Solid propellant and preparation method thereof

Abstract

The invention discloses a solid propellant and a preparation method thereof, and the solid propellant comprises the following components in percentage by mass: 63-85% of an oxidizing agent, 1-5% of a stabilizing agent, 1-5% of a stabilizing agent, 1-5% of a stabilizing agent, 1-5% of a stabilizing agent and 1-5% of a stabilizing agent, 10-20% of an adhesive; 0-15% of a metal fuel; 0.1%-2% of a cross-linking agent; wherein the adhesive is silane modified polyvinyl alcohol. The silane modified polyvinyl alcohol is used as the adhesive to prepare the electronic control solid propellant, so that the thermal stability of the propellant is improved, the phenomenon of self-sustaining thermal decomposition of the propellant after power failure and extinguishment is relieved, and the extinguishment performance of the propellant after power failure is improved; by improving the thermal stability of the propellant, the phenomenon of large-area melting and softening of a combustion surface in the ignition combustion process of the propellant is overcome, and the reliability of repeated ignition is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of solid propellants, and in particular relates to a solid propellant and a preparation method thereof. Background Art

[0002] Solid rocket engines are the core components of missiles, and their power and working fluid sources are all derived from solid propellants. However, traditional solid propellants are formed by mixing and pouring oxidizers, adhesives, metal fuels and other raw materials at one time, and once ignited and burned, they cannot be extinguished, which makes it difficult for solid rocket engines to achieve repeated starts and variable thrust adjustment.

[0003] Electronically controlled solid propellants overcome the defects of traditional solid propellants and show good energy controllable release capabilities. Under the action of applied voltage or current, electronically controlled solid propellants can achieve repeated ignition multiple times, and the burning rate can be adjusted in real time as the applied voltage changes. Solid rocket engines based on electronically controlled solid propellants can greatly improve the maneuverability and flexibility of missile weapons. The repeated ignition performance of electronically controlled solid propellants is closely related to their thermal stability. If the thermal decomposition temperature of the propellant is low, the heat generated after ignition and combustion will cause the propellant to be unable to completely extinguish after power failure, and it will continue to self-decompose under the action of residual heat, and even self-sustaining combustion. In addition, in order to improve the burning rate and specific impulse characteristics of the propellant, it is often hoped to increase the metal content or energetic additives in the propellant, which leads to a significant increase in the heat release of the propellant combustion, an increase in the difficulty of extinguishing the propellant after power failure, and a decrease in the repeated ignition performance.

[0004] Existing electronically controlled solid propellants are mainly composed of oxidizers, binders and metal fuels. When polyvinyl alcohol is used as a binder, since the thermal decomposition starting temperature of polyvinyl alcohol is lower than that of oxidizers (perchlorates, nitrates, etc.) and metal fuels, the thermal decomposition starting temperature of the propellant mainly depends on the thermal stability of polyvinyl alcohol. Due to the low thermal decomposition starting temperature of polyvinyl alcohol, the thermal decomposition temperature of the propellant is low, the thermal stability is poor, and the repeated ignition performance is low. Summary of the invention

[0005] In order to overcome the defects in the prior art of low thermal decomposition temperature of the adhesive polyvinyl alcohol and the propellant, continuous self-decomposition of the propellant after power failure, and low reliability of repeated ignition, the embodiments of the present invention provide a solid propellant with improved thermal stability and a preparation method thereof.

[0006] The present invention includes a solid propellant, and the mass percentage content of each component is calculated as 100%, and the mass percentage content of each component is as follows:

[0007] Oxidant: 63-85%;

[0008] Adhesive: 10-20%;

[0009] Metal fuel: 0-15%;

[0010] Cross-linking agent: 0.1-2%;

[0011] The binder is silane-modified polyvinyl alcohol.

[0012] Furthermore, the silane is one or a mixture of more than one of vinyltrimethoxysilane, trimethoxy(p-tolyl)silane, trimethyloxyphenylsilane, allyltrimethoxysilane, benzyltriethoxysilane, phenyltriethoxysilane, vinyltriethoxysilane, phenyltriethoxysilane, allyltriethoxysilane, triethoxyethynylsilane, and trimethoxy(4-vinylphenyl)silane.

