Low-thermal-expansion low-friction polyimide composite material and preparation method and application thereof

Abstract

The invention discloses a low-thermal-expansion low-friction polyimide composite material as well as a preparation method and application thereof. The low-thermal-expansion and low-friction polyimide composite material provided by the invention comprises phenylacetylene-terminated polyimide resin; the preparation method comprises the following steps: modifying graphene oxide modified by gamma-aminopropyltriethoxysilane through phenylacetylene phthalic anhydride; and chopped carbon fibers. According to the preparation method, the phenylacetylene-terminated polyimide resin is reinforced by adopting the phenylacetylene phthalic anhydride modified gamma-aminopropyltriethoxysilane modified graphene oxide and the short carbon fibers together; the phenylacetylene phthalic anhydride modified gamma-aminopropyltriethoxysilane modified graphene oxide can react with phenylacetylene terminated polyimide resin, so that the compatibility and dispersion uniformity of the phenylacetylene phthalic anhydride modified gamma-aminopropyltriethoxysilane modified graphene oxide in the resin are improved, and the graphene and the short carbon fibers play a better synergistic effect; the friction resistance, the thermal dimensional stability and the mechanical property of the phenylacetylene-terminated polyimide resin are greatly improved.

Description

Technical Field

[0001] The present invention relates to the field of composite materials, and in particular to a low-thermal expansion and low-friction polyimide composite material, and a preparation method and application thereof. Background Art

[0002] Aircraft engine bushings are accessories used outside mechanical parts to achieve sealing, wear protection and other functions. They play a vital role and are usually made of cast iron, cast steel or other special alloy materials. However, such bushings require frequent addition of lubricants to reduce wear between other parts, resulting in short maintenance cycles and high costs. Compared with traditional metal materials, polymer materials have self-lubricating functions and do not require additional lubricants such as high-temperature grease, which can shorten equipment maintenance cycles and effectively reduce costs.

[0003] Polyimide (PI) has excellent high temperature resistance, mechanical properties and corrosion resistance, and can be used in extreme environments such as high temperature, low temperature and high pressure. However, the surface friction coefficient of pure polyimide material is large, which leads to large energy loss and wear during equipment operation. At present, there have been many reports on the introduction of nanofillers into PI to improve its wear resistance. Common fillers include silica, aluminum oxide, molybdenum disulfide, graphene oxide, carbon nanotubes, etc. However, the dispersibility of such fillers in polyimide is not high, resulting in limited improvement in the performance of polyimide, and the modification of a single material does not maximize the enhancement of friction performance. Summary of the invention

[0004] In view of this, the present invention provides a low thermal expansion and low friction polyimide composite material, a preparation method and application thereof. The present application provides a polyimide composite material having good friction resistance, thermal dimensional stability and mechanical properties.

[0005] The present application provides a low thermal expansion and low friction polyimide composite material, comprising:

[0006] Phenylacetylene terminated polyimide resin;

[0007] γ-aminopropyltriethoxysilane-modified graphene oxide modified with phenylacetylene phthalic anhydride;

[0008] Chopped carbon fiber.

[0009] The present application adopts phenylacetylene phthalic anhydride-modified γ-aminopropyltriethoxysilane-modified graphene oxide and short-cut carbon fibers to jointly reinforce the phenylacetylene-terminated polyimide resin. The phenylacetylene phthalic anhydride-modified γ-aminopropyltriethoxysilane-modified graphene oxide can react with the phenylacetylene-terminated polyimide resin to improve its compatibility and dispersion uniformity in the resin, so that the graphene and the short-cut carbon fibers can play a better synergistic role, and the friction resistance, thermal dimensional stability and mechanical properties of the phenylacetylene-terminated polyimide resin are greatly improved.

[0010] The low thermal expansion and low friction polyimide composite material includes a phenylacetylene terminated polyimide resin, which has a high melting point, high thermal stability, good flame retardancy, etc. In some specific implementations, the molecular weight of the phenylacetylene terminated polyimide resin is 1500 g / mol to 2500 g / mol, preferably 1800 g / mol to 2300 g / mol. The present application has no special restrictions on the source of the phenylacetylene terminated polyimide resin, which can be purchased on the market.

[0011] The low thermal expansion and low friction polyimide composite material includes graphene oxide modified by γ-aminopropyltriethoxysilane modified by phenylacetylene phthalic anhydride, such as graphene oxide modified by γ-aminopropyltriethoxysilane (γ-APS) modified by 4-phenylacetylene phthalic anhydride (4-PEPA). In some specific implementations, in the graphene oxide modified by γ-aminopropyltriethoxysilane modified by phenylacetylene phthalic anhydride, the mass ratio of γ-aminopropyltriethoxysilane modified by phenylacetylene phthalic anhydride to graphene oxide is 15:1 to 25:1, preferably 18:1 to 25:1, and more preferably 20:1 to 25:1. In some specific implementations, the thickness of the graphene oxide is 0.8nm to 3nm. The present application has no special restrictions on the source of the graphene oxide modified by γ-aminopropyltriethoxysilane modified by phenylacetylene phthalic anhydride, and it can be prepared according to the following method:

[0012] The graphene oxide and phenylacetylene phthalic anhydride modified γ-aminopropyltriethoxysilane are reacted under acidic conditions to obtain phenylacetylene phthalic anhydride modified γ-aminopropyltriethoxysilane modified graphene oxide.

