Chitosan heat-insulating and flame-retardant gas gel and preparation method thereof

Abstract

The present invention discloses a chitosan heat-insulating, flame-retardant gas gel and a preparation method thereof, relating to the technical field of aerogel preparation. The method comprises subjecting polyacrylonitrile fibers to amidoximation modification to obtain amidoxime-based polyacrylonitrile fibers; preparing a single layer of montmorillonite; adding chitosan and the single layer of montmorillonite to an acidic reagent, and after the chitosan is fully dissolved, adding amidoxime-based polyacrylonitrile fibers, silica nanofibers, and a crosslinking agent, stirring to obtain a mixed solution; and freeze-drying the mixed solution to obtain the chitosan heat-insulating, flame-retardant gas gel. The method enhances the mechanical strength of the aerogel while simultaneously crosslinking the chitosan and amidoxime-based polyacrylonitrile fibers with each other, as well as physically crosslinking the montmorillonite and chitosan.

Description

Technical Field

[0001] The invention relates to a chitosan heat-insulating and fire-resistant gas gel and a preparation method thereof, belonging to the technical field of aerogel preparation. Background Art

[0002] Chitosan is an alkaline natural polysaccharide containing a large number of polar functional groups such as hydroxyl groups, amino groups, and anhydride bonds, as well as lone pairs of electrons. It is a common biomass material.

[0003] Aerogels made from chitosan offer advantages such as low density, high porosity, flexibility, elasticity, and flame retardancy. Furthermore, choosing chitosan as an aerogel material is highly consistent with future energy-saving and environmentally friendly flame-retardant aerogel materials. However, the low mechanical strength of chitosan aerogels has limited practical applications.

[0004] The optimization of the mechanical properties and flame retardant and thermal insulation properties of chitosan-based aerogels is of great research value, but there are still certain challenges. Studies have shown that hybridizing chitosan with phenolic resin and introducing polyurethane porous sponge can effectively improve the mechanical properties of aerogels, but at the same time it will lead to an increase in the heat release rate. In addition, the use of nanosilver and cross-linking agents to enhance chitosan aerogels can improve their mechanical strength and biodegradability, but due to the formation of a macroporous structure, it has a certain impact on the thermal insulation performance. Therefore, it is of great significance to develop a new method that can improve the mechanical strength of chitosan aerogels without affecting their flame retardant and thermal insulation properties, but it still faces great challenges.

[0005] Montmorillonite, a layered silicate mineral with a unique layered structure and interlayer ion exchange properties, also possesses excellent thermal stability, flame retardancy, and mechanical properties. Therefore, it is often used as a clay-based flame retardant, eliminating the need for large amounts of fillers and finding widespread application in flame retardant systems. However, the introduction of montmorillonite into chitosan aerogel systems can increase the fluidity of the sol-gel system, making it difficult to solidify, ultimately impacting the structural integrity and mechanical properties of the material. Summary of the Invention

[0006] The purpose of the present invention is to overcome the deficiencies in the prior art and provide a chitosan thermal insulation and flame retardant gas gel and a preparation method thereof. By crosslinking chitosan and amidoxime-based polyacrylonitrile fibers individually and simultaneously with each other, as well as physically crosslinking montmorillonite and chitosan, the mechanical strength of the aerogel is enhanced while improving its thermal insulation and flame retardant efficiency.

[0007] To achieve the above object, the present invention is implemented by adopting the following technical solutions:

[0008] In one aspect, the present invention provides a method for preparing a chitosan heat-insulating, flame-retardant, gas-fired gel, comprising:

[0009] The polyacrylonitrile fiber is modified by amidoximation to obtain amidoxime-based polyacrylonitrile fiber;

[0010] Preparation of single-layer montmorillonite;

[0011] Chitosan and monolayer montmorillonite are added to an acidic reagent, and after the chitosan is fully dissolved, amidoxime-based polyacrylonitrile fiber, silica nanofiber and a cross-linking agent are added, and the mixture is stirred to obtain a mixed solution;

[0012] The mixed solution is freeze-dried to obtain the chitosan heat-insulating and fire-resistant gel.

