Lightweight thermoplastic composite material film for spacecraft skin

Abstract

The invention relates to the technical field of spacecraft skins, in particular to a lightweight thermoplastic composite material film for a spacecraft skin. The thermoplastic composite material film is prepared by the following steps: dipping carbon fibers and a hollow ceramic tube in a mixed solution consisting of polyetherimide and graphene oxide dissolved in N-methyl pyrrolidone, and then carrying out heat treatment to obtain modified carbon fibers and modified hollow ceramic tubes; adding polyarylene ether nitrile into a double-screw extruder, melting, adding the modified hollow ceramic tube, and continuously mixing for 10-15 minutes to obtain a resin matrix; the preparation method comprises the following steps: mixing modified carbon fibers with a resin matrix, casting the mixed material to form a film, cooling to room temperature, rolling to obtain unidirectional prepregs, crosswise and symmetrically laying the unidirectional prepregs, and carrying out hot press molding to obtain the lightweight thermoplastic composite film for the spacecraft skin. The film prepared by the invention has the effects of low density, high strength and extreme climate resistance.

Description

A lightweight thermoplastic composite film for spacecraft skin Technical Field

[0001] This application relates to the field of spacecraft skin technology, specifically to a lightweight thermoplastic composite film for spacecraft skin. Background Technology

[0002] As a core component protecting the cabin structure and maintaining the internal environment, spacecraft skin must simultaneously meet multiple stringent requirements, including lightweight (to reduce launch costs), high strength (to withstand impacts from space debris, aerodynamic loads, and thermal stress), excellent weather resistance (to resist cosmic radiation and high / low temperature cycling), and in-plane isotropy (to adapt to complex stress distributions). Currently, spacecraft skin materials are mainly metals such as aluminum alloys and titanium alloys, which, while having high strength, also have high density, significantly increasing launch loads. While polymer-based composite materials, such as carbon fiber reinforced epoxy resin, achieve lightweighting, they suffer from problems such as high brittleness due to cross-linking curing, poor recyclability, and insufficient long-term temperature resistance. A composite material is needed to solve the problems of high density, low strength, and poor high / low temperature stability. Summary of the Invention

[0003] In view of the above, this application provides a lightweight thermoplastic composite film for spacecraft skin, which has the effects of low density, high strength and resistance to extreme weather.

[0004] To achieve the above objectives, this application provides a lightweight thermoplastic composite film for spacecraft skin. The preparation process includes the following steps: S1, carbon fibers and hollow ceramic tubes are respectively immersed in a mixture of polyetherimide and graphene oxide dissolved in N-methylpyrrolidone, followed by heat treatment to obtain modified carbon fibers and modified hollow ceramic tubes. In the above process, polyetherimide is a high molecular polymer containing functional groups such as imide groups, ketone groups, carboxyl groups, and amino groups. N-methylpyrrolidone is a good solvent for it, forming a homogeneous solution. Graphene oxide contains hydrophilic functional groups such as epoxy groups, hydroxyl groups, and carboxyl groups. The epoxy groups in graphene oxide can undergo ring-opening reactions with the amino groups in polyetherimide to form CN bonds and generate hydroxyl groups. It can also form hydrogen bonds with polyetherimide, which is beneficial for dispersion in the solution and can avoid agglomeration. When carbon fibers are immersed in the mixture, polyetherimide and graphene oxide adhere to the surface of carbon fibers by combining with the hydroxyl and carboxyl groups on the surface of carbon fibers through a dual action of physical entanglement and chemical bonding.

[0005] S2. By weight, add 45-55 parts of polyarylether nitrile to a twin-screw extruder, melt it, add 15-25 parts of modified hollow ceramic tube, and continue to mix for 10-15 minutes to obtain a resin matrix; S3. By weight, mix 25-35 parts of modified carbon fiber with the resin matrix, then cast the mixture into a film, cool it to 25-28℃ and then wind it up to obtain a unidirectional prepreg. Cross-symmetrically lay up the unidirectional prepreg and then hot press it to obtain a lightweight thermoplastic composite film for spacecraft skin.

