Low coefficient of expansion, high strength engineering plastic and method for making same

Abstract

This invention relates to the field of engineering plastics technology, specifically to low-expansion-coefficient, high-strength engineering plastics and their preparation methods. The method includes: uniformly mixing modified thermoplastic polyimide, polyetheretherketone, expansion-inhibiting filler, and silane coupling agent to obtain a premix; and extruding the premix using a screw extruder to obtain the low-expansion-coefficient, high-strength engineering plastic. This invention incorporates tannic acid-nano zinc oxide into the matrix through in-situ compounding, which, combined with the added expansion-inhibiting filler, ensures that the engineering plastic possesses both good antistatic properties and a low coefficient of thermal expansion, thus reducing the difference in thermal expansion coefficient with metal or ceramic substrates.

Description

Technical Field

[0001] This invention relates to the field of engineering plastics technology, specifically to low-expansion-coefficient, high-strength engineering plastics and their preparation methods. Background Technology

[0002] Thermoplastic polyimide, as a high-performance material in the field of special engineering plastics, has excellent high temperature resistance, mechanical strength and electrical insulation properties. It has a wide long-term operating temperature range and good dimensional stability, and is widely used in high-end fields such as aerospace, electronics and electrical engineering, and precision instruments. It is especially suitable for the preparation of structural parts and electronic packaging materials that are composite with metal or ceramic substrates.

[0003] However, existing thermoplastic polyimide engineering plastics still have significant technical shortcomings in practical applications: On the one hand, as an insulating material, its surface easily accumulates static electricity and attracts dust and impurities, which not only affects the appearance and performance of the product but may also cause electrostatic discharge, damaging precision electronic components; on the other hand, thermoplastic polyimide has a high coefficient of thermal expansion, which differs greatly from that of metal and ceramic substrates. During high and low temperature cycling and processing, it is prone to warping, cracking, delamination, and other problems due to thermal stress, which seriously reduces the reliability and service life of the composite structure. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides engineering plastics with low coefficient of thermal expansion and high strength, as well as their preparation methods, ensuring that the engineering plastics possess both good antistatic properties and a low coefficient of thermal expansion.

[0005] To achieve the above objectives, the present invention provides the following technical solution: A low coefficient of thermal expansion and high strength engineering plastic, comprising the following raw materials in parts by weight: 60-75 parts of modified thermoplastic polyimide, 10-20 parts of polyetheretherketone, 15-20 parts of expansion-inhibiting filler, and 0.3-0.5 parts of silane coupling agent.

[0006] Preferably, the modified thermoplastic polyimide is prepared by: S11. Add 2,2'-bis(trifluoromethyl)diaminobiphenyl to N,N-dimethylacetamide while stirring, then add phthalic anhydride and continue stirring for 30-40 minutes until completely dissolved. Then add bisphenol A diether dianhydride and 3,3',4,4'-biphenyltetracarboxylic anhydride in batches and continue stirring for 10-12 hours to obtain a polyamic acid solution. S12. Add tannic acid-nano zinc oxide to polyamic acid solution and stir for 2-3 hours. Then add pyridine and acetic anhydride in sequence and carry out chemical imidization reaction at room temperature for more than 2 hours to obtain intermediate solution. S13. The intermediate liquid is stirred and added to deionized water. The precipitate is filtered, washed and dried to obtain modified thermoplastic polyimide.

[0007] Preferably, in step S11, the mass ratio of 2,2'-bis(trifluoromethyl)diaminobiphenyl, bisphenol A diether dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride and phthalic anhydride is 5:7:2:0.05, wherein the ratio of 2,2'-bis(trifluoromethyl)diaminobiphenyl to N,N-dimethylacetamide is 1:(10-12) g / mL.

[0008] Preferably, in step S12, the tannic acid-nano zinc oxide is prepared by ultrasonically dispersing tannic acid and nano zinc oxide in deionized water, continuously stirring at room temperature for 1-1.5 hours, and then filtering, washing and drying.

[0009] Preferably, the mass ratio of tannic acid to nano zinc oxide is 1:1, and the material-to-liquid ratio of tannic acid to deionized water is 1:800 g / mL.

