A high-temperature-resistant polyimide aerogel composite material, a preparation method and application thereof

Abstract

The application discloses a high-temperature-resistant polyimide aerogel composite material and a preparation method and application thereof. On the basis of a chemical imidization-supercritical drying method, metal oxide organic precursors or non-metal oxide organic precursors are innovatively added as reinforcing phases, and an effective and feasible one-way vacuum impregnation composite method of aerogel and fiber preform is first proposed, so that the polyimide aerogel is conveniently modified and reinforced. The high-temperature-resistant polyimide aerogel composite material prepared by the method has the highest application environment of 420 DEG C, a thermal decomposition temperature of 700 DEG C, excellent high-temperature resistance, strong thermal stability, a room temperature and normal pressure thermal conductivity of 0.020-0.032 W / (m*K), a density of 0.09-0.20 g / cm 3 , a stress of 0.3-0.8 MPa under 3% stress compression conditions, low density, high strength, and better matching with the current demand of light-weight high-strength high-performance organic thermal protection materials in the field of aviation and aerospace in the temperature range of 320-700 DEG C.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of high-performance thermal protection materials in the field of aerospace, and particularly relates to a high-temperature-resistant polyimide aerogel composite material and a preparation method and application thereof. BACKGROUND

[0002] Thermal protection materials play an indispensable role in the field of aerospace, and light-weight high-strength high-performance organic thermal protection materials are of great significance to the load lightening, carrying capacity improvement, flight speed increase and range extension of aircraft. With the high-level development of aerospace technology, traditional thermal protection materials are difficult to adapt to the performance requirements of the thermal protection system of the current aircraft due to various defects, and therefore, it is urgent to develop new high-performance organic thermal protection materials with light weight, high strength and high-temperature resistance. Aerogel is currently known as the lightest and lowest thermal conductivity solid material, and is known as super thermal insulation material. Due to its excellent temperature-resistant and thermal insulation performance, it has attracted much attention in the field of aerospace. Inorganic aerogels represented by SiO2 are widely used in many fields, but their defects such as brittleness, easy breakage and insufficient thermal stability limit their practical application in the field of aerospace. In contrast, organic polymer aerogel materials have better flexibility, mechanical properties and thermal stability, and show great application potential in the field of aerospace. Among them, polyimide aerogel has attracted much attention due to its excellent comprehensive performance and outstanding application performance in the field of aerospace. Zhang et al. reported a polyimide aerogel material that can withstand 200℃, with a thermal decomposition temperature of 504℃. Although it has good mechanical properties, the thermal stability of the prepared polyimide aerogel is insufficient, and the elastic modulus decreases by 9% after environmental cycling at 150℃ to -50℃. At the same time, its dimensional stability is insufficient: the shrinkage rate is more than 9.7% under the condition of 200℃, 2400s [ACS Applied Nano Materials. 2023, 6, 7269-7279]. Zhang et al. reported a polyimide aerogel with more excellent comprehensive performance, which was prepared by hybridizing Al2O3 with polyimide aerogel. A high-temperature-resistant polyimide aerogel was prepared by introducing 2,4,6-triaminopyrimidine as a crosslinking agent, which enhanced the three-dimensional network skeleton of the polyimide aerogel. The prepared polyimide aerogel has a density of 0.128g / cm 3, the lowest thermal conductivity is 0.0235 W / (m·K), and the highest temperature it can withstand is 250℃. After 5 high-temperature cycles (250℃, 2400s), the aerogel has a mass change rate of ≤0.3%, a shrinkage rate of ≤2.53%, a thermal conductivity change of ≤3%, and a bulk density that remains almost unchanged [ACS Applied Nano Materials. 2023, 6, 15925-15936]. Zhang et al. reported a super-light aramid nanofiber / polyimide composite aerogel. The aerogel exhibits excellent elasticity, ultra-low density (5.18 g / cm 3 ), low thermal conductivity (0.0286 W / (m·K)), high decomposition temperature (470℃), and a maximum temperature resistance of 200℃. [Materials Chemistry Frontiers, 2021, 5(2): 804-816]. Zhang, Wang et al. reported a polyimide / silicon hybrid aerogel composite material with a small overall shrinkage rate, moderate compression performance, and excellent thermal stability, with a density of 0.152 g / cm 3 , an overall shrinkage rate of 3.52%, a compression stress of 0.39 MPa at 3% strain, a thermal conductivity of 0.0254 W / (m·K), and a maximum temperature resistance of 309℃. [ACS Applied Nano Materials. 2023, 6, 9, 7269-7279]. Fiber thermal insulation materials are commonly used on the leeward side of aircraft wings and fuselages at temperatures of 320-700℃. The high-temperature resistance of the above-mentioned polyimide aerogel is still difficult to meet the actual application requirements. Therefore, if the polyimide aerogel material can meet the requirements of light weight, high strength, and low room temperature and normal pressure thermal conductivity, and also has excellent high-temperature resistance, it will have unparalleled advantages and broad application prospects. However, how to match the light weight, high strength, ultra-low room temperature and normal pressure thermal conductivity, and excellent high-temperature resistance of the polyimide aerogel is a technical problem that has plagued the field of thermal insulation for many years. SUMMARY