[0006] In the above process, the resin matrix melts again into a viscous flow state. The modified carbon fiber surface coated with polyetherimide-graphene oxide achieves complete wetting with the resin melt through interfacial affinity. The graphene oxide adheres to the carbon fiber surface, significantly increasing the surface roughness and specific surface area of ​​the fiber. When the molten polyarylene ether nitrile is wetted, the polyarylene ether nitrile molecular chains embed into the grooves between the graphene oxide sheets, forming a strong mechanical interlocking effect, which enhances the adhesion between the fiber and the matrix. The oxygen-containing functional groups in the graphene oxide form hydrogen bonds with the cyano groups in the polyarylene ether nitrile, further enhancing the binding effect. Polyarylene ether nitrile and polyetherimide have similar structures, both containing aromatic rings and ether bonds, and the two have good compatibility. The fiber monofilaments can be wrapped by the resin matrix without any bare areas.

[0007] Furthermore, the carbon fiber is composed of short carbon fibers and continuous carbon fibers, with a mass ratio of short carbon fibers to continuous carbon fibers of 1:2-3.

[0008] Furthermore, the mass ratio of polyetherimide to graphene oxide is 8:1-2.

[0009] Furthermore, the twin-screw extruder has a temperature of 320-350℃ and a rotation speed of 300-500rpm.

[0010] Furthermore, the mixing in step S3 is carried out at a temperature of 350-360°C and a pressure of 0.5-0.6 MPa.

[0011] Furthermore, in the film casting process, the slit gap of the casting die is 0.1-0.11 mm, and the casting speed is 0.8-0.85 m / min.

[0012] Furthermore, the cross-symmetric ply is orthogonally symmetric ply according to [0° / 90°].

[0013] Furthermore, the hot pressing process is carried out at a temperature of 360-370℃, a pressure of 2-2.5MPa, and a time of 10-15min.

[0014] In summary, this application has the following beneficial effects: By adding short carbon fibers and continuous carbon fibers, the two work together in the composite system to achieve synergistic enhancement of mechanical properties. Continuous carbon fibers, as the main skeleton of the composite system, are oriented along the main stress direction of the film and bear most of the tensile and bending loads. Their high modulus and high strength improve the basic load-bearing capacity of the film. Short carbon fibers, as an auxiliary reinforcing phase, fill the gaps between continuous carbon fibers and prevent crack propagation through bridging effect. The high aspect ratio of short carbon fibers can be interspersed in the gaps of the continuous carbon fiber network, reducing the internal porosity of the composite material and improving the matrix. Continuity; by adding hollow ceramic tubes as a rigid skeleton to disperse some stress, a rigid-flexible network is formed with carbon fibers. The carbon fibers bear the load along the axial direction, while the hollow ceramic tubes resist lateral deformation, reducing local stress concentration. The carbon fibers and hollow ceramic tubes are modified with graphene oxide and polyetherimide to improve the interfacial bonding with the resin matrix and the mechanical and weather resistance of the film. Polyetherimide is a high-performance thermoplastic resin whose molecular chains contain a large number of polar groups, which can combine with the hydroxyl and carboxyl groups on the carbon fiber surface through both physical entanglement and chemical bonding. On the one hand, the flexible segments of polyetherimide penetrate into the micropores of the carbon fiber, forming... On the one hand, it forms mechanical anchoring; on the other hand, the polar groups in polyetherimide form hydrogen bonds with the -OH groups on the carbon fiber surface, enhancing the interfacial shear strength; graphene oxide, a two-dimensional nanosheet with a single-atom-layer structure containing functional groups such as hydroxyl and epoxy groups, can bind to the polyetherimide molecular chain through hydrogen bonds, effectively improving the dispersibility of graphene oxide. Simultaneously, graphene oxide sheets are inserted between the carbon fiber and polyetherimide, forming a gradient interface of carbon fiber-polyetherimide-graphene oxide. The rough structure on the carbon fiber surface and the wrinkles of the graphene oxide sheets interlock, producing a mechanical locking effect similar to micro-tooth interlocking. Graphene oxide, as a chemical... The bridge reacts with polyetherimide to form covalent bonds, and forms mechanical interlocking and hydrogen bonds with polyaryletheronitrile, further enhancing the interfacial shear strength. Graphene oxide itself has ultra-high tensile strength and modulus, and as a nano-reinforcing phase dispersed on the fiber surface, it can form a nano-reinforcing network between the fiber and the resin. When the composite material is under load, the graphene oxide sheets share part of the load through stress transfer, improving the overall tensile strength of the film. The hollow ceramic tube is lightweight, high temperature resistant, and resistant to acid and alkali corrosion. As an inert skeleton, it enhances the stability of the composite material in extreme environments and, together with polyetherimide and polyaryletheronitrile, improves the weather resistance of the film. Detailed Implementation