[0010] Preferably, in step S12, the tannic acid-nano zinc oxide accounts for 2-3% of the mass of the polyamic acid solution; pyridine accounts for 4% of the volume of the polyamic acid solution; and acetic anhydride accounts for 5% of the volume of the polyamic acid solution.

[0011] Preferably, the method for preparing the expansion-inhibiting filler is as follows: S21. Carbon nanofibers are subjected to nitric acid oxidation treatment, and the resulting active nanofibers and sodium dodecylbenzene sulfonate are ultrasonically dispersed in deionized water to obtain a nanofiber suspension. S22. Dissolve zirconium oxychloride in deionized water to obtain solution A; dissolve ammonium metatungstate in deionized water to obtain solution B; mix solution A and solution B to obtain the precursor solution; S23. Add the precursor solution to the nanofiber suspension and stir for 1-1.5 h. At the same time, adjust the pH of the system to 6.5-7.5 with ammonia water. Continue stirring at 50-55℃ for 2-3 h. After filtration, washing, drying and calcination, the expansion inhibition filler is obtained.

[0012] Preferably, in step S21, the mass ratio of the active nanofibers to sodium dodecylbenzenesulfonate is 20:1; and the material-to-liquid ratio of the active nanofibers to deionized water is 1:12 g / mL.

[0013] Preferably, in step S22, the ratio of zirconium oxychloride to deionized water is 1.6:100 g / mL; the ratio of ammonium metatungstate to deionized water is 3:25 g / mL; the amount of deionized water used in solution A and solution B is the same; and in step S23, the volume ratio of precursor solution to nanofiber suspension is (8-10):3.

[0014] This invention also provides a method for preparing engineering plastics with low coefficient of thermal expansion and high strength, comprising the following steps: (1) The modified thermoplastic polyimide, polyether ether ketone, expansion-inhibiting filler and silane coupling agent are uniformly mixed to obtain a premix; (2) The premixed material is extruded through a screw extruder to obtain a low expansion coefficient and high strength engineering plastic.

[0015] This invention provides a low coefficient of thermal expansion, high-strength engineering plastic and its preparation method, which has the following advantages compared with the prior art: This invention adds tannic acid-nano zinc oxide to the matrix through in-situ composite, and then works together with the added expansion-inhibiting filler to ensure that the engineering plastic has good antistatic properties while also having a low coefficient of thermal expansion, thus reducing the difference in the coefficient of thermal expansion with the metal or ceramic substrate.

[0016] This invention coats zirconium tungstate onto the surface of carbon nanofibers, which can precisely weaken the high thermal expansion of the plastic matrix by relying on the strong negative expansion characteristics of zirconium tungstate. It also avoids the problem of excessive conductivity of pure carbon nanofibers causing short circuits and leakage in the substrate. At the same time, the use of fiber fillers also significantly improves the overall strength of the plastic matrix.

[0017] This invention achieves a synergistic antibacterial effect by coating nano-zinc oxide with tannic acid, thereby improving the antibacterial properties of the plastic matrix. Furthermore, the surface modification of nano-zinc oxide by tannic acid allows it to be better dispersed in the plastic matrix, which has a positive effect on improving the strength and antistatic properties of the matrix. Attached Figure Description

[0018] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings: Figure 1 These are cross-sectional morphology diagrams of the modified thermoplastic polyimide of Example 1 and the thermoplastic polyimide of Comparative Example 1 of the present invention. Detailed Implementation

[0019] The following embodiments are provided to illustrate the implementation of this application in detail, so that the process of how this application uses technical means to solve technical problems and achieve technical effects can be fully understood and implemented accordingly.

[0020] The raw materials in this invention are sourced from: 2,2'-Di(trifluoromethyl)diaminobiphenyl, phthalic anhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, nano zinc oxide, and sodium dodecylbenzenesulfonate were purchased from Aladdin Reagent Co., Ltd.; tannic acid, carbon nanofibers, zirconium oxychloride (zirconium oxychloride hydrate), ammonium metatungstate (ammonium metatungstate hydrate), and polyetheretherketone were purchased from Shanghai Maclean Biochemical Technology Co., Ltd.; acetic anhydride, concentrated nitric acid, and ammonia were purchased from Sinopharm Chemical Reagent Co., Ltd.; N,N-dimethylacetamide and pyridine were purchased from Tianjin Fuchen Chemical Reagent Co., Ltd.; bisphenol A diether dianhydride was purchased from Shanghai Adamas Reagent Co., Ltd.; and silane coupling agent (KH-540) was purchased from Nanjing Liansi Chemical Co., Ltd.