[0013] Furthermore, the oxidant is one of lithium nitrate, sodium nitrate, potassium nitrate, lithium perchlorate, sodium perchlorate, potassium perchlorate, aluminum perchlorate, barium perchlorate, calcium perchlorate or magnesium perchlorate, or a mixture of more than one of them.

[0014] Furthermore, the cross-linking agent is one or a mixture of more than one of boric acid or borax.

[0015] Furthermore, the metal fuel is one or a mixture of more than one of aluminum powder, boron powder, magnesium powder, copper powder or tungsten powder.

[0016] Furthermore, the particle size of the metal fuel is 50 nm to 10 μm.

[0017] A method for preparing any of the above solid propellants, comprising the following steps:

[0018] S1, preparing silane-modified polyvinyl alcohol;

[0019] S2, mixing an oxidant, a cross-linking agent, a metal fuel and silane-modified polyvinyl alcohol in deionized water, and stirring the mixture under vacuum to prepare a propellant slurry;

[0020] S3, pouring and drying the propellant slurry to obtain a solid propellant.

[0021] Furthermore, step S1 includes the following steps:

[0022] S1.1, dissolving polyvinyl alcohol in distilled water, the mass ratio of polyvinyl alcohol to distilled water is 1:30-100, the dissolution temperature is 70-90°C, and cooling to room temperature to obtain a polyvinyl alcohol aqueous solution;

[0023] S1.2, dissolving the silane reagent in anhydrous methanol, the molar ratio of polyvinyl alcohol to silane is 1:1.2-1.5, and the volume ratio of the silane reagent to anhydrous methanol is 1:5-10, to obtain a silane methanol solution; mixing the silane methanol solution with the polyvinyl alcohol aqueous solution for reaction, the reaction pH is 2-5, the reaction temperature is 25-35°C, and the reaction time is 24-72h to obtain a mixed solution;

[0024] S1.3. Add anhydrous ethanol to the mixed solution to precipitate a white flocculent precipitate. Filter the white flocculent precipitate, wash it with anhydrous methanol, and vacuum dry it at 40-50° C. for 12-24 h to obtain silane-modified polyvinyl alcohol.

[0025] Furthermore, in step S2, the stirring temperature is 0-15°C, the stirring speed is 200-300 r / min, and the stirring time is 10-20 min.

[0026] Furthermore, in step S3, the drying temperature is 20 to 50° C., and the drying time is 2 to 7 days.

[0027] Beneficial effects of the present invention:

[0028] The silane-modified polyvinyl alcohol prepared by the present invention increases the thermal decomposition temperature of polyvinyl alcohol by introducing silicon atoms and substituents of different structures, and at the same time increases the length of its side chains, weakens the strength of hydrogen bonds between polyvinyl alcohol molecules, reduces the crystallinity of the system, and thus improves its compatibility with other components of the propellant.

[0029] The present invention adopts silane-modified polyvinyl alcohol as an adhesive to prepare an electrically controlled solid propellant, thereby improving the thermal stability of the propellant, alleviating the phenomenon of self-sustaining thermal decomposition of the propellant after power failure and extinguishing, and improving the extinguishing performance of the propellant after power failure; by improving the thermal stability of the propellant, the phenomenon of large-area melting and softening of the combustion surface during the ignition and combustion process of the propellant is overcome, and the reliability of repeated ignition is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Attached Figure 1 This is a comparison chart of the thermogravimetric curves of the polyvinyl alcohol modified with allyltrimethoxysilane in Example 2 of the present invention and the conventional unmodified polyvinyl alcohol. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solution and advantages of the present invention more clear, the present invention is further described in detail below in conjunction with specific implementation methods. It should be understood that the specific implementation methods described here are only used to explain the present invention and are not intended to limit the present invention.

[0032] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art to which the present invention belongs. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items. In addition, the technical solutions between the various embodiments of the present invention can be combined with each other, but it must be based on the ability of ordinary technicians in the field to implement. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0033] The embodiment of the present invention provides a solid catalyst, and the mass percentage content of each component is calculated as 100%, and the mass percentage content of each component is as follows:

[0034] Oxidant: 63-85%;

[0035] Adhesive: 10-20%;

[0036] Metal fuel: 0-15%;

[0037] Cross-linking agent: 0.1-2%;

[0038] Wherein, the adhesive is silane-modified polyvinyl alcohol.