[0013] The present application uses γ-aminopropyl triethoxysilane modified with phenylacetylene phthalic anhydride as a modifier to modify graphene, thereby increasing the compatibility and dispersion uniformity of the modified graphene in the resin. The present application has no particular restrictions on the source of the γ-aminopropyl triethoxysilane modified with phenylacetylene phthalic anhydride, and it can be purchased from the market.

[0014] In the present application, graphene oxide and phenylacetylene phthalic anhydride modified γ-aminopropyl triethoxysilane are mixed in a solvent and reacted under acidic conditions to obtain graphene oxide modified by phenylacetylene phthalic anhydride modified γ-aminopropyl triethoxysilane. In some specific implementations, the solvent includes but is not limited to dimethylformamide (DMF), dimethylacetamide (DMAC), N-methylpyrrolidone (NMP), etc., preferably DMF. In some specific implementations, the acidic conditions can be hydrochloric acid. In some specific implementations, the temperature of the reaction is 50°C to 100°C, and the time is 8h to 18h.

[0015] The low thermal expansion and low friction polyimide composite material includes chopped carbon fibers. In some specific implementations, the length of the chopped carbon fibers is 0.5 mm to 2.5 mm, preferably 1.0 mm to 2.0 mm. In order to improve the compatibility of the chopped carbon fibers with the resin, an epoxy resin sizing agent layer or a polyimide sizing agent layer is preferably formed on the surface of the chopped carbon fibers. The present application has no special restrictions on the epoxy resin sizing agent and the polyimide sizing agent, and the relevant products purchased on the market can be used.

[0016] In the low thermal expansion and low friction polyimide composite material disclosed in the present application, the mass ratio of the phenylacetylene phthalic anhydride modified γ-aminopropyltriethoxysilane modified graphene oxide to the phenylacetylene terminated polyimide resin is 5:995 to 20:980, preferably 15:985, calculated as graphene oxide; the mass ratio of the chopped carbon fiber to the phenylacetylene terminated polyimide resin is 10:90 to 20:80, preferably 15:85.

[0017] The present application also provides a method for preparing a low thermal expansion and low friction polyimide composite material, comprising:

[0018] a) mixing and reacting phenylacetylene phthalic anhydride-modified γ-aminopropyltriethoxysilane-modified graphene oxide, phenylacetylene-terminated polyimide resin and short carbon fibers to obtain a blended material;

[0019] b) drying the blended material to obtain a low thermal expansion and low friction polyimide composite material.

[0020] This application uses phenylacetylene phthalic anhydride modified γ-aminopropyl triethoxysilane modified graphene oxide, phenylacetylene terminated polyimide resin and short carbon fibers as raw materials, and reacts after mixing. Phenylacetylene phthalic anhydride modified γ-aminopropyl triethoxysilane modified graphene oxide and phenylacetylene terminated polyimide resin can react to improve the compatibility and dispersion uniformity of graphene oxide in the resin. Phenylacetylene phthalic anhydride modified γ-aminopropyl triethoxysilane modified graphene oxide, phenylacetylene terminated polyimide resin and short carbon fibers are as described above, and this application will not repeat them here. In some specific implementations, the temperature of the mixed reaction of phenylacetylene phthalic anhydride modified γ-aminopropyl triethoxysilane modified graphene oxide, phenylacetylene terminated polyimide resin and short carbon fibers is 50°C to 100°C, and the time is 8h to 12h.

[0021] After the reaction is completed, the blended raw material is obtained and then dried. In some specific implementations, vacuum drying can be used for drying, and the drying temperature is 200° C. to 240° C. After drying, a low thermal expansion and low friction polyimide composite material can be obtained.

[0022] The low thermal expansion and low friction polyimide composite material prepared in the present application has a low friction coefficient and a low thermal expansion coefficient, and is applied to wear-resistant parts such as engine bushings. Based on this, the present application preferably includes molding the obtained low thermal expansion and low friction polyimide composite material to obtain a polyimide composite workpiece, such as an engine bushing, etc. The present application has no special restrictions on the molding method, which can be a self-autoclave molding process, a compression molding process or a hot extrusion process, etc., and those skilled in the art can select according to their needs.

