Ultralow-temperature solid propellant based on high cis-HTPB and preparation method of ultralow-temperature solid propellant

Abstract

The invention relates to an ultralow-temperature solid propellant based on high cis-HTPB and a preparation method thereof, and belongs to the field of solid propellants, the solid propellant comprises the following components by mass: 67%-77% of an oxidant, 12%-20% of a metal fuel, 6.5%-9.5% of an adhesive HTPB, 2%-8% of a plasticizer, 0%-3% of a burning rate catalyst, 0.4%-1% of a curing agent, 0%-0.8% of a cross-linking agent, and 0%-2% of a function regulator; wherein the adhesive HTPB is synthesized through oxidative cracking, the content of cis-allyl primary hydroxyl groups in the adhesive HTPB is higher than 50%, and the plasticizer is a nonyl oleate plasticizer LZS-404 with more flexible chains than dioctyl sebacate DOS and dioctyl adipate DOA. The low-temperature solid propellant breaks through the lower limit of the glass transition temperature of the solid propellant and reaches-96 DEG C or below, the low-temperature adaptability of the solid propellant is improved while the characteristics of energy, combustion and the like are maintained, and the low-temperature solid propellant is suitable for rocket engine charging for deep space exploration tasks and engine charging for extreme scenes such as plateau regions, extremely cold northern regions and high altitudes.

Description

Technical Field

[0001] The invention belongs to the technical field of solid propellants, and in particular relates to an ultra-low temperature solid propellant based on high-cis HTPB and a preparation method thereof. Background Art

[0002] Solid propellant is the power source of rocket engines, and temperature adaptability is an important performance of solid propellant. At present, higher requirements are put forward for the low-temperature performance of solid propellant, requiring the propellant to improve its low-temperature adaptability while maintaining its energy, mechanical and other properties.

[0003] The glass transition temperature is an important indicator of the low temperature adaptability of the propellant. When the ambient temperature of the propellant is close to the glass transition temperature T g When the plasticizer is heated, the matrix material composed of plasticizer, adhesive and solidified network structure will change from high elastic state to glassy state, and the mechanical properties of the propellant will change essentially, the elongation will drop significantly, and the strength and modulus will increase significantly, which will affect the use of the propellant.

[0004] At present, the most widely used solid propellant is hydroxybutyric acid (HTPB) propellant, which has good processing properties, mechanical properties and excellent storage properties, a wide range of burning rate adjustment, and, especially compared with polyether / azide propellants, has a lower glass transition temperature, generally around -70°C, which can meet the propellant requirements of existing platforms. However, there is still a gap in the requirements for solid engine charges (glass transition temperature ≤ -80°C) under mission profiles such as deep space exploration.

[0005] Therefore, further improving the low-temperature adaptability of solid propellants to ensure that the propellants remain structurally reliable and can burn normally at -80°C, and to provide stable and reliable power energy for the engine, has become an important issue that needs to be urgently addressed in the current development of space exploration. Summary of the invention

[0006] The technical problem solved by the present application is: to overcome the shortcomings of the prior art and provide an ultra-low temperature solid propellant based on high-cis HTPB and a preparation method thereof, which greatly reduces the glass transition temperature of the solid propellant and improves the low-temperature adaptability of the solid propellant while ensuring that the comprehensive performance of the propellant meets the requirements of the engine charge, so as to meet the high requirements for the performance indicators of the solid propellant for rocket engine charges for deep space exploration missions and engine charges for extreme scenarios such as plateau areas, extremely cold northern regions, and high altitudes.

[0007] In order to obtain a HTPB ultra-low temperature solid propellant with a lower glass transition temperature and better comprehensive performance, the present invention adopts a HTPB synthesized by oxidative cracking with a molar content of cis-allyl primary hydroxyl group higher than 50% as an adhesive. Compared with traditional free radical polymerization and anionic polymerization HTPB adhesives, the main chain of the high cis-HTPB adhesive synthesized by oxidative cracking has better flexibility, is not easy to be oriented or crystallized under low temperature conditions, and can still rotate and bend the chain segments, and has better low temperature performance, thereby improving the low temperature adaptability of the propellant. At the same time, it is matched with a nonyl oleate plasticizer LZS-404 with more flexible chains and a lower glass transition temperature than dioctyl sebacate DOS and dioctyl adipate DOA, giving the propellant a lower glass transition temperature and improving the low temperature performance of the propellant.

