Continuous fiber reinforced composite material for stent-free inflatable gas film and preparation method of continuous fiber reinforced composite material

Abstract

The invention discloses a continuous fiber reinforced composite material for a stent-free inflatable gas film and a preparation method of the continuous fiber reinforced composite material, and relates to the technical field of preparation of stent-free inflatable gas film materials. S2, constructing a fiber reinforcement body; s3, performing composite molding to prepare a green body; and S4, repairing treatment and performance detection. The three-step method of ultrasonic cleaning, gradient coupling agent treatment and segmented drying is adopted, the interface bonding force of fibers and resin is enhanced, all the resin and auxiliaries are fully and evenly mixed and reacted through resin premixing, uniform permeation of the resin is ensured through vacuum pressure in resin permeation forming, and defects are avoided; pressurizing and curing step by step, heating and pressurizing to ensure sufficient curing of the resin, and improving the surface performance and service life of the gas film through surface finishing, defect repairing and spraying of a protective coating.

Description

Technical Field

[0001] The present invention relates to the technical field of the preparation of stentless inflatable air film materials, and specifically relates to a continuous fiber reinforced composite material for stentless inflatable air films and a preparation method thereof. Background Technique

[0002] As a new type of building structure form, the stentless inflatable air film has many advantages, such as large span, light self-weight, fast construction speed, and recyclability, etc. Therefore, it has been widely used in multiple fields. The continuous fiber reinforced composite material has advantages such as high specific strength, high specific modulus, strong designability of material properties, good corrosion resistance and durability. Apply the continuous fiber reinforced composite material to the stentless inflatable air film.

[0003] In the prior art, during the preparation process of the composite material, due to the significant polarity difference and surface energy mismatch between the resin matrix and the fiber reinforcement, it is difficult to form effective chemical bonding and physical meshing at the interface phase, resulting in insufficient interfacial shear strength and prone to early failure risks such as fiber pull-out and interfacial debonding. At the preparation process level, the fiber surface treatment process is extensive, only simple solvent cleaning or single coupling agent coating is used. At the same time, during the resin curing, the cross-linking degree of the resin matrix is uneven in local areas, forming a curing stress concentration area, and the porosity inside the material is high, resulting in large fluctuations in the mechanical properties of the material and being difficult to support the stability of large air film structures, making the comprehensive performance of the composite material unstable, and the airtightness and durability are limited. Summary of the Invention

[0004] The purpose of the present invention is to provide a continuous fiber reinforced composite material for stentless inflatable air films and a preparation method thereof, so as to solve the problem that due to the poor compatibility between the resin and the fiber and the poor control of parameters during the preparation process, the mechanical properties of the material fluctuate greatly and it is difficult to support the stability of large air film structures proposed in the above background technique.

[0005] To achieve the above purpose, the present invention provides the following technical solution: A preparation method of a continuous fiber reinforced composite material for stentless inflatable air films, including the following steps: S1. Pretreatment of raw materials: Weigh different raw materials according to the corresponding weight parts, and perform different operations of pretreatment according to the characteristics of the raw materials; S2. Construction of fiber reinforcement: Use three-dimensional braiding technology to construct a three-dimensional fiber braided preform, prepare a spinning solution to spray on the surface of the three-dimensional fiber braided preform to form a nanofiber network, and make the fiber reinforcement; S3. Composite molding to prepare a blank: Place the prepared fiber reinforcement inside a mold for resin infiltration molding, and then perform pressure curing through a hot pressing molding device to obtain a molded composite material blank; S4, Repair Treatment and Performance Detection: Trim and process the surface of the green body, and conduct performance detection on the prepared continuous fiber-reinforced composite material for the stentless inflatable air film.

[0006] Preferably, in step S1, the raw material pretreatment includes the following steps: S11, Fiber Surface Modification: Weigh carbon fiber, glass fiber, and silicon carbide fiber, and ultrasonically clean them in deionized water for 30 minutes respectively. Immerse the cleaned fibers in the prepared coupling agent solution, stir to make the coupling agent molecules adsorb on the fiber surface, take out the fibers, rinse them with deionized water until neutral, and conduct drying treatment on the fibers; S12, Resin Premixing: In a reaction kettle equipped with a stirring device and a temperature control system, sequentially add cyanate resin, epoxy resin, and unsaturated polyester resin, start stirring, control the stirring speed at 50 - 100 revolutions per minute to preliminarily mix the three resins. Add a coupling agent, a toughening agent, a flame retardant, an anti-ultraviolet agent, an imidazole catalyst, and a lubricant to the reaction kettle, and continue stirring to fully mix and react all components for 1 - 2 hours to form a uniform resin mixing system.

