A PBO fiber filled rubber type ablation resistant thermal insulation material and a preparation method thereof

Abstract

The application discloses a PBO fiber filled rubber type ablation resistant thermal insulation material and a preparation method thereof, and belongs to the technical field of rubber. The material components are as follows: rubber, 100 parts; accelerator, 0-20 parts; vulcanizing agent, 0.5-10 parts; PBO fiber, 0-80 parts; reinforcing agent, 0-50 parts; plasticizer, 0-20 parts; flame retardant, 0-30 parts; ablation resistant filler, 0-30 parts; porcelain forming filler, 0-20 parts. The PBO fiber is pretreated or / and non-pretreated. The preparation method of the rubber type ablation resistant thermal insulation material is disclosed. The application solves the stress concentration problem caused by the uneven dispersion of the PBO fiber in the rubber matrix, effectively improves the interface bonding force between the fiber and the thermal insulation material matrix, and realizes the consistency of the mechanical properties of the thermal insulation material in all directions under the condition that the fiber filling amount is more.

Description

Technical Field

[0001] This invention belongs to the technical field of solid rocket engine insulation layer materials, and prepares a solid rocket engine internal insulation material with excellent mechanical properties and ablation resistance. Background Technology

[0002] Flexible ablation materials, serving as a protective layer in the combustion chamber of solid rocket motors, are located between the combustion chamber shell and the propellant grain. They act as thermal insulation, preventing the shell from reaching destructive temperatures that threaten its structural integrity. These materials possess resistance to high-temperature ablation, high-speed thermal erosion, and excellent mechanical properties, making them a crucial component of high-performance solid propellant rocket motors in many aerospace and military applications. During rocket engine operation, the insulation material continuously degrades under extreme conditions of high temperature, high pressure, and high-speed thermal erosion, forming a carbonized layer. This carbonized layer creates a temperature gradient, slowing heat transfer and providing thermal protection for the shell. Therefore, forming a dense, complete, and high-strength carbonized layer is essential for achieving good ablation resistance.

[0003] Rubber matrices alone cannot form a robust carbonized layer after carbonization. To obtain high-performance ablation-resistant materials, ablation-resistant fiber fillers and other compounding systems are typically added to the rubber matrix to impart good mechanical, interfacial, and ablation properties. Fillers have a significant impact on ablation composites. Studying their mechanism of action and establishing the relationship between filler characteristics and composite material performance is beneficial for better designing processing formulations and forming high-performance ablation-resistant materials. Fibers, as embedded skeleton materials, can fix more of the carbonized matrix, prevent delamination and peeling, effectively enhance the strength of the carbon layer, and improve the composite material's resistance to high-speed heat flow erosion. The excellent thermal stability of fibers ensures high mechanical strength of the carbonized matrix, which is beneficial for maintaining the fiber structure and reinforcing the carbon layer, improving erosion resistance. Simultaneously, fibers should also have low density and thermal conductivity to achieve lightweight and heat insulation effects in flexible insulation materials. Therefore, the thermal stability of fibers and interfacial interactions are key factors affecting the erosion resistance of insulation materials, providing guidance for the research and application of ablation material performance.

[0004] Because asbestos fibers are carcinogenic, and glass and carbon fibers are prone to breakage during processing, their reinforcing effect on the carbon layer structure is poor. Currently, organic fibers are widely used to reinforce flexible thermal insulation materials, such as aramid fiber (KF), polyimide fiber (PI), phenolic fiber (PF), and poly(p-phenylenebenzodioxazole) fiber (PBO). PBO fiber's molecular backbone contains benzene and dioxazole ring groups, exhibiting high thermal stability and resistance to decomposition. PBO fiber has an initial decomposition temperature of 643℃, a maximum decomposition rate temperature of 678℃, a residual char value of 64.7% at 800℃, a limiting oxygen index of 68, and a modulus of 220 GPa, far exceeding the other three organic fibers. As a "four-super" super fiber—ultra-high strength, ultra-high modulus, ultra-high flame retardancy, and ultra-high heat resistance—PBO fiber boasts the best heat resistance among high-performance organic fibers and is used as a new generation of reinforcing fiber for advanced composite materials in the aerospace field. Summary of the Invention

[0005] This invention provides a solid rocket insulation layer material with excellent mechanical properties and ablation resistance, and its preparation method.

[0006] To improve the ablation resistance of thermal insulation materials while ensuring they possess good mechanical properties to meet the actual operating requirements of engines, it is of great significance to develop a thermal insulation material with excellent ablation resistance and a simple molding process. This invention provides a flexible solid rocket motor internal thermal insulation material filled with PBO fibers, possessing excellent mechanical properties and ablation resistance, capable of meeting the design and usage requirements of high-performance solid rocket motors.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] This invention first provides an ablation-resistant flexible thermal insulation material, comprising the following components in parts by weight: rubber, 100 parts; accelerator, 0-20 parts; vulcanizing agent, 0.5-10 parts; fiber, 0-80 parts (not zero); reinforcing agent, 0-50 parts; plasticizer, 0-20 parts; flame retardant, 0-30 parts; ablation-resistant filler, 0-30 parts; and ceramic filler, 0-20 parts.

[0009] Preferably, the ablation-resistant flexible thermal insulation material comprises the following components in parts by weight: rubber, 100 parts; accelerator, 0-15 parts; vulcanizing agent, 0.5-5 parts; fiber, 0-30 parts (not zero); reinforcing agent, 0-30 parts; plasticizer, 0-20 parts; flame retardant, 0-20 parts; ablation-resistant filler, 0-20 parts; and ceramic filler, 0-20 parts.

[0010] Furthermore, the rubber is one or more of the following: natural rubber (NR), butadiene rubber (BR), styrene-butadiene rubber (SBR), chloroprene rubber (CR), nitrile rubber (NBR), ethylene propylene rubber (EPM), grafted modified ethylene propylene rubber (g-EPM), ethylene propylene diene monomer (EPDM), polyurethane elastomer (PU), silicone rubber (SR), fluororubber (FKM), polyphosphazene elastomer (PZ), chlorosulfonated polyethylene rubber (CSM), polysulfide rubber (PSR), and polyisoprene rubber (IR).

[0011] Furthermore, the promoter is one or more of the following: thiazoles, sulfenamides, thiurams, dithiocarbamates, guanidines, and xanthates.

[0012] Furthermore, the vulcanizing agent is one or more of sulfur, organic peroxides, and metal oxides.

[0013] Furthermore, the reinforcing agent is one or more of carbon black, silica, silicate, calcium carbonate, montmorillonite, and zinc oxide.

[0014] Furthermore, the plasticizer is one or more of the following: liquid ethylene propylene rubber, liquid hydroxyl-terminated polybutadiene, aliphatic hydrocarbons, cycloalkanes, aromatic hydrocarbon processing oils, phthalates, aliphatic diesters, fatty acids, phosphate esters, polyesters, epoxy compounds, and chlorine-containing compounds.

[0015] Furthermore, the flame retardant is one or more of the following: inorganic (e.g., aluminum hydroxide, magnesium hydroxide, boron compounds, molybdenum compounds, antimony trioxide), phosphorus (ammonium polyphosphate, tricresyl phosphate, phosphite), and organic halogen (e.g., decabromodiphenyl ethane, decabromodiphenyl ether (DBDPO), tetrabromobisphenol A bis(2,3-dialkylpropyl) ether (TBAB), octabromodiphenyl ether (OBDPO), chlorinated paraffin, tetrachlorophthalic anhydride, tetrachlorobisphenol A, hexachlorocyclopentadiene, bis(hexachlorocyclopentadiene)cyclooctane, perchlorocyclopentanedecane, tetrachlorophthalic anhydride, and chloramphenicol).