[0015] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the embodiments of this application. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this invention.

[0016] The raw materials used in the specific embodiments of this application are analytical grade. Additionally: short carbon fibers have a length of 0.2-0.5 mm, a diameter of 7 μm, a tensile strength of 3.0 GPa, and a modulus of 230 GPa; continuous carbon fibers have a length of 6-12 mm, a diameter of 7 μm, a tensile strength of 3.5 GPa, and a modulus of 240 GPa; the polyetherimide has a molecular weight of 50,000-80,000; hollow ceramic tubes have a wall thickness of 10 nm, a diameter of 30-50 nm, and a length of 10-15 μm; the carbon nanotubes are selected from Anhui Kerun Nanotechnology Co., Ltd., CAS: 308068-56-6.

[0017] Example 1: A method for preparing a lightweight thermoplastic composite film for spacecraft skin, comprising the following steps: S1, carbon fibers (the mass ratio of short carbon fibers to continuous carbon fibers is 1:2) and hollow ceramic tubes are respectively immersed in a mixture of polyetherimide particles dissolved in N-methylpyrrolidone and graphene oxide (the mass ratio of polyetherimide particles to graphene oxide is 8:1), and then the carbon fibers and hollow ceramic tubes coated with polyetherimide and graphene oxide are heat-treated at 300°C for 2 hours using an infrared heater to obtain modified carbon fibers and modified hollow ceramic tubes; S2, 45 parts by mass of polyarylene ether nitrile are added to a twin-screw extruder (temperature 320°C, speed 50 rpm). After melting, 15 parts of hollow ceramic tubes are added and kneaded for another 10 minutes to obtain a resin matrix. S3. By mass, 25 parts of modified carbon fiber and resin matrix are mixed in a kneader (temperature 350℃, pressure 0.5MPa). The mixture is then extruded into a film through a casting machine (gap 0.1mm, casting speed 0.8m / min). After cooling to 25℃, it is wound up to obtain a unidirectional prepreg with a thickness of 0.2mm. The unidirectional prepreg is then laid up symmetrically at an angle of (0° / 90°) (3 layers). The prepreg layers are placed in a hot press (mold temperature 360℃, pressure 2MPa) and kept at the temperature and pressure for 15 minutes to obtain a lightweight thermoplastic composite film for spacecraft skin.

[0018] Example 2: A method for preparing a lightweight thermoplastic composite film for spacecraft skin, comprising the following steps: S1, carbon fibers (the mass ratio of short carbon fibers to continuous carbon fibers is 1:3) and hollow ceramic tubes are respectively immersed in a mixture of polyetherimide particles dissolved in N-methylpyrrolidone and graphene oxide (the mass ratio of polyetherimide particles to graphene oxide is 8:2), and then the carbon fibers and hollow ceramic tubes coated with polyetherimide and graphene oxide are heat-treated at 300°C for 2 hours using an infrared heater to obtain modified carbon fibers and modified hollow ceramic tubes; S2, by mass, 50 parts of polyarylene ether nitrile are added to a twin-screw extruder (temperature 320°C, speed 50 rpm), and after melting, 20 parts are added... Modified hollow ceramic tubes were further mixed for 10 minutes to obtain a resin matrix. S3. By mass, 30 parts of modified carbon fiber and resin matrix were mixed in a kneader (temperature 350℃, pressure 0.5MPa) to ensure that the fiber monofilaments were completely coated with resin. The mixture was then extruded into a film through a casting machine (gap 0.1mm, casting speed 0.8m / min). After cooling to 25℃, it was wound up to obtain a unidirectional prepreg with a thickness of 0.2mm. The unidirectional prepreg was then laid up symmetrically at an angle of (0° / 90°) (4 layers). The prepreg layers were placed in a hot press (mold temperature 360℃, pressure 2MPa) and kept at the temperature and pressure for 15 minutes to obtain a lightweight thermoplastic composite film for spacecraft skin.