[0021] Example 1 The preparation method of modified thermoplastic polyimide is as follows: S11. Add 2,2'-bis(trifluoromethyl)diaminobiphenyl to N,N-dimethylacetamide while stirring, then add phthalic anhydride and continue stirring for 40 min until completely dissolved. Then add bisphenol A diether dianhydride and 3,3',4,4'-biphenyltetracarboxylic anhydride in batches and continue stirring for 10 h to obtain a polyamic acid solution. The mass ratio of 2,2'-bis(trifluoromethyl)diaminobiphenyl, bisphenol A diether dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride and phthalic anhydride is 5:7:2:0.05, and the ratio of 2,2'-bis(trifluoromethyl)diaminobiphenyl to N,N-dimethylacetamide is 1:12 g / mL. S12. Tannic acid and nano zinc oxide (tannic acid: nano zinc oxide = 1:1, w / w) are ultrasonically dispersed in deionized water, and the ratio of tannic acid to deionized water is controlled at 1:800 g / mL. The mixture is stirred continuously at room temperature for 1 hour, and then filtered, washed and dried to obtain tannic acid-nano zinc oxide. S13. Add tannic acid-nano zinc oxide to polyamic acid solution and stir for 3 hours. Then add pyridine and acetic anhydride in sequence and carry out chemical imidization reaction at room temperature for more than 2 hours to obtain intermediate solution. The composition of the polyamic acid solution is as follows: tannic acid-nano zinc oxide accounts for 2% of the mass of the polyamic acid solution; pyridine accounts for 4% of the volume of the polyamic acid solution; and acetic anhydride accounts for 5% of the volume of the polyamic acid solution. S14. The intermediate liquid is stirred and added to deionized water. The precipitate is filtered, washed and dried to obtain modified thermoplastic polyimide.

[0022] Example 2 The preparation method of modified thermoplastic polyimide is as follows: S11. Add 2,2'-bis(trifluoromethyl)diaminobiphenyl to N,N-dimethylacetamide while stirring, then add phthalic anhydride and continue stirring for 30 min until completely dissolved. Then add bisphenol A diether dianhydride and 3,3',4,4'-biphenyltetracarboxylic anhydride in batches and continue stirring for 12 h to obtain a polyamic acid solution. The mass ratio of 2,2'-bis(trifluoromethyl)diaminobiphenyl, bisphenol A diether dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride and phthalic anhydride is 5:7:2:0.05, and the ratio of 2,2'-bis(trifluoromethyl)diaminobiphenyl to N,N-dimethylacetamide is 1:10 g / mL. S12. Tannic acid and nano zinc oxide (tannic acid: nano zinc oxide = 1:1, w / w) are ultrasonically dispersed in deionized water, and the ratio of tannic acid to deionized water is controlled at 1:800 g / mL. The mixture is stirred continuously at room temperature for 1.5 h, and then filtered, washed and dried to obtain tannic acid-nano zinc oxide. S13. Add tannic acid-nano zinc oxide to polyamic acid solution and stir for 2 hours. Then add pyridine and acetic anhydride in sequence and carry out chemical imidization reaction at room temperature for more than 2 hours to obtain intermediate solution. The composition of the polyamic acid solution is as follows: tannic acid-nano zinc oxide accounts for 3% of the mass of the polyamic acid solution; pyridine accounts for 4% of the volume of the polyamic acid solution; and acetic anhydride accounts for 5% of the volume of the polyamic acid solution. S14. The intermediate liquid is stirred and added to deionized water. The precipitate is filtered, washed and dried to obtain modified thermoplastic polyimide.

