A method of bonding a highly plasticized azide polyether propellant to an insulating layer

Abstract

The application relates to a method for bonding a large plasticized azide polyether propellant and a thermal insulation layer, belonging to the field of interface bonding of solid rocket engines, wherein the plasticizing ratio of the large plasticized azide polyether propellant is 1.4-2.0, the liner is an HTPB liner or a PBT liner, the thermal insulation layer is a phenylpropoxazine resin modified ternary ethylene-propylene rubber thermal insulation material, the vulcanization temperature is 150-170 DEG C, the vulcanization pressure is 5-15 MPa, and the vulcanization time is 30-120 min. The phenylpropoxazine resin modified ternary ethylene-propylene rubber thermal insulation layer is adopted, the adverse influence of small molecule migration on the interface bonding performance is obviously reduced, the ratio of the combined peeling strength to the propellant body strength is increased from 0.72 to 1.32, the increase is more than 83%, the minimum peeling strength and the average peeling strength are all increased by more than 160%, and the interface bonding performance of the large plasticized azide polyether propellant and the liner is greatly improved.

Description

Technical Field

[0001] This invention relates to the field of azide polyether propellant loading technology, and to a method for improving the adhesion performance between highly plasticized azide polyether propellant and the insulation layer. Background Technology

[0002] The combustion chamber of a solid rocket motor mainly consists of a shell, solid propellant, a liner, and an insulation layer. The solid propellant and insulation layer are bonded together by the liner to form a unified propellant charge. The quality of the interfacial bonding between these three components directly affects the structural integrity and operational reliability of the solid rocket motor. Statistics show that approximately one-third of solid rocket motor failures in domestic and international tests are due to interfacial bonding failure. Interfacial bonding failure is one of the major challenges facing my country's solid propulsion technology industry and a significant weakness affecting the reliability of solid rocket motors.

[0003] Azide propellants typically incorporate large amounts of energetic plasticizers to further enhance their energy. However, highly plasticized propellants often lead to significant migration of components at the interface, resulting in lower interfacial adhesion strength. Therefore, reducing the amount of migration between the insulation layer and the propellant is crucial for improving the interfacial adhesion performance of highly plasticized azide polyether propellants. Summary of the Invention

[0004] The technical problem solved by this application is to overcome the shortcomings of the prior art and provide a method to improve the adhesion performance between highly plasticized polyether azide propellant and HTPB liner. Without adjusting the existing liner, propellant formulation and patching and casting process, the method aims to significantly improve the interfacial adhesion performance of the insulation layer / liner / highly plasticized polyether azide propellant.

[0005] The above-mentioned objectives of the present invention are mainly achieved through the following technical solutions:

[0006] A method for bonding a highly plasticized azide polyether propellant to an insulation layer includes sequentially bonding an insulation layer, a liner, and the highly plasticized azide polyether propellant to the housing of a combustion chamber. The highly plasticized azide polyether propellant has a plasticizing ratio of 1.4 to 2.0, and the insulation layer is made of a material selected from phenylpropane-modified EPDM insulation material or phenylpropane-modified nitrile butadiene insulation coating material.

[0007] The benzoxazine resin-modified EPDM insulation material is a co-cured insulation material of DCP, sulfur-cured benzoxazine resin, and EPDM. Its raw materials include the following components by weight: 100 parts EPDM rubber; 30-100 parts benzoxazine resin; 10-15 parts ablation-resistant fiber; 3-30 parts solid filler; 6-12 parts flame retardant system; 2-5 parts process aids; and 4.5-9 parts vulcanization system.

[0008] The vulcanization system includes a vulcanizing agent, a co-vulcanization catalyst, and an accelerator. The vulcanizing agent is at least one of sulfur, dicumyl peroxide, and benzoyl peroxide, and the co-vulcanization catalyst is 2-methylimidazole or 4-methylimidazole.

[0009] The phenylpropoxazine resin-modified EPDM insulation material has a vulcanization temperature of 150℃~170℃, a vulcanization time of 1h~2h, and a vulcanization pressure of 10MPa~20MPa.

[0010] The phenylpropoxazine resin-modified nitrile butadiene insulation coating material is a co-cured insulation material of DCP and sulfur-cured phenylpropoxazine resin and nitrile butadiene. Its raw materials include the following components by weight: 100 parts nitrile rubber, 20-30 parts dioctyl phthalate, 20-75 parts heat-resistant resin, 30-60 parts silica, 6-16 parts fiber, 4-9 parts zinc oxide, 0.5-3 parts antioxidant, 1-4 parts stearic acid, 1-6 parts accelerator, 2-4 parts vulcanizing agent, and 0.2-1 parts resin curing catalyst.