[0003] The purpose of the present application is to solve the technical problem that the existing polyimide aerogel material is difficult to match the performance requirements of high-performance organic thermal protection materials in the aerospace field, and to provide a high-temperature-resistant polyimide aerogel composite material, a preparation method and application thereof. The present application innovatively uses a single-direction vacuum impregnation composite method for aerogel and fiber preform, which maintains ultra-low room temperature and normal pressure thermal conductivity and low density while improving the temperature resistance and mechanical strength of the polyimide aerogel. The prepared high-temperature-resistant polyimide aerogel composite material meets the performance requirements of high-performance thermal protection materials in the aerospace field.

[0004] To solve the above technical problems, the technical scheme adopted by the present application is as follows: a preparation method of a high-temperature-resistant polyimide aerogel composite material, comprising the following steps:

[0005] S1, under ice bath stirring conditions, diamine and dianhydride are added to an organic solvent respectively, and stirring is performed for 20-50 min to prepare a polyamide acid solution; the mass ratio of the diamine and the dianhydride is 1:1-1:1.4;

[0006] S2, a dehydrating agent is added to the polyamide acid solution, and after stirring, a metal oxide organic precursor or a non-metal oxide organic precursor is added, and stirring is performed until a homogeneous phase is formed, and then a catalyst and a crosslinking agent are added respectively, and stirring is continuously performed until a polyimide sol is formed;

[0007] S3, the polyimide sol is subjected to unidirectional vacuum impregnation with a previously prepared fiber preform, and the polyimide sol needs to completely immerse the previously prepared fiber preform; and then the same is placed in an oven for temperature rising and aging to form a fiber preform reinforced polyimide initial state gel;

[0008] S4, the fiber preform reinforced polyimide initial state gel is placed in a water bath with a set temperature of 45-90℃, and an organic solvent is used for solvent replacement, and the solvent replacement is performed for 3-8 times, and the solvent is replaced every 1-10 h to obtain a fiber preform reinforced polyimide final state gel;

[0009] S5, the fiber preform reinforced polyimide final state gel is subjected to CO2 supercritical fluid drying to obtain a fiber preform reinforced high-temperature-resistant polyimide aerogel composite material.

[0010] Preferably, in S1, the diamine is one or a mixture of several of p-phenylenediamine, 4,4'-diamino diphenyl ether, 4,4'-diamino-2,2'-dimethyl diphenyl, toluene diisocyanate, diphenyl methane diisocyanate; the dianhydride is one or a mixture of several of pyromellitic dianhydride, 3,3',4,4'-biphenyl tetracarboxylic dianhydride, 3,3',4,4'-benzophenone tetracarboxylic dianhydride, 4,4'-oxybisphthalic anhydride; and the organic solvent is one or a mixture of several of dimethylacetamide, N,N-dimethylformamide, dimethyl phthalate, dimethyl sulfoxide, N-methyl pyrrolidone.