[0007] Preferably, in step S11, when conducting drying treatment on the fibers, the drying process uses gradient heating, from 50°C → 80°C → 100°C, with each stage maintaining the temperature for 1 hour.

[0008] Preferably, in step S2, the fiber reinforcement construction includes the following steps: S21, Fabrication of the Braided Preform: Use three-dimensional braiding technology to braid the pretreated carbon fiber, glass fiber, and silicon carbide fiber according to the ratio and braiding structure to make a three-dimensional fiber braided preform; S22, Preparation of the Electrospun Fiber Web: Weigh 5 - 10 parts by weight of the microcapsule-type repair agent, urea-formaldehyde capsules containing cyanate prepolymer, with a particle size of 50 - 100 μm, add them to anhydrous ethanol or N,N-dimethylformamide, stir at 200 - 300 revolutions per minute for 30 minutes to hydrophilize the capsule surface, and obtain the pretreated microcapsules; In the spinning solution, add the pretreated microcapsules according to 5% - 10% of the weight of the spinning solution, continue stirring for 1 - 2 hours, with a rotation speed of 500 - 600 revolutions per minute, to form a polymer solution - microcapsule composite spinning solution; Adopt electrospinning technology to spray the composite spinning solution onto the surface of the three-dimensional braided preform to form a uniform nanofiber web, and prepare the fiber reinforcement.

[0009] Preferably, in step S22, during the electrospinning process, the voltage is 20 - 30 kV; the spinning distance is 20 - 30 cm; the solution feeding rate is 0.1 - 0.5 mL / h; during the spraying process, a vibration of 50 - 100 Hz with an amplitude of 1 - 2 mm is applied to the mold platform to promote the uniform distribution of microcapsules in the fiber web.

[0010] Preferably, in step S3, the preparation of the composite formed blank includes the following steps: S31. Resin infiltration molding: Place the prepared fiber reinforcement in the mold, evacuate the inside of the mold to keep the vacuum degree in the mold between -0.08 and -0.1 MPa for 10 - 20 minutes, introduce the resin mixture system preheated to 30 - 50 °C into the mold, and let the resin infiltrate into the fiber reinforcement. The infiltration time is 30 - 60 minutes. S32. Pressure curing to obtain the formed blank: After the resin infiltration is completed, transfer the mold to the hot - press forming equipment for pressure curing treatment. Raise the mold temperature to 80 - 100 °C at a heating rate of 5 - 10 °C / minute, maintain the pressure at 1 - 3 MPa, and keep the temperature for 30 - 60 minutes to preliminarily cure the resin. Then continue to raise the temperature to 120 - 150 °C, increase the pressure to 3 - 5 MPa, and keep the temperature for 1 - 2 hours to completely cure the resin. Finally, cool naturally to room temperature, release the pressure, and take out the formed composite material blank.

[0011] Preferably, in step S4, the repair treatment and performance detection include the following steps: S41. Surface finishing and defect treatment: Perform surface finishing on the cured composite material blank, remove the burrs at the edges and the excess resin, and perform grinding treatment after repairing the surface defects. S42. Perform performance detection on the prepared continuous fiber - reinforced composite material for the stent - free inflatable air film.

[0012] A continuous fiber - reinforced composite material for a stent - free inflatable air film is made from the following raw materials by weight: 15 - 30 parts by weight of carbon fiber, 10 - 20 parts by weight of glass fiber, 5 - 10 parts by weight of silicon carbide fiber, 45 - 80 parts by weight of resin - based composite material, 0.5 - 2 parts by weight of coupling agent, 3 - 8 parts by weight of toughening agent, 5 - 10 parts by weight of flame retardant, 1 - 3 parts by weight of ultraviolet light absorber, 0.5 - 5 parts by weight of lubricant.

[0013] Preferably, the resin - based composite material includes 30 - 50 parts by weight of cyanate ester resin, 10 - 20 parts by weight of epoxy resin, and 5 - 10 parts by weight of unsaturated polyester resin.