[0019] Example 3: A method for preparing a lightweight thermoplastic composite film for spacecraft skin, comprising the following steps: S1, carbon fibers (the mass ratio of short carbon fibers to continuous carbon fibers is 1:3) and hollow ceramic tubes are respectively immersed in a mixture of polyetherimide particles dissolved in N-methylpyrrolidone and graphene oxide (the mass ratio of polyetherimide particles to graphene oxide is 8:1), and then the carbon fibers and hollow ceramic tubes coated with polyetherimide and graphene oxide are heat-treated at 300°C for 2 hours using an infrared heater to obtain modified carbon fibers and modified hollow ceramic tubes; S2, by mass, 55 parts of polyarylene ether nitrile are added to a twin-screw extruder (temperature 320°C, speed 50 rpm), and after melting, 25 parts are added... Modified hollow ceramic tubes were further mixed for 10 minutes to obtain a resin matrix. S3. By mass, 35 parts of modified carbon fiber and resin matrix were mixed in a kneader (temperature 350℃, pressure 0.5MPa) to ensure that the fiber monofilaments were completely coated with resin. The mixture was then extruded into a film through a casting machine (gap 0.1mm, casting speed 0.8m / min). After cooling to 25℃, it was wound up to obtain a unidirectional prepreg with a thickness of 0.2mm. The unidirectional prepreg was then laid up symmetrically at an angle of (0° / 90°) (5 layers). The prepreg layers were placed in a hot press (mold temperature 360℃, pressure 2MPa) and kept at temperature and pressure for 15 minutes to obtain a lightweight thermoplastic composite film for spacecraft skin.

[0020] Comparative Example 1: The difference between this comparative example and Example 3 is that continuous carbon fibers are used instead of short carbon fibers.

[0021] Comparative Example 2 differs from Example 3 in that carbon nanotubes are used instead of graphene oxide.

[0022] Comparative Example 3 differs from Example 3 in that it uses a silane coupling agent to modify the carbon fiber.

[0023] Performance testing was conducted on the lightweight thermoplastic composite film for spacecraft skin prepared in Examples 1-3 and Comparative Examples 1-3.

[0024] Interlaminar shear strength test: The lightweight thermoplastic composite film for spacecraft skin prepared in Examples 1-3 and Comparative Examples 1-3 was placed on the support of a universal testing machine, ensuring that the center of the film was aligned with the indenter and the fiber direction was perpendicular to the loading direction. The loading rate was 3 mm / min, and loading was continued until interlaminar failure occurred. The maximum shear force at this point was recorded, and the interlaminar shear strength was calculated. Impact performance test: The lightweight thermoplastic composite film for spacecraft skin prepared in Examples 1-3 and Comparative Examples 1-3 was tested using a pendulum impact testing machine, and the impact strength was calculated. Thermal insulation performance test: Examples 1-3 and Comparative Examples 1-3 were tested using a pendulum impact testing machine. The lightweight thermoplastic composite film for spacecraft skin prepared in Examples 1-3 was placed in a sample chamber and irradiated with a laser beam in a vacuum environment, ensuring that the surface was perpendicular to the laser beam and the back side faced the infrared detector. The laser pulse energy was 30 mJ, and the temperature was increased from 25°C to 300°C at a rate of 10°C / min. The thermal conductivity was calculated. High and low temperature stability test: The lightweight thermoplastic composite film for spacecraft skin prepared in Examples 1-3 and Control Examples 1-3 was placed in a high and low temperature cycling test chamber, kept at -180°C for 2 hours and then kept at 300°C for 2 hours. This was one cycle, and a total of 100 cycles were performed. The tensile strength retention rate was 90%.