[0013] Furthermore, the polyacrylonitrile fiber is subjected to amidoximation modification to obtain amidoxime-based polyacrylonitrile fiber, comprising:

[0014] The polyacrylonitrile fiber is added into a hydroxylamine hydrochloride solution for heating reaction. After the reaction is completed, the polyacrylonitrile fiber is taken out, washed multiple times, and dried to obtain the amidoxime-based polyacrylonitrile fiber.

[0015] Furthermore, at least one of the following conditions must be met:

[0016] The concentration of the hydroxylamine hydrochloride solution is 0.5-0.6 mol / L;

[0017] The heating temperature range is 65~75℃;

[0018] The reaction time is 2 to 2.5 hours;

[0019] The drying temperature is 60-70°C.

[0020] Furthermore, the amidoxime group conversion rate in the amidoxime modification of the polyacrylonitrile fiber is 20-30%.

[0021] Furthermore, the preparation method of the single-layer montmorillonite includes:

[0022] Montmorillonite was added into water, stirred and ultrasonicated, and the supernatant was collected after centrifugation to obtain a monolayer montmorillonite dispersion;

[0023] The single-layer montmorillonite dispersion is freeze-dried to obtain the single-layer montmorillonite.

[0024] Furthermore, the single-layer stripping efficiency of the method for preparing the single-layer montmorillonite dispersion is 40-50%.

[0025] Furthermore, the stirring time is 12-24 hours; and / or the ultrasonic time is 30-40 minutes; and / or the centrifugal speed range is 5000-7000 rpm; and / or the concentration of the monolayer montmorillonite dispersion is 4-5 g / L.

[0026] Furthermore, the mass ratio of the chitosan to the monolayer montmorillonite is 6:(1-6); and / or the mass ratio of the amidoxime-based polyacrylonitrile fiber to the silica nanofiber is 10:(1-6).

[0027] Furthermore, at least one of the following conditions must be met:

[0028] The pH range of the acidic reagent is 3 to 4;

[0029] The acidic reagent is one or more of formic acid, hydrochloric acid, and acetic acid;

[0030] The cross-linking agent is an aldehyde-containing cross-linking agent;

[0031] The stirring time is until the fibers are evenly dispersed and the cross-linking reaction is complete;

[0032] The freeze-drying condition parameters include freezing at -70~-65°C for 4~5 hours and then freeze-drying for 36~48 hours.

[0033] On the other hand, the present invention also provides a chitosan thermal insulation and flame retardant gas gel, which is prepared by the preparation method of the chitosan thermal insulation and flame retardant gas gel as described in any of the above items, and the limiting oxygen index of the chitosan thermal insulation and flame retardant gas gel is 50-65%.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] The present invention modifies polyacrylonitrile fibers by amidoxime treatment. In a hydroxylamine hydrochloride solution, the C≡N groups on the surface of the polyacrylonitrile fibers are converted to C-NH2 groups. The C-NH2 groups facilitate crosslinking between the amidoxime-based polyacrylonitrile fibers (AOPAN) and chitosan. Silica nanofibers have the advantages of flexibility, fire resistance, low density, and low thermal conductivity. When blended with chitosan in a reaction solution, they can effectively improve the mechanical strength of the aerogel while further enhancing its flame retardancy. Montmorillonite flakes carry a negative charge, and under acidic conditions, the amino groups of chitosan can be partially protonated. The effective combination of the positively charged chitosan and the negatively charged montmorillonite gives the composite aerogel a complete block structure. The combination of montmorillonite and chitosan synergistically enhances the compression properties of the aerogel. The montmorillonite flakes also provide the aerogel with excellent flame retardancy.

[0036] The present invention also adds a cross-linking agent containing an aldehyde group. The aldehyde group in the cross-linking agent reacts with the amino group of chitosan and the C-NH2 group of the amidoxime-based polyacrylonitrile fiber to produce a Schiff base reaction, thereby generating a strongly cross-linked interpenetrating network structure between chitosan and chitosan, AOPAN and AOPAN, and chitosan and AOPAN. The chitosan and montmorillonite are physically cross-linked and coated on the surface of the interpenetrating network structure, making the aerogel extremely mechanically strong.