[0014] Preferably, the coupling agent is one of silane coupling agent and titanate coupling agent, the toughening agent is one of carboxyl-terminated nitrile rubber and polyethersulfone, the flame retardant is one of aluminum hydroxide and red phosphorus, the ultraviolet light absorber is one of benzophenone and benzotriazole, and the lubricant is one of stearic acid and polyethylene wax.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: In the raw material pretreatment stage of the present invention, the fiber surface modification adopts a three-step method of "ultrasonic cleaning - gradient coupling agent treatment - segmented drying", which effectively removes impurities and oil stains, enhances the interfacial bonding force between the fiber and the resin, avoids stress concentration, and in the resin premixing, each resin and additive are fully and evenly mixed and reacted. When constructing the fiber reinforcement, the three-dimensional braiding technology accurately controls the braiding parameters to ensure uniform distribution of the fibers and prevent defects. The nanofiber web formed by electrospinning further improves the interfacial performance and overall uniformity. In the composite molding stage, resin infiltration molding uses vacuum pressure to ensure uniform resin infiltration and avoid defects; pressurized curing is carried out by stepwise heating and pressurization to ensure full curing of the resin, improve the material density. In the repair treatment and performance testing links, the surface performance and service life of the air film are improved by surface finishing, defect repair and spraying protective coatings, and then comprehensive performance testing is carried out. The process is optimized according to the results to ensure that the performance of the air film meets the actual use requirements, comprehensively guaranteeing and improving the quality and performance of the continuous fiber reinforced composite material for the stentless inflatable air film from all aspects. Specific embodiments

[0016] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0017] Embodiment 1: The present invention provides a technical solution: a continuous fiber reinforced composite material for a stentless inflatable air film, which is made of the following raw materials in parts by weight: 25 parts by weight of carbon fiber, 15 parts by weight of glass fiber, 8 parts by weight of silicon carbide fiber, 63 parts by weight of resin matrix composite material, 1.2 parts by weight of coupling agent, 5 parts by weight of toughening agent, 7 parts by weight of flame retardant, 2 parts by weight of ultraviolet light absorber and 3 parts by weight of lubricant; The resin matrix composite material includes 30 - 50 parts by weight of cyanate resin, 10 - 20 parts by weight of epoxy resin, and 5 - 10 parts by weight of unsaturated polyester resin.

[0018] A preparation method of a continuous fiber reinforced composite material for a stentless inflatable air film includes the following steps: S1. Raw material pretreatment: Weigh different raw materials and perform pretreatment with different operations according to the characteristics of the raw materials; In step S1, the pretreatment of the raw materials includes the following steps: S11. Fiber surface modification: Weigh carbon fiber, glass fiber, and silicon carbide fiber, and ultrasonically clean them in deionized water for 30 minutes respectively to remove impurities and oil on the fiber surface. Prepare a coupling agent solution with a concentration of 4%. Immerse the cleaned fibers in the coupling agent solution and stir at 40 °C for 1.5 hours to enable the coupling agent molecules to be fully adsorbed on the fiber surface and improve the interfacial bonding force between the fiber and the resin. Take out the fibers, rinse them with deionized water until neutral, and then perform a drying treatment on the fibers. During the drying process, a gradient temperature increase is adopted, from 50 °C → 80 °C → 100 °C, with each stage maintained for 1 hour to avoid stress concentration on the fiber surface; S12. Resin premixing: In a reaction kettle equipped with a stirring device and a temperature control system, add the corresponding weight parts of cyanate resin, epoxy resin, and unsaturated polyester resin in sequence. Start stirring, and control the stirring speed at 80 revolutions per minute to preliminarily mix the three resins evenly. Add the corresponding weight parts of coupling agent, toughening agent, flame retardant, ultraviolet light absorber, imidazole catalyst, and lubricant to the reaction kettle, and continue stirring. At the same time, raise the temperature of the reaction kettle to 60 °C and maintain the stirring speed at 125 revolutions per minute to allow the components to fully mix and react for 1.5 hours to form a uniform resin mixture system; The coupling agent is one of silane coupling agent and titanate coupling agent; the toughening agent is one of carboxyl-terminated nitrile rubber and polyethersulfone; the flame retardant is one of aluminum hydroxide and red phosphorus; the ultraviolet light absorber is one of benzophenones and benzotriazoles; the lubricant is one of stearic acid and polyethylene wax; S2. Fiber reinforcement construction: Use three-dimensional braiding technology to construct a three-dimensional fiber braided preform, prepare a spinning solution, spray it on the surface of the three-dimensional fiber braided preform to form a nanofiber network, and make a fiber reinforcement; In step S2, the fiber reinforcement construction includes the following steps: S21. Braided preform production: Use three-dimensional braiding technology to braid the pretreated carbon fiber, glass fiber, and silicon carbide fiber according to the set ratio and braiding structure to form a three-dimensional fiber braided preform with a specific thickness and shape. The braiding structure is one of orthogonal braiding and angle interlock braiding. During the braiding process, by controlling the braiding parameters, including braiding speed and fiber tension, ensure uniform fiber distribution and avoid defects such as fiber buckling and fracture; S22. Preparation of electrospun fiber web: Weigh 5 - 10 parts by weight of the microcapsule - type repair agent, urea - formaldehyde capsules containing cyanate ester prepolymer, with a particle size of 50 - 100 μm, add them to anhydrous ethanol or N,N - dimethylformamide, and stir at 200 - 300 revolutions per minute for 30 minutes to hydrophilize the capsule surface, obtaining the pretreated microcapsules; In the spinning solution, add the pretreated microcapsules at 5% - 10% of the weight of the spinning solution, and continue to stir for 1 - 2 hours at a rotation speed of 500 - 600 revolutions per minute to form a polymer solution - microcapsule composite spinning solution, ensuring that the capsules are evenly dispersed and there is no agglomeration (observing the dispersion state through an optical microscope, requiring the distance between individual capsules ≥ 200 μm); Use the electrospinning technique to spray the composite spinning solution onto the surface of the three - dimensional braided preform to form a uniform nanofiber web, and obtain the fiber - reinforced body.

