A method for preparing composite aerogel powder under atmospheric pressure and the preparation method thereof

Abstract

The present invention relates to the field of aerogel materials, and particularly to a method for preparing composite aerogel powder by an atmospheric pressure method and its preparation method, which is used to solve the problems that the existing aerogel materials have poor mechanical properties and high-temperature resistance, and high production costs, making it difficult to achieve large-scale industrial production; the composite aerogel powder combines the advantages of alumina aerogel and polyimide aerogel, enabling the two materials to support each other and jointly bear external forces, thereby improving the overall performance of the material. After doping and modifying carbon fibers into it, it can support the interpenetrating network structure, avoid pore shrinkage, collapse and cracking, and further improve the overall stability of the material, endowing the composite aerogel powder with excellent heat insulation performance, mechanical properties and high-temperature resistance. Moreover, by using the atmospheric pressure method, the high-temperature and high-pressure conditions required for the supercritical drying process are avoided, the equipment is simple, the cost is low, and the safety is high, which is conducive to large-scale production.

Description

Technical Field

[0001] The present invention relates to the field of aerogel materials, and particularly to a method for preparing composite aerogel powder by an atmospheric pressure method and its preparation method. Background Art

[0002] Aerogel is a new type of material with a nano-porous structure, having excellent properties such as extremely low density, high specific surface area, and low thermal conductivity, and has broad application prospects in the fields of thermal insulation, adsorption separation, catalysis, etc.

[0003] Most of the existing aerogel materials are prepared by chemical drying or supercritical drying techniques. Although these methods can obtain high-performance aerogels, they are usually complex in operation and high in cost, and it is difficult to achieve large-scale industrial production. In addition, traditional inorganic aerogels have a low thermal conductivity but are relatively brittle, resulting in poor mechanical properties. Traditional organic aerogels have excellent mechanical properties but have the disadvantage of poor high-temperature resistance. Therefore, single-component aerogels all have different disadvantages and cannot meet the actual application, making it difficult to meet the requirements of specific application scenarios for the comprehensive performance of materials.

[0004] Therefore, developing a method for preparing composite aerogel powder by an atmospheric pressure method and its preparation method is of great significance for improving the mechanical properties and high-temperature resistance of aerogel materials and reducing production costs. Summary of the Invention

[0005] In order to overcome the above technical problems, the purpose of the present invention is to provide a method for preparing composite aerogel powder by an atmospheric pressure method and its preparation method, which solves the problems that the existing aerogel materials have poor mechanical properties and high-temperature resistance, high production costs, and are difficult to achieve large-scale industrial production.

[0006] The purpose of the present invention can be achieved by the following technical solutions:

[0007] A method for preparing composite aerogel powder by an atmospheric pressure method, comprising the following components in parts by weight:

[0008] 20 - 25 parts of 4,4'-diaminodiphenyl ether, 30 - 35 parts of pyromellitic dianhydride, 90 - 100 parts of N-methylpyrrolidone, 5 - 7 parts of pyridine, 15 - 21 parts of propionic anhydride, 3 - 11 parts of 3-aminopropyltriethoxysilane, 6 - 10 parts of aluminum isopropoxide, 7 - 11 parts of acetic acid, 18 - 22 parts of deionized water, and 0.5 - 7.5 parts of modified carbon fiber;

[0009] Among them, the modified carbon fiber is prepared by the following steps:

[0010] Step a1: Add carbon fiber, concentrated nitric acid, and concentrated sulfuric acid into a three-necked flask equipped with a stirrer and a thermometer. Stir and react for 20 - 30 min under the conditions of a temperature of 25 - 30°C and a stirring rate of 300 - 400 r / min. Then, continue to stir and react for 2 - 3 h under the condition of heating to 85 - 90°C. After the reaction is completed, cool the reaction product to room temperature, then perform vacuum filtration. Wash the filter cake with distilled water 3 - 5 times, and then place it in a vacuum drying oven and dry it for 2 - 3 h under the condition of a temperature of 60 - 65°C to obtain oxidized carbon fiber;

[0011] Step a2: Add 3,4-dihydroxybenzaldehyde and anhydrous methanol into a three-necked flask equipped with a stirrer, a thermometer, a gas pipe, and a constant-pressure dropping funnel. Introduce nitrogen for protection. Stir and react for 20 - 30 min under the conditions of a temperature of 25 - 30°C and a stirring rate of 300 - 400 r / min. Then, gradually add a 1,3-diamino-2-hydroxypropane solution dropwise while stirring, controlling the dropping rate at 1 - 2 drops / s. After the addition is completed, continue to stir and react for 6 - 8 h under the condition of heating to 60 - 65°C. After the reaction is completed, cool the reaction product to room temperature, then pour it into ice water, then perform vacuum filtration. Wash the filter cake with distilled water 3 - 5 times, and then place it in a vacuum drying oven and dry it for 2 - 3 h under the condition of a temperature of 60 - 65°C to obtain a polyhydroxy intermediate;

[0012] Step a3: Add the polyhydroxy intermediate, benzyltriethylammonium chloride, and epichlorohydrin into a three-necked flask equipped with a stirrer, a thermometer, and a gas pipe. Introduce nitrogen for protection. Stir and react for 20 - 30 min under the conditions of a temperature of 25 - 30°C and a stirring rate of 300 - 400 r / min. Then, continue to stir and react for 6 - 8 h under the condition of heating to 90 - 95°C. Then, add a sodium hydroxide solution and continue to stir and react for 3 - 5 h. After the reaction is completed, cool the reaction product to room temperature, then wash it 3 - 5 times with distilled water, and then rotate and evaporate to remove the solvent to obtain a polyepoxy intermediate;

