Preparation method of high-temperature-resistant carbon fiber-polyimide composite material based on CS-CNTS-POSS

Abstract

The invention discloses a preparation method of a high-temperature-resistant carbon fiber-polyimide composite material based on CS-CNTS-POSS, and relates to the technical field of material science and engineering.The preparation method comprises the following preparation steps that 1, carbon fiber surface activation treatment is conducted, specifically, desizing treatment and acid oxidation treatment are conducted on carbon fibers in sequence, and activated CF is obtained; and step 2, synthesis of aminated polyhedral oligomeric silsesquioxane: carrying out hydrolysis and precondensation on the amino silane coupling agent in an acidic alcohol solution, and then adding an aprotic solvent to promote further polycondensation so as to generate amino-functionalized POSS (Polyhedral Oligomeric Silsesquioxane). According to the preparation method of the high-temperature-resistant carbon fiber-polyimide composite material based on CS-CNTS-POSS, chitosan with excellent adhesion is used as a bottom layer to be tightly adsorbed on the surface of the fiber, then a mechanical interlocking and enhanced network is established through carbon nanotubes, and finally the high-temperature-resistant carbon fiber-polyimide composite material based on CS-CNTS-POSS is prepared by means of the organic-inorganic hybridization characteristic of POSS. And an interface layer which is high in thermal stability and can participate in covalent bonding of resin is formed on the outermost layer.

Description

Technical Field

[0001] This invention relates to the fields of materials science and engineering technology, specifically to a method for preparing high-temperature resistant carbon fiber-polyimide composite materials based on CS-CNTS-POSS. Background Technology

[0002] Carbon fiber reinforced polymer composites (CFRPs) are widely used in aerospace, automotive manufacturing, and sporting goods due to their excellent properties such as high specific strength, high specific modulus, aging resistance, corrosion resistance, and low density. However, the smooth surface of carbon fibers, the scarcity of active functional groups, and their strong chemical inertness make them prone to generating microscopic defects at the interface during the composite process with the resin matrix. These defects can become crack initiations under external loads, leading to macroscopic material failure. Therefore, one of the current research focuses is to modify the surface of carbon fibers to enhance the interfacial bonding between them and the resin, thereby optimizing the interfacial properties at the microscopic level.

[0003] Polyhedral oligomeric silsesquioxane (POSS) is an inorganic-organic hybrid material with a nanoscale cage-like structure. Its molecular core is a highly symmetrical, three-dimensionally ordered rigid inorganic framework composed of silicon-oxygen bonds (Si-O-Si), surrounded by designable and modifiable organic functional groups (R). This unique hybrid structure allows POSS to modify polymer materials at the molecular level. When applied to carbon fiber reinforced polyimide composite systems, POSS not only serves as a highly efficient nano-reinforcing phase, significantly improving the thermal stability, mechanical properties, and oxidation resistance of the matrix, but its reactive functional groups can also chemically bond with the carbon fiber surface and resin matrix, constructing a robust interfacial transition layer. This effectively improves interfacial compatibility and inhibits interfacial damage, making it a key component for achieving high-performance composite materials.

[0004] CNTs are stable, heat-resistant, and have a large specific surface area. Different functional groups on their surface can be grafted with other molecules to form various composite materials. Chitosan (CS) is a biopolymer discovered in recent years with excellent physicochemical and biological properties. CS molecules have amine and hydroxyl functional groups, which readily combine with other molecules through intermolecular forces to form complexes.

[0005] However, there is limited research on the synergistic application of CS-CNTs-POSS in carbon fiber and resin; therefore, this invention proposes a method for preparing high-temperature resistant carbon fiber-polyimide composite materials based on CS-CNTS-POSS. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides a method for preparing high-temperature resistant carbon fiber-polyimide composite materials based on CS-CNTS-POSS, thus solving the problems mentioned in the background section.

[0007] To achieve the above objectives, the present invention provides the following technical solution: a method for preparing high-temperature resistant carbon fiber-polyimide composite materials based on CS-CNTS-POSS, comprising the following preparation steps:

[0008] Step 1: Carbon fiber surface activation treatment: The carbon fiber is subjected to desizing and acid oxidation treatment in sequence to obtain activated CF;

[0009] Step 2, Synthesis of Aminated Polyhedral Oligomeric Silsesquioxanes: The aminosilane coupling agent is hydrolyzed and pre-condensed in an acidic alcohol solution, and then an aprotic solvent is added to promote its further condensation, generating amino-functionalized POSS.

