Al / HMX / neutral macromolecular bonding agent compound and preparation method thereof

Abstract

The invention provides a preparation method of an Al / HMX / neutral macromolecular bonding agent compound, which comprises the following steps: dissolving HMX and a neutral macromolecular bonding agent in a solvent to obtain a mixed solution, adding aluminum powder into the mixed solution, carrying out ultrasonic dispersion to obtain a dispersion liquid, and carrying out spray granulation on the dispersion liquid on a spray dryer to obtain the Al / HMX / neutral macromolecular bonding agent compound. The neutral macromolecular bonding agent is a bipolymer obtained by copolymerization of acrylonitrile and hydroxyethyl acrylate nitrate or a terpolymer obtained by copolymerization of acrylonitrile, hydroxyethyl acrylate and vinyltriethoxysilane. According to the Al / HMX / neutral macromolecular bonding agent compound provided by the invention, the contact area of the reducing agent aluminum powder and the oxidizing agent HMX is increased, the reaction mass transfer distance is shortened, and sufficient combustion and efficient energy release of the aluminum powder are effectively improved; meanwhile, the solid block-shaped macromolecular bonding agent is assembled into a micron-sized composite material, so that the dispersion uniformity of the solid block-shaped macromolecular bonding agent is improved, the contact area of the solid block-shaped macromolecular bonding agent and HMX is increased, and the mechanical property and preparation process conditions of the propellant can be greatly improved.

Description

Technical Field

[0001] The invention belongs to the technical field of energetic materials, relates to a macromolecular bonding agent composite, and specifically relates to an Al / HMX / neutral macromolecular bonding agent composite and a preparation method thereof. Background Art

[0002] Solid propellant is the power source of missile and rocket engines. It is an energetic composite material with specific properties. Its components burn in the combustion chamber, converting chemical energy into thermal energy to generate high-temperature and high-pressure combustion gas. The combustion gas expands and accelerates through the nozzle, converting thermal energy into kinetic energy. The high-speed backward combustion gas gives the engine a reaction force, providing a certain thrust for the engine. The performance of solid propellant will have a direct impact on the combat capability and survivability of strategic and tactical missiles.

[0003] High energy has always been a hot topic in the research of solid propellants. In order to further increase the energy of propellants, metal aluminum powder with high theoretical calorific value has become an inevitable choice for improving the energy of propellants. The particle size and content of metal aluminum powder greatly affect the combustion performance and actual energy level of propellants. Although a large number of studies have confirmed that the application of nano aluminum powder in propellants can greatly improve the energy and energy release efficiency of propellants, nano aluminum powder faces problems such as poor dispersibility, difficulty in maintaining activity and poor process performance in actual applications.

[0004] The explosive heat of HMX is 6200 kJ·kg -1 , the explosion speed is 9110m·s -1 , with high energy characteristics, large density and good thermal stability, it is widely used in composite solid propellants. HMX can affect the energy performance, burning rate, flame structure and mechanical properties of solid propellants, and can also significantly change the agglomeration of aluminum on the burning surface of the propellant and the characteristics of the condensed phase combustion products. In composite propellants, the content of HMX is usually very high. Due to its smooth crystal surface and basic chemical inertness, it is difficult to form effective physical and chemical bonds, and it will partially dissolve in polar plasticizers, forming a soft interface layer between the nitramine filler and the adhesive matrix, which will produce dehumidification when subjected to external forces, which will reduce the mechanical properties and safety performance of the propellant. Adding an appropriate amount of bonding agent to the propellant can effectively improve the interface properties between the filler and the adhesive system in the propellant, reduce the occurrence of dehumidification, and effectively improve the mechanical properties of the propellant.

[0005] Neutral macromolecular bonding agent (NPBA) contains multiple polar groups, which can be adsorbed on the surface of fillers and react with isocyanates to form a tough coating on the surface of solid particles. NPBA is generally copolymerized by acrylonitrile (AN), acrylate (MA) and hydroxy acrylate. The cyano group of NPBA can be adsorbed on the surface of ammonium nitrate particles, and the hydroxyl group can undergo a cross-linking reaction with the curing agent.