[0019] Among them, the electrospinning parameters are adjusted as follows: ① Voltage: 20 - 30 kV (increase the electric field force, overcome the weight of the microcapsules, and ensure the spraying stability); ② Spinning distance: 20 - 30 cm (extend the flight time to avoid the capsules directly hitting the preform due to inertia and causing rupture); ③ Solution feeding speed: 0.1 - 0.5 mL / h (reduce the liquid spraying amount per unit time to avoid nozzle blockage); ④ During the spraying process, apply vibration with a frequency of 50 - 100 Hz (amplitude 1 - 2 mm) to the mold platform to promote the uniform distribution of the microcapsules in the fiber web and avoid sedimentation and caking.

[0020] S3. Preparation of the green body by composite molding: Place the prepared fiber - reinforced body inside the mold for resin infiltration molding, and then perform pressure curing through a hot - pressing molding device to obtain the molded composite material green body; In step S3, the preparation of the green body by composite molding includes the following steps: S31. Resin infiltration molding: Place the prepared fiber - reinforced body in the mold. The mold surface is pre - coated with a release agent to facilitate subsequent demolding. Cover the mold with a sealing film to ensure the tightness of the whole system. Connect a vacuum pump through a vacuum pipeline to evacuate the inside of the mold, keep the vacuum degree inside the mold at - 0.09 MPa for 15 minutes to remove the air inside the mold. Introduce the pre - heated resin mixture system at 40 °C into the mold through the feed pipeline. Under the action of the vacuum pressure, the resin will uniformly penetrate into the fiber - reinforced body. Control the feed speed to ensure the smoothness of the resin infiltration process and avoid defects such as bubbles and dry spots. The infiltration time is 45 minutes; S32. Obtaining a formed blank by pressure curing: After the resin infiltration is completed, transfer the mold to a hot pressing and forming device for pressure curing treatment. First, raise the mold temperature to 90°C at a heating rate of 8°C per minute, maintain a pressure of 2 MPa, and keep the temperature for 45 minutes to preliminarily cure the resin. Then, continue to raise the temperature to 135°C, increase the pressure to 4 MPa, and keep the temperature for 1.5 hours to completely cure the resin. Finally, naturally cool to room temperature, release the pressure, and take out the formed composite material blank; S4. Repair treatment and performance testing: Trim and treat the surface of the blank, and perform performance testing on the prepared continuous fiber-reinforced composite material for the non-support inflatable air film; In step S4, the repair treatment and performance testing include the following steps: S41. Surface trimming and defect treatment: Trim the surface of the cured composite material blank, remove the burrs on the edge and the excess resin, and make the size of the air film meet the design requirements. For small bubbles and fiber exposure defects that appear, repair them with the same resin mixture as the resin system to ensure that the surface of the blank is flat and smooth. Grind the surface of the trimmed composite material, and then spray a protective coating with weather resistance and waterproofness to further improve the surface performance and service life of the air film; S42. Conduct comprehensive performance testing on the prepared continuous fiber-reinforced composite material for the non-support inflatable air film, including tensile strength, flexural strength, impact toughness, flame retardancy, and ultraviolet resistance. Optimize and adjust the preparation process according to the test results to ensure that the performance of the air film meets the actual use requirements; The material composition of the present invention includes a fiber reinforcement, a resin matrix composite material, and an additive; The fiber reinforcement includes carbon fiber, glass fiber, and silicon carbide fiber. By complementing the properties of different fibers, the specific strength, specific modulus, and high-temperature resistance of the composite material are improved; the resin matrix composite material includes cyanate resin, epoxy resin, and unsaturated polyester resin. The multi-resin composite system takes into account high temperature resistance, bonding strength, and processing fluidity; The additives include: coupling agents (silane / titanate), which improve the interfacial compatibility between the fiber and the resin; toughening agents (carboxyl-terminated nitrile rubber / polyethersulfone), which enhance the impact resistance; flame retardants (aluminum hydroxide / red phosphorus), ultraviolet light stabilizers (benzophenone / benzotriazole), and lubricants (stearic acid / polyethylene wax), which endow flame retardancy, weather resistance, and processing convenience.

