A polyacrylonitrile-itaconic acid fiber felt reinforced carbon aerogel composite material, its preparation method and application

Abstract

The present invention belongs to the technical field of aerogel composite materials, and provides a polyacrylonitrile-itaconic acid fiber felt reinforced carbon aerogel composite material, a preparation method thereof, and an application thereof. The preparation method of the present invention comprises the following steps: impregnating a polyacrylonitrile-itaconic acid fiber felt in a prepolymer solution composed of a phenolic monomer, an aldehyde monomer, an alcohol solvent, and an acidic catalyst under normal pressure, and then performing a sol-gel reaction, and sequentially performing normal pressure drying and carbonization reaction on the obtained composite material precursor; the acidic catalyst comprises one or more of hydrochloric acid, salicylic acid, m-hydroxybenzoic acid, and gallic acid. The present invention uses a polyacrylonitrile-itaconic acid fiber felt as a reinforcing body, and through impregnation, curing, and carbonization in a prepolymer solution containing an acidic catalyst, the obtained carbon aerogel composite material has high porosity, low density, high specific surface area, low thermal conductivity, and excellent mechanical properties and heat insulation properties.

Description

Technical Field

[0001] The present invention relates to the technical field of aerogel composite materials, and particularly to a polyacrylonitrile-itaconic acid fiber felt reinforced carbon aerogel composite material, a preparation method thereof, and an application thereof. Background Art

[0002] With the development of new high-speed aerospace vehicles, there is an urgent need for high-performance thermal insulation materials with ultra-high temperature resistance, low thermal conductivity, and relatively high strength. Carbon aerogel is a three-dimensional network structure nanoporous material formed by the interconnected carbon nanoparticles, which has the advantages of low density, ultra-high temperature resistance, and low radiative thermal conductivity. However, it has the disadvantages of low strength, high brittleness, and large inherent volume shrinkage during the preparation process, which limits its application in the field of aerospace thermal insulation. Therefore, the development of new high-performance thermal insulation materials with properties such as ultra-high temperature resistance, ultra-low thermal conductivity, and sufficient strength has become one of the main research hotspots in the field of thermal insulation materials.

[0003] Researchers are committed to improving the comprehensive thermal insulation and mechanical properties of carbon aerogel. Chinese Patent CN115504451A uses the high-temperature hydrothermal method to obtain carbon aerogel with a high specific surface area (1100 - 1600 m 2 / g) through gelation, aging, supercritical drying, and high-temperature carbonization in sequence. It selects alkali metal-based sodium carbonate as a catalyst, and the contained Na ＋ has a corrosive effect on the equipment for subsequent high-temperature carbonization, which is not conducive to large-scale production. Moreover, supercritical drying has high requirements for equipment, increasing the production cost. Chinese Patent CN118954482A uses fiber-reinforced carbon aerogel to obtain a fiber-reinforced carbon aerogel composite material through gelation, aging, drying, solvent replacement, and high-temperature carbonization. The solvent replacement process prolongs the preparation cycle and increases the raw material cost. Chinese Patent CN118637937B impregnates carbon aerogel with an impregnating solution formed by mixing phenolic aerogel powder, phenolic resin, and a dispersant, and obtains an ablation-resistant thermal insulation carbon aerogel composite material with a low density (0.26 - 0.41 g / cm 3 ) and general room-temperature thermal insulation (0.055 - 0.068 W / m·K) through ultrasonic secondary impregnation, gelation, aging, and carbonization. Its process is complex, the preparation cycle is long, and the equipment requirements are high.

[0004] Therefore, it is of great significance to research and obtain a preparation method of a polyacrylonitrile-itaconic acid fiber felt reinforced carbon aerogel composite material with good mechanical properties, short preparation cycle, and low production cost, so as to better solve a series of problems such as long preparation cycle, high equipment requirements, poor mechanical properties, high brittleness, and high production cost. Summary of the Invention

[0005] The purpose of the present invention is to provide a polyacrylonitrile-itaconic acid fiber felt reinforced carbon aerogel composite material, a preparation method thereof, and an application thereof in order to overcome the deficiencies of the prior art.