[0039] The present invention uses silane-modified polyvinyl alcohol as an adhesive, introduces silicon atoms and substituents of different structures, thereby increasing the thermal decomposition temperature of the polyvinyl alcohol and increasing the length of its side chains, thereby weakening the strength of hydrogen bonding between polyvinyl alcohol molecules and reducing the degree of crystallization of the system, thereby improving its compatibility with other components of the propellant; by using silane-modified polyvinyl alcohol as an adhesive to prepare an electrically controlled solid propellant, the thermal stability of the propellant is improved, the phenomenon of self-sustaining thermal decomposition of the propellant after power failure and extinguishing is alleviated, and the extinguishing performance of the propellant after power failure is improved; by improving the thermal stability of the propellant, the phenomenon of large-area melting and softening of the combustion surface during the ignition and combustion process of the propellant is overcome, and the reliability of repeated ignition is improved.

[0040] In a preferred embodiment, the silane is one of vinyltrimethoxysilane, trimethoxy(p-tolyl)silane, trimethyloxyphenylsilane, allyltrimethoxysilane, benzyltriethoxysilane, phenyltriethoxysilane, vinyltriethoxysilane, phenyltriethoxysilane, allyltriethoxysilane, triethoxyethynylsilane, trimethoxy(4-vinylphenyl)silane, or a mixture of more than one of them.

[0041] In a preferred embodiment, the oxidant is one of lithium nitrate, sodium nitrate, potassium nitrate, lithium perchlorate, sodium perchlorate, potassium perchlorate, aluminum perchlorate, barium perchlorate, calcium perchlorate or magnesium perchlorate, or a mixture of more than one of them.

[0042] In a preferred embodiment, the crosslinking agent is boric acid or borax or a mixture of more than one thereof.

[0043] In a preferred embodiment, the metal fuel is one or a mixture of more than one of aluminum powder, boron powder, magnesium powder, copper powder or tungsten powder.

[0044] In a preferred embodiment, the particle size of the metal fuel is 50 nm to 10 μm.

[0045] The present invention also provides a method for preparing the above solid propellant, comprising the following steps:

[0046] S1, preparing silane-modified polyvinyl alcohol,

[0047] S2, dissolving the oxidant in deionized water to prepare a solution with a concentration of 30-70%, adding a cross-linking agent, a metal fuel and silane-modified polyvinyl alcohol in sequence, and performing vacuum stirring to obtain a propellant slurry;

[0048] S3. pouring the obtained propellant slurry into a combustion chamber or a mold under normal pressure or vacuum conditions, and obtaining a solidified propellant after drying.

[0049] The embodiments of the present invention can prepare the solid propellant with improved thermal stability.

[0050] In a preferred embodiment, step S1 further comprises the following steps:

[0051] S1.1, adding distilled water to polyvinyl alcohol, wherein the mass ratio of polyvinyl alcohol to water is 1:30-100, heating to 70-90°C under stirring until the polyvinyl alcohol is completely dissolved, and cooling to room temperature to obtain a polyvinyl alcohol aqueous solution;

[0052] S1.2, weighing a silane reagent and dissolving it in anhydrous methanol at a molar ratio of polyvinyl alcohol to silane of 1:1.2-1.5, wherein the volume ratio of the silane reagent to anhydrous methanol is 1:5-10, to obtain a silane methanol solution;

[0053] Adding the silane methanol solution to the polyvinyl alcohol aqueous solution, and dropping a hydrochloric acid solution with a concentration of 0.1 to 0.5 mol / L to adjust the pH to 2 to 5, reacting at 25 to 35° C. for 24 to 72 hours to obtain a mixed solution;

[0054] S1.3. After the reaction is complete, anhydrous methanol is slowly added to the mixed solution. The volume ratio of the mixed solution to anhydrous ethanol is 1:3-5. A white flocculent precipitate is precipitated. The white flocculent precipitate is filtered out, washed with anhydrous methanol for 3-5 times, and then vacuum dried at 40-50°C for 12-24h to obtain silane-modified polyvinyl alcohol, which is crushed to 80-120 mesh.

