Carbon fiber reinforced ethylene-propylene-diene monomer / polyphosphazene scouring-resistant thermal insulation material and preparation method thereof

Abstract

The invention relates to the technical field of thermal insulation materials, and particularly discloses a carbon fiber reinforced ethylene-propylene-diene monomer / polyphosphazene scouring-resistant thermal insulation material and a preparation method thereof. The thermal insulation material is prepared by taking carbon fibers as a framework, dipping ethylene-propylene-diene monomer / polyphosphazene rubber and vulcanizing, the ethylene-propylene-diene monomer / polyphosphazene rubber material is prepared from the following raw materials: ethylene-propylene-diene monomer, polyphosphazene, ablation-resistant resin, a flame retardant, a vulcanizing agent and a vulcanization accelerator. During preparation, the ethylene propylene diene monomer and the polyphosphazene are plastified firstly and then mixed with other raw materials to prepare green sheets, and the green sheets are dissolved with a solution and then subjected to vacuum impregnation, drying and vulcanization forming of the carbon fibers. According to the invention, the EPDM and polyphosphazene composite matrix is used as a dipping glue solution, so that the prepared C3D / EPDM / PZ scouring-resistant thermal insulation material has the advantages of low smoke, flame retardance, ablation resistance and the like compared with the traditional rubber-based thermal insulation material, and has good interface adhesion with EPDM (Ethylene-Propylene-Diene Monomer).

Description

Technical Field

[0001] The invention relates to the technical field of thermal protection materials for solid rocket engines, and in particular to a carbon fiber reinforced EPDM / polyphosphazene erosion-resistant insulation material and a preparation method thereof. Background Art

[0002] The insulation layer of a solid rocket engine is located between the engine casing and the solid propellant. It takes away most of the heat through continuous decomposition and ablation, thereby protecting the engine casing from damage by high-temperature, high-pressure combustion gases. As a new type of thermal protection material, carbon fiber reinforced erosion-resistant insulation material is mainly composed of a carbon fiber reinforcement phase and a flexible resin matrix. It has the advantages of high strength, high carbonization and high temperature resistance, and is often used as a reinforcement layer for the insulation layer of a solid rocket engine. Ethylene propylene diene monomer (EPDM) has the advantages of low density, high temperature resistance and aging resistance. It is currently the most widely used insulation material, but due to its low oxygen index, it will produce a lot of smoke when burned, which can easily expose the launch site and trajectory of the missile. Polyphosphazene (PZ) is an inorganic polymer material with the advantages of less smoke, erosion resistance and low ablation rate, which can be used to prepare low-smoke flame-retardant insulation materials.

[0003] CN113861699 A discloses a low-smoke flame-retardant ablation-resistant thermal insulation material that is resistant to small molecule migration and has low smoke emission, and a preparation method thereof. A polyphosphazene elastomer matrix, an activator, a reinforcing agent, a heat-resistant filler, an ablation-resistant filler, etc. are prepared into a mixed rubber by a solid phase mixing method or a solution mixing method. After vulcanization and molding, the flame retardancy, ablation resistance, interface adhesion and resistance to small molecule migration are effectively improved.

[0004] CN114773862 A discloses a thermal insulation material based on a polyphosphazene system, a preparation method and an application thereof. The thermal insulation material is prepared by mixing polyphosphazene as a matrix, adding aramid fiber, carbon fiber, phenolic resin, fumed silica and other functional additives, and has good ablation resistance and erosion resistance.

[0005] Although the above-mentioned polyphosphazene material has excellent properties of ablation resistance and erosion resistance, it has the defects of high thermal conductivity and high cost, and is difficult to process. Summary of the invention

[0006] The present invention provides a carbon fiber reinforced EPDM / polyphosphazene erosion resistant thermal insulation material and a preparation method thereof, wherein a three-dimensional carbon fiber fabric (C 3D ) as the skeleton, EPDM rubber and polyphosphazene as the matrix materials, and various functional additives are added to prepare C 3D / EPDM / PZ erosion-resistant insulation material has the characteristics of low smoke, ablation resistance and excellent mechanical properties.

[0007] The technical scheme of the present invention is to provide a carbon fiber reinforced EPDM / polyphosphazene erosion-resistant thermal insulation material, which is prepared by taking carbon fiber as a skeleton, impregnating EPDM / polyphosphazene rubber material and then vulcanizing; the EPDM / polyphosphazene rubber material comprises the following components in parts by weight: 30-70 parts of EPDM rubber, 30-70 parts of polyphosphazene, 10-20 parts of ablation-resistant resin, 10-15 parts of flame retardant, 0.5-2 parts of vulcanizing agent and 0.5-2 parts of vulcanization accelerator.