[0006] To achieve the above-mentioned invention object, the present invention provides the following technical solutions:

[0007] The present invention provides a preparation method of a polyacrylonitrile-itaconic acid fiber felt reinforced carbon aerogel composite material, comprising the following steps:

[0008] 1) Mix a phenolic monomer, an aldehyde monomer, an alcohol solvent and an acidic catalyst to obtain a prepolymer solution;

[0009] 2) Immerse the polyacrylonitrile-itaconic acid fiber felt in the prepolymer solution under normal pressure and then carry out a sol-gel reaction to obtain a composite precursor;

[0010] 3) Sequentially carry out atmospheric drying and carbonization reaction on the composite precursor to obtain a polyacrylonitrile-itaconic acid fiber felt reinforced carbon aerogel composite material;

[0011] The acidic catalyst includes one or more of hydrochloric acid, salicylic acid, m-hydroxybenzoic acid and gallic acid.

[0012] Preferably, the molar ratio of the phenolic monomer, the aldehyde monomer, the acidic catalyst and the alcohol solvent in step 1) is 1: 2.0-2.5: 3.6-5.0: 40-45.

[0013] Preferably, the phenolic monomer includes one or more of phenol, resorcinol, aminophenol, butylphenol and bisphenol A; the aldehyde monomer includes one or more of formaldehyde, glutaraldehyde, paraformaldehyde and furfural; the alcohol solvent includes one or more of absolute ethanol, n-propanol, isopropanol and n-butanol.

[0014] Preferably, the rotation speed of the mixing in step 1) is 300-450 rpm, and the mixing temperature is 30-50 °C.

[0015] Preferably, the polyacrylonitrile-itaconic acid fiber felt is prepared by the following steps: obtaining an acrylonitrile copolymer by polymerizing acrylonitrile, itaconic acid, an initiator and a solvent, and sequentially carrying out dry-jet wet spinning and needling on the acrylonitrile copolymer to obtain a polyacrylonitrile-itaconic acid fiber felt; the mass ratio of acrylonitrile to itaconic acid is 97-99: 2.

[0016] Preferably, the temperature of the sol-gel reaction in step 2) is 60-70 °C, and the time of the sol-gel reaction is 11-13 h.

[0017] Preferably, the temperature of the atmospheric drying in step 3) is 90-120 °C, and the time of the atmospheric drying is 10-18 h.

[0018] Preferably, the temperature of the carbonization reaction in step 3) is 800 - 1400 °C, the time of the carbonization reaction is 2 h, and the heating rate from room temperature to the carbonization reaction temperature is 3 - 5 °C / min; the carbonization reaction is carried out under a nitrogen atmosphere.

[0019] The present invention also provides a polyacrylonitrile-itaconic acid fiber felt reinforced carbon aerogel composite material prepared by the preparation method of the polyacrylonitrile-itaconic acid fiber felt reinforced carbon aerogel composite material. The density of the polyacrylonitrile-itaconic acid fiber felt reinforced carbon aerogel composite material is 0.13 - 0.16 g / cm 3 , and the specific surface area is 1662 - 1942 m 2 / g, and the room temperature thermal conductivity is 0.017 - 0.049 W / m·K ， The compressive strength is 2.17 - 4.03 MPa.

[0020] The present invention also provides an application of the polyacrylonitrile-itaconic acid fiber felt reinforced carbon aerogel composite material, and the application of the polyacrylonitrile-itaconic acid fiber felt reinforced carbon aerogel composite material in thermal insulation, adsorption and electromagnetic shielding.

[0021] The beneficial effects of the present invention include the following points:

[0022] 1) The present invention uses a polyacrylonitrile-itaconic acid fiber felt as a reinforcing body, and prepares a composite material through processes such as impregnation, curing, and carbonization, functionalizes the network of the carbon aerogel, improves the network strength, reduces the volume shrinkage, and the prepared polyacrylonitrile-itaconic acid fiber felt reinforced carbon aerogel composite material has high porosity, low density, high specific surface area, low thermal conductivity and excellent mechanical properties and heat insulation properties.

