Polymorphic fiber reinforced resin matrix composite structure

Abstract

The invention discloses a polymorphic fiber reinforced resin-based composite structure, and belongs to the technical field of fiber reinforced composites, the polymorphic fiber reinforced resin-based composite structure comprises a polymorphic reinforced fiber system and a modified resin composition, the polymorphic reinforced fiber system comprises continuous reinforced fibers and gradient length discontinuous fibers, modified layers are arranged on the surfaces of the continuous reinforced fibers and the gradient length discontinuous fibers; the modified resin composition shows a single glass transition temperature before and after being heated at 400 DEG C for 1 hour, and the performance retention rate meets preset requirements after being aged at 300 DEG C for 1000 hours; through the synergistic effect of the fiber surface modification layer and the epoxy group modified polyarylene sulfide compatilizer, the interface bonding effect between the fiber and resin and between fibers in different forms is effectively enhanced; and by compounding the anti-aging agent, the degradation speed of the resin in a high-temperature environment can be delayed, the composite material is ensured to keep stable performance under a long-term high-temperature working condition, and the use requirements in the high-temperature environment are met.

Description

Technical Field

[0001] This invention relates to the field of fiber-reinforced composite materials technology, and in particular to a multimorphic fiber-reinforced resin-based composite structure. Background Technology

[0002] Fiber-reinforced resin matrix composites are widely used in aerospace, automotive manufacturing, and electronics industries due to their high strength and lightweight properties. Among existing technologies, patent CN112334519A discloses a fiber-reinforced resin matrix that uses a combination of two thermoplastic resins with different glass transition temperatures. While this partially solves the problems of resin impregnation of fibers and thermal stability, significant shortcomings still exist in practical applications.

[0003] The shortcomings of existing technologies are mainly reflected in four aspects: First, the interfacial bonding performance is poor. The compatibility between continuous reinforcing fibers and discontinuous fibers, and between fibers and the resin matrix, is limited, resulting in low interlaminar shear strength of composite materials. Under stress, interfacial delamination is prone to occur, affecting the overall structural integrity. Second, the heat aging resistance is insufficient. When exposed to high-temperature environments above 300℃ for a long time, the resin composition is prone to thermal degradation, the glass transition temperature stability decreases, and the mechanical properties are significantly reduced. Third, the fiber morphology design is monotonous. Discontinuous fibers use a fixed length range, which cannot simultaneously meet the high fluidity required for molding complex-shaped components and the high strength requirements of structural parts. Fourth, the impregnation uniformity is poor. During the mixing of multi-morphological fibers, they are prone to agglomeration, resulting in insufficient resin impregnation. The local porosity is difficult to control effectively, affecting the surface quality and performance of the product.

[0004] To address the aforementioned issues, there is an urgent need to develop a multi-morphological fiber-reinforced resin-based composite structure that optimizes fiber morphology design, enhances interfacial bonding, improves heat aging resistance, and maintains molding flexibility, thereby expanding its application range in high-temperature and high-stress scenarios. Summary of the Invention

[0005] Purpose of the invention: In view of the shortcomings of existing patents, the present invention aims to solve the following problems: 1. Insufficient interfacial bonding between polymorphic fibers and resin, and between fibers; 2. Decrease in the stability and mechanical properties of resin compositions under long-term high temperature conditions; 3. Inability to balance molding flowability and mechanical strength in discontinuous fiber length design; 4. High porosity caused by uneven impregnation of polymorphic fibers.

[0006] Technical solution: To solve the above-mentioned technical problems, according to one aspect of the present invention, more specifically, a multimorphic fiber-reinforced resin-based composite structure, comprising the following: 1. Multimorphic Reinforced Fiber System Multimorphic reinforcing fiber systems provide mechanical support for composite materials. They include two types: continuous reinforcing fibers and gradient length discontinuous fibers, and both types of fibers have a modified layer on their surface.

[0007] The continuous reinforcing fibers are selected from PAN-based carbon fibers or para-aramid fibers, and are in the form of unidirectional doubling, woven fabrics, or knitted fabrics. The selected continuous reinforcing fibers have a single fiber diameter of 7μm and a total of 12,000 filaments, which ensures structural strength while facilitating full resin impregnation.

[0008] The gradient-length discontinuous fibers are selected from carbon fiber, glass fiber, or basalt fiber, and include three types: short fibers, medium-length fibers, and long fibers, which are mixed in a mass ratio of 2:3:5. The short fibers are 5 mm long, the medium-length fibers are 30 mm long, and the long fibers are 80 mm long. Through the gradient length design, both molding flowability and structural mechanical strength are synergistically considered.