[0008] Optionally, the carbon fiber is a three-dimensional carbon fiber fabric with an area density of 1.8-2.5 g / cm 2 , thickness is 4~8mm.

[0009] Optionally, the substituent of the polyphosphazene is one or more of aryloxy, arylamino and alkoxy.

[0010] Optionally, the EPDM / polyphosphazene compound meets at least one of the following conditions: 1) The ablation-resistant resin is one or more of phenolic resin, benzoxazine resin and epoxy resin; 2) The flame retardant is one or more of ammonium polyphosphate, triphenyl phosphate, and melamine cyanurate; 3) The vulcanizing agent is one or more of sulfur, diisopropylbenzene peroxide, di-tert-butyl diisopropylbenzene peroxide, and 4,4′-dimorpholine disulfide; 4) The vulcanization accelerator is one or more of tetramethylthiuram disulfide, 2-mercaptobenzothiazole, zinc dibutyldithiocarbamate, triallyl isocyanurate, and NN′-m-phenylene bismaleimide.

[0011] Optionally, the EPDM / polyphosphazene rubber material is dissolved and dispersed in a solvent to prepare a glue solution.

[0012] Optionally, the solvent is one or more of acetone, cyclohexane, ethanol, toluene and xylene.

[0013] The present invention also relates to a method for preparing the thermal insulation material, comprising the following steps: S1, plasticizing EPDM rubber and polyphosphazene, then adding ablation-resistant resin, flame retardant, vulcanizing agent and vulcanization accelerator to mix, and thinning through several times to obtain a mixed rubber green sheet; S2, cutting the mixed rubber sheet, adding solvent, mixing and soaking until a uniform rubber solution is formed; S3, placing the carbon fiber in the glue solution, performing vacuum impregnation, and drying after the impregnation to obtain C 3D / EPDM / PZ prepreg; S4, prepreg vulcanization molding to obtain C 3D / EPDM / PZ erosion-resistant insulation material.

[0014] Optionally, in S1, the plasticizing temperature is 40-60° C., the mixing temperature is 60-100° C., and the thickness of the mixed rubber sheet is 1.2-1.5 mm.

[0015] Optionally, the glue solution in S3 is preheated before dipping, and the preheating temperature is 40-50°C.

[0016] Optionally, in S4, the vulcanization temperature is 150-170° C., the vulcanization pressure is 10-15 MPa, and the vulcanization time is 100-150 min.

[0017] The present invention has the following beneficial effects: 1. The present invention uses three-dimensional carbon fiber fabric as the reinforcement phase and uses EPDM and PZ composite matrix as the impregnation glue to prepare C 3D / EPDM / PZ erosion-resistant insulation material has the advantages of low smoke, flame retardancy and ablation resistance compared to traditional rubber-based insulation materials; its mechanical properties are also better than EPDM insulation materials.

[0018] 2. The present invention uses EPDM and PZ as a mixed matrix. The addition of PZ improves the compatibility of EPDM with other polymers and enhances their interfacial bonding properties. The prepared C 3D / EPDM / PZ erosion-resistant insulation material has good adhesion to the interface of EPDM insulation layer.

[0019] 3. When preparing the thermal insulation material of the present invention, a vacuum introduction process is used to make the EPDM and PZ composite matrix adhesive adhere to the three-dimensional carbon fiber fabric. The prepared prepreg has uniform adhesive impregnation, stable molding quality, high production efficiency, and can be suitable for large-scale production. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 Example 2 prepared C 3D Schematic diagram of the interface bonding between / EPDM / PZ erosion-resistant insulation material and EPDM insulation layer after oxygen-acetylene flame ablation.

[0021] Figure 2 The following are the actual pictures of the rubber mixtures prepared in Example 3 and Comparative Example 5. DETAILED DESCRIPTION

[0022] The present invention is described in detail below in conjunction with specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and a specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0023] The experimental methods in the following examples are conventional methods unless otherwise specified. The raw materials, reagents, etc. used in the following examples are commercially available products unless otherwise specified.

[0024] The invention provides a carbon fiber reinforced EPDM / polyphosphazene erosion-resistant thermal insulation material. The thermal insulation material is prepared by taking a three-dimensional carbon fiber fabric as a skeleton, impregnating an EPDM / polyphosphazene rubber compound and then vulcanizing the material. The EPDM / polyphosphazene rubber compound comprises the following components in parts by weight: 30-70 parts of EPDM rubber, 30-70 parts of polyphosphazene, 10-20 parts of ablation-resistant resin, 10-15 parts of a flame retardant, 0.5-2 parts of a vulcanizing agent and 0.5-2 parts of a vulcanization accelerator.