[0025] The results are shown in Table 1: Table 1

[0026] As shown in Table 1, the lightweight thermoplastic composite film for spacecraft skin prepared in the embodiments of this application has excellent mechanical properties, thermal insulation properties, and stability under high and low temperature environments, especially Example 2, which shows the best results. Compared with Example 3, Comparative Example 1 uses continuous carbon fibers instead of short carbon fibers. The continuous and oriented arrangement of fibers leads to complete fracture upon impact, with cracks propagating rapidly along the fiber direction, reducing impact strength. The oriented continuous fibers form continuous thermal conductive pathways, increasing thermal conductivity. However, the results show that its interlaminar shear strength, impact strength, and other mechanical properties are reduced. The thermal conductivity was improved, but the stability in high and low temperature environments was reduced, indicating that Comparative Example 1 was not as good as Example 2. Compared with Example 3, Comparative Example 2 used carbon nanotubes instead of graphene oxide. The high strength and toughness of carbon nanotubes can improve the impact resistance of the film. Carbon nanotubes have excellent thermal conductivity, which will improve the overall thermal conductivity, indicating that Comparative Example 2 was not as good as Example 3. The difference between Comparative Example 3 and Example 3 is that carbon fibers were modified with silane coupling agents. Without the auxiliary reinforcement effect of graphene oxide, the test results showed that the mechanical properties and high and low temperature stability were relatively low, indicating that Comparative Example 3 was not as good as Example 3.

[0027] The above description is merely an example and illustration of the concept of this application. Those skilled in the art can make various modifications or additions to the specific embodiments described or use similar methods to replace them, as long as they do not deviate from the inventive concept or exceed the scope defined in the claims, they should all fall within the protection scope of this application.

Claims

1. A lightweight thermoplastic composite film for spacecraft skin, characterized in that, The thermoplastic composite film is prepared by the following steps: S1, carbon fibers and hollow ceramic tubes are respectively impregnated in a mixture of polyetherimide and graphene oxide dissolved in N-methylpyrrolidone, followed by heat treatment to obtain modified carbon fibers and modified hollow ceramic tubes; S2, by weight, 45-55 parts of polyarylene ether nitrile are added to a twin-screw extruder, melted, and then 15-25 parts of modified hollow ceramic tubes are added, and the mixture is further mixed for 10-15 minutes to obtain a resin matrix; S3, by weight, 25-35 parts of modified carbon fibers are mixed with the resin matrix, and then the mixture is cast into a film, cooled to 25-28°C, and then wound up to obtain a unidirectional prepreg. The unidirectional prepreg is cross-symmetrically laid up and then placed in a hot press to obtain a lightweight thermoplastic composite film for spacecraft skin.

2. The lightweight thermoplastic composite film for spacecraft skin according to claim 1, characterized in that, The carbon fiber is composed of short carbon fibers and continuous carbon fibers, with a mass ratio of short carbon fibers to continuous carbon fibers of 1:2-3.

3. A lightweight thermoplastic composite film for spacecraft skin according to claim 1, characterized in that, The polyetherimide and graphene oxide are present in a mass ratio of 8:1-2.

4. A lightweight thermoplastic composite film for spacecraft skin according to claim 1, characterized in that, The twin-screw extruder has a temperature of 320-340℃ and a rotation speed of 50-60rpm.

5. A lightweight thermoplastic composite film for spacecraft skin according to claim 1, characterized in that, The mixing in step S3 is carried out at a temperature of 350-360℃ and a pressure of 0.5-0.6MPa.

6. A lightweight thermoplastic composite film for spacecraft skin according to claim 1, characterized in that, The casting process involves a casting die with a slit gap of 0.1-0.11 mm and a casting speed of 0.8-0.85 m / min.

7. A lightweight thermoplastic composite film for spacecraft skin according to claim 1, characterized in that, The cross-symmetric ply is laid in a 0° / 90° orthogonal symmetric ply configuration.

8. A lightweight thermoplastic composite film for spacecraft skin according to claim 1, characterized in that, The hot pressing process involves a temperature of 360-370℃, a pressure of 2-2.5MPa, and a time of 10-15min.

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