[0011] Preferably, the dehydrating agent in S2 is a mixture of one or more of acetyl chloride, acetic anhydride, propionic anhydride, and chlorosulfoxide; the metal oxide organic precursor or non-metal oxide organic precursor is a mixture of one or more of ZrO2, titanium isopropoxide chloride, chlorosilicate, Al2O3, diethylaluminum acetylide, B2O3, V2O5, CuO, copper ethylenediamine, copper acetate, and Fe2O3; the catalyst is a mixture of one or more of triethylamine, methylpyridine, and pyridine; and the crosslinking agent is a mixture of one or more of octaaminophenyl cage silsesquioxane, 1,3,5-tris(4-aminophenyl)benzene, triphenylmethane triisocyanate, 1,3,5-benzene tricarbonyl chloride, and 1,3,5-tris(4-aminophenoxy)benzene.

[0012] Preferably, the molar ratio of the dehydrating agent, the metal oxide organic precursor or non-metal oxide organic precursor, the catalyst, the crosslinking agent, and the diamine is 0.03-0.05:0.01-0.10:0.01-0.015:0.01-0.015:1.

[0013] Preferably, the fibers in the fiber preform in S3 are a combination of one or more of carbon fibers, quartz fibers, basalt fibers, glass fibers, zirconia fibers, polyimide fibers, mullite fibers, polyurethane fibers, aluminum silicate fibers, and boron fibers, and the fiber preform has a bulk density of 0.04-0.15 g / cm3. 3 .

[0014] Preferably, the temperature aging in S3 is aging at 20-50℃ for 18 h.

[0015] Further preferably, the organic solvent in S4 is a mixture of one or more of methanol, ethanol, and isopropanol.

[0016] Further preferably, the CO2 supercritical fluid drying in S5 is performed at a pressure of 10-18 MPa and a temperature of 40-80℃ for 6-18 h, and the pressure is released at a speed of 100-240 kPa / min after drying is completed.

[0017] The application also provides a high-temperature-resistant polyimide aerogel composite prepared by the preparation method.

[0018] The application also provides a use of the high-temperature-resistant polyimide aerogel composite in preparing high-performance thermal protection materials in the field of aerospace.

[0019] The application has the following beneficial effects:

[0020] 1.The second step of the preparation method of the high-temperature-resistant polyimide aerogel composite of the present application innovatively adds a reinforcing phase such as a metal oxide organic precursor or a non-metal oxide organic precursor, and adds a crosslinking agent to introduce a crosslinking structure to reinforce and modify the polyimide aerogel, thereby improving the stability of the molecular structure of the polyimide aerogel and the mutual support between the molecular chains, enhancing the network skeleton structure, and endowing the polyimide aerogel with excellent mechanical properties and thermal stability; in the third step, a unidirectional vacuum impregnation composite technology is used to perfectly composite the fiber preform and the aerogel, thereby providing the aerogel with stronger crosslinking degree and skeleton strength, greatly inhibiting the volume shrinkage of the aerogel, and further improving the high-temperature-resistant performance and mechanical properties of the polyimide aerogel composite.

[0021] 2.The high-temperature-resistant polyimide aerogel composite prepared by the method of the present application can be applied at an environment of up to 420℃, has a thermal decomposition temperature of 700℃, excellent high-temperature-resistant performance, strong thermal stability, a thermal conductivity of 0.020-0.032 W / (m·K) at normal temperature and pressure, a density of 0.09-0.20 g / cm 3 , a stress of 0.3-0.8 MPa under 3% stress compression, low density, high strength, and better matches the current demand for lightweight high-strength high-performance organic thermal protection materials in the field of aerospace at a temperature range of 320-700℃. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 The present application is a preparation method of a high-temperature-resistant polyimide aerogel composite. DETAILED DESCRIPTION

[0023] The present application will be further described below in combination with the drawings and specific examples.