[0055] In a preferred embodiment, in step S2, the stirring temperature is 0-15°C, the stirring speed is 200-300 r / min, and the stirring time is 10-20 min.

[0056] In a preferred embodiment, in step S3, the drying temperature is 20-50° C., and the drying time is 2-7 days.

[0057] Example 1

[0058] This embodiment provides a solid propellant, wherein the oxidizer is lithium perchlorate, the metal fuel is aluminum powder, the cross-linking agent is boric acid, and the binder is polyvinyl alcohol modified with vinyltrimethoxysilane. The sum of the mass percentage content of each component is 100%, and the mass percentage content of each component is:

[0059] Lithium perchlorate: 75%;

[0060] Vinyltrimethoxysilane-modified polyvinyl alcohol: 18%;

[0061] Aluminum powder: 5%;

[0062] Boric acid: 2%.

[0063] This embodiment also provides a method for preparing the above solid propellant, comprising the following steps:

[0064] S1, preparing vinyltrimethoxysilane-modified polyvinyl alcohol, is further divided into the following steps:

[0065] S1.1. Weigh 1g of polyvinyl alcohol into a beaker, add distilled water at a mass ratio of polyvinyl alcohol to water of 1:40, heat to 90°C under stirring until the polyvinyl alcohol is completely dissolved, and cool to room temperature to obtain a polyvinyl alcohol aqueous solution;

[0066] S1.2. Weigh vinyl trimethoxysilane reagent in a molar ratio of polyvinyl alcohol to vinyl trimethoxysilane of 1:1.2 and dissolve it in 10 mL of anhydrous methanol to obtain a vinyl trimethoxysilane methanol solution; add the vinyl trimethoxysilane methanol solution to the polyvinyl alcohol aqueous solution, and dropwise add a 0.1 mol / L hydrochloric acid solution into the mixed solution to adjust the pH to 2-3, and react the mixed solution at 35°C for 24 hours to obtain a mixed solution;

[0067] S1.3, after the reaction is complete, anhydrous methanol is slowly added to the mixed solution, the volume ratio of the mixed solution to anhydrous methanol is 1:5, a white flocculent precipitate is precipitated, the white flocculent precipitate is filtered out, washed with anhydrous methanol 3 times, and then vacuum dried at 50°C for 24h to obtain vinyltrimethoxysilane-modified polyvinyl alcohol, which is crushed to 80-120 mesh;

[0068] S2. Weigh the raw materials according to the components, dissolve lithium perchlorate in deionized water to prepare a solution with a concentration of 30-70%, add boric acid, aluminum powder and polyvinyl alcohol modified with vinyltrimethoxysilane in sequence, place the container at 0°C and perform vacuum stirring for 10 minutes at a speed of 260 r / min to obtain a propellant slurry;

[0069] S3. Pour the obtained propellant slurry into a combustion chamber or a mold under normal pressure or vacuum conditions, and dry it by hot air circulation at 35° C. for 5 days to obtain a solidified propellant.

[0070] According to thermogravimetric analysis, the thermal decomposition temperature of polyvinyl alcohol modified with vinyltrimethoxysilane in this embodiment is 330°C, which is 96°C higher than the thermal decomposition temperature of polyvinyl alcohol; the thermal decomposition temperature of the prepared propellant is 228°C, which is 20°C higher than that of comparative example 1.

[0071] Example 2

[0072] This embodiment provides a solid propellant, wherein the oxidizer is lithium perchlorate, the metal fuel is aluminum powder, the cross-linking agent is boric acid, and the binder is polyvinyl alcohol modified with allyltrimethoxysilane. The sum of the mass percentage content of each component is 100%, and the mass percentage content of each component is:

[0073] Lithium perchlorate: 75%;

[0074] Allyltrimethoxysilane-modified polyvinyl alcohol: 18%;

[0075] Aluminum powder: 5%;

[0076] Boric acid: 2%.