[0023] Example 3 The preparation method of the expansion-inhibiting filler is as follows: S21. Carbon nanofibers are subjected to nitric acid oxidation treatment (using concentrated nitric acid for gentle boiling reflux treatment for 1.5 h). The resulting active nanofibers and sodium dodecylbenzenesulfonate are ultrasonically dispersed in deionized water at a mass ratio of 20:1. The material-liquid ratio of active nanofibers to deionized water is controlled at 1:12 g / mL to obtain a nanofiber suspension. S22. Dissolve zirconium oxychloride in deionized water at a material-to-liquid ratio of 1.6:100g / mL to obtain solution A; dissolve ammonium metatungstate in deionized water at a material-to-liquid ratio of 3:25g / mL to obtain solution B; control the amount of deionized water in solution A and solution B to be the same, mix solution A and solution B to obtain precursor solution; S23. The precursor solution was added to the nanofiber suspension at a volume ratio of 10:3 and stirred for 1 hour. At the same time, the pH of the system was adjusted to 7.5 using ammonia water. Stirring was continued at 50°C for 3 hours. After filtration, washing, drying and calcination, the expansion-inhibiting filler was obtained.

[0024] Example 4 The preparation method of the expansion-inhibiting filler is as follows: S21. Carbon nanofibers are subjected to nitric acid oxidation treatment (using concentrated nitric acid for gentle boiling reflux treatment for 1.5 h). The resulting active nanofibers and sodium dodecylbenzenesulfonate are ultrasonically dispersed in deionized water at a mass ratio of 20:1. The material-liquid ratio of active nanofibers to deionized water is controlled at 1:12 g / mL to obtain a nanofiber suspension. S22. Dissolve zirconium oxychloride in deionized water at a material-to-liquid ratio of 1.6:100g / mL to obtain solution A; dissolve ammonium metatungstate in deionized water at a material-to-liquid ratio of 3:25g / mL to obtain solution B; control the amount of deionized water in solution A and solution B to be the same, mix solution A and solution B to obtain precursor solution; S23. The precursor solution was added to the nanofiber suspension at a volume ratio of 8:3 and stirred for 1.5 h. At the same time, the pH of the system was adjusted to 6.5 using ammonia water. The mixture was stirred for another 2 h at 55 °C. After filtration, washing, drying and calcination, the expansion-inhibiting filler was obtained.

[0025] Example 5 A method for preparing low-expansion-coefficient, high-strength engineering plastics includes the following steps: (1) Weigh out the following by weight: 75 parts of modified thermoplastic polyimide, 10 parts of polyether ether ketone, 20 parts of expansion-inhibiting filler, and 0.3 parts of silane coupling agent in Example 3; (2) Mix the above raw materials evenly, and extrude the resulting premix through a screw extruder to obtain a low expansion coefficient and high strength engineering plastic.

[0026] Example 6 A method for preparing low-expansion-coefficient, high-strength engineering plastics includes the following steps: (1) Weigh out the following by weight: 60 parts of modified thermoplastic polyimide, 20 parts of polyether ether ketone, 15 parts of expansion-inhibiting filler, and 0.5 parts of silane coupling agent from Example 4; (2) Mix the above raw materials evenly, and extrude the resulting premix through a screw extruder to obtain a low expansion coefficient and high strength engineering plastic.

[0027] Example 7 A method for preparing low-expansion-coefficient, high-strength engineering plastics includes the following steps: (1) Weigh out the following by weight: 70 parts of modified thermoplastic polyimide, 15 parts of polyether ether ketone, 16 parts of expansion-inhibiting filler, and 0.4 parts of silane coupling agent from Example 4; (2) Mix the above raw materials evenly, and extrude the resulting premix through a screw extruder to obtain a low expansion coefficient and high strength engineering plastic.

[0028] Comparative Example 1 It is basically the same as Example 7, except that the modified thermoplastic polyimide is replaced with thermoplastic polyimide.

[0029] The preparation method of thermoplastic polyimide is as follows: S11. Referring to Example 1, a polyamic acid solution is obtained; S12. Pyridine and acetic anhydride are added sequentially to the polyamic acid solution, and a chemical imidization reaction is carried out at room temperature for more than 2 hours to obtain an intermediate solution. S13. Stir the intermediate liquid and add it to deionized water. Filter, wash and dry the precipitate to obtain thermoplastic polyimide.

[0030] Comparative Example 2 It is basically the same as Example 7, except that the modified thermoplastic polyimide is replaced with a composite thermoplastic polyimide.