[0037] The chitosan, montmorillonite, polyacrylonitrile fiber and silicon dioxide nanofiber used in the present invention are all cheap and readily available materials, and the preparation method of the aerogel is simple, and has high practical application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 Schematic diagrams of scanning electron micrographs of aerogels prepared in Example 1 and Comparative Example 1 of the present invention, wherein the aerogel prepared in Comparative Example 1 is shown without the addition of montmorillonite, and the aerogel prepared in Example 1 is shown with the addition of montmorillonite;

[0039] Figure 2 Schematic diagram of scanning electron microscopy of aerogels prepared in Example 1, Comparative Example 1, Example 2 and Comparative Example 2 of the present invention;

[0040] Figure 3 Schematic diagram comparing the compressive strain-stress curves of the aerogels prepared in Example 1 of the present invention and Comparative Example 1;

[0041] Figure 4 Schematic diagram comparing the combustion heat release rate curves of the aerogels prepared in Example 1 of the present invention and Comparative Example 1;

[0042] Figure 5 Schematic diagram comparing total heat release curves of aerogels prepared in Example 1 of the present invention and Comparative Example 1;

[0043] Figure 6 Schematic diagram comparing the thermal insulation effects of aerogels prepared in Example 1 of the present invention and Comparative Example 1;

[0044] Figure 7 Schematic diagram comparing the thermal conductivity of aerogels prepared in Example 1, Comparative Example 1 and Comparative Example 3 of the present invention. DETAILED DESCRIPTION

[0045] The present invention will be further described below in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention.

[0046] Example 1

[0047] The present invention provides a method for preparing a chitosan heat-insulating and flame-retardant gas gel, comprising the following steps:

[0048] (1) 1 g of polyacrylonitrile (PAN) fiber was placed in 500 mL of hydroxylamine hydrochloride solution (0.5 mol / L) and treated at 65 °C for 2 h. After the reaction was completed, the fiber was washed with distilled water several times to remove the residual hydroxylamine hydrochloride, and then dried in an oven at 60 °C to obtain amidoxime-based polyacrylonitrile fiber (AOPAN fiber) with an amidoxime group conversion rate of 25%.

[0049] (2) 1 g of montmorillonite was placed in 100 mL of water and stirred for 24 h, ultrasonicated for 30 min, and centrifuged at 5000 rpm for 20 min. The supernatant was taken to obtain a monolayer montmorillonite dispersion. The monolayer montmorillonite dispersion was first frozen at -67°C for 4 h and then freeze-dried for 24 h to obtain a dry monolayer montmorillonite. The monolayer stripping efficiency of the monolayer montmorillonite dispersion in the preparation method of this embodiment was about 45%. The calculation method of the monolayer stripping efficiency was as follows: the mass of the dry monolayer montmorillonite / the mass of the montmorillonite initially added.

[0050] (3) Chitosan and monolayer montmorillonite were added to 100 mL of hydrochloric acid solution with a pH of 4. The mass ratio of chitosan to monolayer montmorillonite was 1:1. After the chitosan was fully dissolved, amino oxime-based polyacrylonitrile fiber and silica nanofiber were added. The mass ratio of amino oxime-based polyacrylonitrile fiber to silica nanofiber was 5:1. Glutaraldehyde was added at the same time and stirred for 3 h until the fibers were evenly dispersed and the cross-linking reaction was complete.

[0051] (4) The evenly dispersed mixed liquid was poured into a mold, frozen at -70 °C for 4 h, and freeze-dried in a freeze dryer for 36 h to obtain chitosan heat-insulating and flame-retardant gas gel.

[0052] Example 2

[0053] (1) 1.2 g of polyacrylonitrile (PAN) fiber was placed in 600 mL of hydroxylamine hydrochloride solution (0.55 mol / L) and treated at 70 °C for 2.5 h. After the reaction was completed, the fiber was washed with distilled water several times to remove the residual hydroxylamine hydrochloride, and then dried in an oven at 60 °C to obtain amidoxime-based polyacrylonitrile fiber (AOPAN fiber) with an amidoxime group conversion rate of 28%.

[0054] (2) 1.5 g of montmorillonite was placed in 200 mL of water and stirred for 24 h, ultrasonicated for 40 min, and centrifuged at 6000 rpm for 15 min. The supernatant was taken to obtain a monolayer montmorillonite dispersion. The monolayer montmorillonite dispersion was first frozen at -67°C for 4 h and then freeze-dried for 24 h to obtain a dry monolayer montmorillonite. The monolayer stripping efficiency of the monolayer montmorillonite dispersion in the preparation method of this embodiment was approximately 47%.