[0013] Step a4: Add oxidized carbon fiber and acetone into a three-necked flask equipped with a stirrer and a thermometer. Perform ultrasonic treatment for 15 - 25 min under the condition of an ultrasonic power of 200 - 300 W. Then, add the polyepoxy intermediate and stir and react for 20 - 30 min under the conditions of a temperature of 25 - 30°C and a stirring rate of 300 - 400 r / min. Then, continue to stir and react for 2 - 3 h under the condition of heating to 60 - 65°C. After the reaction is completed, cool the reaction product to room temperature, then perform vacuum filtration. Place the filter cake in a vacuum drying oven and dry it for 2 - 3 h under the condition of a temperature of 60 - 65°C to obtain modified carbon fiber.

[0014] As a further solution of the present invention: the dosage ratio of the carbon fiber, concentrated nitric acid and concentrated sulfuric acid in step a1 is 3 g: 30 - 40 mL: 10 - 15 mL.

[0015] As a further solution of the present invention: the carbon fiber in step a1 is a polyacrylonitrile-based T300 carbon fiber with an average length of 6 mm and an average diameter of 7 μm.

[0016] As a further solution of the present invention: the mass fraction of the concentrated nitric acid in step a1 is 68%; the mass fraction of the concentrated sulfuric acid is 98%.

[0017] As a further solution of the present invention: the dosage ratio of the 3,4-dihydroxybenzaldehyde, anhydrous methanol and 1,3-diamino-2-hydroxypropane solution in step a2 is 20 mmol: 20 - 25 mL: 10 - 12 mL.

[0018] As a further solution of the present invention: the 1,3-diamino-2-hydroxypropane solution in step a2 is a solution formed by dissolving 1,3-diamino-2-hydroxypropane in anhydrous methanol according to 10 mmol: 10 mL.

[0019] As a further solution of the present invention: the dosage ratio of the polyhydroxy intermediate, benzyltriethylammonium chloride, epichlorohydrin and sodium hydroxide solution in step a3 is 3 g: 30 - 35 mL: 0.1 - 0.2 g: 20 - 25 mL.

[0020] As a further solution of the present invention: the mass fraction of the sodium hydroxide solution in step a3 is 20 - 25%.

[0021] As a further solution of the present invention: the dosage ratio of the oxidized carbon fiber, acetone and multi-epoxy intermediate in step a4 is 5 g: 80 - 100 mL: 3 - 17 g.

[0022] As a further solution of the present invention: a preparation method for preparing composite aerogel powder by an atmospheric pressure method, comprising the following steps:

[0023] Step 1: Weigh 20 - 25 parts of 4,4'-diaminodiphenyl ether, 30 - 35 parts of pyromellitic dianhydride, 90 - 100 parts of N-methylpyrrolidone, 5 - 7 parts of pyridine, 15 - 21 parts of propionic anhydride, 3 - 11 parts of 3-aminopropyltriethoxysilane, 6 - 10 parts of aluminum isopropoxide, 7 - 11 parts of acetic acid, 18 - 22 parts of deionized water and 0.5 - 7.5 parts of modified carbon fiber by weight, and set aside;

[0024] Step 2: Add aluminum isopropoxide, acetic acid, and deionized water into a three-necked flask equipped with a stirrer and a thermometer. Stir and react for 1 - 2 h under the conditions of a temperature of 25 - 30 °C and a stirring rate of 300 - 400 r / min to obtain an alumina sol;

[0025] Step 3: Add 4,4'-diaminodiphenyl ether, pyromellitic dianhydride, and N-methylpyrrolidone into a three-necked flask equipped with a stirrer and a thermometer. Stir and react for 20 - 30 min under the conditions of a temperature of 25 - 30 °C and a stirring rate of 300 - 400 r / min. Then add pyridine and propionic anhydride and continue to stir and react for 2 - 3 h. Then add 3-aminopropyltriethoxysilane, alumina sol, and modified carbon fiber and continue to stir and react for 1 - 1.5 h. Then let it stand for gelation for 20 - 30 h. Then immerse the gel in absolute ethanol for 10 - 15 h. Then place it in a vacuum drying oven and dry it at normal pressure for 20 - 30 h under the condition of a temperature of 50 - 55 °C. Then raise the temperature to 80 - 85 °C and continue to dry at normal pressure for 2 - 3 h. Then after pulverization, a composite aerogel powder is obtained.