[0011] The phenylpropoxazine resin-modified nitrile insulating coating material has a vulcanization temperature of 150℃~170℃, a vulcanization time of 1h~2h, and a vulcanization pressure of 10MPa~20MPa.

[0012] The plasticizer is one or a combination of N-butylnitrooxyethyl nitramine (Bu-NENA), bis(2,2-dinitropropanol)formaldehyde / bis(2,2-dinitropropanol)acetal (BDNPF / BDNPA, A3), terminal ester polyazolidone glycidyl ether (GAPE), nitroglycerin (NG), diisooctyl sebacate (DOS), tributyl phosphate (TBP), diethylene glycol dinitrate (DEGDN), and triethylene glycol dinitrate (TEGDN).

[0013] The liner is either an HTPB liner or a PBT liner.

[0014] In summary, this application includes at least the following beneficial technical effects:

[0015] 1. Based on the characteristic that highly plasticized propellants affect interfacial adhesion performance, the insulation layer was optimized. Phenylexiconol-modified EPDM insulation material was selected as the insulation layer for several reasons: First, the characteristic that phenylpropoxazine resin does not release small molecules during vulcanization reduces the impact of small molecules on interfacial adhesion performance; second, by appropriately increasing the vulcanization temperature, the small molecules of EPDM rubber are volatilized during the vulcanization stage, thereby reducing the release of small molecules at the propellant curing temperature; third, the sufficient entanglement between phenylpropoxazine resin and EPDM resin makes the insulation layer material more dense, reducing the mutual migration between the small molecules of the highly plasticized propellant and the small molecules of the insulation layer, which helps ensure that the interfacial propellant cures as designed, achieving a curing and cross-linking degree close to that of the bulk propellant.

[0016] 2. It can significantly improve the problem of near-interface propellant weakening, increase the joint peel strength by more than 84%, and increase the minimum peel strength and average peel strength by more than 160%.

[0017] 3. Without adjusting the existing liner, propellant formulation, patching, and casting processes, the adverse effects of small molecule migration on interfacial adhesion performance were significantly reduced. This increased the ratio of combined peel strength to propellant bulk strength from 0.72 to 1.32, an increase of over 83%. The minimum peel strength and average peel strength were both increased by over 160%, significantly improving the interfacial adhesion performance between the highly plasticized azide polyether propellant and the liner. Detailed Implementation

[0018] The present invention will be further described below with reference to embodiments.

[0019] The EPDM insulation layers used in the comparative examples were all obtained commercially.

[0020] Comparative Example 1

[0021] At room temperature, a 0.4mm to 0.6mm thick lining layer is uniformly coated on the surface of the EPDM insulation layer. The lining material is HTPB. The specimen is placed in an oven for pre-curing. After pre-curing, a 1.4 azidopolyether propellant slurry with a plasticizing ratio of N-butylnitroethyl nitramine (Bu-NENA) is poured into the specimen mold using a wall-mounted casting method. The plasticizer in the azidopolyether propellant slurry is N-butylnitroethyl nitramine. The specimen is then placed in an oven for curing and molding to complete the interface bonding and obtain the bonded part.

[0022] Rectangular tear test specimens of propellant / liner / insulation layer were prepared using adhesive components. The tear strength test standard was QJ2038.1A-2004. The tensile strength of the propellant body was measured to be 1013 kPa, the combined tear strength was 727 kPa, and the ratio of the combined tear strength to the propellant body strength was 0.72.

[0023] Comparative Example 2

[0024] At room temperature, a 0.4mm to 0.6mm thick lining layer is uniformly coated on the surface of the EPDM insulation layer. The lining material is HTPB. The specimen is placed in an oven for pre-curing. After pre-curing, a 1.4 azidopolyether propellant slurry with a plasticizing ratio of N-butylnitroethyl nitramine (Bu-NENA) is poured into the specimen mold using a wall-mounted casting method. The plasticizer in the azidopolyether propellant slurry is N-butylnitroethyl nitramine. The specimen is then placed in an oven for curing and molding to complete the interface bonding and obtain the bonded part.

[0025] Rectangular tear test specimens of propellant / liner / insulation layer were prepared using adhesive components. The tear strength test standard was QJ2038.1A-2004. The tensile strength of the propellant body was measured to be 910 kPa, the combined tear strength was 451 kPa, and the ratio of the combined tear strength to the propellant body strength was 0.68.