[0023] 2) By adding an alcohol solvent and an acidic catalyst during the sol-gel reaction process in the present invention, compared with an alkaline catalyst, the acidic catalyst will shorten the solution-gel reaction time, accelerate the reaction rate, without solvent replacement and supercritical freeze-drying, and the volume shrinkage is less than 20%, thereby reducing energy consumption; the acidic catalyst has a pore-forming effect, endows the composite material with high porosity, reduces the volume shrinkage rate of the polyacrylonitrile-itaconic acid fiber felt reinforced carbon aerogel composite material during the atmospheric pressure drying process, increases the specific surface area, and improves the production efficiency.

[0024] 3) By reasonably controlling process parameters such as the raw material ratio, the sol-gel reaction time, and the carbonization temperature in the present invention, the regulation of the pore size distribution and porosity of the polyacrylonitrile-itaconic acid fiber felt reinforced carbon aerogel composite material can be realized.

[0025] 4) The preparation method of the present invention does not require solvent replacement and secondary activation processes, does not require freeze-drying, only requires atmospheric drying, has low raw material costs, simple processes, and strong processability, provides an effective method for the large-scale production of carbon aerogels, and has important practical significance for the development of new aerospace vehicles. Description of the Drawings

[0026] Figure 1 It is the nitrogen adsorption test diagram of the polyacrylonitrile-itaconic acid fiber felt reinforced carbon aerogel composite material prepared in Example 1;

[0027] Figure 2 It is the SEM diagram of the polyacrylonitrile-itaconic acid fiber felt reinforced carbon aerogel composite material prepared in Example 1;

[0028] Figure 3 It is the X-ray diffraction spectrum diagram of the polyacrylonitrile-itaconic acid fiber felt reinforced carbon aerogel composite material prepared in Example 1;

[0029] Figure 4 It is the Raman spectrum diagram of the polyacrylonitrile-itaconic acid fiber felt reinforced carbon aerogel composite material prepared in Example 1;

[0030] Figure 5 It is the compression stress-strain curve diagram of the polyacrylonitrile-itaconic acid fiber felt reinforced carbon aerogel composite material prepared in Example 1. Detailed Embodiments

[0031] The present invention provides a preparation method of a polyacrylonitrile-itaconic acid fiber felt reinforced carbon aerogel composite material, comprising the following steps:

[0032] 1) Mix a phenolic monomer, an aldehyde monomer, an alcohol solvent, and an acidic catalyst to obtain a prepolymer solution;

[0033] 2) Immerse the polyacrylonitrile-itaconic acid fiber felt in the prepolymer solution at atmospheric pressure and then carry out a sol-gel reaction to obtain a composite precursor;

[0034] 3) Subject the composite precursor to atmospheric drying and carbonization reactions in sequence to obtain a polyacrylonitrile-itaconic acid fiber felt reinforced carbon aerogel composite material;

[0035] The acidic catalyst includes one or more of hydrochloric acid, salicylic acid, m-hydroxybenzoic acid, and gallic acid.

[0036] In the present invention, the molar ratio of the phenolic monomer, the aldehyde monomer, the acidic catalyst, and the alcohol solvent in step 1) is preferably 1:2.0 - 2.5:3.6 - 5.0:40 - 45, more preferably 1:2.2 - 2.4:4.0 - 4.8:41 - 44, and even more preferably 1:2.3:4.3 - 4.5:42 - 43.

[0037] In the present invention, the phenolic monomer preferably includes one or more of phenol, resorcinol, aminophenol, butylphenol, and bisphenol A; the aldehyde monomer preferably includes one or more of formaldehyde, glutaraldehyde, paraformaldehyde, and furfural; the alcohol solvent preferably includes one or more of absolute ethanol, n-propanol, isopropanol, and n-butanol.

[0038] In the present invention, the rotation speed of the mixing in step 1) is preferably 300 - 450 rpm, more preferably 320 - 400 rpm, and even more preferably 350 - 360 rpm; the temperature of the mixing is preferably 30 - 50 °C, more preferably 35 - 45 °C, and even more preferably 40 °C.