[0026] Advantages of the present invention:

[0027] A method for preparing a composite aerogel powder by an atmospheric pressure method and its preparation method according to the present invention obtain an alumina sol by stirring and reacting aluminum isopropoxide, acetic acid, and deionized water. By stirring and reacting 4,4'-diaminodiphenyl ether, pyromellitic dianhydride, and N-methylpyrrolidone, then adding pyridine, propionic anhydride, 3-aminopropyltriethoxysilane, alumina sol, and modified carbon fiber and continuing to stir and react, then standing for gelation, and immersing the gel in absolute ethanol, then drying at normal pressure and pulverizing, a composite aerogel powder is obtained; the composite aerogel powder prepared by this preparation method combines the advantages of alumina aerogel and polyimide aerogel, and the two are compounded to form an interpenetrating network structure. Alumina has a high melting point and high thermal stability and can withstand high-temperature environments without structural changes. Polyimide has excellent mechanical strength. After the two are combined, the two materials can support each other and jointly bear external forces, thereby improving the overall performance of the material. After doping modified carbon fiber into it, it can support the interpenetrating network structure, avoid pore shrinkage, collapse, and cracking, and further improve the overall stability of the material, endowing the composite aerogel powder with excellent heat insulation performance, mechanical properties, and high-temperature resistance performance, and being suitable for a variety of high-temperature and low-thermal conductivity application scenarios, especially showing significant technical advantages in the fields of aerospace, high-temperature insulation, and thermal insulation materials, significantly improving the performance of the product, and using the atmospheric pressure method to avoid the high-temperature and high-pressure conditions required by the supercritical drying process, with simple equipment, low cost, and high safety, which is conducive to large-scale production.

[0028] In the process of preparing the composite aerogel powder, a modified carbon fiber was first prepared. First, the carbon fiber was treated with concentrated nitric acid and concentrated sulfuric acid to remove impurities on the surface of the carbon fiber and introduce a large number of active groups (hydroxyl groups, carboxyl groups) at the same time, obtaining oxidized carbon fiber. Then, 3,4-dihydroxybenzaldehyde and 1,3-diamino-2-hydroxypropane were reacted. The aldehyde group on 3,4-dihydroxybenzaldehyde reacted with the amino group on 1,3-diamino-2-hydroxypropane to form a Schiff base structure, forming a polyhydroxy intermediate containing a large number of hydroxyl groups. Then, the polyhydroxy intermediate and epichlorohydrin were reacted. After the ring-opening and ring-closing reactions of epichlorohydrin, a large number of epoxy groups were introduced onto the hydroxyl groups of the polyhydroxy intermediate, obtaining a polyepoxy intermediate. Finally, the oxidized carbon fiber was treated with the polyepoxy intermediate. The active groups on the oxidized carbon fiber reacted with the epoxy groups on the polyepoxy intermediate, and at the same time, a large number of epoxy groups were introduced onto the oxidized carbon fiber, obtaining the modified carbon fiber; The carbon fiber has the advantages of light weight, high strength, and high stiffness. After adding it to the composite aerogel powder, it can significantly improve the mechanical properties of the composite aerogel powder. Moreover, after the carbon fiber is wrapped with the polyepoxy intermediate, it can be protected, further improving its comprehensive performance, and greatly improving its dispersibility, enabling it to be evenly dispersed inside the aerogel powder. And the large number of introduced epoxy groups can be connected to the inside of the composite aerogel powder in the form of chemical bonds, further improving the mechanical properties of the composite aerogel powder. Detailed implementation mode

[0029] The following will combine the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present invention.

[0030] Example 1:

[0031] This embodiment is a preparation method for preparing composite aerogel powder by an atmospheric pressure method, including the following steps:

[0032] Step S1: Add 3 g of polyacrylonitrile-based T300 carbon fiber with an average length of 6 mm and an average diameter of 7 μm, 30 mL of concentrated nitric acid with a mass fraction of 68%, and 10 mL of concentrated sulfuric acid with a mass fraction of 98% into a three-necked flask equipped with a stirrer and a thermometer. Stir and react at a temperature of 25 °C and a stirring rate of 300 r / min for 20 min, and then continue to stir and react at a temperature of 85 °C for 2 h. After the reaction is completed, cool the reaction product to room temperature, then vacuum filter, wash the filter cake 3 times with distilled water, and then place it in a vacuum drying oven and dry it at a temperature of 60 °C for 2 h to obtain oxidized carbon fiber;

[0033] Step S2: Add 20 mmol of 3,4-dihydroxybenzaldehyde and 20 mL of anhydrous methanol into a three-necked flask equipped with a stirrer, a thermometer, a gas pipe, and a constant-pressure dropping funnel. Introduce nitrogen for protection. Stir and react for 20 min at a temperature of 25 °C and a stirring rate of 300 r / min. Then, while stirring, gradually add dropwise 10 mL of a 1,3-diamino-2-hydroxypropane solution formed by dissolving 10 mmol of 1,3-diamino-2-hydroxypropane in 10 mL of anhydrous methanol, controlling the dropping rate at 1 drop / s. After the dropping is complete, continue to stir and react at 60 °C for 6 h. After the reaction is completed, cool the reaction product to room temperature, then pour it into ice water, and then perform vacuum filtration. Wash the filter cake with distilled water 3 times, and then place it in a vacuum drying oven and dry it at 60 °C for 2 h to obtain a polyhydroxy intermediate;

[0034] Step S3: Add 3 g of the polyhydroxy intermediate, 30 mL of benzyltriethylammonium chloride, and 0.1 g of epichlorohydrin into a three-necked flask equipped with a stirrer, a thermometer, and a gas pipe. Introduce nitrogen for protection. Stir and react for 20 min at a temperature of 25 °C and a stirring rate of 300 r / min. Then, continue to stir and react at 90 °C for 6 h. Then, add 20 mL of a 20% sodium hydroxide solution by mass and continue to stir and react for 3 h. After the reaction is completed, cool the reaction product to room temperature, then wash it with distilled water 3 times, and then remove the solvent by rotary evaporation to obtain a polyepoxy intermediate;