[0023] The low thermal expansion and low friction polyimide composite material provided by the present application includes: phenylacetylene terminated polyimide resin; graphene oxide modified by γ-aminopropyltriethoxysilane modified by phenylacetylene phthalic anhydride; and chopped carbon fibers. The present application uses graphene oxide modified by γ-aminopropyltriethoxysilane modified by phenylacetylene phthalic anhydride and chopped carbon fibers to jointly reinforce the phenylacetylene terminated polyimide resin. Graphene oxide modified by γ-aminopropyltriethoxysilane modified by phenylacetylene phthalic anhydride can react with the phenylacetylene terminated polyimide resin to improve its compatibility and uniformity of dispersion in the resin, thereby making the graphene and chopped carbon fibers play a better synergistic role, greatly improving the friction resistance, thermal dimensional stability and mechanical properties of the phenylacetylene terminated polyimide resin. Experimental results show that the polyimide composite material provided in the present application has a friction coefficient as low as 0.2, a tensile strength of 85.9 MPa, a modulus of 8.8 GPa, and a thermal expansion coefficient as low as 24.8 ppm / K, and can be used in wear-resistant parts such as engine bushings. DETAILED DESCRIPTION

[0024] It should be understood that the expression "one or more of..." includes each of the items recited after the expression individually and in various different combinations of two or more of the recited items, unless otherwise understood from the context and usage. The expression "and / or" in combination with three or more recited items should be understood to have the same meaning, unless otherwise understood from the context.

[0025] The use of the terms "comprising", "having" or "containing", including their grammatical synonyms, should generally be understood as open and non-restrictive, for example not excluding other unrecited elements or steps, unless otherwise specifically stated or otherwise understood from the context.

[0026] It should be understood that the order of steps or the order in which certain actions are performed is not important as long as the present invention remains operable. In addition, two or more steps or actions may be performed simultaneously.

[0027] The use of any and all examples or exemplary language, such as "for example" or "including", herein is intended only to better illustrate the invention and does not limit the scope of the invention unless otherwise claimed. No language in this specification should be construed as indicating that any non-claimed element is essential to the practice of the invention.

[0028] In addition, the numerical ranges and parameters used to define the present invention are approximate values, and the relevant values ​​in the specific embodiments have been presented as accurately as possible. However, any numerical value inherently inevitably contains standard deviations due to individual test methods. Therefore, unless otherwise expressly stated, it should be understood that all ranges, quantities, values ​​and percentages used in this disclosure are modified by "about". Here, "about" generally means that the actual value is within plus or minus 10%, 5%, 1% or 0.5% of a specific value or range.

[0029] The present application provides a low thermal expansion and low friction polyimide composite material, comprising:

[0030] Phenylacetylene terminated polyimide resin;

[0031] γ-aminopropyltriethoxysilane-modified graphene oxide modified with phenylacetylene phthalic anhydride;

[0032] Chopped carbon fiber.

[0033] The present application adopts graphene oxide modified by γ-aminopropyl triethoxysilane modified by phenylacetylene phthalic anhydride and chopped carbon fibers to jointly enhance the phenylacetylene terminated polyimide resin. Graphene oxide modified by γ-aminopropyl triethoxysilane modified by phenylacetylene phthalic anhydride can react with the phenylacetylene terminated polyimide resin to improve its compatibility and uniformity of dispersion in the resin, so that graphene and chopped carbon fibers can play a better synergistic role, greatly improving the friction resistance, thermal dimensional stability and mechanical properties of the phenylacetylene terminated polyimide resin. The experimental results show that the polyimide composite material provided by the present application has a friction coefficient as low as 0.2, a tensile strength of 85.9MPa, a modulus of 8.8GPa, and a thermal expansion coefficient as low as 24.8ppm / K, which can be applied to wear-resistant parts such as engine bushings.

[0034] The present invention is further described below in conjunction with the following examples. The protection scope of the present invention is not limited by the following examples.

[0035] In the following examples, the molecular weight of the phenylacetylene-terminated polyimide resin is 2000 g / mol, and the length of the chopped carbon fibers is 2 mm.

[0036] Example 1

[0037] 0.6 g of graphene oxide with a thickness of less than 3 nm, 15 g of γ-aminopropyltriethoxysilane modified with phenylacetylene phthalic anhydride and 3 mL of hydrochloric acid with a mass concentration of 37% were added to 300 mL of DMF solution, and the mixture was stirred at 80° C. for 15 h to obtain graphene oxide modified with γ-aminopropyltriethoxysilane modified with phenylacetylene phthalic anhydride.

[0038] Examples 2 to 4, Comparative Examples 1 to 4

[0039] According to the formula shown in Table 1, phenylacetylene-terminated polyimide resin, chopped carbon fibers and modified graphene oxide prepared in Example 1 were mixed in 600 mL of DMF, and heated with stirring at 80° C. for 10 h to obtain a blended solution;

[0040] The blended solution is vacuum dried at 220° C. to obtain a low thermal expansion and low friction polyimide material.