[0010] Step 3: Preparation of composite coating solution: Chitosan is dissolved in dilute acid solution, followed by the addition of carbon nanotubes and aminated POSS. After dispersion and stirring, a stable CS-CNTs-POSS composite coating solution is formed.

[0011] Step 4: Carbon fiber interface engineering modification: The activated carbon fiber is immersed in the composite coating solution, and then the pH value of the system is adjusted by adding alkaline buffer solution, so that the CS-CNTs-POSS composite is formed and immobilized in situ on the carbon fiber surface through electrostatic interaction and chemical deposition, thus obtaining modified CF.

[0012] Step 5, Prepreg preparation and imidization: The modified carbon fiber is impregnated with a polyimide precursor solution, and after drying to remove the solvent, it is heat-treated to complete the pre-imidization of the polyimide to obtain the prepreg.

[0013] Step 6: Hot pressing molding: The prepreg is placed in a mold and cured under pressure by programmed temperature rise to finally obtain the high-temperature resistant carbon fiber-polyimide composite material.

[0014] Preferably, in step one, the carbon fiber desizing treatment method is as follows: after refluxing CF with acetone at 60-80℃ for 46-50h, it is washed with deionized water 3-5 times, and then dried at room temperature.

[0015] In step one, the acid oxidation treatment of carbon fiber uses a mixed acid of concentrated nitric acid and concentrated sulfuric acid, with a mass fraction of 5-15%, a treatment temperature of 25-35℃, and a treatment time of 6-24h.

[0016] Preferably, in step two, the aminosilane coupling agent is γ-aminopropyltriethoxysilane; the acidic alcohol solution is an anhydrous methanol solution containing concentrated hydrochloric acid, the reaction temperature is 50-80℃, and the reaction time is 1-6h; the aprotic solvent is tetrahydrofuran.

[0017] Preferably, in step three, the mass ratio of chitosan, carbon nanotubes and aminated POSS is (25-35):1:(0.4-0.6); the dilute acid solution is selected from a 2% acetic acid solution.

[0018] Preferably, in step four, the alkaline buffer solution is a mixed solution of methanol, deionized water, and sodium hydroxide, with a volume ratio of 1:3 to 5:5.

[0019] Preferably, in step five, the heat treatment process to complete the thermal closed-loop is as follows: first, the solvent is removed by drying at 170-190℃, then preliminary imidization is carried out at 210-250℃, and then the furnace is cooled to room temperature.

[0020] Preferably, in step six, the programmed temperature rise curing process specifically involves: heating at a rate of 2-5℃ / min under a pressure of 5-8MPa, and performing at least two stages of heat preservation curing within a temperature range of 280-370℃.

[0021] Preferably, the heat is maintained at 280℃ for 2-6 hours, at 300℃ for 2-6 hours, at 340℃ for 2-6 hours, and at 360℃ for 2-6 hours.

[0022] Beneficial effects

[0023] This invention provides a method for preparing high-temperature resistant carbon fiber-polyimide composite materials based on CS-CNTS-POSS. Compared with existing technologies, it has the following advantages:

[0024] This method for preparing high-temperature resistant carbon fiber-polyimide composites based on CS-CNTS-POSS constructs a unique "flexible-rigid-tough" three-layer interface structure on the carbon fiber surface using chitosan, carbon nanotubes, and cage-like silsesquioxanes. First, chitosan's excellent adhesion acts as a bottom layer, tightly adsorbing onto the fiber surface. Then, carbon nanotubes establish a mechanical interlocking and reinforcing network. Finally, leveraging the organic-inorganic hybrid properties of POSS, a highly thermally stable interface layer that can participate in resin covalent bonding is formed on the outermost layer. This design achieves a multi-level synergistic effect from molecular chemical bonding to nanoscale reinforcement, providing a new approach to solving the problems of weak interfacial adhesion and high-temperature performance degradation in traditional composite materials. This allows the material to maintain its lightweight while improving interlaminar shear strength and heat resistance, making it particularly suitable for extreme environments above 300°C. Through the synergistic design of fibers and resins, CS-CNTs-POSS functions simultaneously in both the interface and the matrix, ultimately improving the interfacial properties and bulk heat resistance of the composite material. Attached Figure Description

[0025] Figure 1 The process flow diagram provided for this invention;

[0026] Figure 2 This is a SEM image of the high-temperature resistant carbon fiber-polyimide composite material provided in Example 1 of the present invention. Detailed Implementation

[0027] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] Example 1

[0029] Step 1: Reflux 10g of carbon fiber (CF) with acetone at 80℃ for 48h to remove sizing agent, then wash it 3-5 times in deionized water, dry it at room temperature, immerse it in 10wt% HNO3 / H2SO4 aqueous solution, and place it under room temperature for immersion treatment for 12h to obtain activated carbon fiber.