[0035] Step S4: Add 5 g of oxidized carbon fiber and 80 mL of acetone into a three-necked flask equipped with a stirrer and a thermometer. Perform ultrasonic treatment for 15 min under an ultrasonic power of 200 W. Then, add 3 g of the polyepoxy intermediate and stir and react at a temperature of 25 °C and a stirring rate of 300 r / min for 20 min. Then, continue to stir and react at 60 °C for 2 h. After the reaction is completed, cool the reaction product to room temperature, then perform vacuum filtration. Place the filter cake in a vacuum drying oven and dry it at 60 °C for 2 h to obtain a modified carbon fiber;

[0036] Step S5: Weigh 20 parts of 4,4'-diaminodiphenyl ether, 30 parts of pyromellitic dianhydride, 90 parts of N-methylpyrrolidone, 5 parts of pyridine, 15 parts of propionic anhydride, 3 parts of 3-aminopropyltriethoxysilane, 6 parts of aluminum isopropoxide, 7 parts of acetic acid, 18 parts of deionized water, and 0.5 part of the modified carbon fiber by weight for standby;

[0037] Step S6: Add aluminum isopropoxide, acetic acid, and deionized water into a three-necked flask equipped with a stirrer and a thermometer. Stir and react for 1 h under the conditions of a temperature of 25°C and a stirring rate of 300 r / min to obtain an alumina sol;

[0038] Step S7: Add 4,4'-diaminodiphenyl ether, pyromellitic dianhydride, and N-methylpyrrolidone into a three-necked flask equipped with a stirrer and a thermometer. Stir and react for 20 min under the conditions of a temperature of 25°C and a stirring rate of 300 r / min. Then add pyridine and propionic anhydride and continue to stir and react for 2 h. Then add 3-aminopropyltriethoxysilane, alumina sol, and modified carbon fiber and continue to stir and react for 1 h. Then let it stand and gel for 20 h. Then immerse the gel in absolute ethanol for 10 h. Then place it in a vacuum drying oven and dry it at normal pressure at a temperature of 50°C for 20 h. Then raise the temperature to 80°C and continue to dry at normal pressure for 2 h. Then, after pulverization, obtain the composite aerogel powder.

[0039] Example 2:

[0040] This example is a preparation method for preparing composite aerogel powder by an atmospheric pressure method, including the following steps:

[0041] Step S1: Add 3 g of polyacrylonitrile-based T300 carbon fiber with an average length of 6 mm and an average diameter of 7 μm, 35 mL of concentrated nitric acid with a mass fraction of 68%, and 12 mL of concentrated sulfuric acid with a mass fraction of 98% into a three-necked flask equipped with a stirrer and a thermometer. Stir and react for 25 min under the conditions of a temperature of 28°C and a stirring rate of 350 r / min. Then raise the temperature to 88°C and continue to stir and react for 2.5 h. After the reaction is completed, cool the reaction product to room temperature. Then perform vacuum filtration, wash the filter cake 4 times with distilled water. Then place it in a vacuum drying oven and dry it at a temperature of 62°C for 2.5 h to obtain oxidized carbon fiber;

[0042] Step S2: Add 20 mmol of 3,4-dihydroxybenzaldehyde and 22 mL of anhydrous methanol into a three-necked flask equipped with a stirrer, a thermometer, a gas pipe, and a constant-pressure dropping funnel. Introduce nitrogen for protection. Stir and react for 25 min at a temperature of 28 °C and a stirring rate of 350 r / min. Then, while stirring, gradually add dropwise 11 mL of a 1,3-diamino-2-hydroxypropane solution formed by dissolving 10 mmol of 1,3-diamino-2-hydroxypropane in 10 mL of anhydrous methanol, controlling the dropping rate at 1 drop / s. After the dropping is completed, continue to stir and react for 7 h under the condition of heating to 62 °C. After the reaction ends, cool the reaction product to room temperature, then pour it into ice water, and then perform vacuum filtration. Wash the filter cake 4 times with distilled water, and then place it in a vacuum drying oven and dry it for 2.5 h at a temperature of 62 °C to obtain a polyhydroxy intermediate;

[0043] Step S3: Add 3 g of the polyhydroxy intermediate, 32 mL of benzyltriethylammonium chloride, and 0.15 g of epichlorohydrin into a three-necked flask equipped with a stirrer, a thermometer, and a gas pipe. Introduce nitrogen for protection. Stir and react for 25 min at a temperature of 28 °C and a stirring rate of 350 r / min. Then, continue to stir and react for 7 h under the condition of heating to 92 °C. Then, add 22 mL of a sodium hydroxide solution with a mass fraction of 22% and continue to stir and react for 4 h. After the reaction ends, cool the reaction product to room temperature, then wash it 4 times with distilled water, and then rotate and evaporate to remove the solvent to obtain a polyepoxy intermediate;

[0044] Step S4: Add 5 g of oxidized carbon fiber and 90 mL of acetone into a three-necked flask equipped with a stirrer and a thermometer. Ultrasonically treat for 20 min under the condition of an ultrasonic power of 250 W. Then, add 10 g of the polyepoxy intermediate and stir and react for 25 min at a temperature of 28 °C and a stirring rate of 350 r / min. Then, continue to stir and react for 2.5 h under the condition of heating to 62 °C. After the reaction ends, cool the reaction product to room temperature, then perform vacuum filtration. Place the filter cake in a vacuum drying oven and dry it for 2.5 h at a temperature of 62 °C to obtain modified carbon fiber;