[0008] The technical solution of the present invention is as follows:

[0009] A super-low temperature solid propellant based on high-cis HTPB, the solid propellant comprising the following components in percentage by mass:

[0010] Oxidant 67% to 77%, metal fuel 12% to 20%, adhesive HTPB 6.5% to 9.5%, plasticizer 2% to 8%, burning rate catalyst 0% to 3%, curing agent 0.4% to 1%, cross-linking agent 0% to 0.8%, function regulator 0% to 2%.

[0011] The adhesive HTPB is HTPB synthesized by oxidative cleavage and has a cis-allyl primary hydroxyl content of more than 50%, and the plasticizer is a nonyl oleate plasticizer LZS-404 having more flexible chains than dioctyl sebacate DOS and dioctyl adipate DOA.

[0012] The oxidant is ammonium perchlorate AP.

[0013] The metal fuel is aluminum powder Al.

[0014] The combustion rate catalyst is a combination of one or more commonly used combustion rate catalysts such as calcium carbonate, n-octylferrocene, and catocene.

[0015] The curing agent is a combination of one or more compounds containing two or more isocyanate groups in the molecule such as toluene diisocyanate TDI, isophorone diisocyanate IPDI, dimer acid diisocyanate DDI, etc.

[0016] The cross-linking agent is a combination of one or more compounds such as aziridine and castor oil, which have two or more groups that can react with active hydrogen or isocyanate groups.

[0017] The functional regulators are bonding agents, stabilizers, curing catalysts and process aids.

[0018] A method for preparing an ultra-low temperature solid propellant based on high-cis HTPB comprises the following steps:

[0019] (1) Weigh the above raw materials according to the above mass fractions, fully premix the metal fuel, the binder HTPB, the crosslinking agent, the plasticizer, the burning rate catalyst and the functional regulator to make the components evenly dispersed, and keep the mixture in an oven at 40 to 60° C. for not less than 60 minutes to make the metal fuel fully infiltrated by the binder HTPB with a smaller main chain polarity, thereby obtaining a premix slurry;

[0020] (2) Add the premix slurry, oxidant and curing agent into a vertical mixer in sequence and mix them thoroughly to make the components evenly dispersed to form a propellant slurry with good processability. The mixing time is not less than 90 minutes and the mixing temperature is 40 to 60° C.;

[0021] (3) Pouring: Use vacuum pouring method to pour the uniformly mixed propellant slurry into the engine housing or various molds. The residual pressure during the pouring process shall not exceed 1.33 kPa, and the pouring temperature shall be controlled at 40-60°C;

[0022] (4) Curing: Place the poured charge engine or various charge molds in a constant temperature oven for constant temperature curing. The curing temperature is 40 to 60°C and the curing time is 120 to 216 hours.

[0023] Compared with the prior art, the present invention has the following main advantages:

[0024] (1) The ultra-low temperature solid propellant based on high cis-HTPB provided by the present invention adopts an HTPB synthesized by oxidation cleavage, which has better main chain flexibility and is not easy to be oriented or crystallized under low temperature conditions, and has a cis-allyl primary hydroxyl content of more than 50% as a binder, and is combined with a nonyl oleate plasticizer LZS-404 with more flexible chains than dioctyl sebacate DOS and dioctyl adipate DOA, thereby increasing the free volume of polymer molecules, achieving the polymer molecules to maintain interchain movement under low temperature conditions, and lowering the glass transition temperature of the solid propellant;

[0025] (2) The propellant provided by the present invention breaks through the lower limit of the glass transition temperature of solid propellants and can reach below -96°C, thereby improving the low-temperature adaptability of solid propellants while maintaining energy, combustion and other characteristics. It has passed the -70°C Engine ignition test. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 HTPB propellant for ultra-low temperature environments Pt curve of low temperature ignition test. DETAILED DESCRIPTION

[0027] In order to enable those skilled in the art to better understand the present invention, an ultra-low temperature solid propellant based on high-cis HTPB and a preparation method thereof of the present invention are further described in detail below in conjunction with specific embodiments.

