corrosion-resistant high-strength carbon fiber ETFE composite material according to claim 1, characterized in that, The preparation method of the non-covalently modified boron nitride nanosheets of polyethyleneimine includes the following steps: S401. Add boron nitride powder to N-methylpyrrolidone solvent, perform ultrasonic crushing and exfoliation, and then centrifuge to collect the supernatant to obtain boron nitride nanosheet dispersion. S402. Add the polyethyleneimine aqueous solution to the boron nitride nanosheet dispersion, stir and react, centrifuge to collect the precipitate, wash and dry to obtain the polyethyleneimine non-covalently modified boron nitride nanosheets. The ultrasonic fragmentation power is 800-1200W, and the time is 4-8h; The polyethyleneimine has a hyperbranched structure and a molecular weight of 10,000 to 25,000. The mass ratio of the polyethyleneimine to the boron nitride powder is 1:(5-10).

5. The corrosion-resistant high-strength carbon fiber ETFE composite material according to claim 1, characterized in that, The fluorinated polyolefin wax is a polytetrafluoroethylene modified polyethylene wax.

6. The corrosion-resistant high-strength carbon fiber ETFE composite material according to claim 1, characterized in that, The fluorinated leveling agent is a perfluoropolyether modified polyacrylate.

7. A method for preparing the corrosion-resistant high-strength carbon fiber ETFE composite material according to any one of claims 1 to 6, characterized in that, The method includes the following steps: S1. The non-covalently modified boron nitride nanosheets of polyethyleneimine, the epoxy-terminated fluorinated siloxane oligomer, the fluorinated anhydride-terminated polyimide oligomer and a portion of the ETFE resin are premixed in a high-speed mixer to obtain functionalized masterbatch. S2. The functionalized masterbatch, the remaining portion of the ETFE resin, the maleic anhydride-grafted polyolefin elastomer, the PTFE micro powder, the fluorinated polyolefin wax, the fluorinated leveling agent, and the nano-sized fumed silica are placed in the main feed port of a twin-screw extruder for melt blending, and the aminated carbon fiber is added to the molten matrix through the side feed port. The mixture is then extruded and granulated to obtain composite granules. S3. The composite granules are hot-pressed to obtain the carbon fiber ETFE composite material; The mass of a portion of the ETFE resin is 10-30% of the total mass of the ETFE resin.

8. The method for preparing corrosion-resistant high-strength carbon fiber ETFE composite material according to claim 7, characterized in that, The twin-screw extruder has a processing temperature of 300–340°C and a screw speed of 200–400 rpm.

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