[0024] Example 39

[0025] In the first step, 1:1.1 of p-phenylenediamine and pyromellitic anhydride were respectively added to a dimethylacetamide solvent under ice bath stirring, and stirred for 45 min to prepare a polyamide acid solution.

[0026] In the second step, 0.05 parts (compared with the amount of diamine, the amount of diamine is 1 part, and the same below) of acetic anhydride were added to 1 part of the polyamide acid solution prepared in the first step, 0.10 parts of ZrO2 were further added, and after stirring to form a homogeneous phase, 0.015 parts of methylpyridine and 0.015 parts of octaaminophenyl cage silsesquioxane were respectively added, and stirred constantly to form a polyimide sol.

[0027] In the third step, the polyimide sol prepared in the second step was mixed with 0.10 g / cm 3The basalt fiber preform is subjected to unidirectional vacuum impregnation to form a fiber preform-reinforced polyimide initial-state gel.

[0028] The fiber preform-reinforced polyimide initial-state gel prepared in the third step is placed in a water bath at 70°C for solvent replacement, and the organic solvent is replaced four times, with the solvent being replaced every 8 hours, to obtain a fiber preform-reinforced polyimide final-state gel.

[0029] The fiber preform-reinforced polyimide final-state gel prepared in the fourth step is placed in a CO2 supercritical drying device, heated to 70°C, and flushed with CO2 to 14 MPa, and dried for 12 hours, and then the pressure is slowly released at a speed of 170 kPa / min to obtain a fiber preform-reinforced high-temperature-resistant polyimide aerogel composite material.

[0030] The high-temperature-resistant polyimide aerogel composite material prepared in this example has a density of 0.194 g / cm 3 , a thermal conductivity of 0.0318 W / (m·K) at room temperature and normal pressure, a compressive stress of 0.67 MPa under a 3% compressive strain, and a maximum tolerance temperature of 420°C.

[0031] Example 1

[0032] In the first step, 4,4'-diamino diphenyl ether and 3,3',4,4'-biphenyl tetracarboxylic dianhydride in a 1:1.1 ratio are added to N,N-dimethylformamide solvent under ice bath stirring conditions, and stirred for 45 min to obtain a polyamic acid solution.

[0033] In the second step, 0.05 parts (based on the amount of diamine, the amount of diamine is 1 part, and the same below) of acetic anhydride are added to 1 part of the polyamic acid solution prepared in the first step, and then 0.10 parts of titanium triisopropoxide are added, and after stirring to form a homogeneous phase, 0.015 parts of triethylamine and 0.015 parts of octaaminophenyl cage silsesquioxane are added, and stirring is continued until a polyimide sol is formed.

[0034] In the third step, the polyimide sol prepared in the second step is subjected to unidirectional vacuum impregnation with 0.05 g / cm 3 of carbon fiber preform, and then aged in an oven at 30°C to form a fiber preform-reinforced polyimide initial-state gel.

[0035] In the fourth step, the fiber preform-reinforced polyimide initial-state gel prepared in the third step is placed in a water bath at 70°C for solvent replacement, and the organic solvent is replaced four times, with the solvent being replaced every 8 hours, to obtain a fiber preform-reinforced polyimide final-state gel.

[0036] Fifth step, the fiber preform reinforced polyimide final state gel prepared in the fourth step is placed into a CO2 supercritical drying device, heated to 70℃, CO2 is injected to 14 MPa, dried for 12 h, and then the pressure is slowly released at a speed of 170 kPa / min to obtain a fiber preform reinforced high-temperature-resistant polyimide aerogel composite material.

[0037] The density of the high-temperature-resistant polyimide aerogel composite material prepared in this example is 0.181 g / cm 3 , the thermal conductivity at room temperature and normal pressure is 0.0295 W / (m·K), the compressive stress under a 3% compressive strain condition is 0.54 MPa, and the highest tolerance temperature is 382℃.