[0030] Step 2: Measure 100 mL of anhydrous methanol (CH3OH), 10 mL of γ-aminopropyltriethoxysilane (KH-550) and 10 mL of concentrated hydrochloric acid (HCl) solution. Under nitrogen protection, stir the mixture at 70 °C and 500 rpm for 24 h using a magnetic stirrer. Then add 100 mL of tetrahydrofuran (THF) and continue the reaction for 2 h. Dry the mixture to obtain amination-modified POSS solid particles.

[0031] Step 3: Dissolve 0.3g chitosan (CS) in 150mL of 2% acetic acid solution for 30min, then add 10mg carbon nanotubes (CNTs) and 5mg aminated POSS, sonicate for 10min, and stir in a 40℃ water bath for 6h to form a stable CS-CNTs-POSS composite coating solution.

[0032] Step 4: The activated carbon fiber is impregnated in the composite coating solution, and then the pH value of the system is adjusted by adding alkaline buffer (made by mixing 10 mL NaOH, 40 mL H2O and 50 mL MeOH), ultrasonically treated for 2 h, and dried to obtain modified CF.

[0033] Step 5: Pass the modified carbon fiber through the polyimide impregnation tank, and then use a rectangular iron frame to collect the fiber bundles wetted by the adhesive solution. After collection, place it in a 150°C forced-air oven and continue heating until the residual solvent is completely removed. Then, perform post-treatment on the polyimide solution to complete the thermal closure. The post-treatment process is: 180°C / h, 230°C / h. After the heat treatment is completed, cool it to room temperature with the furnace and cut it into 40mm×80mm prepreg sheets.

[0034] Step 6: Place the prepreg sheet into a mold coated with a release agent, place the mold into a hot molding press, heat to 300℃ at a rate of about 5℃ / min and hold at that temperature for 2 hours without pressure, apply appropriate pressure and vent the air 3 times during the process, and then begin the curing process. The curing process is as follows: 280℃ / 2h + 300℃ / 2h + 340℃ / 2h + 360℃ / 2h. Maintain pressure throughout the curing process with a pressure value of 5MPa, and finally obtain a high-temperature resistant carbon fiber-polyimide composite material.

[0035] Figure 2 This is a scanning electron microscope (SEM) image of the CS-CNTs-POSS coated carbon fiber surface prepared in Example 1 of this invention. It can be observed that the CNTs intertwine to form a three-dimensional network structure. On top of this CNT network, numerous smaller, granular or clustered protrusions are attached, corresponding to successfully grafted POSS. Simultaneously, a thin film matrix formed by CS (the relatively flat area in the image) firmly bonds the CNTs and POSS together around the entire structure, encapsulating them on the carbon fiber surface to form a dense and stable composite layer. After synergistic modification by POSS, CNTs, and CS, the carbon fiber surface is coated with a composite layer, increasing the fiber surface roughness.

[0036] Example 2

[0037] Step 1: Reflux 10g of CF with acetone at 60℃ for 46h to remove sizing agent, then wash it 3 times with deionized water, dry it at room temperature, immerse it in 5wt% HNO3 / H2SO4 aqueous solution, and place it under room temperature for immersion treatment for 6h to obtain activated carbon fiber.

[0038] Step 2: Measure 100 mL of anhydrous CH3OH, 10 mL of KH-550 and 10 mL of concentrated HCl solution. Under nitrogen protection, stir the mixture at 500 rpm at 50 °C for 24 h using a magnetic stirrer. Then add 100 mL of tetrahydrofuran (THF) and continue the reaction for 1 h. Dry the mixture to obtain amination-modified POSS solid particles.

[0039] Step 3: Dissolve 0.25g CS in 150mL of 2% acetic acid solution for 30min, then add 10mg CNTs and 4mg aminated POSS, sonicate for 10min, and stir in a 40℃ water bath for 6h to form a stable CS-CNTs-POSS composite coating solution.