[0028] A super-low temperature solid propellant based on high-cis HTPB, the solid propellant comprising the following components in percentage by mass:

[0029] Oxidant 67% to 77%, metal fuel 12% to 20%, adhesive HTPB 6.5% to 9.5%, plasticizer 2% to 8%, burning rate catalyst 0% to 3%, curing agent 0.4% to 1%, cross-linking agent 0% to 0.8%, function regulator 0% to 2%.

[0030] The adhesive HTPB is HTPB synthesized by oxidative cleavage and has a cis-allyl primary hydroxyl content of more than 50%, and the plasticizer is a nonyl oleate plasticizer LZS-404 having more flexible chains than dioctyl sebacate DOS and dioctyl adipate DOA.

[0031] The oxidant is ammonium perchlorate AP.

[0032] The metal fuel is aluminum powder Al.

[0033] The burning rate catalyst is a combination of one or more commonly used burning rate catalysts such as calcium carbonate, n-octylferrocene, and catocene.

[0034] The curing agent is a combination of one or more compounds containing two or more isocyanate groups in the molecule such as toluene diisocyanate TDI, isophorone diisocyanate IPDI, dimer acid diisocyanate DDI, etc.

[0035] The cross-linking agent is a combination of one or more compounds such as aziridine and castor oil, which have two or more groups that can react with active hydrogen or isocyanate groups in their molecules.

[0036] Functional regulators are bonding agents, stabilizers, curing catalysts and process aids.

[0037] A method for preparing an ultra-low temperature solid propellant based on high-cis HTPB comprises the following steps:

[0038] Step 1: Weigh the above raw materials according to the above mass fractions, fully premix the metal fuel, binder HTPB, crosslinking agent, plasticizer, burning rate catalyst and functional regulator to make the components evenly dispersed, and keep them in an oven at 40-60°C for no less than 60 minutes to make the metal fuel fully infiltrated by the binder HTPB with a smaller main chain polarity, to obtain a premix slurry;

[0039] Step 2: Add the premixed slurry, oxidant and curing agent into the vertical mixer in sequence and mix them thoroughly to make the components dispersed evenly to form a propellant slurry with good processability. The mixing time is not less than 90 minutes and the mixing temperature is 40-60°C.

[0040] Step 3: Use vacuum casting method to pour the evenly mixed propellant slurry into the engine housing or various molds. The residual pressure during the pouring process shall not exceed 1.33kPa, and the pouring temperature shall be controlled at 40-60℃;

[0041] Step 4: Place the poured charge engine or various charge molds into a constant temperature oven for constant temperature curing. The curing temperature is 40-60°C and the curing time is 120-216 hours.

[0042] According to the commonly used propellant formula composition and content range in the prior art, a reference propellant was designed under the same conditions using traditional free radical polymerization HTPB or anionic polymerization HTPB compounded with traditional free radical polymerization HTPB adhesive and dioctyl sebacate DOS or dioctyl adipate DOA plasticizer to compare performance with the solid propellant of the present invention.

[0043] In terms of propellant performance testing, the glass transition temperature is tested using GJB770B-2005 method 407.1; the tensile strength and elongation are tested using GJB770B-2005 method 413.1; the density is tested using the method specified in QJ917A-1997; and the burning rate is tested using GJB770B-2005 method 706.2.

[0044] Preparation Example 1

[0045] The preparation method of high cis-HTPB comprises: oxidizing and cracking butadiene rubber by hydrogen peroxide, and then reducing the end groups to obtain HTPB with a cis-1,4 content of 75%.