[0016] Furthermore, the ablation-resistant filler is a phenolic resin, such as boron phenolic resin (boron phenolic resin TH-390, boron phenolic resin FBO-389, boron phenolic resin SFB, boron phenolic resin THC-400), aminophenolic resin, barium phenolic resin, clay, montmorillonite, phenolic hollow microspheres, silica or glass microspheres, cork, or one or more of these.

[0017] Furthermore, the ceramic filler is one or more of silazane and siloxane.

[0018] Furthermore, the fiber is one or more of the following: pulp containing a poly(p-phenylenebenzodioxazole) structure, chopped fiber, long fiber, and fiber cloth, i.e., PBO-containing fiber.

[0019] In addition to PBO fiber, the solid rocket motor internal insulation material formulation prepared by this invention can also be used in combination with one or more of the following: carbon fiber, glass fiber, ceramic fiber, aramid fiber, aramid pulp, aramid sulfone fiber, aramid sulfone pulp, phenolic fiber, polyimide fiber, and asbestos fiber.

[0020] In this invention, the fibers may be surface pretreated or left untreated.

[0021] Fiber pretreatment methods include dispersion treatment and / or chemical modification. Dispersion treatment facilitates the uniform distribution of fibers in the matrix. To further enhance the interfacial interaction between the fiber and the matrix and improve the mechanical properties of the insulation material, the fiber surface can be chemically modified.

[0022] The fiber pretreatment preparation process is as follows:

[0023] (1) Fiber dispersion treatment: the fibers are dispersed to improve the uniform distribution of the fibers in the matrix.

[0024] (2) Fiber chemical modification: After removing impurities from the surface of PBO fibers (which may be broken or not broken) and drying them, they are reacted with chemical modifiers or plasma etched to increase the number of polar functional groups on the fiber surface and improve the surface free energy of the fiber. This can enhance the interfacial bonding force between the fiber and the matrix, and give the flexible thermal insulation material excellent mechanical properties and ablation resistance.

[0025] Furthermore, the chemical modifier is a mixture of coupling agent, anhydrous ethanol and distilled water, wherein the concentration of coupling agent is 0-40% and not 0.

[0026] Furthermore, the coupling agent is one or more of hydrocarbon silanes.

[0027] This invention further provides a method for preparing the above-mentioned ablation-resistant flexible thermal insulation material, comprising the following steps:

[0028] Step S1: Weigh according to the formula, and first plasticize the raw rubber on a two-roll mill;

[0029] Step S2: After the mixture is evenly mixed, add the accelerator, flame retardant, ablation resistant filler, fiber, reinforcing agent, plasticizer, and ceramic filler in sequence, and pass through the mixture several times in a thin stream.

[0030] Step S3: Finally, add the vulcanizing agent, mix evenly, pass through the thin sheet several times, and then roll it out for later use. Vulcanize it using a flat vulcanizing machine to prepare PBO fiber-filled ablation-resistant flexible insulation material.

[0031] Furthermore, before vulcanization, the mixed rubber compound is conditioned at room temperature for no less than 12 hours.

[0032] Furthermore, the vulcanization conditions are: vulcanization temperature of 130℃~170℃, vulcanization time of 30min~100min, and vulcanization pressure of 5MPa~30MPa.

[0033] The method for preparing a PBO fiber-filled ablation-resistant flexible thermal insulation material according to the present invention has the following advantages:

[0034] (1) The PBO fiber used in this invention has the characteristics of high strength, high modulus, excellent heat resistance and flame retardancy, which is conducive to giving full play to the high performance advantage of fiber as a skeleton material and preparing a rocket engine internal heat insulation material with excellent mechanical properties and ablation resistance.

[0035] (2) The preparation process adopted in this invention can still maintain good mechanical properties even when more fiber is filled. That is, the mechanical properties in the direction perpendicular to the calendering and the direction parallel to the calendering are basically the same. This solves the problem of excessive differences in mechanical properties of fiber-filled rubber materials in different directions, ensures the performance reliability of the insulation material under different conditions, and can adapt to the special requirements of the engine for the mechanical properties of the insulation layer.

[0036] (3) This product has excellent process performance and good fluidity. In addition to being used as an internal heat insulation layer material for solid rocket engines, it also has good application prospects in the field of civilian heat insulation flexible materials. Attached Figure Description

[0037] The embodiments and comparative examples of the present invention will be further described with reference to the accompanying drawings.

[0038] Figure 1 The images show the surface microstructure of the fibers used in Example 8 and Comparative Examples 1, 2, and 4.

[0039] Figure 2 Microscopic images showing the dispersion of fibers in Sample 8 and Comparative Examples 1, 2, and 4.

[0040] Figure 3 The images show the microstructure of the tensile cross-sections of samples from Example 8 and Comparative Examples 1, 2, and 4.

[0041] Figure 4 The images show the microstructure of the tensile cross-sections before and after fiber modification in Examples 39 and 14, as well as the dispersion of the fibers in the matrix.

[0042] Figure 5 The images show the microscopic morphology of the carbon layer surface (a) and the cross-section of the carbon layer after ablation of the sample in Example 3.

[0043] Figure 6 This is a diagram showing the bonding effect of the sample in Example 15 with metal steel and aluminum. Detailed Implementation

[0044] To enable those skilled in the art to better understand and implement the technical solutions of the present invention, the present invention will be further described below with reference to specific embodiments. However, the embodiments are only for illustration and are not intended to limit the present invention.

[0045] Example 1

[0046] EPDM rubber, 100 parts; dicumyl peroxide, 5 parts; PBO pulp, 20 parts; silica, 40 parts; dioctyl sebacate, 10 parts. The specific implementation method is as follows:

[0047] Plasticize EPDM raw rubber on a two-roll mill for 3 minutes. After mixing evenly, add PBO pulp, silica, and dioctyl sebacate in sequence. Control the temperature of the rubber compound at about 40℃ and pass it through a thin pass 10 times. Add dicumyl peroxide and mix evenly. Pass it through a thin pass 10 times and then sheet it out. After adjusting to room temperature for 24 hours, hot press and vulcanize at 160℃ for 50 minutes at a vulcanization pressure of 10MPa to prepare ablation-resistant EPDM insulation material.

[0048] Example 2

[0049] SR rubber, 100 parts; dicumyl peroxide, 2 parts; PBO-3mm, 15 parts; silica, 35 parts; boron phenolic resin TH-390, 5 parts. The specific implementation method is as follows:

[0050] Plasticize the SR raw rubber on a two-roll mill for 5 minutes. After mixing evenly, add boron phenolic resin TH-390, PBO-3mm, and silica in sequence. Control the temperature of the rubber compound at about 60℃ and pass it through a thin pass 10 times. Add dicumyl peroxide and mix evenly. Pass it through a thin pass 10 times and then sheet it out. After adjusting to room temperature for 24 hours, hot press and vulcanize at 140℃ for 50 minutes at a vulcanization pressure of 10MPa to prepare the ablation-resistant SR insulation material.

[0051] Example 3

[0052] EPDM rubber, 100 parts; thiazole accelerator, 15 parts; sulfur / dicumyl peroxide, 3 parts; PBO-3mm, 25 parts; silica, 30 parts; aluminum hydroxide, 30 parts. The specific implementation method is as follows:

[0053] Plasticize EPDM raw rubber on a two-roll mill for 3 minutes. After mixing evenly, add thiazole accelerator, aluminum hydroxide, PBO-3mm, and silica in sequence. Control the temperature of the rubber compound at about 40℃ and pass it through a thin pass 10 times. Add vulcanizing agent, mix evenly, pass it through a thin pass 10 times, and then sheet it out. After adjusting to room temperature for 24 hours, hot press vulcanize it at 160℃ for 50 minutes at a vulcanization pressure of 10MPa to prepare ablation-resistant EPDM insulation material.