[0055] (3) Chitosan and monolayer montmorillonite were added to 100 mL of hydrochloric acid solution with a pH of 3.5. The mass ratio of chitosan to monolayer montmorillonite was 1:1. After the chitosan was fully dissolved, amine oxime-based polyacrylonitrile fiber and silica nanofiber were added. The mass ratio of amine oxime-based polyacrylonitrile fiber to silica nanofiber was 5:2. Glutaraldehyde was added at the same time and stirred for 3 h until the fibers were evenly dispersed and the cross-linking reaction was complete.

[0056] (4) The evenly dispersed mixed liquid was poured into a mold, frozen at -68°C for 4.5 h, and freeze-dried in a freeze dryer for 45 h to obtain chitosan heat-insulating and flame-retardant gas gel.

[0057] Comparative Example 1:

[0058] The only difference between this comparative example and Example 1 is that no montmorillonite is added, that is, step (2) is deleted, and no single layer of montmorillonite is added in step (3), and chitosan aerogel is prepared.

[0059] Comparative Example 2:

[0060] The only difference between this comparative example and Example 1 is that the mass ratio of amidoxime-based polyacrylonitrile fiber to silica nanofiber is 5:2, and chitosan heat-insulating and flame-resistant gas gel is prepared.

[0061] Comparative Example 3:

[0062] (1) 1.2 g of polyacrylonitrile (PAN) fiber was placed in 600 mL of hydroxylamine hydrochloride solution (0.55 mol / L) and treated at 70 °C for 2.5 h. After the reaction was completed, the fiber was washed with distilled water several times to remove the residual hydroxylamine hydrochloride, and then dried in an oven at 60 °C to obtain amidoxime-based polyacrylonitrile fiber (AOPAN fiber) with an amidoxime group conversion rate of 28%.

[0063] (2) The mass ratio of amine oxime-based polyacrylonitrile fiber and silica nanofiber is 5:2. Glutaraldehyde is added at the same time and stirred for 3 h until the fibers are evenly dispersed and the cross-linking reaction is complete.

[0064] (3) The evenly dispersed mixed liquid was poured into a mold, frozen at -68 °C for 4.5 h, and freeze-dried in a freeze dryer for 45 h to obtain a fiber aerogel without adding chitosan and montmorillonite.

[0065] The scanning electron microscope images of the aerogels prepared in Example 1 and Comparative Example 1 are as follows: Figure 1 As shown, the surfaces of Comparative Example 1 and Example 1 both have relatively uniform porous structures. In Example 1, due to the addition of montmorillonite, the pore size is significantly reduced, but the pore wall is more complete.

[0066] Next, the scanning electron microscope images of the aerogels prepared in Example 1, Comparative Example 1, Example 2 and Comparative Example 2 are shown in FIG. Figure 2 As shown. As can be seen from the figure, the silica nanofibers in Example 1, Comparative Example 1, Example 2 and Comparative Example 2 all form a supporting skeleton on the internal pore wall of the aerogel. In Comparative Example 1, it can be seen that the pore wall of the aerogel is formed by cross-linking AOPAN fibers and chitosan to form a uniform interpenetrating network structure, and the surface of the interpenetrating network structure is coated with chitosan. Since Comparative Example 1 does not add montmorillonite, there is an obvious macroporous structure on the surface, and there is also an obvious macroporous structure between the fibers, and there are only a small amount of adhered objects on the fiber surface. After adding montmorillonite, the pore size between the fibers on the surface of Example 1 becomes smaller. This is because the fibers are coated with chitosan and montmorillonite. The effective combination of chitosan and montmorillonite assembled on the aerogel skeleton formed by amine oxime-based polyacrylonitrile fibers and silica nanofibers makes the aerogel have a complete block structure.

[0067] Then, the aerogel sample was subjected to compression test on a universal testing machine (Instron 5967). The cylindrical specimen (r = 30 mm, h = 10 mm) was compressed to 80% strain at a compression rate of 40 mm / min. Figure 3 As shown in the figure, the addition of montmorillonite increases the sample strength. Comparative Example 1 has a strength of 118 kPa at 80% compressive strain, while Example 1 has a strength of 428 kPa at 80% compressive strain. Compared to Comparative Example 1 without montmorillonite (MMT), Example 1 has a strength of 362.71% that of Comparative Example 1.