[0026] Example 1

[0027] At room temperature, a 0.4mm to 0.6mm lining layer was uniformly coated on the surface of the phenylpropane-oxazine resin-modified EPDM insulation layer. The lining layer material was HTPB. The specimen was placed in an oven for pre-curing. After pre-curing, a plasticizer slurry with a plasticizing ratio of 1.4 was poured into the specimen mold by wall-mounted casting. The plasticizer in the plasticizer slurry was N-butylnitrooxyethylnitrosamine (Bu-NENA). The specimen was then placed in an oven for curing and molding to complete the interface bonding and obtain the bonded part.

[0028] The insulation layer is made of phenylpropane-oxazine resin-modified EPDM insulation material, and its preparation method includes:

[0029] Step 1: Prepare the composite insulation layer material according to its raw material composition (100 parts EPDM rubber; 40 parts benzoxazine resin; 15 parts ablation-resistant fiber; 20 parts solid filler; 8 parts flame retardant system; 3 parts process aids; 7 parts vulcanization system).

[0030] Step 2: First, EPDM rubber is plasticized on a two-roll mill to form a uniform roll. Then, it is mixed evenly with solid fillers to obtain a compound. This compound is then blended with benzoxazine resin using an isoviscosity processing method at a mixing temperature of 60°C and a thin pass of 30 times. Finally, ablation-resistant fibers, flame retardants, and process aids are mixed evenly with the compound on a two-roll mill at a mixing temperature of 30°C and a thin pass of 25 times to obtain the raw material for the benzoxazine resin / EPDM rubber composite insulation layer.

[0031] Step 3: Place the raw material of the mixed insulation layer at 25°C and let it stand for 24 hours. Then, it is rolled on a rolling mill. Add the vulcanization system at 30°C and mix the vulcanization system with the raw material of the mixed insulation layer evenly. After passing through the thin mill 20 times to achieve a uniform state, the sheet is produced.

[0032] Step 4: After sheeting, place the material in the mold and vulcanize it using a flat vulcanizing machine; the vulcanization temperature is 165℃, the time is 1h, and the pressure is 10MPa to obtain a benzoxazine resin / EPDM rubber composite insulation layer.

[0033] Rectangular tear test specimens of propellant / liner / insulation layer were prepared using adhesive components. The tear strength test standard was QJ2038.1A-2004. The tensile strength of the propellant body was measured to be 1013 kPa, and the combined tear strength was 1339 kPa. Compared with Comparative Example 1, the ratio of combined tear strength to propellant body strength was 1.18.

[0034] Example 2

[0035] The only difference from Example 1 is that the slurry of azide polyether propellant with a plasticizing ratio of 1.6 is poured.

[0036] The insulation layer material and preparation method are the same as those in Example 1.

[0037] Rectangular tear test specimens of propellant / liner / insulation layer were made using the obtained adhesive. The tear strength test standard was QJ2038.1A-2004. The tensile strength of the propellant body was measured to be 970 kPa and the combined tear strength was 1259 kPa. Compared with Comparative Example 2, the ratio of combined tear strength to propellant body strength was 1.30.

[0038] Example 5

[0039] The only difference from Example 1 is that the slurry of azide polyether propellant with a plasticizing ratio of 2.0 is poured.

[0040] The insulation layer material and preparation method are the same as those in Example 1.

[0041] Rectangular tear test specimens of propellant / liner / insulation layer were made using the obtained adhesive. The tear strength test standard was QJ2038.1A-2004. The tensile strength of the propellant body was measured to be 910 kPa and the combined tear strength was 1147 kPa. Compared with Comparative Example 2, the ratio of the combined tear strength to the propellant body strength was 1.26.

[0042] Example 6

[0043] The only difference from Example 1 is that the method of preparing the insulation layer is different from that of the insulation layer in Example 1.

[0044] Methods for preparing the insulation layer include:

[0045] Step 1: Prepare the composite insulation layer material according to its raw material composition (100 parts EPDM rubber; 60 parts benzoxazine resin; 15 parts ablation-resistant fiber; 20 parts solid filler; 8 parts flame retardant system; 3 parts process aids; 7 parts vulcanization system).

[0046] Step 2: First, EPDM rubber is plasticized on a two-roll mill to form a uniform roll. Then, it is mixed evenly with solid fillers to obtain a compound. This compound is then blended with benzoxazine resin using an isoviscosity processing method at a mixing temperature of 60°C and a thin pass of 30 times. Finally, ablation-resistant fibers, flame retardants, and process aids are mixed evenly with the compound on a two-roll mill at a mixing temperature of 30°C and a thin pass of 25 times to obtain the raw material for the benzoxazine resin / EPDM rubber composite insulation layer.