[0025] In a preferred embodiment, the carbon fiber is a three-dimensional carbon fiber fabric with a surface density of 1.8 to 2.5 g / cm 2 , including but not limited to 1.8 g / cm 2 , 1.9 g / cm 2 , 2.0 g / cm 2 , 2.3 g / cm 2 and 2.5g / cm 2 ; preferably 1.9 g / cm 2 The thickness of the carbon fiber fabric is 4 to 8 mm, including but not limited to 4 mm, 5 mm, 6 mm, 7 mm or 8 mm, preferably 6 mm.

[0026] In a preferred embodiment, the substituent of the polyphosphazene may be one or more of an aryloxy group, an arylamino group, and an alkoxy group; more preferably, the substituent is an aryloxy group.

[0027] In a preferred embodiment, the ablation-resistant resin is one or more of phenolic resin, benzoxazine resin and epoxy resin; more preferably, the ablation-resistant resin is epoxy resin.

[0028] In a preferred embodiment, the flame retardant is one or more of ammonium polyphosphate, triphenyl phosphate, and melamine cyanurate; more preferably, the flame retardant is ammonium polyphosphate.

[0029] In a preferred embodiment, the vulcanizing agent is one or more of sulfur, diisopropylbenzene peroxide, di-tert-butyl diisopropylbenzene peroxide, and 4,4′-dimorpholine dithioate; more preferably, the vulcanizing agent is diisopropylbenzene peroxide.

[0030] In a preferred embodiment, the vulcanization accelerator is one or more of tetramethylthiuram disulfide, 2-mercaptobenzothiazole, zinc dibutyldithiocarbamate, triallyl isocyanurate, and NN′-m-phenylenebismaleimide; more preferably, the vulcanization accelerator is NN′-m-phenylenebismaleimide.

[0031] In the specific impregnation process, the EPDM / polyphosphazene rubber material is dissolved and dispersed in a solvent to prepare a glue solution. The solvent can be selected from one or more of acetone, cyclohexane, ethanol, toluene, and xylene; and the more preferred solvent is toluene.

[0032] The following is a description with reference to specific embodiments.

[0033] Example 1 The present embodiment provides a method for preparing a carbon fiber reinforced EPDM / polyphosphazene erosion-resistant insulation material. The EPDM / polyphosphazene rubber material includes the following raw materials: 50 parts of EPDM rubber, 50 parts of polyphosphazene (the substituted group is an aromatic group), 13 parts of phenolic resin, 12 parts of ammonium polyphosphate, 2.0 parts of sulfur, 0.8 parts of 2-thiolbenzothiazole, and 0.6 parts of tetramethylthiuram disulfide.

[0034] The preparation method comprises the following steps: (1) Mix EPDM rubber and polyphosphazene in proportion and knead at 50-60°C for 70 minutes; (2) Take out the kneaded rubber mixture, weigh phenolic resin, ammonium polyphosphate, sulfur, 2-mercaptobenzothiazole, and tetramethylthiuram disulfide, add them into an open mill in sequence, mix well, and then produce sheets.

[0035] (3) Cut the mixed rubber sheets and dissolve them in toluene, soak them for 4 days, and stir them at a speed of 1000 r / min for 1 hour to prepare a uniform rubber solution.

[0036] (4) The glue solution was placed in a 40°C oven for preheating for 15 minutes, and then impregnated using a vacuum introduction process. After 60 minutes, the solution was taken out and dried at normal pressure and 60°C to obtain C 3D / EPDM / PZ prepreg; the surface density of the three-dimensional carbon fiber fabric is 1.9g / cm 2 , thickness is 6mm.

[0037] (5) C 3D / EPDM / PZ prepreg was vulcanized at a vulcanization temperature of 160°C, a vulcanization pressure of 10MPa, and a vulcanization time of 120min to obtain C 3D / EPDM / PZ erosion-resistant insulation material.

[0038] Example 2 The present embodiment provides a method for preparing a carbon fiber reinforced EPDM / polyphosphazene erosion-resistant insulation material. The EPDM / polyphosphazene rubber material includes the following raw materials: 50 parts of EPDM rubber, 50 parts of polyphosphazene (the substituted group is an aromatic group), 15 parts of benzoxazine resin, 10 parts of ammonium polyphosphate, 1.5 parts of 4,4′-dithiodimorpholine, and 1.2 parts of 2-thiolbenzothiazole.

[0039] The preparation method is the same as that of Example 1, wherein the solvent in step (3) is changed from toluene to a mixed solvent of cyclohexane and xylene in a volume ratio of 1:1.