[0006] NPBA is a macromolecular polymer, which is a solid block at room temperature. After being dissolved in the binder / plasticizer system, it agglomerates and cannot be evenly dispersed. During the kneading process, NPBA will not melt into a liquid (melting point > 60°C). Therefore, directly adding NPBA is not conducive to its dissolution and adsorption to the surface of nitramine, which in turn affects the process and mechanical properties of the propellant. Summary of the invention

[0007] In view of the shortcomings of the prior art, the purpose of the present invention is to provide an Al / HMX / neutral macromolecular bonding agent composite and a preparation method thereof, so as to solve the problems in the prior art that the neutral macromolecular bonding agent is difficult to disperse evenly, resulting in poor mechanical properties of the propellant and complex preparation process.

[0008] In order to solve the above technical problems, the present invention adopts the following technical solutions to achieve the above problems:

[0009] A method for preparing an Al / HMX / neutral macromolecular bonding agent composite, the method comprising the following steps:

[0010] Step 1, dissolving HMX and a neutral macromolecular bonding agent in a solvent to obtain a mixed solution;

[0011] Step 2: adding aluminum powder to the mixed solution and dispersing by ultrasonic to obtain a dispersion, and spraying and granulating the dispersion in a spray dryer to obtain an Al / HMX / neutral macromolecular bonding agent complex.

[0012] The present invention also has the following technical features:

[0013] The neutral macromolecular bonding agent is a binary copolymer or a ternary copolymer, wherein the binary copolymer is obtained by copolymerizing acrylonitrile and hydroxyethyl acrylate nitrate, and the ternary copolymer is obtained by copolymerizing acrylonitrile, hydroxyethyl acrylate and vinyl triethoxysilane.

[0014] The mass ratio of the aluminum powder, HMX and neutral macromolecular bonding agent is (8-10): (48-50): (0.2-0.25).

[0015] The mass ratio of the aluminum powder, HMX and neutral macromolecular bonding agent is 8:48:0.2.

[0016] The ratio of the total mass of the aluminum powder, HMX and the neutral macromolecular bonding agent to the mass of the solvent is 1: (1-1.1).

[0017] The solvent is selected from one of tetrahydrofuran, dimethyl sulfoxide and dimethylformamide.

[0018] The particle size of the aluminum powder is 50-100 nm.

[0019] The air inlet temperature of the spray dryer is 180-190° C., the feed rate of the spray dryer is 3-5 mL / min, and the high-purity nitrogen flow rate is 360-400 L / h.

[0020] The present invention also protects an Al / HMX / neutral macromolecular bonding agent complex, wherein the Al / HMX / neutral macromolecular bonding agent complex is prepared by the preparation method of the Al / HMX / neutral macromolecular bonding agent complex as described in any one of claims 1 to 8.

[0021] The particle size of the Al / HMX / neutral macromolecular bonding agent complex is 1-43 μm.

[0022] Compared with the prior art, the present invention has the following technical effects:

[0023] (I) The neutral macromolecular bonding agent proposed in the present invention has a low sensitivity, which not only increases the contact area between the reducing agent aluminum powder and the oxidizing agent HMX and shortens the reaction mass transfer distance, but also effectively improves the full combustion of the aluminum powder and the efficient energy release; at the same time, the solid block macromolecular bonding agent is assembled into a micron-scale composite material, which improves the dispersion uniformity of the solid block macromolecular bonding agent and increases the contact area between the solid block macromolecular bonding agent and HMX, which can greatly improve the mechanical properties and preparation process conditions of the solid propellant.

[0024] (II) The spray drying method proposed in the present invention is simple to operate, has a short cycle, is easy to remove the solvent and scale up the production, and the prepared Al / HMX / neutral macromolecular bonding agent composite has good dispersibility. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is the SEM picture of Al / HMX / acrylonitrile and hydroxyethyl acrylate nitrate copolymer composite.