[0047] Step 3: Place the raw material of the mixed insulation layer at 25°C and let it stand for 24 hours. Then, it is rolled on a rolling mill. Add the vulcanization system at 30°C and mix the vulcanization system with the raw material of the mixed insulation layer evenly. After passing through the thin mill 20 times to achieve a uniform state, the sheet is produced.

[0048] Step 4: After sheeting, place the material in the mold and vulcanize it using a flat vulcanizing machine; the vulcanization temperature is 165℃, the time is 1h, and the pressure is 10MPa to obtain a benzoxazine resin / EPDM rubber composite insulation layer.

[0049] Rectangular tear test specimens of propellant / liner / insulation layer were made using the obtained adhesive. The tear strength test standard was QJ2038.1A-2004. The tensile strength of the propellant body was measured to be 1013 kPa and the combined tear strength was 1354 kPa. Compared with Comparative Example 1, the ratio of the combined tear strength to the propellant body strength was 1.34.

[0050] Example 7

[0051] The only difference from Example 1 is that the method of preparing the insulation layer is different from that of the insulation layer in Example 1.

[0052] Methods for preparing the insulation layer include:

[0053] Step 1: Prepare the composite insulation layer material according to its raw material composition (100 parts EPDM rubber; 80 parts benzoxazine resin; 15 parts ablation-resistant fiber; 20 parts solid filler; 8 parts flame retardant system; 3 parts process aids; 7 parts vulcanization system).

[0054] Step 2: First, EPDM rubber is plasticized on a two-roll mill to form a uniform roll. Then, it is mixed evenly with solid fillers to obtain a compound. This compound is then blended with benzoxazine resin using an isoviscosity processing method at a mixing temperature of 60°C and a thin pass of 30 times. Finally, ablation-resistant fibers, flame retardants, and process aids are mixed evenly with the compound on a two-roll mill at a mixing temperature of 30°C and a thin pass of 25 times to obtain the raw material for the benzoxazine resin / EPDM rubber composite insulation layer.

[0055] Step 3: Place the raw material of the mixed insulation layer at 25°C and let it stand for 24 hours. Then, it is rolled on a rolling mill. Add the vulcanization system at 30°C and mix the vulcanization system with the raw material of the mixed insulation layer evenly. After passing through the thin mill 20 times to achieve a uniform state, the sheet is produced.

[0056] Step 4: After sheeting, place the material in the mold and vulcanize it using a flat vulcanizing machine; the vulcanization temperature is 165℃, the time is 1h, and the pressure is 10MPa to obtain a benzoxazine resin / EPDM rubber composite insulation layer.

[0057] Rectangular tear test specimens of propellant / liner / insulation layer were made using the obtained adhesive components. The tear strength test standard was QJ2038.1A-2004. The tensile strength of the propellant body was measured to be 1013 kPa, and the combined tear strength was 1391 kPa. Compared with Comparative Example 1, the ratio of combined tear strength to propellant body strength was 1.37, and the elongation of the composite insulation layer material was 50%.

[0058] Example 8

[0059] The only difference from Example 7 is the raw material composition of the composite insulation layer material (90 parts of EPDM rubber; 90 parts of benzoxazine resin).

[0060] Rectangular tear test specimens of propellant / liner / insulation layer were fabricated using the obtained adhesive components. The tear strength was tested according to the standard QJ2038.1A-2004. The tensile strength of the propellant body was measured to be 1013 kPa, and the combined tear strength was 1399 kPa. Compared with Comparative Example 1, the ratio of combined tear strength to propellant body strength was 1.38. The elongation of the composite insulation layer material was 13%.

[0061] Example 9

[0062] The only difference from Example 7 is the composition of the composite insulation layer material (80 parts of EPDM rubber; 100 parts of benzoxazine resin).

[0063] Rectangular tear-off specimens of propellant / liner / insulation layer were fabricated using the obtained adhesive components. The tear strength was tested according to the standard QJ2038.1A-2004. The tensile strength of the propellant body was measured to be 1013 kPa, and the combined tear strength was 1403 kPa. Compared with Comparative Example 1, the ratio of combined tear strength to propellant body strength was 1.38. The elongation of the composite insulation layer material was 8%.

[0064] Example 10

[0065] The only difference from Example 1 is that the method of preparing the insulation layer is different from that of the insulation layer in Example 1.

[0066] Methods for preparing the insulation layer include:

[0067] Step 1: Prepare the composite insulation layer material according to its raw material composition (100 parts EPDM rubber; 40 parts benzoxazine resin; 15 parts ablation-resistant fiber; 20 parts solid filler; 8 parts flame retardant system; 3 parts process aids; 7 parts vulcanization system).