[0054] Example 4

[0055] NBR, 100 parts; sulfur, 2 parts; PBO-3mm, 30 parts; silica, 25 parts; dibutyl phthalate, 12 parts. The specific implementation method is as follows:

[0056] Plasticize the NBR raw rubber on a two-roll mill for 5 minutes. After it is evenly mixed, add PBO-3mm, silica, and dibutyl phthalate in sequence. Control the temperature of the rubber compound at about 60℃ and pass it through a thin pass 10 times. Add sulfur, mix evenly, pass it through a thin pass 10 times, and then sheet it out. After adjusting to room temperature for 24 hours, hot press and vulcanize it at 160℃ for 70 minutes at a vulcanization pressure of 15MPa to prepare the ablation-resistant NBR insulation material.

[0057] Example 5

[0058] EPDM rubber, 100 parts; thiazole accelerator, 13 parts; dicumyl peroxide, 4 parts; PBO-6mm, 18 parts; silica, 30 parts; dioctyl sebacate, 12 parts. The specific implementation method is as follows:

[0059] Plasticize EPDM raw rubber on a two-roll mill for 3 minutes. After mixing evenly, add thiazole accelerator, PBO-6mm, silica, and dioctyl sebacate in sequence. Control the temperature of the rubber compound at about 40℃ and pass it through a thin pass 10 times. Add dicumyl peroxide and mix evenly. Pass it through a thin pass 10 times and then sheet it. After adjusting to room temperature for 24 hours, hot press and vulcanize at 160℃ for 50 minutes at a vulcanization pressure of 10MPa to prepare ablation-resistant EPDM insulation material.

[0060] Example 6

[0061] EPDM rubber, 100 parts; thiazole accelerator, 6 parts; sulfur / dicumyl peroxide, 3.5 parts; PBO-9mm, 12 parts; silica, 40 parts; magnesium hydroxide, 20 parts. The specific implementation method is as follows:

[0062] Plasticize EPDM raw rubber on a two-roll mill for 3 minutes. After mixing evenly, add thiazole accelerator, magnesium hydroxide, PBO-9mm, and silica in sequence. Control the temperature of the rubber compound at about 40℃ and pass it through a thin pass 10 times. Add sulfur / diisopropylbenzene peroxide, mix evenly, pass it through a thin pass 10 times, and then sheet it out. After adjusting to room temperature for 24 hours, hot press and vulcanize at 160℃ for 50 minutes at a vulcanization pressure of 10MPa to prepare ablation-resistant EPDM insulation material.

[0063] Example 7

[0064] SR rubber, 100 parts; 2,5-dimethyl-2,5-bis-(tert-butylperoxy)hexane, 3 parts; PBO-3mm, 15 parts; silica, 20 parts; acetal resin, 15 parts. The specific implementation method is as follows:

[0065] Plasticize the SR raw rubber on a two-roll mill for 5 minutes. After mixing evenly, add acetal phenolic resin, PBO-3mm, and silica in sequence. Control the temperature of the rubber compound at about 60℃ and pass it through a thin pass 10 times. Add 2,5-dimethyl-2,5-bis-(tert-butylperoxy)hexane, mix evenly, pass it through a thin pass 10 times, and then sheet it out. After adjusting to room temperature for 24 hours, hot press and vulcanize at 140℃ for 50 minutes at a vulcanization pressure of 10MPa to prepare the ablation-resistant SR insulation material.

[0066] Example 8

[0067] EPDM rubber, 100 parts; guanidine accelerator, 10 parts; sulfur, 3.5 parts; PBO-3mm, 5 parts; silica, 35 parts; paraffin oil, 7 parts. The specific implementation method is as follows:

[0068] The prepared fibers were centrifugally dispersed using a fiber processing device with a fan speed controlled at 1500 r / min. The dispersed fibers were first soaked in anhydrous ethanol for 12 h, washed with distilled water, and finally dried in a vacuum oven at 120°C for 24 h. Fiber modification was performed as follows: 1) The fibers were mixed with a 30% concentration of coupling agent (vinyltriethoxysilane) in a mixture of anhydrous ethanol and distilled water; 2) The mixture was heated for 4 h (60°C); 3) The treated fibers were washed three times with acetone and distilled water and dried at 120°C for 24 h.

[0069] Plasticize EPDM raw rubber on a two-roll mill for 5 minutes. After mixing evenly, add guanidine accelerator, PBO-3mm, silica, and paraffin oil in sequence. Control the temperature of the rubber compound at about 60℃ and pass it through a thin mill 15 times. Add sulfur, mix evenly, pass it through a thin mill 15 times, and then sheet it out. After adjusting to room temperature for 24 hours, hot press and vulcanize at 150℃ for 40 minutes at a vulcanization pressure of 15MPa to prepare ablation-resistant EPDM insulation material.

[0070] Example 9

[0071] NBR, 100 parts; thiazole accelerator, 7 parts; dicumyl peroxide, 3 parts; PBO-3mm, 20 parts; silica, 25 parts; dibutyl phthalate, 15 parts; barium phenolic resin, 20 parts. The specific implementation method is as follows:

[0072] The prepared fibers were centrifugally dispersed using a fiber processing device with a fan speed controlled at 1500 r / min. The dispersed fibers were first soaked in anhydrous ethanol for 12 h, then washed with distilled water, and finally dried in a vacuum oven at 120°C for 24 h. Fiber modification was performed as follows: 1) The fibers were mixed with a 10% concentration of coupling agent (vinyltrimethoxysilane) in a mixture of anhydrous ethanol and distilled water; 2) The mixture was heated for 4 h (60°C); 3) The treated fibers were washed three times with acetone and distilled water and dried at 120°C for 24 h.

[0073] The NBR raw rubber was plasticized on a two-roll mill for 5 minutes. After it was mixed evenly, thiazole accelerator, barium phenolic resin, PBO-3mm, silica, and dibutyl phthalate were added in sequence. The temperature of the rubber compound was controlled at about 60℃. The mixture was passed through a thin mill 10 times. Then, dicumyl peroxide was added and mixed evenly. After passing through a thin mill 10 times, the mixture was sheeted out. After adjusting to room temperature for 24 hours, it was hot-pressed and vulcanized at 160℃ for 70 minutes at a vulcanization pressure of 15MPa to prepare the ablation-resistant NBR insulation material.

[0074] Example 10

[0075] SR rubber, 100 parts; 2,5-dimethyl-2,5-bis-(tert-butylperoxy)hexane, 3 parts; PBO-3mm, 15 parts; silica, 20 parts; acetal resin, 15 parts. The specific implementation method is as follows:

[0076] The prepared fibers were centrifugally dispersed using a fiber processing device with a fan speed controlled at 1500 r / min. The dispersed fibers were first soaked in anhydrous ethanol for 12 h, then washed with distilled water, and finally dried in a vacuum oven at 120 °C for 24 h. Fiber modification was performed as follows: 1) The fibers were mixed with a 20% concentration mixture of anhydrous ethanol and distilled water containing a coupling agent (vinyltris(β-methoxyethoxy)silane); 2) The mixture was heated for 4 h (60 °C); 3) The treated fibers were washed three times with acetone and distilled water and dried at 120 °C for 24 h.

[0077] Plasticize the SR raw rubber on a two-roll mill for 5 minutes. After mixing evenly, add acetal phenolic resin, PBO-3mm, and silica in sequence. Control the temperature of the rubber compound at about 60℃ and pass it through a thin pass 10 times. Add 2,5-dimethyl-2,5-bis-(tert-butylperoxy)hexane, mix evenly, pass it through a thin pass 10 times, and then sheet it out. After adjusting to room temperature for 24 hours, hot press and vulcanize at 140℃ for 50 minutes at a vulcanization pressure of 10MPa to prepare the ablation-resistant SR insulation material.