[0039] In the present invention, the mixing in step 1) preferably involves mixing the phenolic monomer, the alcohol solvent, and the acidic catalyst to obtain a mixed solution, and then mixing the aldehyde monomer with the mixed solution to obtain a prepolymer solution; the mixing time of the phenolic monomer, the alcohol solvent, and the acidic catalyst is preferably 10 - 40 min, more preferably 20 - 30 min, and even more preferably 25 min; the mixing time of the aldehyde monomer with the mixed solution is preferably 10 min.

[0040] In the present invention, the polyacrylonitrile-itaconic acid fiber felt is preferably prepared by the following steps: under a nitrogen atmosphere, acrylonitrile, itaconic acid, an initiator, and a solvent are mixed, and the mixed solution undergoes a polymerization reaction to obtain an acrylonitrile copolymer; the acrylonitrile copolymer is sequentially filtered and degassed to obtain a spinning dope; the spinning dope is sequentially subjected to dry-jet wet spinning, drawing, oiling, drying densification, hot steam drawing, and heat setting to obtain polyacrylonitrile-itaconic acid fibers, and then the fibers are needled to obtain the polyacrylonitrile-itaconic acid fiber felt.

[0041] In the present invention, the mass ratio of acrylonitrile to itaconic acid is preferably 97 - 99:2, more preferably 98:2; in the mixed solution, the total mass concentration of acrylonitrile and itaconic acid is preferably 23 - 28%, more preferably 24 - 26%, and even more preferably 25%, and the mass concentration of the initiator is preferably 0.7 - 0.9%, more preferably 0.8%; the initiator is preferably azobisisobutyronitrile.

[0042] In the present invention, the temperature of the polymerization reaction is preferably 50 - 70 °C, more preferably 55 - 65 °C, and even more preferably 60 °C, and the time of the polymerization reaction is preferably 11 - 13 h, more preferably 12 h.

[0043] In the present invention, itaconic acid is used as the second comonomer.

[0044] In the present invention, the atmospheric pressure impregnation in step 2) is carried out at room temperature, and the time of the atmospheric pressure impregnation is preferably 8 - 12 min, more preferably 9 - 11 min, and even more preferably 10 min.

[0045] In the present invention, the temperature of the sol-gel reaction in step 2) is preferably 60-70 °C, more preferably 62-67 °C, and still more preferably 65 °C. The time of the sol-gel reaction is preferably 11-13 h, more preferably 12 h.

[0046] In the present invention, the sol-gel reaction is preferably carried out in a closed mold.

[0047] In the present invention, the temperature of the atmospheric drying in step 3) is preferably 90-120 °C, more preferably 95-110 °C, and still more preferably 100-105 °C. The time of the atmospheric drying is preferably 10-18 h, more preferably 11-15 h, and still more preferably 12 h.

[0048] In the present invention, the temperature of the carbonization reaction in step 3) is preferably 800-1400 °C, more preferably 1000-1300 °C, and still more preferably 1100-1200 °C. The time of the carbonization reaction is preferably 2 h. The heating rate from room temperature to the carbonization reaction temperature is preferably 3-5 °C / min, more preferably 3.5-4.5 °C / min, and still more preferably 4 °C / min. The carbonization reaction is preferably carried out under a nitrogen atmosphere.

[0049] The present invention also provides a polyacrylonitrile-itaconic acid fiber felt reinforced carbon aerogel composite material prepared by the preparation method of the polyacrylonitrile-itaconic acid fiber felt reinforced carbon aerogel composite material.

[0050] In the present invention, the density of the polyacrylonitrile-itaconic acid fiber felt reinforced carbon aerogel composite material is 0.13-0.16 g / cm 3 , the specific surface area is 1662-1942 m 2 / g, the room temperature thermal conductivity is 0.017-0.049 W / m·K, and the compressive strength is 2.17-4.03 MPa.

[0051] The present invention also provides an application of the polyacrylonitrile-itaconic acid fiber felt reinforced carbon aerogel composite material, and the application of the polyacrylonitrile-itaconic acid fiber felt reinforced carbon aerogel composite material in thermal insulation, adsorption and electromagnetic shielding.