[0021] The technical principle of this application specifically includes the following content: 1. Strengthening of interfacial bonding force Fiber surface modification: One end of the coupling agent molecule adsorbs on the fiber (for example, the silane coupling agent reacts with the hydroxyl groups on the surface of glass fiber), and the other end crosslinks with the resin to form a "fiber-coupling agent-resin" chemical bond, solving the problem of poor compatibility; Nanofiber network: The micron-scale fiber network formed by electrospinning increases the surface roughness of the fiber, expands the resin infiltration area, and further improves the interfacial bonding strength through mechanical interlocking.

[0022] 2. Control of uniformity and density Three-dimensional braiding: Precise control of the spatial distribution of fibers, avoiding the interlayer delamination defects of traditional laminated structures, and realizing the design of anisotropic properties; Vacuum infiltration + stepwise curing: The vacuum environment removes air to ensure that the resin completely fills the fiber gaps; stepwise heating and pressurization avoid uneven curing shrinkage, reduce bubbles and pores, and improve the density of the material.

[0023] 3. Synergistic effect of multi-resin composite system Cyanate ester resin: High temperature resistance and good electrical insulation; Epoxy resin: High bonding strength and excellent chemical resistance, compensating for the lack of toughness of cyanate ester; Unsaturated polyester resin: Low cost and easy processing, improving the overall molding fluidity. The three are compounded to achieve performance balance.

[0024] 4. Synergistic effect of functional additives Toughening agent: Carboxyl-terminated nitrile rubber is dispersed in the resin to form an elastic phase, absorbing impact energy; Flame retardant: Aluminum hydroxide decomposes endothermically and releases water vapor to dilute combustible gases, and red phosphorus forms a carbon layer to block heat transfer; Ultraviolet absorber: Absorbing ultraviolet energy, inhibiting the photo-oxidative degradation of the resin, and prolonging the service life of the gas film.

[0025] 5. Self-healing function When microcracks (width ≥ 5μm) occur at the interface, the crack propagation stress causes the microcapsule wall (urea-formaldehyde resin) to rupture, releasing the cyanate ester prepolymer; The prepolymer is secondarily cured at room temperature or under heating (40 - 60°C) under the action of a latent catalyst in the resin matrix (0.1 - 0.5 parts by weight of imidazole catalyst added in the resin premixing in step S12), filling the crack and reconstructing the interfacial bonding. By dispersing the microcapsule repair agent in the electrospinning solution and adjusting the spinning parameters to ensure its uniform distribution, the composite material interface can be given self-healing function. The key to integrating this technology lies in the compatibility between the repair agent and the spinning solution, the protection of the integrity of the capsules during the spinning process, and the coordination between the activation conditions of the repair agent and the resin system, ultimately realizing the self-healing cycle of "crack triggering - repair agent release - secondary curing", and improving the long-term reliability of the gas film structure.

[0026] In addition, it is necessary to supplement the compatibility of the microcapsules with the existing process. Resin penetration stage (S31): The microcapsule wall material (urea-formaldehyde) is insoluble in the resin mixture system (cyanate ester, epoxy, unsaturated polyester), ensuring the integrity of the capsules before curing. Curing stage (S32): The curing temperature (120 - 150 °C) is lower than the heat resistance limit of the urea-formaldehyde capsules (usually ≥180 °C), avoiding premature rupture and ensuring that the repair agent is released only when cracks occur during service.