[0078] Example 11

[0079] EPDM rubber, 100 parts; thiuram-based accelerator, 10 parts; dicumyl peroxide, 2 parts; PBO-3mm, 15 parts; silica, 25 parts; tributyl phosphate, 9 parts; ammonium polyphosphate, 12 parts. The specific implementation method is as follows:

[0080] Plasticize EPDM raw rubber on a two-roll mill for 5 minutes. After mixing evenly, add thiuram-based accelerator, ammonium polyphosphate, fiber, reinforcing agent, and tributyl phosphate in sequence. Control the temperature of the rubber compound at about 60℃ and pass it through a thin pass 15 times. Add dicumyl peroxide and mix evenly. Pass it through a thin pass 15 times and then sheet it. After adjusting to room temperature for 24 hours, hot press and vulcanize at 150℃ for 40 minutes at a vulcanization pressure of 15MPa to prepare ablation-resistant EPDM insulation material.

[0081] Example 12

[0082] EPDM rubber, 100 parts; thiazole accelerator, 15 parts; sulfur / dicumyl peroxide, 2.5 parts; PBO-3mm, 20 parts; silica, 20 parts; decabromodiphenyl ethane, 15 parts. The specific implementation method is as follows:

[0083] Plasticize EPDM raw rubber on a two-roll mill for 5 minutes. After mixing evenly, add thiazole accelerator, decabromodiphenyl ethane, PBO-3mm, and silica in sequence. Control the temperature of the rubber compound at about 60℃ and pass it through a thin pass 15 times. Add sulfur / diisopropylbenzene peroxide, mix evenly, pass it through a thin pass 15 times, and then sheet it out. After adjusting to room temperature for 24 hours, hot press and vulcanize at 150℃ for 40 minutes at a vulcanization pressure of 15MPa to prepare ablation-resistant EPDM insulation material.

[0084] Example 13

[0085] NBR, 100 parts; thiuram-based accelerator, 10 parts; sulfur, 4 parts; PBO-6mm, 8 parts; silica, 35 parts; tributyl phosphate, 8 parts; ammonium polyphosphate, 25 parts; acetal-phenolic resin, 20 parts. The specific implementation method is as follows:

[0086] The NBR raw rubber is plasticized on a two-roll mill for 5 minutes. After it is mixed evenly, thiuram-based accelerator, ammonium polyphosphate, acetal phenolic resin, PBO-6mm, silica, and tributyl phosphate are added in sequence. The temperature of the rubber compound is controlled at about 60℃. The mixture is passed through a thin mill 10 times. Sulfur is added and mixed evenly. The mixture is then passed through a thin mill 10 times and sheeted out. After adjusting to room temperature for 24 hours, it is hot-pressed and vulcanized at 160℃ for 70 minutes at a vulcanization pressure of 15MPa to prepare the ablation-resistant NBR insulation material.

[0087] Example 14

[0088] EPDM rubber, 100 parts; sulfenamide accelerator, 15 parts; sulfur / dicumyl peroxide, 5 parts; PBO-3mm, 20 parts; silica, 35 parts; paraffin oil, 7 parts. Specific implementation method is as follows:

[0089] The prepared fibers were centrifugally dispersed using a fiber processing device with a fan speed controlled at 1500 r / min. The dispersed fibers were first soaked in anhydrous ethanol for 12 h, then washed with distilled water, and finally dried in a vacuum oven at 120°C for 24 h. Fiber modification was performed as follows: 1) The fibers were mixed with a 35% concentration of coupling agent (vinyltrimethoxysilane) in a mixture of anhydrous ethanol and distilled water; 2) The mixture was heated for 4 h (60°C); 3) The treated fibers were washed three times with acetone and distilled water and dried at 120°C for 24 h.

[0090] Plasticize EPDM raw rubber on a two-roll mill for 5 minutes. After mixing evenly, add sulfenamide accelerator, PBO-3mm, silica, and paraffin oil in sequence. Control the temperature of the rubber compound at about 70℃ and pass it through a thin pass 20 times. Add sulfur / diisopropylbenzene peroxide, mix evenly, pass it through a thin pass 20 times, and then sheet it out. After adjusting to room temperature for 24 hours, hot press and vulcanize at 170℃ for 55 minutes at a vulcanization pressure of 10MPa to prepare ablation-resistant EPDM insulation material.

[0091] Example 15

[0092] EPDM rubber, 100 parts; thiazole accelerator, 12 parts; dicumyl peroxide, 3 parts; PBO pulp, 25 parts; silica, 25 parts; paraffin oil, 15 parts; boron phenolic resin FBO-389, 20 parts. The specific implementation method is as follows:

[0093] Plasticize EPDM raw rubber on a two-roll mill for 5 minutes. After mixing evenly, add thiazole accelerator, boron phenolic resin FBO-389, fiber, reinforcing agent, and plasticizer in sequence. Control the temperature of the rubber compound at about 50℃ and pass it through a thin pass 15 times. Add vulcanizing agent, mix evenly, pass it through a thin pass 15 times, and then sheet it out. After adjusting to room temperature for 24 hours, hot press vulcanize it at 160℃ for 60 minutes at a vulcanization pressure of 15MPa to prepare ablation-resistant EPDM insulation material.

[0094] Example 16

[0095] EPDM rubber, 100 parts; sulfenamide accelerator, 16 parts; sulfur / dicumyl peroxide, 4 parts; PBO-3mm, 20 parts; silica, 20 parts; boron phenolic resin SFB, 10 parts. The specific implementation method is as follows:

[0096] Plasticize EPDM raw rubber on a two-roll mill for 5 minutes. After mixing evenly, add sulfenamide accelerator, boron phenolic resin SFB, PBO-3mm, and silica in sequence. Control the temperature of the rubber compound at about 50℃ and pass it through a thin pass 15 times. Add sulfur / diisopropylbenzene peroxide, mix evenly, pass it through a thin pass 15 times, and then sheet it. After adjusting to room temperature for 24 hours, hot press and vulcanize at 160℃ for 60 minutes at a vulcanization pressure of 10MPa to prepare ablation-resistant EPDM insulation material.

[0097] Example 17

[0098] NBR, 100 parts; thiazole accelerator, 7 parts; dicumyl peroxide, 3 parts; PBO-3mm, 20 parts; silica, 25 parts; dibutyl phthalate, 15 parts; barium phenolic resin, 20 parts. The specific implementation method is as follows:

[0099] The NBR raw rubber was plasticized on a two-roll mill for 5 minutes. After it was mixed evenly, thiazole accelerator, barium phenolic resin, PBO-3mm, silica, and dibutyl phthalate were added in sequence. The temperature of the rubber compound was controlled at about 60℃. The mixture was passed through a thin mill 10 times. Then, dicumyl peroxide was added and mixed evenly. After passing through a thin mill 10 times, the mixture was sheeted out. After adjusting to room temperature for 24 hours, it was hot-pressed and vulcanized at 160℃ for 50 minutes at a vulcanization pressure of 15MPa to prepare the ablation-resistant NBR insulation material.

[0100] Example 18

[0101] EPDM rubber, 100 parts; sulfur / dicumyl peroxide, 2.5 parts; PBO-3mm, 18 parts; silica, 30 parts; ammonium polyphosphate, 18 parts; boron phenolic resin TH-390, 20 parts. The specific implementation method is as follows:

[0102] Plasticize EPDM raw rubber on a two-roll mill for 5 minutes. After mixing evenly, add ammonium polyphosphate, boron phenolic resin TH-390, PBO-3mm, and silica in sequence. Control the temperature of the rubber compound at about 50℃ and pass it through a thin pass 15 times. Add sulfur / diisopropylbenzene peroxide, mix evenly, pass it through a thin pass 15 times, and then sheet it out. After adjusting to room temperature for 24 hours, hot press and vulcanize at 160℃ for 60 minutes at a vulcanization pressure of 15MPa to prepare ablation-resistant EPDM insulation material.