[0040] Example 3 The present embodiment provides a method for preparing a carbon fiber reinforced EPDM / polyphosphazene erosion-resistant insulation material. The EPDM / polyphosphazene rubber material includes the following raw materials: 50 parts of EPDM rubber, 50 parts of polyphosphazene (the substituted group is an aromatic group), 14 parts of epoxy resin, 11 parts of melamine cyanurate, 2.0 parts of dicumyl peroxide, 0.5 parts of 2-thiolbenzothiazole, and 0.5 parts of tetramethylthiuram disulfide.

[0041] The preparation method is the same as Example 1.

[0042] Example 4 The present embodiment provides a method for preparing a carbon fiber reinforced EPDM / polyphosphazene erosion-resistant insulation material. The EPDM / polyphosphazene rubber material includes the following raw materials: 60 parts of EPDM rubber, 40 parts of polyphosphazene (the substituted group is aromatic amino), 13 parts of benzoxazine resin, 10 parts of triphenyl phosphate, 1.6 parts of diisopropylbenzene peroxide, and 1.0 part of NN′-m-phenylene bismaleimide.

[0043] The preparation method is the same as that of Example 1, wherein the solvent in step (3) is changed from toluene to acetone.

[0044] Example 5 The present embodiment provides a method for preparing a carbon fiber reinforced EPDM / polyphosphazene erosion-resistant insulation material. The EPDM / polyphosphazene rubber material includes the following raw materials: 60 parts of EPDM rubber, 40 parts of polyphosphazene (the substituted group is alkoxy), 15 parts of epoxy resin, 12 parts of triphenyl phosphate, 1.3 parts of diisopropyl peroxide, and 0.7 parts of triallyl isocyanurate.

[0045] The preparation method is the same as that of Example 1, wherein the solvent in step (3) is changed from toluene to a mixed solvent of acetone and ethanol in a volume ratio of 1:1.

[0046] Example 6 The present embodiment provides a method for preparing a carbon fiber reinforced EPDM / polyphosphazene erosion-resistant insulation material. The EPDM / polyphosphazene rubber material includes the following raw materials: 70 parts of EPDM rubber, 30 parts of polyphosphazene (the substituted group is aromatic amino), 16 parts of epoxy resin, 14 parts of melamine cyanurate, 2.0 parts of 4,4′-dithiodimorpholine, and 1.2 parts of 2-thiolbenzothiazole.

[0047] The preparation method is the same as that of Example 1, wherein the solvent in step (3) is changed from toluene to a mixed solvent of cyclohexane and xylene in a volume ratio of 1:1.

[0048] Comparative Example 1 The market uses carbon fiber braided body to reinforce the erosion-resistant thermal insulation material.

[0049] Comparative Example 2 The formulation steps are the same as those in Example 1, except that the polyphosphazene is completely replaced with EPDM rubber, and the preparation method is the same as that in Example 1.

[0050] Comparative Example 3 The formulation steps are the same as those in Example 1, except that the EPDM rubber is completely replaced by polyphosphazene, and the preparation method is the same as that in Example 1.

[0051] Comparative Example 4 The formula is the same as that of Example 2, except that the plasticizing and mixing steps in the preparation method are omitted, and all raw materials are directly dissolved in a solvent. The rest of the preparation method is the same as that of Example 3.

[0052] Comparative Example 5 The formula is the same as that of Example 2, except that the plasticizing step in the preparation method is omitted, and all raw materials are directly mixed. The rest of the preparation method is the same as that of Example 3.

[0053] The thermal insulation materials prepared in the above examples and comparative examples were tested for tensile strength, elongation at break, oxygen-acetylene wire ablation rate and smoke density. 3D Interface bonding performance between / EPDM / PZ erosion-resistant insulation material and EPDM insulation layer. Test standards are shown in Table 1, and test results are shown in Tables 2~3.

[0054] Table 1. Test standards

[0055] Table 2. Performance test results

[0056] Table 3, C 3D Test on the tearing and shearing properties of the interface between / EPDM / PZ erosion-resistant composite material and EPDM insulation layer

[0057] The results show that compared with Comparative Example 1, the C 3D The erosion-resistant thermal insulation material of / EPDM / PZ has higher ablation resistance and lower smoke density; compared with Comparative Examples 2 and 3, the material prepared in Example 1 has higher bonding performance, indicating that using EPDM and PZ as a mixed matrix improves the compatibility of EPDM with other polymers, enhances the interface bonding performance, and produces unexpected technical effects. Compared with Examples 1-6, the C prepared in Comparative Examples 4 and 5 3DThe mechanical properties and ablation resistance of / EPDM / PZ erosion-resistant insulation materials are poor, indicating that when the raw materials are not plasticized or mixed, the rubber linear macromolecules cannot be transformed into a cross-linked network structure, thereby failing to improve the mechanical and thermal properties of the material.