[0068] Step 2: First, EPDM rubber is plasticized on a two-roll mill to form a uniform roll. Then, it is mixed evenly with solid fillers to obtain a compound. This compound is then blended with benzoxazine resin using an isoviscosity processing method at a mixing temperature of 60°C and a thin pass of 30 times. Finally, ablation-resistant fibers, flame retardants, and process aids are mixed evenly with the compound on a two-roll mill at a mixing temperature of 30°C and a thin pass of 25 times to obtain the raw material for the benzoxazine resin / EPDM rubber composite insulation layer.

[0069] Step 3: Place the raw material of the mixed insulation layer at 25°C and let it stand for 24 hours. Then, it is rolled on a rolling mill. Add the vulcanization system at 30°C and mix the vulcanization system with the raw material of the mixed insulation layer evenly. After passing through the thin mill 20 times to achieve a uniform state, the sheet is produced.

[0070] Step 4: After sheeting, place the material in the mold and vulcanize it using a flat vulcanizing machine; the vulcanization temperature is 155℃, the time is 1h, and the pressure is 10MPa to obtain a benzoxazine resin / EPDM rubber composite insulation layer.

[0071] Rectangular tear test specimens of propellant / liner / insulation layer were made using the obtained adhesive components. The tear strength test standard was QJ2038.1A-2004. The tensile strength of the propellant body was measured to be 1013 kPa and the combined tear strength was 1329 kPa. Compared with Comparative Example 1, the ratio of the combined tear strength to the propellant body strength was 1.31.

[0072] Example 11

[0073] The only difference from Example 1 is that the method of preparing the insulation layer is different from that of the insulation layer in Example 1.

[0074] Methods for preparing the insulation layer include:

[0075] Step 1: Prepare the composite insulation layer material according to its raw material composition (100 parts EPDM rubber; 40 parts benzoxazine resin; 15 parts ablation-resistant fiber; 20 parts solid filler; 8 parts flame retardant system; 3 parts process aids; 7 parts vulcanization system).

[0076] Step 2: First, EPDM rubber is plasticized on a two-roll mill to form a uniform roll. Then, it is mixed evenly with solid fillers to obtain a compound. This compound is then blended with benzoxazine resin using an isoviscosity processing method at a mixing temperature of 60°C and a thin pass of 30 times. Finally, ablation-resistant fibers, flame retardants, and process aids are mixed evenly with the compound on a two-roll mill at a mixing temperature of 30°C and a thin pass of 25 times to obtain the raw material for the benzoxazine resin / EPDM rubber composite insulation layer.

[0077] Step 3: Place the raw material of the mixed insulation layer at 25°C and let it stand for 24 hours. Then, it is rolled on a rolling mill. Add the vulcanization system at 30°C and mix the vulcanization system with the raw material of the mixed insulation layer evenly. After passing through the thin mill 20 times to achieve a uniform state, the sheet is produced.

[0078] Step 4: After sheeting, place the material in the mold and vulcanize it using a flat vulcanizing machine; the vulcanization temperature is 170℃, the time is 1h, and the pressure is 10MPa to obtain a benzoxazine resin / EPDM rubber composite insulation layer.

[0079] Rectangular tear test specimens of propellant / liner / insulation layer were made using the obtained adhesive. The tear strength test standard was QJ2038.1A-2004. The tensile strength of the propellant body was measured to be 1013 kPa and the combined tear strength was 1406 kPa. Compared with Comparative Example 1, the ratio of the combined tear strength to the propellant body strength was 1.39.

[0080] Example 12

[0081] The only difference from Example 1 is that the material and preparation method of the insulation layer are different from those in Example 1.

[0082] The insulation layer material is phenylpropoxazine resin modified nitrile insulation material, and its preparation method is as follows: Step 1, 100 parts of nitrile rubber and 25 parts of plasticizer DOP are plasticized on a two-roll mill, and the plasticized rubber is left to stand for 16 hours.

[0083] Step 2: Mix 125 parts of nitrile rubber plasticized compound, 75 parts of oxazine resin, 40 parts of fumed silica, 10 parts of aramid fiber, 5 parts of zinc oxide, and 1.5 parts of stearic acid evenly in an internal mixer. The discharge temperature of the compound is 100℃ to obtain a first-stage compound. After 24 hours of use, mix 2.5 parts of antioxidant D, 2.5 parts of accelerator TMTD, 2.5 parts of vulcanizing agent DCP, and 0.4 parts of 2-methylimidazole with the first-stage compound in an internal mixer evenly. The discharge temperature of the compound is 70℃ to obtain a second-stage compound. After 24 hours of use, the compound is sheeted and rolled into triangular bundles on an open mill.