[0040] Step 4: The activated carbon fiber is impregnated in the composite coating solution, and then the pH value of the system is adjusted by adding alkaline buffer (made by mixing 10 mL NaOH, 30 mL H2O and 50 mL MeOH), ultrasonically treated for 2 h, and dried to obtain modified CF;

[0041] Step 5: Pass the modified carbon fiber through the polyimide impregnation tank, and then use a rectangular iron frame to collect the fiber bundles wetted by the adhesive solution. After collection, place it in a 150°C forced-air oven and continue heating until the residual solvent is completely removed. Then, perform post-treatment on the polyimide solution to complete the thermal closure. The post-treatment process is: 170°C / h, 210°C / h. After the heat treatment is completed, cool it to room temperature with the furnace and cut it into 40mm×80mm prepreg sheets.

[0042] Step 6: Place the prepreg sheet into a mold coated with a release agent, place the mold into a hot molding press, heat to 280°C at a rate of approximately 2°C / min, and hold at this temperature for 2 hours without pressure. Apply appropriate pressure during this period to degas the material three times. After degassing, begin the curing process. The curing process is as follows: 280°C / 4h + 300°C / 3h + 340°C / 4h + 360°C / 3h. Maintain pressure throughout the curing process at a pressure of 6MPa. The final product is a high-temperature resistant carbon fiber-polyimide composite material.

[0043] Example 3

[0044] Step 1: Reflux 10g of CF with acetone at 70℃ for 50h to remove sizing agent, then wash 5 times with deionized water, dry at room temperature, immerse in 15wt% HNO3 / H2SO4 aqueous solution, and place it under room temperature for 24h to obtain activated carbon fiber.

[0045] Step 2: Measure 100 mL of anhydrous CH3OH, 10 mL of KH-550 and 10 mL of concentrated HCl solution. Under nitrogen protection, stir the mixture at 80 °C and 500 rpm for 24 h using a magnetic stirrer. Then add 100 mL of THF and continue the reaction for 6 h. Dry the mixture to obtain amination-modified POSS solid particles.

[0046] Step 3: Dissolve 0.35g CS in 150mL of 2% acetic acid solution for 30min, then add 10mg CNTs and 6mg aminated POSS, sonicate for 10min, and stir in a 40℃ water bath for 6h to form a stable CS-CNTs-POSS composite coating solution.

[0047] Step 4: The activated carbon fiber is impregnated in the composite coating solution, and then the pH value of the system is adjusted by adding alkaline buffer (made by mixing 10 mL NaOH, 50 mL H2O and 50 mL MeOH), ultrasonically treated for 2 h, and dried to obtain modified CF;

[0048] Step 5: Pass the modified carbon fiber through the polyimide impregnation tank, and then use a rectangular iron frame to collect the fiber bundles wetted by the adhesive solution. After collection, place it in a 150°C forced-air oven and continue heating until the residual solvent is completely removed. Then, perform post-treatment on the polyimide solution to complete the thermal closure. The post-treatment process is: 190°C / h, 250°C / h. After the heat treatment is completed, cool it to room temperature with the furnace and cut it into 40mm×80mm prepreg sheets.

[0049] Step 6: Place the prepreg sheet into a mold coated with a release agent, place the mold into a hot molding press, heat to 300℃ at a rate of about 4℃ / min and hold at that temperature for 2 hours without pressure, apply appropriate pressure and vent three times during the process, after which start the curing process. The curing process is as follows: 280℃ / 6h + 300℃ / 2h + 340℃ / 6h + 360℃ / 4h. Maintain pressure throughout the curing process with a pressure value of 8MPa, and finally obtain a high-temperature resistant carbon fiber-polyimide composite material.

[0050] Comparative Example 1

[0051] Compared with Example 1, the difference is that in step three of Example 1, "10mg CNTs and 5mg amination POSS" is replaced with "5mg amination POSS"; the rest remains the same.

[0052] Comparative Example 2

[0053] Compared with Example 1, the difference is that in step three of Example 1, "10mg CNTs and 5mg amination POSS" is replaced with "10mg CNTs"; the rest remains the same.

[0054] Performance testing: The interlaminar shear strength of the specimens was tested in accordance with GB / T 1450.2-2005; the results are shown in Table 1.

[0055] Table 1

[0056] Performance indicators Interlaminar shear strength (MPa) Example 1 72.34 Example 2 70.56 Example 3 71.95 Comparative Example 1 56.06 Comparative Example 2 59.38

[0057] Furthermore, any content not described in detail in this specification is existing technology known to those skilled in the art.