[0031] The preparation method of composite thermoplastic polyimide is as follows: S11. Referring to Example 1, a polyamic acid solution is obtained; S12. Add nano zinc oxide to polyamic acid solution and stir for 3 hours. Then add pyridine and acetic anhydride in sequence and carry out chemical imidization reaction at room temperature for more than 2 hours to obtain intermediate solution. The composition of the polyamic acid solution is as follows: nano zinc oxide accounts for 2% of the mass of the polyamic acid solution; pyridine accounts for 4% of the volume of the polyamic acid solution; and acetic anhydride accounts for 5% of the volume of the polyamic acid solution. S14. The intermediate liquid is stirred and added to deionized water. The precipitate is filtered, washed and dried to obtain composite thermoplastic polyimide.

[0032] Comparative Example 3 A method for preparing high-strength engineering plastics includes the following steps: (1) Weigh out the following by weight: 70 parts of modified thermoplastic polyimide, 15 parts of polyether ether ketone, and 0.4 parts of silane coupling agent as described in Example 1; (2) Mix the above raw materials evenly, and extrude the resulting premix through a screw extruder to obtain high-strength engineering plastics.

[0033] Comparative Example 4 This is essentially the same as Example 7, except that the expansion-inhibiting filler is replaced with carbon nanofiber-zirconium tungstate (carbon nanofiber:zirconium tungstate = 1:2, w / w). The preparation method of zirconium tungstate is as follows: S21. Dissolve zirconium oxychloride in deionized water at a material-to-liquid ratio of 1.6:100g / mL to obtain solution A; dissolve ammonium metatungstate in deionized water at a material-to-liquid ratio of 3:25g / mL to obtain solution B; control the amount of deionized water in solution A and solution B to be the same, mix solution A and solution B to obtain precursor solution; S22. The pH of the precursor solution was adjusted to 6.5 using ammonia water, and the mixture was stirred at 55°C for 2 hours. After filtration, washing, drying and calcination, zirconium tungstate was obtained.

[0034] Performance testing 1. Antistatic performance test: The engineering plastics in Examples 5-7 and Comparative Examples 1-4 were extruded and pressed into samples for testing in accordance with the standard GB / T 31838.2-2019.

[0035] 2. Tensile strength test: The engineering plastics in Examples 5-7 and Comparative Examples 1-4 were extruded and pressed into samples for testing in accordance with the standard GB / T 1040.2-2022.

[0036] The specific test results are shown in Table 1.

[0037] Table 1 Surface resistivity and tensile strength

[0038] Table 1 shows that the engineering plastics in Examples 5-7 have relatively good antistatic and mechanical properties. Compared with Example 7, Comparative Example 1 uses thermoplastic polyimide, which has a significantly increased surface resistivity and a slightly decreased tensile strength. Comparative Example 2 uses composite thermoplastic polyimide, which has a slightly increased surface resistivity and a stronger tensile strength than Comparative Example 1. In Comparative Example 3, no expansion-inhibiting filler was added, so the surface resistivity did not change significantly, but the tensile strength decreased substantially. Comparative Example 4 uses carbon nanofiber-zirconium tungstate, which has a surface resistivity of less than 1×10⁻⁶. 6 The risk of leakage is high, and the tensile strength also decreases accordingly.

[0039] 3. Thermal expansion performance test: The engineering plastics in Examples 5-7 and Comparative Examples 1-4 were extruded and compressed into samples according to GB / T 7320-2018 for testing. The specific test results are shown in Table 2.

[0040] Table 2 Coefficient of thermal expansion

[0041] As shown in Table 2, the engineering plastics in Examples 5-7 have a lower coefficient of thermal expansion; compared with Example 7, the coefficients of thermal expansion of Comparative Examples 1, 2 and 4 have increased; and the coefficient of thermal expansion of Comparative Example 3 has increased significantly.

[0042] 4. Antibacterial Performance Test: The engineering plastics in Example 7 and Comparative Example 2 were tested according to GB / T 31402-2023. Specific test results are shown in Table 3. Table 3 Antibacterial properties

[0043] As shown in Table 3, compared with Example 7, Comparative Example 2 uses composite thermoplastic polyimide, which lacks the addition of tannic acid, resulting in a reduction in antibacterial effect.

[0044] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. Low coefficient of expansion, high strength engineering plastic, characterized in that, The raw materials include the following parts by weight: 60-75 parts of modified thermoplastic polyimide, 10-20 parts of polyether ether ketone, 15-20 parts of expansion-inhibiting filler, and 0.3-0.5 parts of silane coupling agent.