[0052] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0053] In the example, the preparation process of the polyacrylonitrile-itaconic acid fiber felt is as follows: acrylonitrile, itaconic acid, an initiator (azobisisobutyronitrile), and dimethyl sulfoxide are mixed, and the mixed solution is subjected to a polymerization reaction at 60 °C for 12 h to obtain an acrylonitrile copolymer. In the mixed solution, the total mass concentration of acrylonitrile and itaconic acid is 25%, the mass concentration of the initiator is 0.8%, and the mass ratio of acrylonitrile to itaconic acid is 98:2; the acrylonitrile copolymer is sequentially filtered and degassed to obtain a spinning dope; the spinning dope is sequentially subjected to dry-jet wet spinning, drawing, oiling, drying and densification, hot steam drawing, and heat setting to obtain polyacrylonitrile-itaconic acid fibers, and the polyacrylonitrile-itaconic acid fiber felt is obtained by needling; the polyacrylonitrile-itaconic acid fiber felt is washed with deionized water and then placed in an oven and dried at 60 °C for 12 h.

[0054] Example 1

[0055] Phenol, absolute ethanol, and hydrochloric acid (hydrogen chloride concentration of 1 mol / L) are stirred at 30 °C and a rotation speed of 300 rpm for 10 min to obtain a uniform mixed solution; the mixed solution and formaldehyde are mixed and stirred at 30 °C and a rotation speed of 300 rpm for 10 min to obtain a uniform prepolymer solution; among them, the molar ratio of phenol, formaldehyde, hydrogen chloride in hydrochloric acid, and absolute ethanol is 1:2.0:3.6:43.

[0056] The dried polyacrylonitrile-itaconic acid fiber felt is uniformly impregnated in the prepolymer solution at normal pressure and room temperature for 10 min, and then a sol-gel reaction is carried out in a sealed crystallization dish (diameter of 90 mm) at 60 °C for 12 h to obtain a precursor of the polyacrylonitrile-itaconic acid fiber felt reinforced carbon aerogel composite.

[0057] The composite precursor is dried at normal pressure at 100 °C for 12 h to obtain an xerogel; the xerogel is subjected to a carbonization reaction in a high-purity nitrogen atmosphere, heated from room temperature to 800 °C at a rate of 5 °C / min, and carbonized at 800 °C for 2 h to obtain the polyacrylonitrile-itaconic acid fiber felt reinforced carbon aerogel composite.

[0058] The density of the polyacrylonitrile-itaconic acid fiber felt reinforced carbon aerogel composite prepared in Example 1 is 0.13 g / cm 3 , and the specific surface area is 1942 m 2 / g, the thermal conductivity at room temperature is 0.017 W / m·K, the thermal conductivity at 1500 °C is 0.05 W / m·K, the compressive strength is 4.03 MPa, and the compression modulus is 6.72 MPa.

[0059] Example 2

[0060] Cresol, n-propanol and salicylic acid were stirred at 40 °C and 350 rpm for 30 min to obtain a homogeneous mixture; the mixture and glutaraldehyde were mixed and stirred at 40 °C and 350 rpm for 10 min to obtain a homogeneous prepolymer solution; wherein, the molar ratio of cresol, glutaraldehyde, salicylic acid and n-propanol was 1:2.4:4.3:42.

[0061] The dried polyacrylonitrile-itaconic acid fiber felt was evenly impregnated in the prepolymer solution at normal pressure and room temperature for 10 min, and then a sol-gel reaction was carried out in a sealed crystallization dish (diameter 90 mm) at 70 °C for 11 h to obtain a precursor of polyacrylonitrile-itaconic acid fiber felt reinforced carbon aerogel composite.

[0062] The composite precursor was dried at normal pressure at 110 °C for 11 h to obtain a xerogel; the xerogel was subjected to a carbonization reaction in a high-purity nitrogen atmosphere, heated from room temperature to 1000 °C at a rate of 3 °C / min, and carbonized at 1000 °C for 2 h to obtain a polyacrylonitrile-itaconic acid fiber felt reinforced carbon aerogel composite.

[0063] The density of the polyacrylonitrile-itaconic acid fiber felt reinforced carbon aerogel composite prepared in Example 2 was 0.15 g / cm 3 , and the specific surface area was 1777 m 2 / g, the thermal conductivity at room temperature was 0.022 W / m·K, the compressive strength was 2.17 MPa, and the compressive modulus was 3.62 MPa.