[0045] Step S5: Weigh 22 parts of 4,4'-diaminodiphenyl ether, 32 parts of pyromellitic dianhydride, 95 parts of N-methylpyrrolidone, 6 parts of pyridine, 18 parts of propionic anhydride, 7 parts of 3-aminopropyltriethoxysilane, 8 parts of aluminum isopropoxide, 9 parts of acetic acid, 20 parts of deionized water, and 4 parts of modified carbon fiber according to weight parts for standby;

[0046] Step S6: Add aluminum isopropoxide, acetic acid, and deionized water into a three-necked flask equipped with a stirrer and a thermometer. Stir and react for 1.5 h at a temperature of 28 °C and a stirring rate of 350 r / min to obtain an alumina sol;

[0047] Step S7: Add 4,4'-diaminodiphenyl ether, pyromellitic dianhydride, and N-methylpyrrolidone into a three-necked flask equipped with a stirrer and a thermometer. Stir and react for 25 min under the conditions of a temperature of 28°C and a stirring rate of 350 r / min. Then add pyridine and propionic anhydride and continue to stir and react for 2.5 h. Then add 3-aminopropyltriethoxysilane, alumina sol, and modified carbon fiber and continue to stir and react for 1.2 h. Then let it stand for gelation for 25 h. Then immerse the gel in absolute ethanol for 12 h. Then place it in a vacuum drying oven and dry it at normal pressure for 25 h under the condition of a temperature of 52°C. Then raise the temperature to 82°C and continue to dry at normal pressure for 2.5 h. Then, after pulverization, a composite aerogel powder is obtained.

[0048] Example 3:

[0049] This example is a preparation method for preparing composite aerogel powder by the atmospheric pressure method, including the following steps:

[0050] Step S1: Add 3 g of polyacrylonitrile-based T300 carbon fiber with an average length of 6 mm and an average diameter of 7 μm, 40 mL of concentrated nitric acid with a mass fraction of 68%, and 15 mL of concentrated sulfuric acid with a mass fraction of 98% into a three-necked flask equipped with a stirrer and a thermometer. Stir and react for 30 min under the conditions of a temperature of 30°C and a stirring rate of 400 r / min. Then raise the temperature to 90°C and continue to stir and react for 3 h. After the reaction ends, cool the reaction product to room temperature. Then perform vacuum filtration, wash the filter cake with distilled water 5 times. Then place it in a vacuum drying oven and dry it at a temperature of 65°C for 3 h to obtain oxidized carbon fiber;

[0051] Step S2: Add 20 mmol of 3,4-dihydroxybenzaldehyde and 25 mL of anhydrous methanol into a three-necked flask equipped with a stirrer, a thermometer, a gas pipe, and a constant pressure dropping funnel. Introduce nitrogen for protection. Stir and react for 30 min under the conditions of a temperature of 30°C and a stirring rate of 400 r / min. Then, while stirring, gradually dropwise add 12 mL of 1,3-diamino-2-hydroxypropane solution formed by dissolving 1,3-diamino-2-hydroxypropane in anhydrous methanol at a ratio of 10 mmol:10 mL, control the dropping rate at 2 drops / s. After the dropping is completed, raise the temperature to 65°C and continue to stir and react for 8 h. After the reaction ends, cool the reaction product to room temperature. Then pour it into ice water. Then perform vacuum filtration, wash the filter cake with distilled water 5 times. Then place it in a vacuum drying oven and dry it at a temperature of 65°C for 3 h to obtain a polyhydroxy intermediate;

[0052] Step S3: Add 3 g of polyhydroxy intermediate, 35 mL of benzyltriethylammonium chloride, and 0.2 g of epichlorohydrin into a three-necked flask equipped with a stirrer, a thermometer, and a gas pipe. Introduce nitrogen for protection. Stir and react for 30 min at a temperature of 30 °C and a stirring rate of 400 r / min. Then, continue to stir and react for 8 h under the condition of heating to 95 °C. After that, add 25 mL of sodium hydroxide solution with a mass fraction of 25% and continue to stir and react for 5 h. After the reaction is completed, cool the reaction product to room temperature, then wash it 5 times with distilled water, and then rotate and evaporate to remove the solvent to obtain a polyepoxy intermediate;

[0053] Step S4: Add 5 g of oxidized carbon fiber and 100 mL of acetone into a three-necked flask equipped with a stirrer and a thermometer. Ultrasonically treat for 25 min under the condition of an ultrasonic power of 300 W. Then, add 17 g of polyepoxy intermediate and stir and react for 30 min at a temperature of 30 °C and a stirring rate of 400 r / min. Then, continue to stir and react for 3 h under the condition of heating to 65 °C. After the reaction is completed, cool the reaction product to room temperature, then perform vacuum filtration, place the filter cake in a vacuum drying oven, and dry it for 3 h at a temperature of 65 °C to obtain modified carbon fiber;