[0038] Example 18

[0039] First step, 4,4'-diaminodiphenyl ether and 3,3',4,4'-biphenyl tetracarboxylic dianhydride in a 1:1.1 ratio are respectively added to a dimethylacetamide solvent under ice bath stirring conditions, and stirred for 45 min to prepare a polyamic acid solution.

[0040] Second step, 0.05 parts (compared with the amount of diamine, the amount of diamine is 1 part, the same below) of acetic anhydride are added to 1 part of the polyamic acid solution prepared in the first step, 0.10 parts of titanium triisopropoxide are then added, after stirring to homogeneity, 0.015 parts of methylpyridine and 0.015 parts of octaaminophenyl cage silsesquioxane are respectively added, and stirring is continuously performed until a polyimide sol is formed.

[0041] Third step, the polyimide sol prepared in the second step is subjected to single vacuum impregnation with 0.10 g / cm 3 of basalt fiber preform, and then aged in an oven at 30℃ to form a fiber preform reinforced polyimide initial state gel.

[0042] Fourth step, the fiber preform reinforced polyimide initial state gel prepared in the third step is placed in a 70℃ water bath for solvent replacement, and organic solvents are used for replacement 4 times, with the solvents being replaced every 8 h, to obtain a fiber preform reinforced polyimide final state gel.

[0043] Fifth step, the fiber preform reinforced polyimide final state gel prepared in the fourth step is placed into a CO2 supercritical drying device, heated to 70℃, CO2 is injected to 14 MPa, dried for 12 h, and then the pressure is slowly released at a speed of 170 kPa / min to obtain a fiber preform reinforced high-temperature-resistant polyimide aerogel composite material.

[0044] The density of the high-temperature-resistant polyimide aerogel composite material prepared in this example is 0.190 g / cm 3, the thermal conductivity at normal temperature and pressure is 0.0308 W / (m·K), the compressive stress under 3% compressive strain is 0.79 MPa, and the maximum tolerance temperature is 386℃.

[0045] Examples 1-38, 40-171, 173-185, 187-192

[0046] The preparation methods of Examples 1-38, 40-171, 173-185, 187-192 are the same as Example 39, except that the process parameters used are shown in Table 1, wherein the types of diamine, dianhydride, crosslinking agent, metal oxide organic precursor or non-metal oxide organic precursor, fiber preform, and the ratio of diamine to dianhydride are the main factors affecting the experimental data of aerogel material density, thermal conductivity at normal temperature and pressure, mechanical strength performance, and maximum tolerance temperature, and the experimental process parameters not marked in the table have little effect on the above experimental data of aerogel material. As long as they are within the scope described in the disclosure, the aerogel of the present application can be prepared. The specific parameters are shown in Table 1:

[0047] Table 1 Preparation process parameters of high-temperature-resistant polyimide aerogel composite materials

[0048]

[0049]

[0050]

[0051]

[0052]

[0053]

[0054]

[0055]

[0056]

[0057] It can be known from the examples 1-192 that the high-temperature-resistant polyimide aerogel composite prepared in the examples of the application has low thermal conductivity at normal temperature and pressure and high maximum tolerance temperature when octaaminophenyl cage silsesquioxane is selected as a crosslinking agent and basalt fiber is selected as a fiber preform while other parameters are fixed. The thermal conductivity at normal temperature and pressure and the maximum tolerance temperature of the polyimide aerogel are mainly affected by the crosslinking agent and the fiber preform, the mechanical property is mainly affected by the crosslinking agent, and the density is mainly affected by the types and proportions of the diamine and the dianhydride. The application provides a light-weight high-strength high-temperature-resistant polyimide aerogel composite, which can better meet the demand of the current aerospace field for high-performance organic thermal protection materials.

[0058] The specification and drawings of the application are considered to be illustrative rather than restrictive, and on the basis of the application, some substitutions and modifications of some technical features can be made by those skilled in the art according to the disclosed technical content without creative labor, and all are within the protection scope of the application.