[0064] Example 3

[0065] Bisphenol A, n-butanol and m-hydroxybenzoic acid were stirred at 50 °C and 300 rpm for 40 min to obtain a homogeneous mixture; the mixture and furfural were mixed and stirred at 50 °C and 400 rpm for 10 min to obtain a homogeneous prepolymer solution; wherein, the molar ratio of bisphenol A, furfural, m-hydroxybenzoic acid and n-butanol was 1:2.5:5:40.

[0066] The dried polyacrylonitrile-itaconic acid fiber felt was evenly impregnated in the prepolymer solution at normal pressure and room temperature for 10 min, and then a sol-gel reaction was carried out in a sealed crystallization dish (diameter 90 mm) at 70 °C for 11 h to obtain a precursor of polyacrylonitrile-itaconic acid fiber felt reinforced carbon aerogel composite.

[0067] The composite precursor was dried at normal pressure at 90 °C for 18 h to obtain a xerogel; the xerogel was subjected to a carbonization reaction in a high-purity nitrogen atmosphere, heated from room temperature to 1200 °C at a rate of 5 °C / min, and carbonized at 1200 °C for 2 h to obtain a polyacrylonitrile-itaconic acid fiber felt reinforced carbon aerogel composite.

[0068] The density of the polyacrylonitrile-itaconic acid fiber felt reinforced carbon aerogel composite prepared in Example 3 is 0.14 g / cm 3 , the specific surface area is 1801 m 2 / g, the thermal conductivity at room temperature is 0.024 W / m·K, the compressive strength is 3 MPa, and the compression modulus is 5 MPa.

[0069] Example 4

[0070] Butylphenol, isopropanol and gallic acid were stirred at 40 °C and 450 rpm for 25 min to obtain a homogeneous mixture; the mixture and paraformaldehyde were mixed and stirred at 40 °C and 400 rpm for 10 min to obtain a homogeneous prepolymer solution; among them, the molar ratio of butylphenol, paraformaldehyde, gallic acid and isopropanol is 1:2.2:4.5:45.

[0071] The dried polyacrylonitrile-itaconic acid fiber felt was uniformly impregnated in the prepolymer solution at normal pressure and room temperature for 10 min, and then a sol-gel reaction was carried out in a sealed crystallization dish (90 mm in diameter) at 65 °C for 13 h to obtain a precursor of the polyacrylonitrile-itaconic acid fiber felt reinforced carbon aerogel composite.

[0072] The composite precursor was dried at normal pressure at 120 °C for 10 h to obtain an xerogel; the xerogel was carbonized in a high-purity nitrogen atmosphere, heated from room temperature to 1400 °C at a rate of 5 °C / min, and carbonized at 1400 °C for 2 h to obtain the polyacrylonitrile-itaconic acid fiber felt reinforced carbon aerogel composite.

[0073] The density of the polyacrylonitrile-itaconic acid fiber felt reinforced carbon aerogel composite prepared in Example 4 is 0.16 g / cm 3 , the specific surface area is 1705 m 2 / g, the thermal conductivity at room temperature is 0.039 W / m·K, the compressive strength is 2.69 MPa, and the compression modulus is 4.49 MPa.

[0074] Example 5

[0075] 2-Aminophenol, n-butanol and m-hydroxybenzoic acid were stirred at 40 °C and 350 rpm for 30 min to obtain a homogeneous mixture; the mixture and formaldehyde were mixed and stirred at 40 °C and 350 rpm for 10 min to obtain a homogeneous prepolymer solution; among them, the molar ratio of 2-aminophenol, formaldehyde, m-hydroxybenzoic acid and n-butanol is 1:2.4:4.5:42.

[0076] The dried polyacrylonitrile-itaconic acid fiber felt was evenly impregnated in the prepolymer solution at normal pressure and room temperature for 10 min, and then a sol-gel reaction was carried out in a sealed crystallization dish (with a diameter of 90 mm) at 65 °C for 12 h to obtain a precursor of polyacrylonitrile-itaconic acid fiber felt reinforced carbon aerogel composite material.