[0058] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0059] 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 alterations 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. A method for preparing a high-temperature resistant carbon fiber-polyimide composite based on CS-CNTs-POSS, characterized in that, The preparation steps include the following: Step one, carbon fiber surface activation treatment: desizing treatment and acid oxidation treatment are sequentially performed on the carbon fiber to obtain activated CF; Step two, synthesis of aminated polyhedral oligomeric silsesquioxane: amino silane coupling agent is hydrolyzed and pre-condensed in an acidic alcohol solution, and then aprotic solvent is added to promote further condensation to generate aminated POSS; Step three, preparation of a composite coating solution: chitosan is dissolved in a dilute acid solution, and then carbon nanotubes and aminated POSS are added, and after dispersion and stirring, a stable CS-CNTs-POSS composite coating solution is formed; Step four, carbon fiber interface engineering modification: the activated carbon fiber is immersed in the composite coating solution, and then the pH value of the system is adjusted by adding an alkaline buffer solution, so that the CS-CNTs-POSS composite is in situ formed and immobilized on the carbon fiber surface by electrostatic action and chemical deposition to obtain modified CF; Step five, preparation of a prepreg and imidization: the modified carbon fiber is impregnated with a polyimide precursor solution, and after drying to remove the solvent, heat treatment is performed to complete the preliminary imidization of the polyimide to obtain a prepreg; Step six, hot pressing: the prepreg is placed in a mold and cured under pressure by programmed temperature rising to finally obtain the high-temperature-resistant carbon fiber-polyimide composite material.

2. The method for preparing the high-temperature resistant carbon fiber-polyimide composite material based on CS-CNTS-POSS according to claim 1, characterized in that: In step one, the desizing treatment method of the carbon fiber is as follows: the CF is refluxed with acetone at 60-80℃ for 46-50h, then washed with deionized water for 3-5 times, and then dried at room temperature. In step one, the acid oxidation treatment of the carbon fiber uses a mixed acid of concentrated nitric acid and concentrated sulfuric acid, and the mass fraction of the mixed acid is 5-15%, and the treatment time is 6-24h.

3. The method for preparing the high-temperature resistant carbon fiber-polyimide composite material based on CS-CNTS-POSS according to claim 1, characterized in that: In step two, the amino silane coupling agent is γ-aminopropyl triethoxysilane; the acidic alcohol solution is anhydrous methanol solution containing concentrated hydrochloric acid, the reaction temperature is 50-80℃, and the reaction time is 25-30h; and the aprotic solvent is tetrahydrofuran.

4. The method of making CS-CNTS-POSS based high temperature resistant carbon fiber- polyimide composites according to claim 1, characterized in that: In step three, the mass ratio of chitosan, carbon nanotubes and aminated POSS is (25-35):1:(0.4-0.6); and the dilute acid solution is selected from an acetic acid solution with a concentration of 2%.

5. The method of making CS-CNTS-POSS based high temperature resistant carbon fiber- polyimide composites according to claim 1, characterized in that: In step four, the alkaline buffer solution is a mixed solution of methanol, deionized water and sodium hydroxide, and the volume ratio is 1:3-5:

5.

6. The method of making CS-CNTS-POSS based high temperature resistant carbon fiber- polyimide composites according to claim 1, characterized in that: In step five, the heat treatment process for completing thermal ring closure is as follows: first, dry the solvent at 170-190℃, then perform preliminary imidization at 210-250℃, and then cool the furnace to room temperature.

7. The method for preparing the high-temperature resistant carbon fiber-polyimide composite material based on CS-CNTS-POSS according to claim 1, characterized in that: In step six, the programmed temperature rising curing process is as follows: the temperature is raised at a rate of 2-5℃ / min under a pressure of 5-8MPa, and at least two stages of heat preservation curing are performed in the temperature range of 280-370℃.

8. The method of making CS-CNTS-POSS based high temperature resistant carbon fiber- polyimide composites according to claim 7, characterized in that: In step six, the programmed temperature rising curing process is as follows: the temperature is raised at a rate of 2-5℃ / min under a pressure of 5-8MPa, and at least two stages of heat preservation curing are performed in the temperature range of 280-370℃. In step six, the programmed temperature rising curing process is as follows: the temperature is raised at a rate of 2-5℃ / min under a pressure of 5-8MPa, and at least two stages of heat preservation curing are performed in the temperature range of 280-370℃. In step six, the programmed temperature rising curing process is as follows: the temperature is raised at a rate of 2-5℃ / min under a pressure of 5-8MPa, and at least two stages of heat preservation curing are performed in the temperature range of 280-370℃.

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