[0068] The reason for the above performance differences is that the effective combination of chitosan and montmorillonite is due to the fact that chitosan carries a positive charge in an acidic environment, while montmorillonite carries a negative charge in an acidic environment. Chitosan and montmorillonite can be combined together through the force of positive and negative charges and deposited on the surface of the fiber skeleton with an interpenetrating network structure, increasing the mechanical strength of the aerogel while blocking the internal pores of the aerogel. The fibers on the aerogel pore walls are almost completely coated by chitosan and montmorillonite, thereby affecting the internal pore size of the aerogel and causing the porous structure between the fibers on the pore walls to disappear. In Example 2 and Comparative Example 2, due to the increase in the amount of fiber added, a small amount of fiber emerged, and the fibers exposed on the surface may pose a risk of flame combustion.

[0069] The properties of the aerogels prepared in Example 1 and Comparative Example 1 are analyzed in detail below;

[0070] First, the combustion performance of the chitosan aerogels prepared in Example 1 and Comparative Example 1 was tested using a cone calorimeter (6810 Yangyi, using standard ISO 5660-1 (2015), sample size 100 mm×100 mm×5 mm).

[0071] The results are as follows Figure 4 and Figure 5 As shown in the figure, after adding montmorillonite, the heat release values ​​of Example 1 are lower than those of Comparative Example 1, and the flame retardant performance is significantly improved. Heat release rate and total heat release are key parameters for fire risk assessment. Figure 4 It can be observed from the heat release rate curve that the heat release rate of comparative example 1 is 20.7 kW / m 2 The heat release rate of Example 1 is 15.4kW / m 2 , decreased by 25.6%. Figure 5 It can be seen that the total heat release value of Comparative Example 1 is 1.4 MJ / m 2 The total heat release value of Example 1 is 0.99 MJ / m 2 , which decreased by 29.28%. These reductions in heat release performance indicate that the addition of montmorillonite can effectively prevent heat transfer and have a significant inhibitory effect on the combustion process of aerogels.

[0072] The principle behind these test results is that as the amount of montmorillonite added increases, chitosan aerogel rapidly undergoes a carbonization reaction when exposed to fire, driven by the synergistic effect of the montmorillonite nanosheets. The chitosan carbonization products bond the montmorillonite nanosheets together, imparting excellent airtightness to the nanolayer on the surface of the aerogel skeleton. After the addition of montmorillonite, the layered silicate structure becomes impermeable to gas molecules, creating a physical barrier to their diffusion within the composite material. This effectively isolates the gas, forming a flame-retardant coating on the fiber surface, isolating it from flames and significantly promoting char formation. Consequently, the pyrolysis gases from the chitosan cannot escape from the protective layer formed by the chitosan carbonization products bonding the montmorillonite nanosheets together, effectively shielding the fiber skeleton from the effects of heat and oxygen.

[0073] Next, the chitosan aerogels prepared in Example 1 and Comparative Example 1 were subjected to thermal insulation tests. The test method is as follows:

[0074] The chitosan aerogels prepared in Example 1 and Comparative Example 1 were placed on a heating platform (Bangyuan-BY1515 intelligent constant temperature heating platform) and set at 100°C. The surface temperatures of Example 1 and Comparative Example 1 were tested using an infrared thermal imager (Hikvision Micro-Image H21Pro thermal imager).

[0075] Thermal insulation test results are as follows Figure 6 As shown in the figure, it can be seen that the thermal insulation effect of the chitosan aerogel prepared in Example 1 is much better than that of Comparative Example 1. After heating for 300 s, the upper surface temperature is only 38.2°C, which effectively proves that the thermal insulation performance of the chitosan aerogel prepared in Example 1 is superior.