[0054] Step S5: Weigh 25 parts of 4,4'-diaminodiphenyl ether, 35 parts of pyromellitic dianhydride, 100 parts of N-methylpyrrolidone, 7 parts of pyridine, 21 parts of propionic anhydride, 11 parts of 3-aminopropyltriethoxysilane, 10 parts of aluminum isopropoxide, 11 parts of acetic acid, 22 parts of deionized water, and 7.5 parts of modified carbon fiber, and set aside;

[0055] Step S9: Add aluminum isopropoxide, acetic acid, and deionized water into a three-necked flask equipped with a stirrer and a thermometer. Stir and react for 2 h at a temperature of 30 °C and a stirring rate of 400 r / min to obtain an alumina sol;

[0056] Step S7: Add 4,4'-diaminodiphenyl ether, pyromellitic dianhydride, and N-methylpyrrolidone into a three-necked flask equipped with a stirrer and a thermometer. Stir and react for 30 min at a temperature of 30 °C and a stirring rate of 400 r / min. Then, add pyridine and propionic anhydride and continue to stir and react for 3 h. Then, add 3-aminopropyltriethoxysilane, alumina sol, and modified carbon fiber and continue to stir and react for 1.5 h. Then, let it stand and gel for 30 h. Then, immerse the gel in absolute ethanol for 15 h. Then, place it in a vacuum drying oven and dry it at a normal pressure for 30 h at a temperature of 55 °C. Then, raise the temperature to 85 °C and continue to dry at a normal pressure for 3 h. Then, after pulverization, obtain composite aerogel powder.

[0057] Comparative Example 1:

[0058] This comparative example is a preparation method of composite aerogel powder by an atmospheric pressure method, which includes the following steps:

[0059] Step S1: Weigh 25 parts of 4,4'-diaminodiphenyl ether, 35 parts of pyromellitic dianhydride, 100 parts of N-methylpyrrolidone, 7 parts of pyridine, 21 parts of propionic anhydride, and 11 parts of 3-aminopropyltriethoxysilane by weight, and set aside;

[0060] Step S2: Add 4,4'-diaminodiphenyl ether, pyromellitic dianhydride, and N-methylpyrrolidone into a three-necked flask equipped with a stirrer and a thermometer, stir and react at a temperature of 30 °C and a stirring rate of 400 r / min for 30 min, then add pyridine and propionic anhydride and continue to stir and react for 3 h, then add 3-aminopropyltriethoxysilane and continue to stir and react for 1.5 h, then let it stand for gelation for 30 h, then immerse the gel in absolute ethanol for 15 h, then place it in a vacuum drying oven and dry it at a temperature of 55 °C under atmospheric pressure for 30 h, then raise the temperature to 85 °C and continue to dry it under atmospheric pressure for 3 h, and then obtain composite aerogel powder after pulverization.

[0061] Comparative Example 2:

[0062] This comparative example is a preparation method of composite aerogel powder by an atmospheric pressure method, which includes the following steps:

[0063] Step S1: Weigh 25 parts of 4,4'-diaminodiphenyl ether, 35 parts of pyromellitic dianhydride, 100 parts of N-methylpyrrolidone, 7 parts of pyridine, 21 parts of propionic anhydride, 11 parts of 3-aminopropyltriethoxysilane, 10 parts of aluminum isopropoxide, 11 parts of acetic acid, and 22 parts of deionized water by weight, and set aside;

[0064] Step S2: Add aluminum isopropoxide, acetic acid, and deionized water into a three-necked flask equipped with a stirrer and a thermometer, stir and react at a temperature of 30 °C and a stirring rate of 400 r / min for 2 h to obtain aluminum oxide sol;

[0065] Step S3: Add 4,4'-diaminodiphenyl ether, pyromellitic dianhydride, and N-methylpyrrolidone into a three-necked flask equipped with a stirrer and a thermometer, stir and react at a temperature of 30 °C and a stirring rate of 400 r / min for 30 min, then add pyridine and propionic anhydride and continue to stir and react for 3 h, then add 3-aminopropyltriethoxysilane and aluminum oxide sol and continue to stir and react for 1.5 h, then let it stand for gelation for 30 h, then immerse the gel in absolute ethanol for 15 h, then place it in a vacuum drying oven and dry it at a temperature of 55 °C under atmospheric pressure for 30 h, then raise the temperature to 85 °C and continue to dry it under atmospheric pressure for 3 h, and then obtain composite aerogel powder after pulverization.

[0066] Comparative Example 3:

[0067] This comparative example is a preparation method for preparing composite aerogel powder by an atmospheric pressure method, including the following steps:

[0068] Step S1: Add 3 g of polyacrylonitrile-based T300 carbon fiber with an average length of 6 mm and an average diameter of 7 μm, 40 mL of concentrated nitric acid with a mass fraction of 68%, and 15 mL of concentrated sulfuric acid with a mass fraction of 98% into a three-necked flask equipped with a stirrer and a thermometer. Stir and react for 30 min at a temperature of 30 °C and a stirring rate of 400 r / min. Then, continue to stir and react for 3 h at a temperature of 90 °C. After the reaction is completed, cool the reaction product to room temperature, then perform vacuum filtration. Wash the filter cake 5 times with distilled water, and then place it in a vacuum drying oven and dry it for 3 h at a temperature of 65 °C to obtain oxidized carbon fiber;