[0077] This embodiment also provides a method for preparing the above solid propellant, comprising the following steps:

[0078] S1, preparing allyltrimethoxysilane-modified polyvinyl alcohol, is further divided into the following steps:

[0079] S1.1. Weigh 1g of polyvinyl alcohol into a beaker, add distilled water at a mass ratio of polyvinyl alcohol to water of 1:40, heat to 90°C under stirring until the polyvinyl alcohol is completely dissolved, and cool to room temperature to obtain a polyvinyl alcohol aqueous solution;

[0080] S1.2. Weigh allyl trimethoxysilane reagent in a molar ratio of polyvinyl alcohol to allyl trimethoxysilane of 1:1.5 and dissolve it in 10 mL of anhydrous methanol to obtain an allyl trimethoxysilane methanol solution; add the allyl trimethoxysilane methanol solution to the polyvinyl alcohol aqueous solution, and dropwise add a 0.1 mol / L hydrochloric acid solution into the mixed solution to adjust the pH to 2-3, and react the mixed solution at 50°C for 12 hours to obtain a mixed solution;

[0081] S1.3, after the reaction is complete, anhydrous methanol is slowly added to the mixed solution, the volume ratio of the mixed solution to anhydrous methanol is 1:6, a white flocculent precipitate is precipitated, the white flocculent precipitate is filtered out, washed with anhydrous methanol 3 times, and then vacuum dried at 50°C for 12h to obtain allyltrimethoxysilane-modified polyvinyl alcohol, which is crushed to 80-120 mesh;

[0082] S2. Weigh the raw materials according to the components, dissolve lithium perchlorate in deionized water to prepare a solution with a concentration of 30-70%, add boric acid, aluminum powder and polyvinyl alcohol modified with allyltrimethoxysilane in sequence, place the container under vacuum stirring at 10° C., the stirring time is 15 min, the speed is 300 r / min, and a propellant slurry is obtained;

[0083] S3. Pour the obtained propellant slurry into a combustion chamber or a mold under normal pressure or vacuum conditions, and dry it in hot air circulation at 30° C. for 5 days to obtain a solidified propellant.

[0084] According to thermogravimetric analysis, the thermal decomposition temperature of polyvinyl alcohol modified with allyltrimethoxysilane in this embodiment is 338°C, which is 104°C higher than the thermal decomposition temperature of polyvinyl alcohol; the thermal decomposition temperature of the prepared propellant is 236°C, which is 28°C higher than that of comparative example 1.

[0085] As attached Figure 1 As shown, the mass fraction of polyvinyl alcohol begins to drop suddenly from about 230°C, while the mass fraction of polyvinyl alcohol modified with allyltrimethoxysilane in this embodiment begins to drop at about 330°C, indicating that the initial weight loss temperature of the modified polyvinyl alcohol in this embodiment is significantly increased, and it has better thermal stability.

[0086] Comparative Example 1

[0087] In this comparative example, polyvinyl alcohol that has not been modified with silane is used as an adhesive, and the other components are selected the same as those in Examples 1 and 2. The mass percentages of the oxidant, adhesive, metal fuel and cross-linking agent are also the same as those in Examples 1 and 2. Specifically, the sum of the mass percentages of the components in this comparative example is calculated as 100%, and the mass percentages of the components are:

[0088] Lithium perchlorate: 75%;

[0089] Polyvinyl alcohol: 18%;

[0090] Aluminum powder: 5%;

[0091] Boric acid: 2%.

[0092] The preparation method of the propellant in this comparative example is the same as step S2 and step S3 of Examples 1 and 2, and only conventional adjustments are made to the experimental parameters, specifically comprising the following steps:

[0093] S1, crushing polyvinyl alcohol to 80-120 mesh;

[0094] S2. Weigh the raw materials according to the components, dissolve lithium perchlorate in deionized water to prepare a solution with a concentration of 30-70%, add boric acid, aluminum powder and polyvinyl alcohol in sequence, place the container at 0°C and perform vacuum stirring for 10 minutes at a speed of 260 r / min to obtain a propellant slurry;

[0095] S3. Pour the obtained propellant slurry into a combustion chamber or a mold under normal pressure or vacuum conditions, and dry it by hot air circulation at 35° C. for 5 days to obtain a solidified propellant.

[0096] Thermogravimetric analysis showed that the thermal decomposition starting temperature of polyvinyl alcohol in this comparative example was 234°C, and the thermal decomposition temperature of the prepared propellant was 208°C.