[0084] Step 3: The compound rubber is vulcanized on a flat vulcanizing machine under the following conditions: temperature 165℃, time 30min, pressure 10MPa, to obtain the molded heat insulation material.

[0085] Rectangular tear test specimens of propellant / liner / insulation layer were made using the obtained adhesive. The tear strength test standard was QJ2038.1A-2004. The tensile strength of the propellant body was measured to be 1013 kPa and the combined tear strength was 1412 kPa. Compared with Comparative Example 1, the ratio of the combined tear strength to the propellant body strength was 1.39.

[0086] Comparative Example 3

[0087] At room temperature, a 0.4mm to 0.6mm thick lining layer is uniformly coated on the surface of the nitrile insulation jacket. The lining layer is made of PBT material. The jacket is placed into a mold and placed in an oven for pre-curing. After pre-curing, a plasticizer slurry with a plasticizing ratio of 1.4 azidopolyether propellant is poured into the pre-prepared insulation jacket using a free-filling pouring method. The plasticizer in the azidopolyether propellant slurry is bis(2,2-dinitropropanol)formaldehyde / bis(2,2-dinitropropanol)acetal (BDNPF / BDNPA, A3). The jacket is then placed in an oven for curing and molding to complete the interface bonding and obtain the bonded part.

[0088] The propellant / liner / insulation layer peeling billet was made using adhesive components. The peeling performance was tested according to the standard Q / RJ / Z69-2014. The tensile strength of the propellant body was measured to be 1013 kPa, the minimum peeling strength was 8.6 N / cm, and the average peeling strength was 10.3 N / cm.

[0089] Comparative Example 4

[0090] At room temperature, a 0.4mm to 0.6mm thick lining material, PBT lining, is uniformly coated on the surface of the nitrile insulation jacket. The jacket is then placed in a mold and pre-cured in an oven. After pre-curing, a 1.4-dinitropropanol propellant slurry is poured into a square mold containing the insulation jacket material specimen. The plasticizer in the 1.4-dinitropropanol propellant slurry is bis(2,2-dinitropropanol)formaldehyde / bis(2,2-dinitropropanol)acetal (BDNPF / BDNPA, A3). The mold is then placed in an oven for curing and molding to complete the interface bonding and obtain the bonded part.

[0091] The propellant / liner / insulation layer peeling billet was made using adhesive components. The peeling performance was tested according to the standard Q / RJ / Z69-2014. The tensile strength of the propellant body was measured to be 1013 kPa, the minimum peeling strength was 3.33 N / cm, and the average peeling strength was 5.37 N / cm.

[0092] Example 3

[0093] At room temperature, a 0.4mm to 0.6mm thick liner is uniformly coated on the surface of the phenylpropionoxazine resin-modified nitrile butadiene insulation jacket. The liner material is PBT. The jacket is placed into a mold and placed in an oven for pre-curing. After pre-curing, a plasticizer slurry with a plasticizing ratio of 1.4 azidopolyether propellant is poured into the pre-prepared insulation jacket using a free-filling pouring method. The plasticizer in the azidopolyether propellant slurry is bis(2,2-dinitropropanol)formaldehyde / bis(2,2-dinitropropanol)acetal (BDNPF / BDNPA, A3). The jacket is then placed in an oven for curing and molding to complete the interface bonding and obtain the bonded part.

[0094] The insulation covering material is phenylpropoxazine resin modified nitrile butadiene insulation covering material, and the preparation method is as follows:

[0095] Step 1: Plasticize 100 parts of nitrile rubber and 25 parts of plasticizer DOP on a two-roll mill, and let the plasticized rubber stand for 16 hours.

[0096] Step 2: Mix 125 parts of nitrile rubber plasticized compound, 75 parts of oxazine resin, 40 parts of fumed silica, 10 parts of aramid fiber, 5 parts of zinc oxide, and 1.5 parts of stearic acid evenly in an internal mixer. The discharge temperature of the compound is 100℃ to obtain a first-stage compound. After 24 hours of use, mix 2.5 parts of antioxidant D, 2.5 parts of accelerator TMTD, 2.5 parts of vulcanizing agent DCP, and 0.4 parts of 2-methylimidazole with the first-stage compound in an internal mixer evenly. The discharge temperature of the compound is 70℃ to obtain a second-stage compound. After 24 hours of use, the compound is sheeted and rolled into triangular bundles on an open mill.