[0103] Example 19

[0104] EPDM rubber, 100 parts; thiuram-based accelerator, 7 parts; dicumyl peroxide, 3.5 parts; PBO-6mm, 15 parts; silica, 25 parts; boron phenolic resin THC-400, 5 parts. The specific implementation method is as follows:

[0105] Plasticize the EPDM raw rubber on a two-roll mill for 5 minutes. After mixing evenly, add thiuram-based accelerator, boron phenolic resin THC-400, PBO-6mm, and silica in sequence. Control the temperature of the rubber compound at about 50℃ and pass it through a thin pass 15 times. Add dicumyl peroxide and mix evenly. Pass it through a thin pass 15 times and then sheet it. After adjusting to room temperature for 24 hours, hot press and vulcanize at 160℃ for 50 minutes at a vulcanization pressure of 10MPa to prepare ablation-resistant EPDM insulation material.

[0106] Example 20

[0107] SR rubber, 100 parts; thiazole accelerator, 15 parts; dicumyl peroxide, 4 parts; PBO-6mm, 15 parts; carbon black, 40 parts. The specific implementation method is as follows:

[0108] Plasticize the SR raw rubber on a two-roll mill for 5 minutes. After mixing evenly, add thiazole accelerator, PBO-6mm, and carbon black in sequence. Control the temperature of the rubber compound at about 60℃ and pass it through a thin pass 10 times. Add dicumyl peroxide and mix evenly. Pass it through a thin pass 10 times and then sheet it out. After adjusting to room temperature for 24 hours, hot press and vulcanize at 140℃ for 50 minutes at a vulcanization pressure of 10MPa to prepare the ablation-resistant SR insulation material.

[0109] Example 21

[0110] EPDM rubber, 100 parts; sulfur, 1.5 parts; PBO-6mm, 30 parts; silica, 35 parts; dioctyl sebacate, 9 parts; decabromodiphenyl ethane, 20 parts; boron phenolic resin FBO-389, 6 parts. The specific implementation method is as follows:

[0111] Plasticize EPDM raw rubber on a two-roll mill for 5 minutes. After mixing evenly, add decabromodiphenyl ethane, boron phenolic resin FBO-389, PBO-6mm, silica, and dioctyl sebacate in sequence. Control the temperature of the rubber compound at about 50℃ and pass it through a thin pass 10 times. Add sulfur, mix evenly, pass it through a thin pass 10 times, and then sheet it out. After adjusting to room temperature for 24 hours, hot press and vulcanize at 160℃ for 50 minutes at a vulcanization pressure of 10MPa to prepare ablation-resistant EPDM insulation material.

[0112] Example 22

[0113] EPDM rubber, 100 parts; sulfur / dicumyl peroxide, 2 parts; PBO-3mm, 28 parts; silica, 40 parts; paraffin oil, 15 parts; boron phenolic resin FBO-389, 12 parts. The specific implementation method is as follows:

[0114] Plasticize the EPDM raw rubber on a two-roll mill for 5 minutes. After mixing evenly, add boron phenolic resin FBO-389, PBO-3mm, silica, and paraffin oil in sequence. Control the temperature of the rubber compound at about 50℃ and pass it through a thin pass 10 times. Add sulfur / diisopropylbenzene peroxide, mix evenly, pass it through a thin pass 10 times, and then sheet it out. After adjusting to room temperature for 24 hours, hot press and vulcanize at 150℃ for 50 minutes at a vulcanization pressure of 10MPa to prepare the ablation-resistant EPDM thermal insulation material.

[0115] Example 23

[0116] EPDM rubber, 100 parts; thiazole accelerator, 8 parts; sulfur / dicumyl peroxide, 3 parts; PBO-3mm, 25 parts; silica, 30 parts; boron phenolic resin FBO-389, 18 parts. The specific implementation method is as follows:

[0117] Plasticize EPDM raw rubber on a two-roll mill for 5 minutes. After mixing evenly, add thiazole accelerator, boron phenolic resin FBO-389, PBO-3mm, and silica in sequence. Control the temperature of the rubber compound at about 50℃ and pass it through a thin pass 10 times. Add sulfur / diisopropylbenzene peroxide, mix evenly, pass it through a thin pass 10 times, and then sheet it out. After adjusting to room temperature for 24 hours, hot press and vulcanize at 160℃ for 50 minutes at a vulcanization pressure of 10MPa to prepare ablation-resistant EPDM insulation material.

[0118] Example 24

[0119] SR rubber, 100 parts; thiuram-based accelerator, 10 parts; benzoyl peroxide, 3 parts; PBO-9mm, 20 parts; carbon black, 20 parts; acetaminophen-formaldehyde resin, 30 parts. The specific implementation method is as follows:

[0120] Plasticize the SR raw rubber on a two-roll mill for 5 minutes. After mixing evenly, add thiuram-based accelerator, acetal phenol-formaldehyde resin, PBO-9mm, and carbon black in sequence. Control the temperature of the rubber compound at about 60℃ and pass it through a thin pass 10 times. Add benzoyl peroxide, mix evenly, pass it through a thin pass 10 times, and then sheet it out. After adjusting to room temperature for 24 hours, hot press and vulcanize it at 140℃ for 50 minutes at a vulcanization pressure of 10MPa to prepare the ablation-resistant SR thermal insulation material.

[0121] Example 25

[0122] EPDM rubber, 100 parts; dicumyl peroxide, 5 parts; PBO-3mm, 20 parts; silica, 40 parts; ammonium polyphosphate, 30 parts. The specific implementation method is as follows:

[0123] Plasticize EPDM raw rubber on a two-roll mill for 5 minutes. After mixing evenly, add ammonium polyphosphate, PBO-3mm, and silica in sequence, controlling the rubber temperature at around 50℃. Pass through a thin pass 10 times. Add dicumyl peroxide, mix evenly, pass through a thin pass 10 times, and then sheet it out. After adjusting to room temperature for 24 hours, hot press and vulcanize at 150℃ for 70 minutes at a vulcanization pressure of 5MPa to prepare ablation-resistant EPDM insulation material.

[0124] Example 26

[0125] EPDM rubber, 100 parts; thiazole accelerator, 15 parts; benzoyl peroxide, 4.5 parts; PBO-6mm, 10 parts; silica, 30 parts; dioctyl sebacate, 8 parts; aluminum hydroxide, 20 parts. The specific implementation method is as follows:

[0126] Plasticize EPDM raw rubber on a two-roll mill for 5 minutes. After mixing evenly, add thiazole accelerator, aluminum hydroxide, PBO-6mm, silica, and dioctyl sebacate in sequence. Control the temperature of the rubber compound at about 50℃ and pass it through a thin pass 10 times. Add benzoyl peroxide, mix evenly, pass it through a thin pass 10 times, and then sheet it out. After adjusting to room temperature for 24 hours, hot press and vulcanize at 150℃ for 70 minutes at a vulcanization pressure of 5MPa to prepare ablation-resistant EPDM insulation material.