[0046] Example 1

[0047] An ultra-low temperature solid propellant based on high-cis HTPB, the formula composition is shown in Table 1.

[0048] Table 1 Example 1 Components

[0049]

[0050]

[0051] Among them, the functional regulator in this embodiment 1 includes: the mass ratio of alcohol amine bonding agent, triphenyl bismuth curing catalyst, amine antioxidant, and polyamide resin process additive is 6:2:9:6.

[0052] The preparation method is as follows:

[0053] Weigh the raw materials of the formula separately according to the formula ratio;

[0054] First, add the adhesive HTPB, cross-linking agent, functional regulator, and plasticizer components to the premix container in sequence and stir them evenly by hand; then add calcium carbonate and stir them evenly by hand; finally add Al and stir them manually for 5 minutes to obtain a premix slurry;

[0055] The premixed slurry of the present invention is kept warm in an oven at 60°C for not less than 60 minutes;

[0056] The premixed slurry oxidant AP and IPDI components are added to the vertical mixer in batches and mixed thoroughly to make the components dispersed uniformly to form a propellant slurry with good processability; the mixing time is 140 minutes and the mixing temperature is 55°C;

[0057] The uniformly mixed propellant slurry is vacuum poured into the propellant mold at a pouring temperature of 60°C;

[0058] The cast propellant mold was placed in a 60°C constant temperature water bath oven for constant temperature curing for 192 hours to obtain a solid propellant sample.

[0059] Comparative Examples 1-3

[0060] The raw materials and the contents of the raw materials in Comparative Examples 1-3 are different from those in Example 1, and the specific differences are shown in Table 2; the preparation methods of Comparative Examples 1-3 are the same as those in Example 1.

[0061] Table 2 Comparative Examples 1-3 Components

[0062]

[0063]

[0064] Among them, the commercial source of free radical polymerization HTPB is: Liming Chemical Research and Design Institute Co., Ltd.

[0065] The properties of the propellants prepared in Example 1 and Comparative Examples 1-3 are shown in Table 3.

[0066] Table 3 Propellant properties obtained from Example 1 and Comparative Examples 1-3

[0067]

[0068] The above data show that the present invention can effectively reduce the glass transition temperature of the propellant to below -96°C, thereby significantly reducing the glass transition temperature of the propellant while maintaining energy, combustion and other characteristics, thereby improving the low-temperature adaptability of the solid propellant.

[0069] Example 2

[0070] An ultra-low temperature solid propellant based on high-cis HTPB, the formula composition is shown in Table 4.

[0071] Table 4 Example 2 Components

[0072]

[0073]

[0074] Among them, the functional regulator in this embodiment includes: the mass ratio of alcohol amine bonding agent, amine antioxidant and polyamide resin process additive is 7:8:6.

[0075] The preparation method comprises:

[0076] Weigh the raw materials of the formula separately according to the formula ratio;

[0077] First, add the adhesive HTPB, cross-linking agent, functional regulator, plasticizer, and cartocin components into the premix container in sequence and stir them evenly by hand; add Al and stir by hand for 5 minutes to obtain a premix slurry;

[0078] The premixed slurry of the present invention is kept warm in an oven at 60°C for not less than 60 minutes;

[0079] The premixed slurry oxidant AP and TDI components are added to the vertical mixer in batches and mixed thoroughly to make the components dispersed uniformly to form a propellant slurry with good processability; the mixing time is 110 minutes and the mixing temperature is 45°C;

[0080] The uniformly mixed propellant slurry is vacuum poured into the propellant mold at a pouring temperature of 50°C;

[0081] The cast propellant mold was placed in a 50°C constant temperature water bath oven for constant temperature curing for 192 hours to obtain an ultra-low temperature solid propellant based on high-cis HTPB.

[0082] Comparative Examples 4-6

[0083] The raw materials and the contents of the raw materials in Comparative Examples 4-6 are different from those in Example 2. The specific differences are shown in Table 5. The preparation methods of Comparative Examples 4-6 are the same as those in Example 2.