[0076] Finally, the thermal conductivity of the aerogels of Example 1, Comparative Example 1, and Comparative Example 3 was tested using a KES F7 thermal conductivity tester (25±2°C, 35% RH). Figure 7 As shown, all aerogels are ranked from high to low by thermal conductivity as Comparative Example 3, Comparative Example 1, and Example 1. It can be seen that the addition of chitosan and montmorillonite improves thermal insulation performance, demonstrating a certain level of superior thermal insulation performance. The principle behind these test results is based on the combination of chitosan, montmorillonite, and fiber. The pore size between the aerogels is reduced, forming a uniform porous structure within the aerogels. This restricts the macroscopic movement and collisions of gas molecules, effectively reducing air convection. The low thermal conductivity of the montmorillonite and SiO2 fiber materials themselves, combined with the porous structure of the composite material, helps reduce the thermal conductivity of the aerogels.

[0077] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing a chitosan heat-insulating and flame-retardant gas gel, characterized in that: include: The polyacrylonitrile fiber is modified by amidoximation to obtain amidoxime-based polyacrylonitrile fiber; Preparation of single-layer montmorillonite; Chitosan and monolayer montmorillonite are added to an acidic reagent, and after the chitosan is fully dissolved, amidoxime-based polyacrylonitrile fiber, silica nanofiber and a cross-linking agent are added, and the mixture is stirred to obtain a mixed solution; The mixed solution is freeze-dried to obtain a chitosan heat-insulating and fire-resistant gel; The mass ratio of chitosan to monolayer montmorillonite is 6:(1-6); the mass ratio of amidoxime-based polyacrylonitrile fiber to silica nanofiber is 10:(1-6); and the crosslinking agent is an aldehyde-containing crosslinking agent.

2. The method for preparing the chitosan heat-insulating and fire-resistant gas gel according to claim 1, characterized in that: The polyacrylonitrile fiber is subjected to amidoximation modification to obtain amidoxime-based polyacrylonitrile fiber, comprising: The polyacrylonitrile fiber is added into a hydroxylamine hydrochloride solution for heating reaction. After the reaction is completed, the polyacrylonitrile fiber is taken out, washed multiple times, and dried to obtain the amidoxime-based polyacrylonitrile fiber.

3. The method for preparing the chitosan heat-insulating and flame-retardant gas gel according to claim 2, characterized in that: At least one of the following conditions must be met: The concentration of the hydroxylamine hydrochloride solution is 0.5-0.6 mol / L; The heating temperature range is 65~75℃; The reaction time is 2 to 2.5 hours; The drying temperature is 60-70°C.

4. The method for preparing the chitosan heat-insulating and fire-resistant gas gel according to claim 2, characterized in that: The amidoxime group conversion rate in the amidoxime modification of the polyacrylonitrile fiber is 20-30%.

5. The method for preparing the chitosan heat-insulating and fire-resistant gas gel according to claim 1, characterized in that: The preparation method of the single-layer montmorillonite comprises: Montmorillonite was added into water, stirred and ultrasonicated, and the supernatant was collected after centrifugation to obtain a monolayer montmorillonite dispersion; The single-layer montmorillonite dispersion is freeze-dried to obtain the single-layer montmorillonite.

6. The method for preparing the chitosan heat-insulating and fire-resistant gas gel according to claim 5, characterized in that: The single-layer stripping efficiency of the method for preparing the single-layer montmorillonite dispersion is 40-50%.

7. The method for preparing the chitosan heat-insulating and fire-resistant gas gel according to claim 5, characterized in that: The stirring time is 12 to 24 hours; and / or the ultrasonic time is 30 to 40 minutes; and / or the centrifugal speed range is 5000 to 7000 rpm; and / or the concentration of the monolayer montmorillonite dispersion is 4 to 5 g / L.

8. The method for preparing the chitosan heat-insulating and fire-resistant gas gel according to claim 1, characterized in that: At least one of the following conditions must be met: The pH range of the acidic reagent is 3 to 4; The acidic reagent is one or more of formic acid, hydrochloric acid, and acetic acid; The stirring time is until the fibers are evenly dispersed and the cross-linking reaction is complete; The freeze-drying condition parameters include freezing at -70~-65°C for 4~5 hours and then freeze-drying for 36~48 hours.

9. A chitosan heat-insulating and flame-retardant gel, characterized in that: The chitosan thermal insulation and fire-resistant gas gel is prepared by the preparation method of any one of claims 1 to 8, wherein the limiting oxygen index of the chitosan thermal insulation and fire-resistant gas gel is 50-65%.

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