[0097] Step 3: The compound rubber is vulcanized on a flat vulcanizing machine under the following conditions: temperature 165℃, time 30min, pressure 10MPa, to obtain the molded heat insulation material.

[0098] Propellant / liner / insulation layer peel test specimens were prepared using propellant grains. The peel performance was tested according to the standard Q / RJ / Z69-2014. The tensile strength of the propellant body was measured to be 1013 kPa, the minimum peel strength was 22.4 N / cm, and the average peel strength was 30.7 N / cm. Compared with Comparative Example 3, the minimum peel strength increased by 160% and the average peel strength increased by 198%.

[0099] Example 4

[0100] At room temperature, a 0.4mm to 0.6mm thick liner is uniformly coated on the surface of the phenylpropionoxazine resin modified nitrile insulation jacket. The liner material is PBT liner. The jacket is placed into a mold and placed in an oven for pre-curing. After pre-curing, a 1.4 azidopolyether propellant slurry is poured in. The plasticizer in the azidopolyether propellant slurry is bis(2,2-dinitropropanol)formaldehyde / bis(2,2-dinitropropanol)acetal (BDNPF / BDNPA, A3). The slurry is then placed in an oven for curing and molding to complete the interface bonding and obtain the bonded part.

[0101] The insulation layer material and preparation method are the same as those of the insulation layer in Example 3.

[0102] A propellant / liner / insulation layer peeling billet was fabricated using adhesive components. The peeling performance was tested according to the standard Q / RJ / Z69-2014. The tensile strength of the propellant body was measured to be 1013 kPa, the minimum peeling strength was 20.8 N / cm, and the average peeling strength was 29.4 N / cm. Compared with Comparative Example 4, the minimum peeling strength increased by 191%, and the average peeling strength increased by 160%.

[0103] Example 13

[0104] The only difference from Example 3 is that the slurry of azide polyether propellant with a plasticizing ratio of 1.6 is poured.

[0105] Propellant / liner / insulation layer peel test specimens were prepared using propellant grains. The peel performance was tested according to the standard Q / RJ / Z69-2014. The tensile strength of the propellant body was measured to be 1013 kPa, the minimum peel strength was 21.5 N / cm, and the average peel strength was 30.3 N / cm.

[0106] The rectangular tear-off specimens of propellant / liner / insulation layer obtained in the above embodiments and comparative examples were subjected to tear strength tests, and the test results are shown in Table 1.

[0107] Peel strength tests were conducted on the propellant / liner / insulation layer stripping billets obtained in the above embodiments and comparative examples. The test results are shown in Table 2.

[0108] Table 1. Test results of rectangular tear-off specimens of propellant / lining / insulation layer.

[0109] Comparative Example 1 1.4 1013 727 0.72 Comparative Example 2 2.0 910 615 0.68 Example 1 1.4 1013 1339 1.32 Example 2 2.0 910 1147 1.26 Example 5 1.6 970 1259 1.30 Example 6 1.4 1013 1354 1.34 Example 7 1.4 1013 1391 1.37 Example 8 1.4 1013 1399 1.38 Example 9 1.4 1013 1403 1.38 Example 10 1.4 1013 1329 1.31 Example 11 1.4 1013 1406 1.39 Example 12 1.4 1013 1412 1.39

[0110] Table 2. Results of Propellant / Liner / Insulation Layer Peeling Inspection on Billets

[0111]

[0112] Tables 1 and 2 show the different preparation processes of the adhesive components for examining interfacial adhesion under the wall-mounted casting and free-filling propellant loading methods. Through the examples in the two tables above, it can be seen that the technical solution of this application has good adhesion performance under both propellant loading methods.

[0113] According to Table 1, and in conjunction with Examples 1-2, 5, 12, and Comparative Examples 1-2, it can be seen that under the limitations of the insulation layer material and propellant plasticizing ratio specified in this application, the adhesion performance between the propellant / liner / insulation layer is good.