[0027] Continuous fibers such as oxide and non-oxide ceramic fibers (including silicon carbide fibers) are reinforcing materials, and cyanate ester resin is the matrix material. They are jointly used to prepare various continuous fiber-reinforced composites to meet the requirements of material properties for different application scenarios. High-performance glass fiber and carbon fiber-reinforced thermosetting resin matrix composites are an important type of continuous fiber-reinforced composites. Continuous and discontinuous fiber-reinforced composites are classified according to the fiber distribution state of the composites. Continuous fiber-reinforced composites for scaffold-free inflatable air membranes are specific examples of continuous fiber-reinforced composites for specific applications.

[0028] Example 2: A continuous fiber-reinforced composite material for scaffold-free inflatable air membranes and its preparation method provided in this example are generally the same as those in Example 1. The main difference is that it is made from the following raw materials by weight: 15 parts by weight of carbon fiber, 10 parts by weight of glass fiber, 5 parts by weight of silicon carbide fiber, 45 parts by weight of resin matrix composite, 0.5 part by weight of coupling agent, 3 parts by weight of toughening agent, 5 parts by weight of flame retardant, 1 part by weight of ultraviolet absorber, and 0.5 part by weight of lubricant; the resin matrix composite includes 30 parts by weight of cyanate ester resin, 10 parts by weight of epoxy resin, and 5 parts by weight of unsaturated polyester resin.

[0029] Example 3: A continuous fiber-reinforced composite material for scaffold-free inflatable air membranes and its preparation method provided in this example are generally the same as those in Example 1. The main difference is that it is made from the following raw materials by weight: 30 parts by weight of carbon fiber, 20 parts by weight of glass fiber, 10 parts by weight of silicon carbide fiber, 80 parts by weight of resin matrix composite, 2 parts by weight of coupling agent, 8 parts by weight of toughening agent, 10 parts by weight of flame retardant, 3 parts by weight of ultraviolet absorber, and 5 parts by weight of lubricant; the resin matrix composite includes 50 parts by weight of cyanate ester resin, 20 parts by weight of epoxy resin, and 10 parts by weight of unsaturated polyester resin.

[0030] Comparative Example 1: A continuous fiber-reinforced composite material for scaffold-free inflatable air membranes and its preparation method provided in this example are generally the same as those in Example 1. The main difference is that epoxy resin is not added.

[0031] Comparative Example 2: A continuous fiber-reinforced composite material for a stentless inflatable air film provided in this embodiment and its preparation method are substantially the same as those in Example 1, and the main difference is that no lubricant is added.

[0032] Test experiment The continuous fiber-reinforced composite materials for stentless inflatable air films prepared through Examples 1-3 were respectively denoted as Experimental Example Groups 1-3, and the continuous fiber-reinforced composite materials for stentless inflatable air films prepared through Comparative Examples 1-2 were denoted as Comparative Groups 1-2. According to the detection methods of GB / T35465-2017, GB / T35466-2017, GB / T2408-2008, GB / T35467-2017, and GB / T16422.2-2014, the tensile strength, flexural modulus, flame retardant grade, coefficient of thermal expansion, and weather resistance of the continuous fiber-reinforced composite materials for stentless inflatable air films were tested, and the relevant data were experimentally recorded in Table 1.

[0033]

[0034] As can be seen from Table 1, the tensile strengths of Experimental Example Groups 1-3 are all higher than those of Comparative Groups 1-2, indicating that Experimental Example Groups 1-3 are all effective in improving the tensile capacity of the material, and the effect of Experimental Example Group 1 is better, which can better meet the requirements of the air film to resist the tensile force of the internal air pressure. The anti-bending deformation capabilities of Experimental Example Groups 1-3 are all enhanced, and they perform better in resisting the bending deformation caused by external loads. The flame retardant grades of Experimental Example Groups 1-3 all reach UL94V-0, which is better than those of Comparative Groups 1-2. The continuous fiber-reinforced composite materials for stentless inflatable air films prepared in this application have all improved the flame retardant performance of the material and reached a higher safety standard. The coefficient of thermal expansion of Experimental Example Group 1 is lower, and the dimensional stability is better when the temperature changes, which can reduce the structural risks caused by thermal expansion and contraction. After 5000 hours of xenon lamp aging, the tensile strength retention rate of Experimental Example Group 1 is 88%, that of Experimental Example Group 2 is 85%, and that of Experimental Example Group 3 is 80%, all of which are better than those of Comparative Groups 1-2, and the weather resistance of Experimental Example Group 1 is more excellent, and the mechanical properties are better maintained under long-term environmental erosion, and the service life may be longer. Experimental Example Groups 1-3 are superior to Comparative Groups 1-2 in terms of various properties. The continuous fiber-reinforced composite materials for stentless inflatable air films prepared in this application have been significantly improved compared with the materials (comparative groups) prepared by the prior art through material innovation and process optimization, and the comprehensive performance is better.