[0127] Example 27

[0128] EPDM rubber, 100 parts; sulfur / benzoyl peroxide, 3 parts; PBO-3mm, 30 parts; silica, 35 parts; decabromodiphenyl ethane, 10 parts. The specific implementation method is as follows:

[0129] Plasticize EPDM raw rubber on a two-roll mill for 5 minutes. After mixing evenly, add decabromodiphenyl ethane, PBO-3mm, and silica in sequence. Control the temperature of the rubber compound at about 50℃ and pass it through a thin pass 10 times. Add sulfur / benzoyl peroxide, mix evenly, pass it through a thin pass 10 times, and then sheet it out. After adjusting to room temperature for 24 hours, hot press and vulcanize at 150℃ for 70 minutes at a vulcanization pressure of 5MPa to prepare ablation-resistant EPDM insulation material.

[0130] Example 28

[0131] NBR, 100 parts; guanidine accelerator, 15 parts; sulfur, 2 parts; PBO-3mm, 20 parts; silica, 25 parts; acetal resin, 10 parts; silazane, 15 parts. The specific implementation method is as follows:

[0132] The NBR raw rubber is plasticized on a two-roll mill for 5 minutes. After it is mixed evenly, guanidine accelerator, acetal phenolic resin, PBO-3mm, silica, and silazane are added in sequence. The temperature of the rubber compound is controlled at about 60℃. The mixture is passed through a thin mill 10 times. Sulfur is added and the mixture is mixed evenly. After passing through a thin mill 10 times, the mixture is sheeted out. After adjusting to room temperature for 24 hours, it is hot-pressed and vulcanized at 160℃ for 50 minutes at a vulcanization pressure of 15MPa to prepare the ablation-resistant NBR insulation material.

[0133] Example 29

[0134] EPDM rubber, 100 parts; guanidine accelerator, 12 parts; sulfur / dicumyl peroxide, 2 parts; PBO-3mm, 35 parts; silica, 25 parts; paraffin oil, 18 parts; barium phenolic resin, 20 parts. The specific implementation method is as follows:

[0135] Plasticize EPDM raw rubber on a two-roll mill for 5 minutes. After mixing evenly, add guanidine accelerator, barium phenolic resin, PBO-3mm, silica, and paraffin oil in sequence. Control the temperature of the rubber compound at about 50℃ and pass it through a thin pass 10 times. Add sulfur / diisopropylbenzene peroxide, mix evenly, pass it through a thin pass 10 times, and then sheet it out. After adjusting to room temperature for 24 hours, hot press and vulcanize at 150℃ for 60 minutes at a vulcanization pressure of 5MPa to prepare ablation-resistant EPDM insulation material.

[0136] Example 30

[0137] SR rubber, 100 parts; guanidine accelerator, 7 parts; 2,5-dimethyl-2,5-bis-(tert-butylperoxy)hexane, 4 parts; PBO-3mm, 25 parts; silica, 30 parts. The specific implementation method is as follows:

[0138] Plasticize SR raw rubber on a two-roll mill for 5 minutes. After mixing evenly, add guanidine accelerator, PBO-3mm, and silica in sequence. Control the temperature of the rubber compound at about 60℃ and pass it through a thin pass 10 times. Add 2,5-dimethyl-2,5-bis-(tert-butylperoxy)hexane, mix evenly, pass it through a thin pass 10 times, and then sheet it out. After adjusting to room temperature for 24 hours, hot press and vulcanize at 160℃ for 40 minutes at a vulcanization pressure of 15MPa to prepare ablation-resistant SR insulation material.

[0139] Example 31

[0140] EPDM rubber, 100 parts; benzoyl peroxide, 4 parts; PBO-3mm, 20 parts; silica, 35 parts; tributyl phosphate, 6 parts. The specific implementation method is as follows:

[0141] Plasticize EPDM raw rubber on a two-roll mill for 5 minutes. After mixing evenly, add PBO-3mm, silica, and tributyl phosphate in sequence. Control the temperature of the rubber compound at about 50℃ and pass it through a thin pass 10 times. Add benzoyl peroxide, mix evenly, pass it through a thin pass 10 times, and then sheet it out. After adjusting to room temperature for 24 hours, hot press and vulcanize at 160℃ for 55 minutes at a vulcanization pressure of 15MPa to prepare ablation-resistant EPDM thermal insulation material.

[0142] Example 32

[0143] NBR, 100 parts; sulfur, 4 parts; PBO pulp, 20 parts; carbon black, 25 parts; boron phenolic resin TH-390, 5 parts; siloxane, 5 parts. The specific implementation method is as follows:

[0144] Plasticize the NBR raw rubber on a two-roll mill for 5 minutes. After mixing evenly, add boron phenolic resin TH-390, PBO pulp, carbon black, and siloxane in sequence. Control the temperature of the rubber compound at about 60℃ and pass it through a thin pass 10 times. Add sulfur, mix evenly, pass it through a thin pass 10 times, and then sheet it out. After adjusting to room temperature for 24 hours, hot press and vulcanize it at 150℃ for 40 minutes at a vulcanization pressure of 15MPa to prepare the ablation-resistant NBR insulation material.

[0145] Example 33

[0146] EPDM rubber, 100 parts; thiazole accelerator, 6 parts; sulfur / dicumyl peroxide, 4.5 parts; PBO-9mm, 15 parts; silica, 40 parts; silazane, 5 parts. The specific implementation method is as follows:

[0147] Plasticize EPDM raw rubber on a two-roll mill for 5 minutes. After mixing evenly, add thiazole accelerator, PBO-9mm, silica, and silazane in sequence. Control the temperature of the rubber compound at about 60℃ and pass it through a thin pass 10 times. Add sulfur / diisopropylbenzene peroxide, mix evenly, pass it through a thin pass 10 times, and then sheet it. After adjusting to room temperature for 24 hours, hot press and vulcanize at 140℃ for 70 minutes at a vulcanization pressure of 15MPa to prepare ablation-resistant EPDM insulation material.

[0148] Example 34

[0149] NBR, 100 parts; thiazole accelerator, 8 parts; dicumyl peroxide, 3 parts; PBO-3mm, 25 parts; silica, 35 parts; paraffin oil, 5 parts; silazane, 10 parts. The specific implementation method is as follows:

[0150] The NBR raw rubber was plasticized on a two-roll mill for 5 minutes. After it was mixed evenly, thiazole accelerator, PBO-3mm, silica, paraffin oil and silazane were added in sequence. The temperature of the rubber compound was controlled at about 60℃. The mixture was passed through a thin pass 10 times. Then dicumyl peroxide was added and mixed evenly. After passing through a thin pass 10 times, the mixture was sheeted out. After adjusting to room temperature for 24 hours, it was hot-pressed and vulcanized at 160℃ for 70 minutes at a vulcanization pressure of 15MPa to prepare the ablation-resistant NBR insulation material.

[0151] Example 35

[0152] EPDM rubber, 100 parts; dicumyl peroxide, 1 part; PBO-3mm, 8 parts; silica, 20 parts; dioctyl sebacate, 10 parts; silazane, 10 parts. The specific implementation method is as follows:

[0153] Plasticize EPDM raw rubber on a two-roll mill for 5 minutes. After mixing evenly, add PBO-3mm, silica, dioctyl sebacate, and silazane in sequence. Control the temperature of the rubber compound at about 60℃ and pass it through a thin pass 10 times. Add dicumyl peroxide and mix evenly. Pass it through a thin pass 10 times and then sheet it. After adjusting to room temperature for 24 hours, hot press and vulcanize at 150℃ for 60 minutes at a vulcanization pressure of 15MPa to prepare ablation-resistant EPDM insulation material.