[0084] Table 5 Comparative Examples 4-6 Components

[0085]

[0086]

[0087] Among them, the commercial sources of free radical polymerization HTPB and anionic polymerization HTPB are Liming Chemical Research and Design Institute Co., Ltd.

[0088] The properties of the ultra-low temperature solid propellants based on high-cis-HTPB prepared in Example 2 and Comparative Examples 4-6 are shown in Table 6.

[0089] Table 6 Propellant properties obtained from Example 2 and Comparative Examples 4-6

[0090]

[0091] The above data show that the present invention can effectively reduce the glass transition temperature of the propellant. By adjusting the amount of plasticizer, the glass transition temperature can reach -99.8°C. Compared with the comparative example, the glass transition temperature of the propellant is greatly reduced while maintaining the energy, combustion and other characteristics. However, the comparative example containing anionic polymerized HTPB can form a more perfect network structure due to the narrow molecular weight distribution of anionic polymerized HTPB, and exhibits more excellent mechanical properties at +70°C, +20°C, and -55°C. Since the mechanical property test temperature did not reach the glass transition temperature of the propellant sample, the propellant was in a high elastic state, so the mechanical properties of the propellant did not show degradation.

[0092] Example 2: The formula is applied to The standard test engine low temperature ignition test, respectively, assessed the ignition performance at +28℃, -55℃, -70℃, the test Ft curve is shown in Figure 1 When ignited at -55℃ and -70℃, the engine worked normally throughout the whole process, and the Pt curve was smooth and stable, which was consistent with the trend of the working curve at normal temperature (+28℃).

[0093] Example 3

[0094] An ultra-low temperature solid propellant based on high-cis HTPB, the formula composition is shown in Table 7.

[0095] Table 7 Example 7 Components

[0096]

[0097] Among them, the functional regulator in this embodiment 1 includes: the mass ratio of alcohol amine bonding agent, amine antioxidant and polyamide resin process additive is 8:8:6.

[0098] The preparation method is as follows:

[0099] Weigh the raw materials of the formula separately according to the formula ratio;

[0100] First, add the adhesive HTPB, cross-linking agent, functional regulator, plasticizer, and cartocin components into the premix container in sequence and stir them evenly by hand; add Al and stir by hand for 5 minutes to obtain a premix slurry;

[0101] The premixed slurry of the present invention is kept warm in an oven at 60°C for not less than 60 minutes;

[0102] The premixed slurry oxidant AP and TDI components are added to the vertical mixer in batches and mixed thoroughly to make the components dispersed uniformly to form a propellant slurry with good processability; the mixing time is 110 minutes and the mixing temperature is 45°C;

[0103] The uniformly mixed propellant slurry is vacuum poured into the propellant mold at a pouring temperature of 50°C;

[0104] The cast propellant mold was placed in a 50°C constant temperature water bath oven for constant temperature curing for 192 hours to obtain an ultra-low temperature solid propellant based on high-cis HTPB.

[0105] The properties of the propellant prepared in Example 3 are shown in Table 8.

[0106] Table 8 Performance of the propellant obtained in Example 3

[0107]

[0108] The above data show that the present invention can effectively reduce the glass transition temperature of the propellant to below -96°C, achieving the goal of improving the low-temperature adaptability of solid propellants while maintaining energy, combustion and other characteristics. Due to the limitation of thermal insulation equipment, the ignition verification of the low temperature of -80°C has not been carried out. It is analyzed that the glass transition temperature of the ultra-low temperature solid propellant based on high-cis HTPB is much lower than -80°C. Under -80°C conditions, the propellant still exhibits a high elastic state and has the feasibility of ignition at -80°C. It can be better applied to rocket engine charges for deep space exploration missions and engine charges for extreme scenarios such as plateaus and extremely cold areas.