[0035] Through a series of steps such as the fine treatment of raw materials, the construction of fiber reinforcements, composite molding, and subsequent repair and detection, the present invention optimizes the material properties to meet the usage requirements of air films. First, carbon fibers, glass fibers, and silicon carbide fibers are ultrasonically cleaned to remove impurities and oil stains, and then stirred and treated with a coupling agent solution at a specific temperature to improve the interfacial bonding force between the fibers and the resin. During drying, a gradient temperature rise is adopted to avoid stress concentration. At the same time, a resin matrix composite material is formulated in a reaction kettle, and cyanate ester resin, epoxy resin, and unsaturated polyester resin are mixed in sequence, and additives such as coupling agents and toughening agents are added. By controlling the temperature and stirring speed, the components are fully mixed and reacted to form a uniform resin mixing system.

[0036] Using three-dimensional braiding technology, the pretreated fibers are braided into a three-dimensional preform according to a set ratio and structure. During the process, the braiding parameters are strictly controlled to ensure uniform distribution of the fibers. Then, through electrospinning technology, a polymer spinning solution compatible with the resin system is sprayed onto the surface of the preform at a specific voltage, distance, and feeding speed to form a nanofiber network, further improving the interfacial performance and overall uniformity.

[0037] Subsequently, the fiber reinforcement is placed in a mold coated with a release agent, sealed, and evacuated. The preheated resin mixing system is introduced, and it is uniformly infiltrated under vacuum pressure to avoid defects. In a hot pressing and molding device, through stepwise temperature rise and pressure application, the resin is initially cured and then completely cured to obtain a formed blank.

[0038] Finally, the surface of the blank is trimmed to remove burrs, defects are repaired with the same resin mixture, and a protective coating is sprayed after grinding. And the comprehensive performance of the material is detected, and the preparation process is optimized according to the results to ensure that the air film performance meets the actual usage requirements.

[0039] Although the present invention has been described in detail with reference to the foregoing embodiments, for those skilled in the art, they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A preparation method of a continuous fiber reinforced composite material for a stentless inflatable air film, characterized in that, It includes the following steps: S1. Pretreatment of raw materials: Weigh different raw materials and conduct pretreatment according to the characteristics of the raw materials; S2. Construction of fiber reinforcement: Use three-dimensional braiding technology to construct a three-dimensional fiber braided preform, prepare a spinning solution and spray it on the surface of the three-dimensional fiber braided preform to form a nanofiber network, and manufacture the fiber reinforcement; S3. Composite molding to prepare a blank: Place the prepared fiber reinforcement inside a mold for resin infiltration molding, and then perform pressure curing through a hot pressing molding device to obtain a formed composite material blank; S4. Repair treatment and performance testing: Trim and process the surface of the blank, and conduct performance testing on the prepared continuous fiber reinforced composite material for the stentless inflatable air film.

2. The preparation method of a continuous fiber reinforced composite material for a stentless inflatable air film according to claim 1, characterized in that: In step S1, the pretreatment of the raw materials includes the following steps: S11. Fiber surface modification: Weigh carbon fiber, glass fiber, and silicon carbide fiber, put them into deionized water respectively for ultrasonic cleaning for 30 minutes, soak the cleaned fibers in the prepared coupling agent solution, stir to make the coupling agent molecules adsorb on the fiber surface, take out the fibers, rinse them with deionized water until neutral, and conduct drying treatment on the fibers; S12. Resin premixing: In a reaction kettle equipped with a stirring device and a temperature control system, add cyanate resin, epoxy resin, and unsaturated polyester resin in sequence to preliminarily mix the three resins. Add a coupling agent, a toughening agent, a flame retardant, an anti-ultraviolet agent, an imidazole catalyst, and a lubricant to the reaction kettle, and continue stirring to form a uniform resin mixing system.