[0009] The fiber surface modification layer is a silane coupling agent coating or an epoxy-modified polyarylene sulfide coating, with a coating thickness of 2 μm. The modification layer can form active sites on the fiber surface, enhance the chemical bonding between the fiber and the resin matrix, and further improve the interfacial adhesion.

[0010] 2. Modified resin composition The modified resin composition provides bonding and protection for the composite material, exhibiting a single glass transition temperature before and after heating at 400°C for 1 hour, and meeting the preset performance retention requirements after aging at 300°C for 1000 hours.

[0011] The modified resin composition contains four core components: a thermoplastic resin with a glass transition temperature ≥100℃, a polyarylene sulfide prepolymer with a glass transition temperature <100℃, an epoxy-modified polyarylene sulfide compatibilizer, and an anti-aging agent.

[0012] The thermoplastic resin with a glass transition temperature ≥100℃ is selected from at least one of polyetheretherketone, polyetherketoneketone or polyetherimide, which serves as the core heat-resistant component in the composition, providing high heat resistance and basic mechanical strength.

[0013] The polyarylene sulfide prepolymer with a glass transition temperature <100℃ is a mixture of cyclic polyarylene sulfide and linear polyarylene sulfide, wherein the weight-average molecular weight of the cyclic polyarylene sulfide is ≤5000 and the weight-average molecular weight of the linear polyarylene sulfide is 1000~15000. This component mainly improves the resin's impregnation of fibers.

[0014] The epoxy value of the epoxy-modified polyarylene sulfide compatibilizer is 0.3 eq / 100g. Its core function is to connect the thermoplastic resin and the polyarylene sulfide prepolymer, while enhancing the compatibility between the resin and the modified layer on the fiber surface and improving the interfacial bonding force.

[0015] The anti-aging agent is a compound of hindered phenols and phosphites. Specifically, 3,9-bis[2-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionyloxy]-1,1-dimethylethyl-2,4,8,10-tetraoxaspiro[5,5]undecane and phosphite compounds are compounded in a 1:1 ratio, which can effectively slow down the degradation rate of resin under high temperature conditions.

[0016] 3. Preparation method This multimorphic fiber-reinforced resin-based composite structure is prepared through the following steps to ensure full integration of each component and improve product performance: (1) Fiber pretreatment: Continuous reinforcing fibers and gradient length discontinuous fibers were plasma cleaned for 3 minutes to remove organic contaminants from the fiber surface. Subsequently, a modified layer was coated on the surface of both types of fibers, and after coating, they were dried at 120°C for 2 hours for later use.

[0017] (2) Resin premixing: Thermoplastic resin with a glass transition temperature ≥100℃, polyarylene sulfide prepolymer with a glass transition temperature <100℃, epoxy-modified polyarylene sulfide compatibilizer, and anti-aging agent are mixed in a preset ratio and fed into a twin-screw extruder for melt mixing. The extruder barrel temperature is set to 360℃ and the screw speed is 300rpm. After melt mixing, the mixture is granulated to produce resin granules.

[0018] (3) Stepwise impregnation: First, the gradient length discontinuous fibers and resin particles are premixed at a mass ratio of 2:1 and sent to an extruder for melt dispersion at a dispersion temperature of 350℃. Then, the resin melt with dispersed discontinuous fibers and the pretreated continuous reinforcing fibers are sent to the impregnation mold together and impregnated under pressure using an ultrasonic-assisted method with an ultrasonic power of 800W and an impregnation pressure of 0.5MPa.

[0019] (4) Cooling and molding: The processing temperature is controlled at 380℃, which is the preset temperature corresponding to the resin melting point, which can ensure the resin fluidity and molding effect. The resin-impregnated fibers are pulled out of the impregnation mold at a pulling speed of 1m / min, and then cured by a cooling roller at a temperature of 80℃. Finally, a multi-morphological fiber-reinforced resin-based composite structure is obtained with a product thickness of 0.5mm and a fiber volume content of 55%. Beneficial effects

[0020] Significantly enhanced interfacial bonding: Through the synergistic effect of the fiber surface modification layer and the epoxy-modified polyarylene sulfide compatibilizer, the interfacial bonding effect between the fiber and the resin, and between fibers of different shapes, can be effectively enhanced, avoiding the problem of interfacial delamination under stress and improving the overall structure.

[0021] Significantly enhanced heat aging resistance: The combined use of anti-aging agents can slow down the degradation rate of resin under high temperature conditions, ensuring that the composite material maintains stable performance under long-term high temperature conditions and meets the requirements for use in high temperature environments.