[0026] Figure 2 This is the SEM image of the Al / HMX / acrylonitrile, hydroxyethyl acrylate and vinyl triethoxysilane terpolymer composite.

[0027] The specific contents of the present invention are further explained in detail below in conjunction with embodiments. DETAILED DESCRIPTION

[0028] It should be noted that the raw materials in the present invention, unless otherwise specified, are all raw materials known in the prior art.

[0029] In the present invention, the binary copolymer of acrylonitrile and hydroxyethyl acrylate nitrate and the ternary copolymer of acrylonitrile, hydroxyethyl acrylate and vinyl triethoxysilane are both known products.

[0030] Among them, the molecular structure formula of the binary copolymer of acrylonitrile and hydroxyethyl acrylate nitrate is as follows:

[0031]

[0032] The number average molecular weight is 9550.

[0033] The molecular structure of the terpolymer of acrylonitrile, hydroxyethyl acrylate and vinyl triethoxysilane is shown below:

[0034]

[0035] The number average molecular weight is 20,500.

[0036] In accordance with the above technical scheme, specific embodiments of the present invention are given below. It should be noted that the present invention is not limited to the following specific embodiments, and all equivalent changes made on the basis of the technical scheme of this application fall within the protection scope of the present invention.

[0037] Embodiment 1:

[0038] This embodiment provides a method for preparing an Al / HMX / neutral macromolecular bonding agent composite, which comprises the following steps:

[0039] Step 1: add 480 g HMX, 2 g acrylonitrile and a binary copolymer obtained by copolymerization of hydroxyethyl acrylate nitrate into 570 mL tetrahydrofuran solution, and stir at room temperature until dissolved to obtain a mixed solution.

[0040] In this embodiment, the neutral macromolecular bonding agent is a binary copolymer obtained by copolymerizing acrylonitrile and hydroxyethyl acrylate nitrate. The number average molecular weight of the binary copolymer is 9550, and the copolymerization method of the binary copolymer can be a known commonly used copolymerization method.

[0041] Step 2: Add 80 g of aluminum powder to the mixed solution, ultrasonically disperse at room temperature for 30 min, and after uniform dispersion, spray granulate the dispersion on a spray dryer, wherein the particle size of the aluminum powder is 100 nm, the air inlet temperature is 185 ° C, the feed rate is 3.5 mL / min, and the high-purity nitrogen flow rate is 370 L / h to obtain a gray powder Al / HMX / acrylonitrile and hydroxyethyl acrylate nitrate copolymer composite.

[0042] SEM images of Al / HMX / acrylonitrile and hydroxyethyl acrylate nitrate copolymer composites Figure 1 As shown, from Figure 1 It can be seen that the Al / HMX / acrylonitrile and hydroxyethyl acrylate nitrate binary copolymer composite prepared in this example has a particle size of 1.95 μm, a uniform and controllable particle size distribution, good particle dispersion, and no agglomeration.

[0043] The performance test of the Al / HMX / acrylonitrile and hydroxyethyl acrylate nitrate binary copolymer composite prepared in this embodiment was carried out. The Al / HMX / acrylonitrile and hydroxyethyl acrylate nitrate binary copolymer composite prepared in this embodiment was added to the composite solid propellant formula. The formula of the propellant was as follows: the mass fraction of the Al / HMX / acrylonitrile and hydroxyethyl acrylate nitrate binary copolymer composite was 65%, the mass fraction of AP (ammonium perchlorate) was 10%, and the bonding system (GAP (glycidyl polyazide) / PEG (polyethylene glycol) / BuNENA (N-butyl nitroxyethyl ammonium nitrate) / N-100 (multifunctional isocyanate)) was 25%.

[0044] In this embodiment, all raw materials in the bonding system are commonly used raw materials known in the art.

[0045] The mechanical properties of solid propellants were tested using the method specified in 413.1 of the known and publicly known national military standard GJB770B-2005. The test results are shown in Table 1.