3. The preparation method of a continuous fiber reinforced composite material for a stentless inflatable air film according to claim 2, characterized in that: In step S11, when conducting drying treatment on the fibers, the drying process uses gradient heating, from 50°C → 80°C → 100°C, with each stage maintained for 1 hour.

4. The preparation method of a continuous fiber reinforced composite material for a stentless inflatable air film according to claim 3, characterized in that: In step S2, the construction of the fiber reinforcement includes the following steps: S21. Fabrication of the braided preform: Use three-dimensional braiding technology to braid the pretreated carbon fiber, glass fiber, and silicon carbide fiber according to the ratio and braiding structure to make a three-dimensional fiber braided preform; S22. Preparation of the electrospun fiber network: Weigh 5 - 10 parts by weight of a microcapsule-type repair agent, urea-formaldehyde capsules containing cyanate prepolymer, with a particle size of 50 - 100 μm, add them to anhydrous ethanol or N,N-dimethylformamide, stir at 200 - 300 revolutions per minute for 30 minutes to hydrophilize the capsule surface, and obtain the pretreated microcapsules; Add the pretreated microcapsules to the spinning solution at 5% - 10% by weight of the spinning solution, continue stirring for 1 - 2 hours at a rotation speed of 500 - 600 revolutions per minute to form a polymer solution - microcapsule composite spinning solution; Adopt electrospinning technology to spray the composite spinning solution onto the surface of the three-dimensional braided preform to form a uniform nanofiber network, and prepare the fiber reinforcement.

5. The preparation method of a continuous fiber reinforced composite material for a stentless inflatable air film according to claim 4, characterized in that: In step S22, during the electrospinning process, voltage: 20 - 30 kV; spinning distance: 20 - 30 cm; solution feeding speed: 0.1 - 0.5 mL / h; during the spraying process, apply vibration to the mold platform at 50 - 100 Hz with an amplitude of 1 - 2 mm to promote the uniform distribution of the microcapsules in the fiber network.

6. The preparation method of a continuous fiber reinforced composite material for a stentless inflatable air film according to claim 5, characterized in that: In step S3, the preparation of the composite formed blank includes the following steps: S31. Resin infiltration molding: Place the prepared fiber reinforcement in a mold, evacuate the inside of the mold, and introduce a resin mixture system preheated to 30-50 °C into the mold to allow the resin to infiltrate into the fiber reinforcement. S32. Obtain a formed blank by pressure curing: After the resin infiltration is completed, transfer the mold to a hot pressing molding device for pressure curing treatment, then naturally cool to room temperature, release the pressure, and take out the formed composite material blank.

7. The preparation method of a continuous fiber reinforced composite material for a stentless inflatable air film according to claim 6, characterized in that: In step S4, the repair treatment and performance detection include the following steps: S41. Surface finishing and defect treatment: Perform surface finishing on the cured composite material blank, remove burrs and excess resin on the edges, and perform grinding treatment after patching surface defects. S42. Perform performance detection on the prepared continuous fiber-reinforced composite material for the stentless inflatable air film.

8. A continuous fiber-reinforced composite material for a stentless inflatable air film, which uses the preparation method of a continuous fiber-reinforced composite material for a stentless inflatable air film described in any one of the above claims 1-7, characterized in that: It is made from the following raw materials in parts by weight: 15-30 parts by weight of carbon fiber, 10-20 parts by weight of glass fiber, 5-10 parts by weight of silicon carbide fiber, 45-80 parts by weight of resin matrix composite, 0.5-2 parts by weight of coupling agent, 3-8 parts by weight of toughening agent, 5-10 parts by weight of flame retardant, 1-3 parts by weight of ultraviolet absorber, 0.5-5 parts by weight of lubricant.

9. The continuous fiber reinforced composite material for a stentless inflatable air film according to claim 8, characterized in that: The resin matrix composite includes 30-50 parts by weight of cyanate ester resin, 10-20 parts by weight of epoxy resin, and 5-10 parts by weight of unsaturated polyester resin.

10. A continuous fiber-reinforced composite material for a stentless inflatable air film according to claim 8, characterized in that: The coupling agent is one of silane coupling agent and titanate coupling agent, the toughening agent is one of carboxyl-terminated nitrile rubber and polyethersulfone, the flame retardant is one of aluminum hydroxide and red phosphorus, the ultraviolet absorber is one of benzophenones and benzotriazoles, and the lubricant is one of stearic acid and polyethylene wax.

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