[0041] Table 1 Formulas of Examples and Comparative Examples

[0042]

[0043] Comparative Example 5

[0044] Compared with Example 2, the difference is that unmodified graphene oxide is used instead of modified graphene oxide, and the other aspects are the same.

[0045] Comparative Example 6

[0046] Compared with Example 2, the difference is that γ-aminopropyltriethoxysilane-modified graphene oxide is used instead of modified graphene oxide, and the other conditions are the same. Among them, the preparation method of γ-aminopropyltriethoxysilane-modified graphene oxide is the same as that of Example 1, except that γ-aminopropyltriethoxysilane is used instead of γ-aminopropyltriethoxysilane modified with phenylacetylene phthalic anhydride.

[0047] Test Example 1

[0048] The low thermal expansion and low friction polyimide powder materials prepared in Examples 2 to 4 and Comparative Examples 1 to 6 were tested according to the following method:

[0049] Friction coefficient test method: Block-on-ring friction tester;

[0050] Thermal expansion coefficient test method: Thermomechanical analysis (TMA);

[0051] Tensile strength test method: ASTM D638;

[0052] Modulus test method: ASTM D638;

[0053] The results are shown in Table 2, which shows the performance test results of the low thermal expansion and low friction polyimide powders prepared in the examples and comparative examples of the present application.

[0054] Table 2. Performance test data of embodiments and comparative examples

[0055]

[0056]

[0057] As can be seen from Table 2, the present application adds chopped carbon fibers and γ-aminopropyltriethoxysilane-modified graphene oxide modified with phenylacetylene phthalic anhydride to the phenylacetylene-terminated polyimide resin, which greatly reduces the friction coefficient and thermal expansion coefficient of the phenylacetylene-terminated polyimide resin and improves its mechanical strength, so that it has good friction resistance, thermal dimensional stability and mechanical properties.

[0058] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A low thermal expansion and low friction polyimide composite material, characterized in that: include: Phenylacetylene terminated polyimide resin; γ-aminopropyltriethoxysilane-modified graphene oxide modified with phenylacetylene phthalic anhydride; Chopped carbon fiber.

2. The composite material according to claim 1, characterized in that In the graphene oxide modified by phenylacetylene phthalic anhydride-modified γ-aminopropyltriethoxysilane, the mass ratio of phenylacetylene phthalic anhydride-modified γ-aminopropyltriethoxysilane to graphene oxide is 15:1 to 25:1; The mass ratio of the graphene oxide to the phenylacetylene-terminated polyimide resin is 5:995 to 20:980; The mass ratio of the chopped carbon fibers to the phenylacetylene-terminated polyimide resin is 10:90 to 20:

80.

3. The composite material according to claim 1, characterized in that The molecular weight of the phenylethene-terminated polyimide resin is 1500 g / mol to 2500 g / mol.

4. The composite material according to claim 1, characterized in that The length of the chopped carbon fiber is 0.5 mm to 2.5 mm; An epoxy resin sizing agent layer or a polyimide sizing agent layer is formed on the surface of the chopped carbon fiber.

5. A method for preparing a low thermal expansion and low friction polyimide composite material, characterized in that: include: a) mixing and reacting phenylacetylene phthalic anhydride-modified γ-aminopropyltriethoxysilane-modified graphene oxide, phenylacetylene-terminated polyimide resin and short carbon fibers to obtain a blended material; b) drying the blended material to obtain a low thermal expansion and low friction polyimide composite material.

6. The preparation method according to claim 5, characterized in that: In step a), the reaction temperature is 50°C to 100°C and the reaction time is 8h to 12h; The drying temperature in step c) is 200°C to 240°C.

7. The preparation method according to claim 5, characterized in that: The phenylacetylene phthalic anhydride modified γ-aminopropyltriethoxysilane modified graphene oxide is prepared according to the following method: The graphene oxide and phenylacetylene phthalic anhydride-modified γ-aminopropyltriethoxysilane are subjected to modification reaction under acidic conditions to obtain phenylacetylene phthalic anhydride-modified γ-aminopropyltriethoxysilane-modified graphene oxide.

8. The preparation method according to claim 7, characterized in that: The acidic condition is hydrochloric acid; The modification reaction time is 8h to 18h, and the temperature is 50°C to 100°C.

9. The preparation method according to any one of claims 5 to 8, characterized in that: Also includes: The low thermal expansion and low friction polyimide composite material obtained in step b) is molded.

10. An aircraft engine bushing, made of the low thermal expansion and low friction polyimide composite material according to any one of claims 1 to 4, or the low thermal expansion and low friction polyimide composite material prepared by the preparation method according to any one of claims 5 to 9.

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