[0069] Step S2: Add 20 mmol of 3,4-dihydroxybenzaldehyde and 25 mL of anhydrous methanol into a three-necked flask equipped with a stirrer, a thermometer, a gas pipe, and a constant-pressure dropping funnel. Pass nitrogen for protection. Stir and react for 30 min at a temperature of 30 °C and a stirring rate of 400 r / min. Then, while stirring, gradually add dropwise 12 mL of 1,3-diamino-2-hydroxypropane solution formed by dissolving 1,3-diamino-2-hydroxypropane in anhydrous methanol at a ratio of 10 mmol:10 mL, control the dropping rate at 2 drops / s. After the dropping is completed, continue to stir and react for 8 h at a temperature of 65 °C. After the reaction is completed, cool the reaction product to room temperature, then pour it into ice water, then perform vacuum filtration. Wash the filter cake 5 times with distilled water, and then place it in a vacuum drying oven and dry it for 3 h at a temperature of 65 °C to obtain a polyhydroxy intermediate;

[0070] Step S3: Add 3 g of the polyhydroxy intermediate, 35 mL of benzyltriethylammonium chloride, and 0.2 g of epichlorohydrin into a three-necked flask equipped with a stirrer, a thermometer, and a gas pipe. Pass nitrogen for protection. Stir and react for 30 min at a temperature of 30 °C and a stirring rate of 400 r / min. Then, continue to stir and react for 8 h at a temperature of 95 °C. Then, add 25 mL of sodium hydroxide solution with a mass fraction of 25% and continue to stir and react for 5 h. After the reaction is completed, cool the reaction product to room temperature, then wash it 5 times with distilled water, and then rotate and evaporate to remove the solvent to obtain a polyepoxy intermediate;

[0071] Step S4: Add 5 g of oxidized carbon fiber and 100 mL of acetone into a three-necked flask equipped with a stirrer and a thermometer, ultrasonically treat for 25 min under the condition of an ultrasonic power of 300 W, then add 17 g of multi-epoxy intermediate and stir and react for 30 min under the conditions of a temperature of 30 °C and a stirring rate of 400 r / min. Then, continue to stir and react for 3 h under the condition of raising the temperature to 65 °C. After the reaction is completed, cool the reaction product to room temperature, then perform vacuum filtration. Place the filter cake in a vacuum drying oven and dry for 3 h under the condition of a temperature of 65 °C to obtain modified carbon fiber;

[0072] Step S5: Weigh 25 parts of 4,4'-diaminodiphenyl ether, 35 parts of pyromellitic dianhydride, 100 parts of N-methylpyrrolidone, 7 parts of pyridine, 21 parts of propionic anhydride, 11 parts of 3-aminopropyltriethoxysilane, and 7.5 parts of modified carbon fiber by weight, and set aside;

[0073] Step S6: Add 4,4'-diaminodiphenyl ether, pyromellitic dianhydride, and N-methylpyrrolidone into a three-necked flask equipped with a stirrer and a thermometer, stir and react for 30 min under the conditions of a temperature of 30 °C and a stirring rate of 400 r / min. Then, add pyridine and propionic anhydride and continue to stir and react for 3 h. Then, add 3-aminopropyltriethoxysilane and modified carbon fiber and continue to stir and react for 1.5 h. Then, let it stand and gel for 30 h. Then, immerse the gel in absolute ethanol for 15 h. Then, place it in a vacuum drying oven and dry at normal pressure for 30 h under the condition of a temperature of 55 °C. Then, raise the temperature to 85 °C and continue to dry at normal pressure for 3 h. Then, after pulverization, obtain composite aerogel powder.

[0074] Comparative Example 4:

[0075] This comparative example is a preparation method for preparing composite aerogel powder by an atmospheric pressure method, including the following steps:

[0076] Step S1: Weigh 25 parts of 4,4'-diaminodiphenyl ether, 35 parts of pyromellitic dianhydride, 100 parts of N-methylpyrrolidone, 7 parts of pyridine, 21 parts of propionic anhydride, 11 parts of 3-aminopropyltriethoxysilane, 10 parts of aluminum isopropoxide, 11 parts of acetic acid, 22 parts of deionized water, and 7.5 parts of polyacrylonitrile-based T300 carbon fiber with an average length of 6 mm and an average diameter of 7 μm by weight, and set aside;

[0077] Step S2: Add aluminum isopropoxide, acetic acid, and deionized water into a three-necked flask equipped with a stirrer and a thermometer, stir and react for 2 h under the conditions of a temperature of 30 °C and a stirring rate of 400 r / min to obtain aluminum oxide sol;

[0078] Step S3: Add 4,4'-diaminodiphenyl ether, pyromellitic dianhydride, and N-methylpyrrolidone into a three-necked flask equipped with a stirrer and a thermometer. Stir and react for 30 min under the conditions of a temperature of 30°C and a stirring rate of 400 r / min. Then add pyridine and propionic anhydride and continue to stir and react for 3 h. Then add 3-aminopropyltriethoxysilane, alumina sol, and polyacrylonitrile-based T300 carbon fibers with an average length of 6 mm and an average diameter of 7 μm and continue to stir and react for 1.5 h. Then let it stand for gelation for 30 h. Then immerse the gel in absolute ethanol for 15 h. Then place it in a vacuum drying oven and dry it at normal pressure for 30 h under the condition of a temperature of 55°C. Then raise the temperature to 85°C and continue to dry it at normal pressure for 3 h. Then, after pulverization, obtain the composite aerogel powder.