[0114] Based on Examples 1 and 6-10, it can be seen that as the content of phenylpropoxazine resin in the ethylene propylene diene monomer (EPDM) insulation material modified with phenylpropoxazine resin increases, the interfacial bonding strength gradually increases. This is related to the content of phenylpropoxazine resin and the absence of small molecule release during its curing process, resulting in low porosity and near-zero volume shrinkage in the product. Therefore, it can effectively prevent the migration of small molecules from the insulation layer to the propellant, and similarly, it can also prevent the migration of small molecules from the propellant with a high plasticization ratio to the insulation layer, thereby allowing the propellant to cure according to design requirements and thus improving the interfacial bonding strength. In Examples 7, 8, and 9, as the content of phenylpropoxazine resin continues to increase, the resin content in the phenylpropoxazine resin-modified EPDM insulation material gradually becomes a continuous phase, causing the elongation of the insulation material to decrease linearly, but the increase in tear strength decreases. Therefore, within the scope defined in this application, the insulation material has both high tear strength and good elongation. Further increases in the content of phenylpropoxazine resin will lead to the elongation of the insulation material failing to meet the usage requirements.

[0115] Referring to Examples 1 and 10-11, it can be seen that, under the vulcanization conditions specified in this application, the bond strength of the phenylpropoxazine resin-modified EPDM insulation material gradually increases with increasing vulcanization temperature. However, as the vulcanization temperature continues to rise, the insulation material will scorch, rendering it unusable.

[0116] According to Table 2, and in conjunction with Examples 3-4, Example 6, and Comparative Examples 3-4, it can be seen that under the limitations of the insulation layer material and propellant plasticization ratio specified in this application, the adhesion performance between the propellant / liner / insulation layer is good.

[0117] However, the present invention can be implemented in many different forms and should not be construed as being limited to the embodiments set forth herein. In other embodiments of the invention, the components may also be selected from other materials listed herein.

[0118] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make possible changes and modifications to the technical solutions of the present invention by utilizing the methods and techniques disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solutions of the present invention shall fall within the protection scope of the technical solutions of the present invention.

[0119] The contents not described in detail in this application specification are common knowledge to those skilled in the art.

Claims

1. A method for bonding a highly plasticized azide polyether propellant to an insulation layer, characterized in that, include: The insulation layer, lining, and highly plasticized azide polyether propellant are sequentially bonded to the combustion chamber shell; The plasticizing ratio of the highly plasticized azide polyether propellant is 1.4~2.0, and the material of the insulation layer is selected from benzoxazine resin modified EPDM insulation material or benzoxazine resin modified nitrile insulation coating material. The benzoxazine resin-modified EPDM insulation material is a co-cured insulation material of DCP, sulfur-cured benzoxazine resin, and EPDM. The benzoxazine resin-modified EPDM insulation material comprises the following raw materials: 100 parts of EPDM rubber, 30-50 parts of benzoxazine resin, 10-50 parts of ablation-resistant fiber, 3-20 parts of solid filler, 6-12 parts of flame retardant system, 2-5 parts of process aids, and 4.5-9 parts of vulcanization system. The benzoxazine resin-modified nitrile butadiene insulation coating material is a DCP and sulfur-cured benzoxazine resin and nitrile co-cured insulation material. The benzoxazine resin-modified nitrile butadiene insulation coating material comprises the following raw materials: Its raw materials include the following components by weight: 100 parts of nitrile rubber, 20-30 parts of dioctyl phthalate, 20-75 parts of benzoxazine resin, 30-60 parts of silica, 6-16 parts of aramid fiber, 4-9 parts of zinc oxide, 0.5-3 parts of antioxidant, 1-4 parts of stearic acid, 1-6 parts of accelerator, 2-4 parts of vulcanizing agent, and 0.2-1 parts of resin curing catalyst.

2. The method for bonding a highly plasticized azide polyether propellant to an insulation layer according to claim 1, characterized in that, During the preparation of the benzoxazine resin-modified EPDM insulation material: the vulcanization temperature is 150℃~170℃, the vulcanization pressure is 5MPa~15MPa, and the vulcanization time is 30min~120min.

3. A method for bonding a highly plasticized azide polyether propellant to an insulation layer according to claim 1 or 2, characterized in that, During the preparation of the benzoxazine resin modified nitrile insulating coating material: the vulcanization temperature is 150℃~170℃, the vulcanization pressure is 5MPa~15MPa, and the vulcanization time is 30min~120min.

4. The method for bonding a highly plasticized azide polyether propellant to an insulation layer according to claim 1, characterized in that: The plasticizer in the highly plasticized azide polyether propellant is selected from N-butylnitroethyl nitramine, bis(2,2-dinitropropanol)formaldehyde / bis(2,2-dinitropropanol)acetal, ester-terminated polyazide glycidyl ether, nitroglycerin, diisooctyl sebacate, tributyl phosphate, diethylene glycol dinitrate, and triethylene glycol dinitrate.

5. The method for bonding a highly plasticized azide polyether propellant to an insulation layer according to claim 1, characterized in that: The liner is an HTPB liner or a PBT liner.

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