[0077] The composite material precursor was dried at normal pressure at 100 °C for 12 h to obtain an xerogel; the xerogel was subjected to a carbonization reaction under a high-purity nitrogen atmosphere, heated from room temperature to 1000 °C at a rate of 3 °C / min, and carbonized at 1000 °C for 2 h to obtain a polyacrylonitrile-itaconic acid fiber felt reinforced carbon aerogel composite material.

[0078] The density of the polyacrylonitrile-itaconic acid fiber felt reinforced carbon aerogel composite material prepared in Example 5 was 0.14 g / cm 3 , and the specific surface area was 1662 m 2 / g, the room temperature thermal conductivity was 0.049 W / m·K, the compressive strength was 3.42 MPa, and the compression modulus was 5.7 MPa.

[0079] Comparative Example 1

[0080] Phenol, absolute ethanol, and hydrochloric acid (hydrogen chloride concentration: 1 mol / L) were stirred at 30 °C and 300 rpm for 10 min to obtain a uniform mixture; the mixture and formaldehyde were mixed and stirred at 50 °C and 300 rpm for 15 min to obtain a uniform prepolymer solution; among them, the molar ratio of phenol, formaldehyde, hydrogen chloride in hydrochloric acid, and absolute ethanol was 1:2.0:3.6:43.

[0081] The uniform prepolymer solution was placed in a sealed crystallization dish (with a diameter of 90 mm) at 60 °C for a sol-gel reaction for 12 h to obtain a precursor of phenolic aerogel material.

[0082] The precursor of phenolic aerogel material was dried at normal pressure at 100 °C for 12 h to obtain an xerogel; the xerogel was subjected to a carbonization reaction under a high-purity nitrogen atmosphere, heated from room temperature to 800 °C at a rate of 5 °C / min, and carbonized at 800 °C for 2 h to obtain a carbon aerogel material.

[0083] The density of the carbon aerogel material prepared in Comparative Example 1 was 0.083 g / cm 3 , and the specific surface area was 912 m 2 / g, the room temperature thermal conductivity was 0.063 W / m·K, the thermal conductivity at 1500 °C was 0.092 W / m·K, the compressive strength was 0.06 MPa, and the compression modulus was 0.10 MPa.

[0084] As can be seen from Examples 1 to 5 and Comparative Example 1, the polyacrylonitrile-itaconic acid fiber felt reinforced carbon aerogel composite material of the present invention has low thermal conductivity, high specific surface area, relatively high compressive strength and compressive modulus. The polyacrylonitrile-itaconic acid fiber felt reinforced carbon aerogel composite material of the present invention has excellent mechanical properties and heat insulation properties.

[0085] The performance test was carried out on the polyacrylonitrile-itaconic acid fiber felt reinforced carbon aerogel composite material prepared in Example 1. The nitrogen adsorption test chart of the polyacrylonitrile-itaconic acid fiber felt reinforced carbon aerogel composite material prepared in Example 1 is as Figure 1 shown. From Figure 1 it can be seen that the adsorption curve is a typical Type IV adsorption isotherm, indicating that the polyacrylonitrile-itaconic acid fiber felt reinforced carbon aerogel composite material has a rich mesoporous and microporous structure; the SEM chart of the polyacrylonitrile-itaconic acid fiber felt reinforced carbon aerogel composite material prepared in Example 1 is as Figure 2 shown. From Figure 2 it can be seen that the polyacrylonitrile-itaconic acid fiber felt reinforced carbon aerogel composite material prepared in Example 1 has carbon fibers with a hollow structure and a rich pore structure; the X-ray diffraction spectrum chart of the polyacrylonitrile-itaconic acid fiber felt reinforced carbon aerogel composite material prepared in Example 1 is as Figure 3 shown. From Figure 3 it can be seen that obvious carbon diffraction peaks appear between 20° and 30° in the polyacrylonitrile-itaconic acid fiber felt reinforced carbon aerogel composite material prepared in Example 1; the Raman spectrum chart of the polyacrylonitrile-itaconic acid fiber felt reinforced carbon aerogel composite material prepared in Example 1 is as Figure 4 shown. From Figure 4 it can be seen that obvious sp -1 and sp -1 hybrid carbon types appear near 1400 cm 2 and 1600 cm 3 . I D / I G <1, indicating a relatively high degree of graphitization; the compressive stress-strain curve chart of the polyacrylonitrile-itaconic acid fiber felt reinforced carbon aerogel composite material prepared in Example 1 is as Figure 5 shown. From Figure 5 it can be seen that the polyacrylonitrile-itaconic acid fiber felt reinforced carbon aerogel composite material prepared in Example 1 has good compression resistance.