Claims

1. A method for preparing a high temperature resistant polyimide aerogel composite, characterized in that, The preparation method comprises the following steps: S1, under ice bath stirring conditions, diamine and dianhydride are added into an organic solvent respectively, and stirring is performed for 20-50 min to prepare a polyamide acid solution; the mass ratio of the diamine and the dianhydride is 1:1-1:1.4; S2, a dehydrating agent is added into the polyamide acid solution, and after stirring, a metal oxide organic precursor or a non-metal oxide organic precursor is added, and stirring is performed until a homogeneous phase is obtained, and then a catalyst and a crosslinking agent are added respectively, and stirring is continuously performed until a polyimide sol is formed; the mass ratio of the dehydrating agent, the metal oxide organic precursor or the non-metal oxide organic precursor, the catalyst, the crosslinking agent and the diamine is 0.03-0.05:0.01-0.10:0.01-0.015:0.01-0.015:1; the crosslinking agent is octaaminophenyl cage silsesquioxane; S3, one-way vacuum impregnation of the polyimide sol and the previously prepared fiber preform is carried out, the polyimide sol needs to completely immerse the previously prepared fiber preform; then it is placed in an oven for temperature aging to form a fiber preform reinforced polyimide initial state gel; the fiber of the fiber preform is basalt fiber, and the volume density of the fiber preform is 0.04-0.15 g / cm 3 ; S4, the fiber preform reinforced polyimide initial state gel is placed in a water bath with a set temperature of 45-90 DEG C, and solvent replacement is performed using an organic solvent, and the solvent replacement is performed for 3-8 times, and the solvent is replaced once every 1-10 h, and a fiber preform reinforced polyimide final state gel is obtained; S5, the fiber preform reinforced polyimide final state gel is subjected to CO2 supercritical fluid drying to obtain a fiber preform reinforced high-temperature-resistant polyimide aerogel composite material.

2. The production method according to claim 1, characterized by, In the S1, the diamine is one or a mixture of several of p-phenylenediamine, 4,4'-diamino diphenyl ether, 4,4'-diamino-2,2'-dimethyl diphenyl, toluene diisocyanate, diphenyl methane diisocyanate; the dianhydride is one or a mixture of several of pyromellitic dianhydride, 3,3',4,4'-biphenyl tetracarboxylic dianhydride, 3,3',4,4'-benzophenone tetracarboxylic dianhydride, 4,4'-oxybisphthalic anhydride; the organic solvent is one or a mixture of several of dimethylacetamide, N,N-dimethylformamide, dimethyl phthalate, dimethyl sulfoxide, N-methyl pyrrolidone.

3. The preparation method according to claim 1, characterized in that, In the S2, the dehydrating agent is one or a mixture of several of acetyl chloride, acetic anhydride, propionic anhydride, thionyl chloride; the metal oxide organic precursor or the non-metal oxide organic precursor is one or a mixture of several of ZrO2, titanium isopropoxide chloride, chlorosilicate, Al2O3, diethyl aluminum acetylene, B2O3, V2O5, CuO, ethylenediamine copper, copper acetate, Fe2O3; the catalyst is one or a mixture of several of triethylamine, methylpyridine, pyridine.

4. The method of claim 1, wherein, In the S3, the temperature aging is aging at 20-50 DEG C for 18 h.

5. The preparation method according to claim 1, characterized in that, In the S4, the organic solvent is one or a mixture of several of methanol, ethanol, isopropanol.

6. The method of claim 1, wherein, In the S5, the pressure of the CO2 supercritical fluid drying is 10-18 MPa, the temperature is 40-80 DEG C, the drying time is 6-18 h, and after the drying is completed, the pressure is released at a speed of 100-240 kPa / min.

7. The high-temperature-resistant polyimide aerogel composite material prepared by the preparation method in any one of claims 1-6.

8. Use of the high-temperature-resistant polyimide aerogel composite material according to claim 7 in the preparation of high-performance thermal protection materials in the field of aerospace.

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