[0058] Using Example 2 to obtain C 3D The schematic diagram of the interface bonding between the EPDM / PZ erosion-resistant insulation material and the EPDM insulation layer after oxygen-acetylene flame ablation is shown in Figure 1 , respectively, are schematic diagrams of ablation specimen, tearing specimen, and shearing specimen. The surface of the ablation specimen is only slightly concave, and the skeleton is intact, indicating that C 3D / EPDM / PZ erosion-resistant insulation material has excellent ablation resistance. The tearing specimen and shearing specimen show that the broken parts are all in the carbon fiber or insulation layer, indicating that C 3D / EPDM / PZ erosion-resistant insulation material has good bonding performance with EPDM insulation layer.

[0059] The mixed rubber prepared by Example 2 and Comparative Example 5 is shown in Figure 2 , from left to right are the rubber mixes prepared in Example 2 and Comparative Example 5, respectively. The rubber mixes prepared after the mastication step are in a coagulated state, while the rubber mixes prepared without the mastication step are in a loose state and cannot be normally coagulated.

[0060] The above embodiments describe the preferred implementation of the present invention, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and 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.

Claims

1. A carbon fiber reinforced EPDM / polyphosphazene erosion resistant insulation material, characterized in that: The thermal insulation material is made of carbon fiber as a skeleton, impregnated with EPDM / polyphosphazene rubber material and then vulcanized; the EPDM / polyphosphazene rubber material comprises the following components by weight: 30-70 parts of EPDM rubber, 30-70 parts of polyphosphazene, 10-20 parts of ablation-resistant resin, 10-15 parts of flame retardant, 0.5-2 parts of vulcanizing agent and 0.5-2 parts of vulcanization accelerator.

2. The thermal insulation material according to claim 1, characterized in that: The carbon fiber is a three-dimensional carbon fiber fabric with a surface density of 1.8-2.5 g / cm 2 , thickness is 4~8mm.

3. The thermal insulation material according to claim 1, characterized in that: The substituent of the polyphosphazene is one or more of aryloxy, arylamino and alkoxy.

4. The thermal insulation material according to claim 1, characterized in that: EPDM / PPB compounds meet at least one of the following conditions: 1) The ablation-resistant resin is one or more of phenolic resin, benzoxazine resin and epoxy resin; 2) The flame retardant is one or more of ammonium polyphosphate, triphenyl phosphate, and melamine cyanurate; 3) The vulcanizing agent is one or more of sulfur, diisopropylbenzene peroxide, di-tert-butyl diisopropylbenzene peroxide, and 4,4′-dimorpholine disulfide; 4) The vulcanization accelerator is one or more of tetramethylthiuram disulfide, 2-mercaptobenzothiazole, zinc dibutyldithiocarbamate, triallyl isocyanurate, and NN′-m-phenylene bismaleimide.

5. The thermal insulation material according to any one of claims 1 to 4, characterized in that: The EPDM / polyphosphazene rubber material is dissolved and dispersed in a solvent to prepare a rubber solution.

6. The thermal insulation material according to claim 5, characterized in that: The solvent is one or more of acetone, cyclohexane, ethanol, toluene and xylene.

7. The method for preparing the thermal insulation material according to any one of claims 1 to 6, characterized in that: The following steps are involved: S1, plasticizing EPDM rubber and polyphosphazene, then adding ablation-resistant resin, flame retardant, vulcanizing agent and vulcanization accelerator to mix, and thinning through several times to obtain a mixed rubber green sheet; S2, cutting the mixed rubber sheet, adding solvent, mixing and soaking until a uniform rubber solution is formed; S3, placing the carbon fiber in the glue solution, performing vacuum impregnation, and drying after the impregnation to obtain C 3D / EPDM / PZ prepreg; S4, prepreg vulcanization molding to obtain C 3D / EPDM / PZ erosion-resistant insulation material.

8. The preparation method according to claim 7, characterized in that: In S1, the plasticizing temperature is 40-60°C, the mixing temperature is 60-100°C, and the thickness of the mixed rubber sheet is 1.2-1.5 mm.

9. The preparation method according to claim 7 or 8, characterized in that: The glue solution in S3 is preheated before dipping, and the preheating temperature is 40~50℃.

10. The preparation method according to claim 7, characterized in that: In S4, the vulcanization temperature is 150~170℃, the vulcanization pressure is 10~15MPa, and the vulcanization time is 100~150min.

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