[0086] The above is only the preferred implementation manner of the present invention. It should be pointed out that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A method for preparing a polyacrylonitrile-itaconic acid fiber felt reinforced carbon aerogel composite material, characterized in that: The following steps are included: 1) Mixing phenol monomer, aldehyde monomer, alcohol solvent and acid catalyst to obtain a prepolymerization solution; 2) impregnating polyacrylonitrile-itaconic acid fiber felt in a prepolymerization solution at normal pressure and then performing a sol-gel reaction to obtain a composite material precursor; 3) drying and carbonizing the composite material precursor in sequence at normal pressure to obtain a polyacrylonitrile-itaconic acid fiber felt reinforced carbon aerogel composite material; The acidic catalyst comprises one or more of hydrochloric acid, salicylic acid, m-hydroxybenzoic acid and gallic acid; The phenolic monomers include one or more of phenol, resorcinol, aminophenol, butylphenol and bisphenol A; the aldehyde monomers include one or more of glutaraldehyde, paraformaldehyde and furfural; the alcohol solvents include one or more of anhydrous ethanol, n-propanol, isopropanol and n-butanol; Step 1) the molar ratio of the phenolic monomer, the aldehyde monomer, the acidic catalyst and the alcohol solvent is 1:2.0-2.5:3.6-5.0:40-45; The polyacrylonitrile-itaconic acid fiber felt is prepared by the following steps: acrylonitrile, itaconic acid, an initiator and a solvent are polymerized to obtain an acrylonitrile copolymer, and the acrylonitrile copolymer is sequentially subjected to dry-jet wet spinning and needle punching to obtain the polyacrylonitrile-itaconic acid fiber felt; the mass ratio of acrylonitrile to itaconic acid is 97-99:2; Step 3) The temperature of the atmospheric pressure drying is 90-120° C., and the time of the atmospheric pressure drying is 10-18 hours.

2. The method for preparing the polyacrylonitrile-itaconic acid fiber felt reinforced carbon aerogel composite material according to claim 1, characterized in that: Step 1) The mixing speed is 300-450 rpm, and the mixing temperature is 30-50°C.

3. The method for preparing the polyacrylonitrile-itaconic acid fiber felt reinforced carbon aerogel composite material according to claim 1, characterized in that: Step 2) The temperature of the sol-gel reaction is 60-70° C., and the time of the sol-gel reaction is 11-13 hours.

4. The method for preparing the polyacrylonitrile-itaconic acid fiber felt reinforced carbon aerogel composite material according to claim 1 or 3, characterized in that: Step 3) The temperature of the carbonization reaction is 800-1400°C, the time of the carbonization reaction is 2h, and the heating rate from room temperature to the carbonization reaction temperature is 3-5°C / min; the carbonization reaction is carried out under a nitrogen atmosphere.

5. The polyacrylonitrile-itaconic acid fiber felt reinforced carbon aerogel composite material prepared by the method for preparing the polyacrylonitrile-itaconic acid fiber felt reinforced carbon aerogel composite material according to any one of claims 1 to 4, characterized in that: The density of the polyacrylonitrile-itaconic acid fiber felt reinforced carbon aerogel composite material is 0.13-0.16 g / cm 3 , the specific surface area is 1662~1942m 2 / g, thermal conductivity at room temperature is 0.017~0.049W / m·K ， The compression strength is 2.17~4.03MPa.

6. The use of the polyacrylonitrile-itaconic acid fiber felt reinforced carbon aerogel composite material according to claim 5, characterized in that: The polyacrylonitrile-itaconic acid fiber felt reinforced carbon aerogel composite material is used in thermal insulation, adsorption and electromagnetic shielding.

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