[0022] Coordinated optimization of molding and strength: The design of discontinuous fibers with gradient lengths ensures both the high fluidity required for molding complex-shaped components and the high strength requirements of structural parts, thereby improving the molding qualification rate.

[0023] Impregnation uniformity and surface quality optimization: Ultrasonic-assisted stepwise impregnation process can reduce fiber agglomeration, promote uniform resin impregnation, reduce the porosity of composite materials, improve the product surface to avoid defects such as cracks, resin discoloration and fiber exposure, and enhance appearance and performance. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the structure of the present invention. Detailed Implementation

[0025] To make the technical solution of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. Example

[0026] 1. Raw material preparation Continuous reinforcing fiber: PAN-based carbon fiber (Toray T700S-12K) is selected, with a single fiber diameter of 7μm and a total of 12,000 filaments; Gradient length discontinuous fiber: Carbon fiber is selected, with short fiber length of 5mm, medium-length fiber length of 30mm, and long fiber length of 80mm, and the mass ratio of the three is 2:3:5; The modified resin composition consists of the following components: 100 parts of polyether ether ketone (PEEK90G), 20 parts of polyarylene sulfide prepolymer, 3 parts of epoxy-modified polyarylene sulfide compatibilizer, and 0.8 parts of hindered phenol / phosphite compound anti-aging agent. Fiber surface modifier: γ-aminopropyltriethoxysilane, used to prepare the modified layer.

[0027] 2. Preparation steps (1) Fiber pretreatment: Continuous reinforcing fibers and gradient length discontinuous fibers were placed in a plasma cleaning device and cleaned for 3 minutes to remove surface contaminants. Then, a γ-aminopropyltriethoxysilane modified layer was coated on the surface of the two types of fibers using a coating process. The coating thickness was 2 μm. After coating, the fibers were dried in an oven at 120℃ for 2 hours for later use.

[0028] (2) Resin premixing: Weigh each component of the modified resin composition according to the above proportions and put them into a twin-screw extruder. Set the extruder barrel temperature to 360℃ and the screw speed to 300rpm. After melting and mixing each component, granulate to obtain uniform resin particles.

[0029] (3) Stepwise impregnation: The gradient length discontinuous fibers and resin particles are premixed in a high-speed mixer at a mass ratio of 2:1 for 5 minutes, and then fed into an extruder for melt dispersion at 350°C. The resin melt with dispersed discontinuous fibers is introduced into the impregnation mold, and the pretreated continuous reinforcing fibers are simultaneously drawn into the impregnation mold. The ultrasonic equipment (power 800W) is turned on and a pressure of 0.5MPa is applied to ensure that the resin fully impregnates the fibers.

[0030] (4) Cooling and molding: The processing temperature of the impregnation mold outlet is set to 380℃. The impregnated fiber composite material is pulled out at a pulling speed of 1m / min and solidified by a cooling roller at a temperature of 80℃. Finally, a multi-morphological fiber-reinforced resin-based composite structure with a thickness of 0.5mm and a fiber volume content of 55% is obtained.

[0031] In summary, this embodiment employs a combination of PAN-based carbon fiber and gradient discontinuous carbon fiber, coupled with a polyetheretherketone resin system, resulting in mild and easily controllable process parameters. The resulting composite structure emphasizes a balance between comprehensive mechanical properties and molding cost, exhibiting stable interfacial bonding and good impregnation uniformity. It is suitable for general-purpose industrial components requiring a balance between weight and strength, such as automotive body brackets and electronic device housings. Example

[0032] 1. Raw material preparation Continuous reinforcing fiber: Para-aramid fiber is selected, with a single fiber diameter of 8μm and a total of 50,000 filaments; Gradient length discontinuous fiber: Basalt fiber is selected, in which short fiber length is 8mm, medium-length fiber length is 40mm, and long fiber length is 90mm, with a mass ratio of 2:3:5; The modified resin composition consists of the following components: 100 parts of polyether ketone ketone (PEKK7002), 30 parts of polyarylene sulfide prepolymer, 4 parts of epoxy-modified polyarylene sulfide compatibilizer, and 1.2 parts of hindered phenol / phosphite compound anti-aging agent. Fiber surface modifier: γ-glycidyl etheroxypropyltrimethoxysilane, used to prepare the modified layer.