[0079] Perform performance tests on the composite aerogel powders in Examples 1-3 and Comparative Examples 1-4. The test results are shown in the following table:

[0080]

[0081] Referring to the data in the above table, based on the comparison between Examples 1-3 and Comparative Examples 1-4, it can be known that the composite aerogel powder of the present application has excellent heat insulation performance, mechanical properties, and high-temperature resistance performance.

[0082] In the description of this specification, the description referring to terms such as "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0083] The above content is only an example and explanation of the present invention. Those skilled in the art of the present technology can make various modifications or supplements to the described specific embodiments or use similar methods for substitution, as long as they do not deviate from the invention or exceed the scope defined by the present application, they should all fall within the protection scope of the present invention.

Claims

1. A method for preparing composite aerogel powder by a normal pressure method, characterized in that: The preparation method is as follows: Carbon fiber, concentrated nitric acid and concentrated sulfuric acid are stirred to react, and after the reaction, the product is cooled, vacuum filtered, washed and dried to obtain oxidized carbon fiber; 3,4-dihydroxybenzaldehyde and anhydrous methanol are stirred to react, and then 1,3-diamino-2-hydroxypropane solution is added dropwise while stirring, and after the dropwise addition is completed, the reaction is stirred to react, and after the reaction is completed, the reaction product is cooled, poured into ice water, vacuum filtered, and the filter cake is washed and dried to obtain a polyhydroxy intermediate; polyhydroxy intermediates, benzyltriethylammonium chloride and epichlorohydrin are stirred to react, and then sodium hydroxide solution is added to continue stirring the reaction, and after the reaction is completed, the product is cooled, washed, and rotary evaporated to obtain a polyepoxy intermediate; oxidized carbon fiber and acetone are ultrasonically treated, and then the polyepoxy intermediate is added to react with stirring, and after the reaction is completed, the reaction product is cooled, vacuum filtered, and dried to obtain modified carbon fiber; Weigh 20-25 parts of 4,4'-diaminodiphenyl ether, 30-35 parts of pyromellitic anhydride, 90-100 parts of N-methylpyrrolidone, 5-7 parts of pyridine, 15-21 parts of propionic anhydride, 3-11 parts of 3-aminopropyltriethoxysilane, 6-10 parts of aluminum isopropoxide, 7-11 parts of acetic acid, 18-22 parts of deionized water and 0.5-7.5 parts of modified carbon fiber; Aluminum isopropoxide, acetic acid and deionized water are added into a three-necked flask, and stirred for reaction at 25-30° C. and a stirring rate of 300-400 r / min for 1-2 h to obtain an alumina sol; Add 4,4'-diaminodiphenyl ether, pyromellitic acid dianhydride and N-methylpyrrolidone into a three-necked flask, react for 20-30 minutes at 25-30°C and a stirring rate of 300-400r / min, add pyridine and propionic anhydride and continue to stir and react for 2-3 hours, add 3-aminopropyltriethoxysilane, alumina sol and modified carbon fiber and stir and react for 1-1.5 hours, let the gel stand for 20-30 hours, immerse it in anhydrous ethanol for 10-15 hours, dry it at normal pressure at a temperature of 50-55°C for 20-30 hours, then heat it to 80-85°C and continue to dry it at normal pressure for 2-3 hours, and crush it to obtain a composite aerogel powder.

2. The composite aerogel powder prepared by a normal pressure method according to claim 1, characterized in that: The usage ratio of the carbon fiber, concentrated nitric acid and concentrated sulfuric acid in step a1 is 3g:30-40mL:10-15mL.

3. The composite aerogel powder prepared by the normal pressure method according to claim 1, characterized in that: The carbon fiber in step a1 is polyacrylonitrile-based T300 carbon fiber with an average length of 6 mm and an average diameter of 7 μm.

4. The composite aerogel powder prepared by the normal pressure method according to claim 1, characterized in that: The mass fraction of the concentrated nitric acid in step a1 is 68%; the mass fraction of the concentrated sulfuric acid is 98%.

5. The method for preparing composite aerogel powder by a normal pressure method according to claim 1, characterized in that: The usage ratio of the 3,4-dihydroxybenzaldehyde, anhydrous methanol and 1,3-diamino-2-hydroxypropane solution in step a2 is 20 mmol: 20-25 mL: 10-12 mL.

6. The composite aerogel powder prepared by the normal pressure method according to claim 1, characterized in that: The 1,3-diamino-2-hydroxypropane solution in step a2 is a solution formed by dissolving 1,3-diamino-2-hydroxypropane in anhydrous methanol at a ratio of 10 mmol:10 mL.

7. The composite aerogel powder prepared by the normal pressure method according to claim 1, characterized in that: The usage ratio of the polyhydroxy intermediate, benzyltriethylammonium chloride, epichlorohydrin and sodium hydroxide solution in step a3 is 3g:30-35mL:0.1-0.2g:20-25mL.

8. The method for preparing composite aerogel powder by normal pressure method according to claim 1, characterized in that: The mass fraction of the sodium hydroxide solution in step a3 is 20-25%.

9. The method for preparing composite aerogel powder by normal pressure method according to claim 1, characterized in that: The usage ratio of the oxidized carbon fiber, acetone and polyepoxy intermediate in step a4 is 5g:80-100mL:3-17g.

Images