[0154] Example 36

[0155] SR rubber, 100 parts; dicumyl peroxide, 2 parts; PBO pulp, 15 parts; silica, 20 parts; siloxane, 5 parts. The specific implementation method is as follows:

[0156] Plasticize SR raw rubber on a two-roll mill for 5 minutes. After mixing evenly, add PBO pulp, silica, and siloxane in sequence, control the rubber temperature at about 60℃, and pass through a thin pass 10 times. Add dicumyl peroxide, mix evenly, pass through a thin pass 10 times, and then sheet it out. After adjusting to room temperature for 24 hours, hot press and vulcanize at 140℃ for 50 minutes at a vulcanization pressure of 10MPa to prepare ablation-resistant SR insulation material.

[0157] Example 37

[0158] EPDM rubber, 100 parts; sulfur / dicumyl peroxide, 2.5 parts; PBO pulp, 20 parts; silica, 25 parts; ammonium polyphosphate, 20 parts; siloxane, 15 parts. The specific implementation method is as follows:

[0159] Plasticize EPDM raw rubber on a two-roll mill for 5 minutes. After mixing evenly, add ammonium polyphosphate, PBO pulp, silica, and siloxane in sequence. Control the temperature of the rubber compound at about 60℃ and pass it through a thin pass 10 times. Add sulfur / diisopropylbenzene peroxide, mix evenly, pass it through a thin pass 10 times, and then sheet it out. After adjusting to room temperature for 24 hours, hot press and vulcanize at 160℃ for 50 minutes at a vulcanization pressure of 15MPa to prepare ablation-resistant EPDM insulation material.

[0160] Example 38

[0161] EPDM rubber, 100 parts; thiuram-based accelerator, 12 parts; dicumyl peroxide, 1 part; PBO-3mm, 25 parts; silica, 35 parts; acetal resin, 15 parts; siloxane, 20 parts. The specific implementation method is as follows:

[0162] Plasticize EPDM raw rubber on a two-roll mill for 5 minutes. After mixing evenly, add thiuram-based accelerator, acetal phenolic resin, PBO-3mm, silica, and siloxane in sequence. Control the temperature of the rubber compound at about 60℃ and pass it through a thin pass 10 times. Add dicumyl peroxide and mix evenly. Pass it through a thin pass 10 times and then sheet it. After adjusting to room temperature for 24 hours, hot press and vulcanize at 140℃ for 70 minutes at a vulcanization pressure of 15MPa to prepare ablation-resistant EPDM insulation material.

[0163] Example 39

[0164] EPDM rubber, 100 parts; sulfenamide accelerator, 15 parts; sulfur / dicumyl peroxide, 5 parts; PBO-3mm, 20 parts; silica, 35 parts; paraffin oil, 7 parts. Specific implementation method is as follows:

[0165] Plasticize EPDM raw rubber on a two-roll mill for 5 minutes. After mixing evenly, add sulfenamide accelerator, PBO-3mm, silica, and paraffin oil in sequence. Control the temperature of the rubber compound at about 70℃ and pass it through a thin pass 20 times. Add sulfur / diisopropylbenzene peroxide, mix evenly, pass it through a thin pass 20 times, and then sheet it out. After adjusting to room temperature for 24 hours, hot press and vulcanize at 160℃ for 55 minutes at a vulcanization pressure of 10MPa to prepare ablation-resistant EPDM insulation material.

[0166] Comparative Example 1

[0167] EPDM rubber, 100 parts; thiazole accelerator, 12 parts; sulfur, 2 parts; PF, 12 parts; silica, 25 parts; magnesium hydroxide, 10 parts. The specific implementation method is as follows:

[0168] Plasticize EPDM raw rubber on a two-roll mill for 3 minutes. After mixing evenly, add thiazole accelerator, magnesium hydroxide, PF, and silica in sequence. Control the temperature of the rubber compound at about 60℃ and pass it through a thin pass 15 times. Add sulfur, mix evenly, pass it through a thin pass 15 times, and then sheet it out. After adjusting to room temperature for 24 hours, hot press and vulcanize at 150℃ for 60 minutes at a vulcanization pressure of 10MPa to prepare ablation-resistant EPDM insulation material.

[0169] Comparative Example 2

[0170] EPDM rubber, 100 parts; thiazole accelerator, 9 parts; dicumyl peroxide, 4 parts; PI, 15 parts; silica, 30 parts; ammonium polyphosphate, 15 parts. The specific implementation method is as follows:

[0171] Plasticize EPDM raw rubber on a two-roll mill for 3 minutes. After mixing evenly, add thiazole accelerator, ammonium polyphosphate, PI, and silica in sequence. Control the temperature of the rubber compound at about 60℃ and pass it through a thin pass 15 times. Add dicumyl peroxide and mix evenly. Pass it through a thin pass 15 times and then sheet it out. After adjusting to room temperature for 24 hours, hot press and vulcanize at 160℃ for 60 minutes at a vulcanization pressure of 10MPa to prepare ablation-resistant EPDM insulation material.

[0172] Comparative Example 3

[0173] SR rubber, 100 parts; 2,5-dimethyl-2,5-bis-(tert-butylperoxy)hexane, 2 parts; KF, 15 parts; carbon black, 30 parts; boron phenolic resin TH-390, 20 parts. The specific implementation method is as follows:

[0174] Plasticize the SR raw rubber on a two-roll mill for 5 minutes. After mixing evenly, add boron phenolic resin TH-390, KF, and carbon black in sequence, controlling the temperature of the rubber compound at about 60℃. Pass through the mill 10 times. Add 2,5-dimethyl-2,5-bis-(tert-butylperoxy)hexane, mix evenly, pass through the mill 10 times, and then sheet it out. After adjusting to room temperature for 24 hours, hot press and vulcanize at 150℃ for 50 minutes at a vulcanization pressure of 10MPa to prepare the ablation-resistant SR thermal insulation material.

[0175] Comparative Example 4

[0176] EPDM rubber, 100 parts; thiuram-based accelerator, 5 parts; dicumyl peroxide, 5 parts; KF, 18 parts; silica, 35 parts; aluminum hydroxide, 20 parts. The specific implementation method is as follows:

[0177] Plasticize EPDM raw rubber on a two-roll mill for 3 minutes. After mixing evenly, add thiuram-based accelerator, aluminum hydroxide, KF, and silica in sequence. Control the temperature of the rubber compound at about 60℃ and pass it through a thin pass 15 times. Add dicumyl peroxide and mix evenly. Pass it through a thin pass 15 times and then sheet it out. After adjusting to room temperature for 24 hours, hot press and vulcanize at 160℃ for 55 minutes at a vulcanization pressure of 10MPa to prepare ablation-resistant EPDM insulation material.

[0178] Comparative Example 5

[0179] NBR rubber, 100 parts; thiuram-based accelerator, 5 parts; benzoyl peroxide, 2 parts; PI pulp, 20 parts; silica, 35 parts; acetal resin, 10 parts. The specific implementation method is as follows:

[0180] The NBR raw rubber is plasticized on a two-roll mill for 5 minutes. After it is mixed evenly, thiuram-based accelerator, acetal resin, PI pulp, and silica are added in sequence. The temperature of the rubber compound is controlled at about 60℃. The mixture is passed through a thin mill 10 times. Benzoyl peroxide is added and mixed evenly. The mixture is then passed through a thin mill 10 times and sheeted out. After adjusting to room temperature for 24 hours, it is hot-pressed and vulcanized at 160℃ for 50 minutes at a vulcanization pressure of 10MPa to prepare the ablation-resistant NBR insulation material.

[0181] Comparative Example 6

[0182] The ingredients are: 90 parts EPDM rubber, 10 parts PZ rubber, 5 parts thiazole additive, 2 parts dicumyl peroxide, 15 parts PBO-3mm, 35 parts silica, and 10 parts phenolic resin. The specific implementation method is as follows:

[0183] Plasticize EPDM / PZ raw rubber on a two-roll mill for 5 minutes. After mixing evenly, add thiazole accelerator, acetal phenolic resin, PBO-3mm, and silica in sequence. Control the temperature of the rubber compound at about 60℃ and pass it through a thin pass 10 times. Add dicumyl peroxide and mix evenly. Pass it through a thin pass 10 times and then sheet it. After adjusting to room temperature for 24 hours, hot press and vulcanize at 160℃ for 60 minutes at a vulcanization pressure of 15MPa to prepare ablation-resistant EPDM / PZ thermal insulation material.