[0033] 2. Preparation steps (1) Fiber pretreatment: The two types of fibers were plasma cleaned for 3 minutes, coated with a γ-glycidyl etheroxypropyltrimethoxysilane modified layer with a coating thickness of 3 μm, and dried at 120°C for 2 hours; (2) Resin premixing: The components of the resin composition were fed into a twin-screw extruder with a barrel temperature of 370°C and a screw speed of 320 rpm. After melt mixing, the mixture was granulated; (3) Stepwise impregnation: The discontinuous fibers and resin particles were premixed at a mass ratio of 2.5:1, melt-dispersed in an extruder at 360°C, and fed into an impregnation mold together with the continuous fibers. The ultrasonic power was 900W and the impregnation pressure was 0.6MPa; (4) Cooling molding: The processing temperature was 390°C, the pulling speed was 1.2m / min, and the cooling roller temperature was 90°C to obtain a composite structure with a thickness of 1.0mm and a fiber volume content of 60%.

[0034] In summary, this embodiment utilizes para-aramid fibers and basalt gradient discontinuous fibers, combined with a polyether ketone ketone resin system offering superior heat resistance. By increasing fiber volume content and optimizing ultrasonic power and impregnation pressure, the heat resistance and structural toughness of the composite material are enhanced. The resulting product is more suitable for high-temperature, high-stress conditions, such as components around aircraft engines and components inside automotive engine compartments, where stringent requirements for heat aging resistance and mechanical strength are imposed.

[0035] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A multimorphic fiber-reinforced resin-based composite structure, comprising a multimorphic reinforcing fiber system and a modified resin composition, characterized in that: The multimorphic reinforcing fiber system includes continuous reinforcing fibers and gradient length discontinuous fibers, and both the continuous reinforcing fibers and the gradient length discontinuous fibers have a modified layer on their surfaces. The modified resin composition exhibits a single glass transition temperature before and after heating at 400°C for 1 hour, and its performance retention rate meets the preset requirements after aging at 300°C for 1000 hours.

2. The multimorphic fiber-reinforced resin-based composite structure according to claim 1, characterized in that, The gradient length discontinuous fiber includes short fiber, medium-length fiber, and long fiber, with short fiber: medium-length fiber: long fiber mixed in a ratio of 2:3:5, synergistically balancing molding flowability and structural mechanical strength.

3. The multimorphic fiber-reinforced resin-based composite structure according to claim 1, characterized in that, The modified resin composition comprises a thermoplastic resin with a glass transition temperature ≥100℃, a polyarylene sulfide prepolymer with a glass transition temperature <100℃, an epoxy-modified polyarylene sulfide compatibilizer, and an anti-aging agent. The thermoplastic resin with a glass transition temperature ≥100℃ provides high heat resistance and basic mechanical strength; the polyarylene sulfide prepolymer with a glass transition temperature <100℃ improves resin impregnation; the epoxy-modified polyarylene sulfide compatibilizer enhances interfacial bonding; and the anti-aging agent delays resin degradation at high temperatures.

4. The multimorphic fiber-reinforced resin-based composite structure according to claim 1, characterized in that, The fiber surface modification layer is a silane coupling agent coating or an epoxy-modified polyarylene sulfide coating, used to further improve the compatibility between the fiber and the resin.

5. The multimorphic fiber-reinforced resin-based composite structure according to claim 1, characterized in that, It also includes a method for preparing the multimorphic fiber-reinforced resin-based composite structure, the preparation steps of which are as follows: (1) Fiber pretreatment: The continuous reinforcing fibers and the gradient length discontinuous fibers are cleaned and treated respectively. Then, a modified layer is coated on the surface of the two types of fibers and dried for later use. (2) Resin premixing: Thermoplastic resin with glass transition temperature ≥100℃, polyarylene sulfide prepolymer with glass transition temperature <100℃, epoxy-modified polyarylene sulfide compatibilizer, and anti-aging agent are mixed and then melt-blended to form resin particles. (3) Stepwise impregnation: First, the discontinuous fibers of gradient length are premixed with resin particles, and after melt dispersion treatment, they are sent into the impregnation mold together with the pretreated continuous reinforcing fibers, and impregnation is carried out by ultrasonic assistance. (4) Cooling and molding: The processing temperature is controlled to the temperature corresponding to the melting point of the resin. The resin-impregnated fibers are pulled out from the impregnation mold and cured by the cooling roller to obtain a multi-morphological fiber-reinforced resin-based composite structure.

6. The multimorphic fiber-reinforced resin-based composite structure according to claim 1, characterized in that, The multimorphic fiber-reinforced resin-based composite structure is used in aircraft engine peripheral components, automobile body components, electrical and electronic components, or building components.

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