2. The low coefficient of expansion, high-strength engineering plastic of claim 1, wherein, The modified thermoplastic polyimide is prepared by: S11. Add 2,2'-bis(trifluoromethyl)diaminobiphenyl to N,N-dimethylacetamide while stirring, then add phthalic anhydride and continue stirring for 30-40 minutes until completely dissolved. Then add bisphenol A diether dianhydride and 3,3',4,4'-biphenyltetracarboxylic anhydride in batches and continue stirring for 10-12 hours to obtain a polyamic acid solution. S12. Add tannic acid-nano zinc oxide to polyamic acid solution and stir for 2-3 hours. Then add pyridine and acetic anhydride in sequence and carry out chemical imidization reaction at room temperature for more than 2 hours to obtain intermediate solution. S13. The intermediate liquid is stirred and added to deionized water. The precipitate is filtered, washed and dried to obtain modified thermoplastic polyimide.

3. The low coefficient of expansion, high-strength engineering plastic of claim 2, wherein, In step S11, the mass ratio of 2,2'-bis(trifluoromethyl)diaminobiphenyl, bisphenol A diether dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride and phthalic anhydride is 5:7:2:0.05, wherein the ratio of 2,2'-bis(trifluoromethyl)diaminobiphenyl to N,N-dimethylacetamide is 1:(10-12) g / mL.

4. The low coefficient of expansion, high-strength engineering plastic of claim 2, wherein, In step S12, the tannic acid-nano zinc oxide is prepared by ultrasonically dispersing tannic acid and nano zinc oxide in deionized water, stirring continuously at room temperature for 1-1.5 hours, and then filtering, washing and drying.

5. The low coefficient of expansion, high-strength engineering plastic of claim 4, wherein, The mass ratio of tannic acid to nano zinc oxide is 1:1, and the ratio of tannic acid to deionized water is 1:800 g / mL.

6. The low coefficient of expansion, high-strength engineering plastic of claim 2, wherein, In step S12, the tannic acid-nano zinc oxide accounts for 2-3% of the mass of the polyamic acid solution; pyridine accounts for 4% of the volume of the polyamic acid solution; and acetic anhydride accounts for 5% of the volume of the polyamic acid solution.

7. The low coefficient of expansion, high-strength engineering plastic of claim 1, wherein, The preparation method of the expansion-inhibiting filler is as follows: S21. Carbon nanofibers are subjected to nitric acid oxidation treatment, and the resulting active nanofibers and sodium dodecylbenzene sulfonate are ultrasonically dispersed in deionized water to obtain a nanofiber suspension. S22. Dissolve zirconium oxychloride in deionized water to obtain solution A; Ammonium metatungstate was dissolved in deionized water to obtain solution B; Mix solution A and solution B to obtain the precursor solution; S23. Add the precursor solution to the nanofiber suspension and stir for 1-1.5 h. At the same time, adjust the pH of the system to 6.5-7.5 with ammonia water. Continue stirring at 50-55℃ for 2-3 h. After filtration, washing, drying and calcination, the expansion inhibition filler is obtained.

8. The low coefficient of expansion, high-strength engineering plastic of claim 7, wherein, In step S21, the mass ratio of the active nanofibers to sodium dodecylbenzenesulfonate is 20:1; and the material-to-liquid ratio of the active nanofibers to deionized water is 1:12 g / mL.

9. The low coefficient of thermal expansion and high strength engineering plastic according to claim 7, characterized in that, In step S22, the ratio of zirconium oxychloride to deionized water is 1.6:100 g / mL; the ratio of ammonium metatungstate to deionized water is 3:25 g / mL; the amount of deionized water used in solution A and solution B is the same; in step S23, the volume ratio of precursor solution to nanofiber suspension is (8-10):

3.

10. The method for preparing low-expansion coefficient, high-strength engineering plastics according to any one of claims 1-9, characterized in that, Includes the following steps: (1) The modified thermoplastic polyimide, polyether ether ketone, expansion-inhibiting filler and silane coupling agent are uniformly mixed to obtain a premix; (2) The premixed material is extruded through a screw extruder to obtain a low expansion coefficient and high strength engineering plastic.

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