[0184] In the above embodiments and comparative examples, the tensile strength and elongation at break of the insulation material were determined according to GB / T 528-2009 Determination of tensile stress-strain properties of vulcanized rubber or thermoplastic rubber; the linear ablation rate was determined according to GJB 323A-96 Ablation test method for ablation materials; the density was determined according to GB / T 533-2008 Determination of density of vulcanized rubber or thermoplastic rubber; and the bond strength with metal was determined according to GB / T 13936-2014 Determination of tensile shear strength of bond between vulcanized rubber and metal.

[0185] Table 1 Comparison of insulation material performance between examples and comparative examples

[0186]

[0187]

[0188] From the mechanical property data in Table 1, it can be concluded that the insulation material and its preparation method in the embodiment can still maintain good mechanical properties even when there is too much fiber filling. That is, the mechanical properties are basically the same in the parallel calendering direction and the perpendicular calendering direction. In addition, the insulation material in the embodiment has a low density, which effectively reduces the mass of the insulation material, thereby reducing the negative mass of the engine and ultimately increasing the range of the engine.

[0189] Example 8, along with Comparative Examples 1, 2, and 4, describes the effect of fibers on material properties. Figure 1 Among the various fibers, PF, PI, and KF have relatively smooth surfaces, while PBO fibers have a rougher surface than the other three. Figure 3 As can be seen from the PF image, the tensile cross-section of the EPDM / PF material exhibits numerous short PF fiber stubs. The fiber pull-out holes show no obvious stretching of the fibers, and the absence of EPDM matrix adhesion on the fiber surface indicates weak interfacial bonding between the PF fibers and the matrix, hindering their load-bearing capacity and limiting their high performance. This is related to the inherent properties of PF fibers; due to their brittleness, they are prone to breakage during insulation material processing, failing to maintain their original shape and weakening their ability to serve as a carbon layer skeleton, resulting in lower carbon layer strength and increased ablation rate. The PI image shows significant stretching of the PI fibers in the EPDM / PI tensile cross-section. Due to their high flexibility, PI fibers are not easily damaged during processing and maintain their original shape. However, the absence of EPDM matrix adhesion on the pulled-out fiber surface indicates weak interfacial bonding between the PI fibers and the EPDM matrix. The KF fibers exhibit significant tensile stress at the cross-section, and the fiber surface is adhered to a layered EPDM matrix film, indicating a good interfacial bond between the KF fibers and the EPDM matrix. However, the EPDM / KF cross-section shows KF fiber agglomeration, meaning there is no rubber matrix at this point; the fibers are entangled and clustered together. When the material is subjected to external tensile force, stress concentration occurs at this point, leading to material failure. This is consistent with the changes in the mechanical properties of EPDM / KF. The PBO diagram shows significant tensile stress on the PBO fibers, which are stretched into a bent and thin state, appearing somewhat disordered. They clearly bear a certain amount of force, and the fiber surface is adhered to an EPDM matrix film, indicating a strong interfacial bond between the PBO fibers and the EPDM matrix. This is beneficial for stress transfer, leveraging the high performance of the fibers, effectively reinforcing the thermal insulation material, and meeting the operating requirements of rocket engines.

[0190] Examples 17 and 9, 7 and 10, and 39 and 14 respectively describe the effects of PBO fiber modification on the properties of NBR, SR, and EPDM insulation materials. Taking EPDM / PBO as an example, the microstructure of the tensile specimen cross-section and the dispersion of fibers in the material matrix before and after modification are shown below. Figure 4 As shown. From Figure 4 As can be seen, the fibers exhibit tensile activity at the cross-section, indicating that they effectively bear the load when the material is subjected to external forces. After treatment, the pores left by the pulled-out fibers and the fibers remaining in the matrix are clearly visible on the cross-sectional surface, evenly distributed. Microscopic images also show that the modified fibers are more uniformly dispersed in the matrix, avoiding stress concentration caused by uneven dispersion. This is beneficial for the material to withstand greater external forces and improves its mechanical properties. Furthermore, the alkoxy group at one end of the silane coupling agent hydrolyzes to form silanol groups, which are oriented on the fiber surface, while the organic groups at the other end of the coupling agent are oriented on the rubber material surface, participating in the cross-linking and curing reaction. Ultimately, this forms a bridge connecting the fibers and the rubber matrix, enhancing the interfacial bonding force between the fibers and the rubber matrix, making the material denser and stronger, and demonstrating a significant fiber reinforcement effect.

[0191] As can be seen from the microscopic morphology images of the surface and cross-section of the carbon layer after ablation of the sample in Example 3, PBO fibers can promote the connection of carbon residues in the insulation material matrix and form a dense and robust carbonized layer. The fibers, as embedded skeletons of the carbonized matrix, strengthen the carbon layer, prevent delamination and peeling, and effectively improve the resistance to erosion by high-speed heat flow. In addition, the high thermal stability of the fibers helps to maintain the original structure and morphology and strengthen the carbon layer.

[0192] This invention successfully prepared a solid rocket motor internal insulation layer material with high ablation resistance, low density, excellent metal adhesion and mechanical properties by optimizing and modifying PBO fibers and comprehensively formulating ablation-resistant resin, flame retardant system, plasticizer and other components.

[0193] The above embodiments are further detailed descriptions of the present invention and are not intended to limit the present invention. For those skilled in the art, various equivalent substitutions or improvements can be made to the technical solutions and implementation methods of the present invention. It is impossible to exhaustively list all implementation methods here. Any obvious changes or modifications derived from the technical solutions of the present invention are still within the protection scope of the present invention.

Claims

1. Application of a PBO fiber-filled rubber-type ablation-resistant thermal insulation material for use in solid rocket insulation layers; The composition of the PBO fiber-filled rubber-type ablation-resistant thermal insulation material is as follows: NBR, 100 parts; thiazole accelerator, 7 parts; dicumyl peroxide, 3 parts; PBO-3 mm, 20 parts; silica, 25 parts; dibutyl phthalate, 15 parts; barium phenolic resin, 20 parts. The preparation methods include the following: The fibers were centrifugally dispersed using a fiber processing device with a fan speed of 1500 r / min. The dispersed fibers were first soaked in anhydrous ethanol for 12 h, then washed with distilled water, and finally dried in a vacuum oven at 120 ℃ for 24 h. Fiber modification was carried out as follows: 1) The fibers were mixed with a mixture of anhydrous ethanol and distilled water containing 10% vinyltrimethoxysilane coupling agent; 2) The mixture was heated to 60 ℃ and reacted for 4 h; 3) The treated fibers were washed three times with acetone and distilled water and dried at 120 ℃ for 24 h. The NBR raw rubber was plasticized on a two-roll mill for 5 minutes. After it was mixed evenly, thiazole accelerator, barium phenolic resin, PBO-3 mm, silica, and dibutyl phthalate were added in sequence. The temperature of the rubber compound was controlled at 60 ℃, and it was passed through a thin mill 10 times. Then, dicumyl peroxide was added, and the mixture was mixed evenly and passed through a thin mill 10 times before being sheeted. After adjusting to room temperature for 24 hours, it was hot-pressed and vulcanized at 160 ℃ for 70 minutes at a vulcanization pressure of 15 MPa to prepare the ablation-resistant NBR insulation material.

Images