[0046] Comparative Example 1

[0047] This comparative example provides a method for preparing an Al / HMX / neutral macromolecular bonding agent composite. This comparative example adopts the components and proportions disclosed in Example 1, except that in this comparative example, the above-mentioned HMX, aluminum powder and the binary copolymer obtained by copolymerizing acrylonitrile and hydroxyethyl acrylate nitrate are directly physically mixed to obtain an Al / HMX / hydroxyethyl acrylate nitrate binary copolymer mixture.

[0048] The physical mixture of this comparative example 1 is added to a composite solid propellant formula, wherein the propellant formula is as follows: the mass fraction of aluminum powder is 9.27%, the mass fraction of HMX is 55.5%, the mass fraction of acrylonitrile and hydroxyethyl acrylate nitrate copolymer is 0.23%, the mass fraction of AP is 10%, and the mass fraction of the bonding system (GAP / PEG / BuNENA / N-100) is 25%.

[0049] The mechanical properties of solid propellants were tested using the method specified in 413.1 of the known and publicly known national military standard GJB770B-2005. The test results are shown in Table 1.

[0050] Table 1 Experimental results of composite solid propellant

[0051] sample Test temperature / ℃ Tensile strength / MPa Elongation at break % Composite solid propellant of Example 1 20 0.97 95.1 Composite solid propellant of Comparative Example 1 20 0.76 82.3

[0052] It can be seen from Table 1 that the Al / HMX / acrylonitrile and hydroxyethyl acrylate nitrate binary copolymer composite prepared by the present invention can significantly improve the mechanical properties of the composite solid propellant formulation. Compared with Comparative Example 1, the Al / HMX / acrylonitrile and hydroxyethyl acrylate nitrate binary copolymer composite is applied to the composite solid propellant, and the tensile strength of the composite solid propellant is increased from 0.76 MPa to 0.97 MPa, and the elongation at break is increased from 82.3% to 95.1%.

[0053] Embodiment 2:

[0054] This example provides a method for preparing an Al / HMX / neutral macromolecular bonding agent composite, which is substantially the same as the method for preparing an Al / HMX / neutral macromolecular bonding agent composite in Example 1, except that the neutral macromolecular bonding agent in this example is a terpolymer obtained by copolymerization of acrylonitrile, hydroxyethyl acrylate and vinyl triethoxysilane, and the number average molecular weight of the terpolymer is 20500. The copolymerization method of the terpolymer may be a known commonly used copolymerization method.

[0055] SEM images of Al / HMX / acrylonitrile, hydroxyethyl acrylate and vinyl triethoxysilane terpolymer composites Figure 2 As shown, from Figure 2 It can be seen that the particle size of the Al / HMX / acrylonitrile, hydroxyethyl acrylate and vinyl triethoxysilane terpolymer composite of this embodiment is 2.16 μm, the particle size distribution is uniform, and there is no agglomeration.

[0056] The performance test of the Al / HMX / acrylonitrile, hydroxyethyl acrylate and vinyl triethoxysilane ternary copolymer composite prepared in this embodiment was carried out. The Al / HMX / acrylonitrile, hydroxyethyl acrylate and vinyl triethoxysilane ternary copolymer composite prepared in this embodiment was added to the composite solid propellant formula. The formula of the propellant was: the mass fraction of the Al / HMX / acrylonitrile, hydroxyethyl acrylate and vinyl triethoxysilane ternary copolymer composite was 65%, the mass fraction of AP was 10%, and the bonding system (GAP / PEG / BuNENA / N-100) was 25%.

[0057] In this embodiment, all raw materials in the bonding system are commonly used raw materials known in the art.

[0058] The mechanical properties of solid propellants were tested using the method specified in 413.1 of the known and publicly known national military standard GJB770B-2005. The test results are shown in Table 2.