[0109] The above embodiments are exemplary rather than exhaustive and are only intended to further describe the implementation methods of the present invention. Therefore, any equivalent changes or modifications made based on the technical solutions of the patent application of the present invention are included in the protection scope of the present invention.

[0110] The contents not described in detail in this application specification belong to the common knowledge of those skilled in the art.

[0111] The present application is described in detail above in conjunction with specific implementation methods and exemplary examples, but these descriptions cannot be understood as limiting the present application. Those skilled in the art understand that, without departing from the spirit and scope of the present application, a variety of equivalent replacements, modifications or improvements can be made to the technical solution of the present application and its implementation methods, all of which fall within the scope of the present application. The scope of protection of the present application shall be subject to the attached claims.

Claims

1. An ultra-low temperature solid propellant based on high-cis HTPB, characterized in that: Taking the sum of the contents of each component as 100%, it includes: 67% to 77% of oxidant, 12% to 20% of metal fuel, 6.5% to 9.5% of adhesive HTPB, 2% to 8% of plasticizer, 0% to 3% of burning rate catalyst, 0.4% to 1% of curing agent, 0% to 0.8% of cross-linking agent and 0% to 2% of functional regulator.

2. The ultra-low temperature solid propellant based on high-cis HTPB according to claim 1, characterized in that: The adhesive HTPB is HTPB synthesized by oxidative cracking and has a cis-allyl primary hydroxyl molar content higher than 50%, and the plasticizer is a nonyl oleate plasticizer LZS-404.

3. The ultra-low temperature solid propellant based on high-cis HTPB according to claim 2, characterized in that: The oxidative cracking synthesis is to oxidatively crack the butadiene rubber with an oxidant such as hydrogen peroxide or periodic acid, and then reduce the end groups.

4. The ultra-low temperature solid propellant based on high-cis HTPB according to claim 1, characterized in that: The oxidant is ammonium perchlorate.

5. The ultra-low temperature solid propellant based on high-cis HTPB according to claim 1, characterized in that: The metal fuel is aluminum powder.

6. The ultra-low temperature solid propellant based on high-cis HTPB according to claim 1, characterized in that: The burning rate catalyst is selected from calcium carbonate, n-octylferrocene and / or catocene.

7. The ultra-low temperature solid propellant based on high-cis HTPB according to claim 1, characterized in that: The curing agent is a compound containing two or more isocyanate groups in the molecule; the curing agent is selected from toluene diisocyanate TDI, isophorone diisocyanate IPDI or dimer acid diisocyanate DDI.

8. The ultra-low temperature solid propellant based on high-cis HTPB according to claim 1, characterized in that: The cross-linking agent is a compound containing two or more groups that can react with active hydrogen or isocyanate groups; the cross-linking agent is selected from aziridine and / or castor oil.

9. The ultra-low temperature solid propellant based on high-cis HTPB according to claim 1, characterized in that: The functional regulator is selected from bonding agents, stabilizers, curing catalysts and process aids.

10. The method for preparing a high-cis HTPB-based ultra-low temperature solid propellant according to claim 1, characterized in that: include: (1) Premixing the metal fuel, the binder HTPB, the crosslinking agent, the plasticizer, the burning rate catalyst and the functional regulator sufficiently to disperse the components uniformly, and heat-keeping the mixture at 40-60° C. for not less than 60 minutes to allow the metal fuel to be infiltrated by the binder HTPB to obtain a premix slurry; (2) Add the premix slurry, oxidant and curing agent into a vertical mixer in sequence and mix them thoroughly to make the components evenly dispersed to obtain a propellant slurry. The mixing time is not less than 90 minutes and the mixing temperature is 40 to 60° C.; (3) Pouring: Use vacuum pouring method to pour the uniformly mixed propellant slurry into the engine housing or mold. The residual pressure during the pouring process shall not exceed 1.33 kPa, and the pouring temperature shall be controlled at 40-60°C; (4) Curing: Place the poured charge engine or mold in a constant temperature oven for constant temperature curing. The curing temperature is 40 to 60°C and the curing time is 120 to 216 hours.

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