[0097] By comparison, it can be seen that compared with conventional unmodified polyvinyl alcohol, the silane-modified polyvinyl alcohol in the implementation of the present invention has a higher thermal decomposition starting temperature, and the thermal decomposition temperature of the prepared propellant is significantly improved, thereby improving the thermal stability of the propellant, alleviating the phenomenon of self-sustaining thermal decomposition of the propellant after power failure and extinguishing, and improving the extinguishing performance of the propellant after power failure; by improving the thermal stability of the propellant, the large-area melting and softening phenomenon of the burning surface during the ignition and combustion process of the propellant is overcome, and the reliability of its repeated ignition is improved.

[0098] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0099] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

[0100] The contents not described in detail in this specification belong to the prior art known to professional and technical personnel in this field.

Claims

1. A solid propellant, characterized in that: Taking the sum of the mass percentage of each component as 100%, the mass percentage of each component is as follows: Oxidant: 63-85%; Adhesive: 10-20%; Metal fuel: 0-15%; Cross-linking agent: 0.1-2%; The adhesive is silane-modified polyvinyl alcohol.

2. The solid propellant according to claim 1, characterized in that: The silane is one of vinyltrimethoxysilane, trimethoxy(p-tolyl)silane, trimethyloxyphenylsilane, allyltrimethoxysilane, benzyltriethoxysilane, phenyltriethoxysilane, vinyltriethoxysilane, phenyltriethoxysilane, allyltriethoxysilane, triethoxyethynylsilane, and trimethoxy(4-vinylphenyl)silane, or a mixture of more than one of the above.

3. The solid propellant according to claim 1, characterized in that: The oxidant is one of lithium nitrate, sodium nitrate, potassium nitrate, lithium perchlorate, sodium perchlorate, potassium perchlorate, aluminum perchlorate, barium perchlorate, calcium perchlorate or magnesium perchlorate, or a mixture of more than one of the above.

4. The solid propellant according to claim 1, characterized in that: The cross-linking agent is one or a mixture of more than one of boric acid or borax.

5. The solid propellant according to claim 1, characterized in that: The metal fuel is one of aluminum powder, boron powder, magnesium powder, copper powder or tungsten powder, or a mixture of more than one of them.

6. The solid propellant according to claim 5, characterized in that: The particle size of the metal fuel is 50nm-10μm.

7. A method for preparing a solid propellant as claimed in any one of claims 1 to 6, characterized in that: The following steps are involved: S1, preparing silane-modified polyvinyl alcohol; S2, mixing an oxidant, a cross-linking agent, a metal fuel and the silane-modified polyvinyl alcohol in deionized water, and stirring under vacuum to prepare a propellant slurry; S3, pouring and drying the propellant slurry to obtain a solid propellant.

8. The solid propellant according to claim 7, characterized in that: The step S1 comprises the following steps: S1.1, dissolving polyvinyl alcohol in distilled water, the mass ratio of polyvinyl alcohol to distilled water is 1:30-100, the dissolution temperature is 70-90°C, and cooling to room temperature to obtain a polyvinyl alcohol aqueous solution; S1.2, dissolving the silane reagent in anhydrous methanol, the molar ratio of polyvinyl alcohol to silane is 1:1.2-1.5, and the volume ratio of the silane reagent to anhydrous methanol is 1:5-10, to obtain a silane methanol solution; mixing the silane methanol solution with the polyvinyl alcohol aqueous solution for reaction, the reaction pH is 2-5, the reaction temperature is 25-35°C, the reaction time is 24-72h, to obtain a mixed solution; S1.3, adding anhydrous ethanol to the mixed solution to precipitate a white flocculent precipitate, filtering the white flocculent precipitate, washing it with anhydrous methanol, and vacuum drying it at 40-50° C. for 12-24 h to obtain the silane-modified polyvinyl alcohol.

9. The solid propellant according to claim 7, characterized in that: In the step S2, the stirring temperature is 0-15°C, the stirring speed is 200-300 r / min, and the stirring time is 10-20 min.

10. The solid propellant according to claim 7, characterized in that: In step S3, the drying temperature is 20 to 50° C., and the drying time is 2 to 7 days.

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