[0059] Comparative Example 2

[0060] This comparative example provides a method for preparing an Al / HMX / neutral macromolecular bonding agent composite, which adopts the components and proportions disclosed in Example 2, except that in this comparative example, the ternary copolymer obtained by copolymerizing acrylonitrile, hydroxyethyl acrylate and vinyl triethoxysilane in Example 2 is directly physically mixed to obtain a ternary copolymer mixture of Al / HMX / acrylonitrile, hydroxyethyl acrylate and vinyl triethoxysilane.

[0061] The Al / HMX / acrylonitrile, hydroxyethyl acrylate and vinyl triethoxysilane terpolymer mixture of Comparative Example 2 was added to a composite solid propellant formulation, wherein the propellant formulation was as follows: the mass fraction of aluminum powder was 9.27%, the mass fraction of HMX was 55.5%, the mass fraction of the terpolymer obtained by copolymerization of acrylonitrile, hydroxyethyl acrylate and vinyl triethoxysilane was 0.23%, the mass fraction of AP was 10%, and the bonding system (GAP / PEG / BuNENA / N-100) was 25%.

[0062] The mechanical properties of solid propellants were tested using the method specified in 413.1 of the known and publicly known national military standard GJB770B-2005. The test results are shown in Table 2.

[0063] Table 2 Experimental results of composite solid propellant

[0064] sample Test temperature / ℃ Tensile strength / MPa Elongation at break % Composite solid propellant of Example 2 20 1.05 100.4 Composite solid propellant of Comparative Example 2 20 0.76 82.3

[0065] It can be seen from Table 2 that the Al / HMX / acrylonitrile, hydroxyethyl acrylate and vinyl triethoxysilane ternary copolymer composite prepared by the present invention can significantly improve the mechanical properties of the composite solid propellant formulation. Compared with Comparative Example 2, the Al / HMX / acrylonitrile, hydroxyethyl acrylate and vinyl triethoxysilane ternary copolymer composite is applied to the composite solid propellant, and the tensile strength of the propellant is increased from 0.76 MPa to 1.05 MPa, and the elongation at break is increased from 82.3% to 100.4%.

[0066] Tables 1 and 2 illustrate that the neutral macromolecular bonding agent proposed in the present invention increases the contact area between the reducing agent aluminum powder and the oxidizing agent HMX, shortens the reaction mass transfer distance, and effectively improves the full combustion of the aluminum powder and the efficient energy release; at the same time, the solid block macromolecular bonding agent is assembled into a micron-scale composite material, which improves the dispersion uniformity of the solid block macromolecular bonding agent, increases the contact area between the solid block macromolecular bonding agent and HMX, and greatly improves the mechanical properties and preparation process conditions of the solid propellant.

Claims

1. A method for preparing an Al / HMX / neutral macromolecular bonding agent composite, characterized in that: The method comprises the following steps: Step 1, dissolving HMX and a neutral macromolecular bonding agent in a solvent to obtain a mixed solution; Step 2: adding aluminum powder to the mixed solution and dispersing by ultrasonic to obtain a dispersion, and spraying and granulating the dispersion in a spray dryer to obtain an Al / HMX / neutral macromolecular bonding agent complex.

2. The method for preparing the Al / HMX / neutral macromolecular bonding agent composite according to claim 1, characterized in that: The neutral macromolecular bonding agent is a binary copolymer or a ternary copolymer, wherein the binary copolymer is obtained by copolymerizing acrylonitrile and hydroxyethyl acrylate nitrate, and the ternary copolymer is obtained by copolymerizing acrylonitrile, hydroxyethyl acrylate and vinyl triethoxysilane.

3. The method for preparing the Al / HMX / neutral macromolecular bonding agent composite according to claim 1, characterized in that: The mass ratio of the aluminum powder, HMX and neutral macromolecular bonding agent is (8-10): (48-50): (0.2-0.25).

4. The method for preparing the Al / HMX / neutral macromolecular bonding agent composite according to claim 1, characterized in that: The mass ratio of the aluminum powder, HMX and neutral macromolecular bonding agent is 8:48:0.

2.

5. The method for preparing the Al / HMX / neutral macromolecular bonding agent composite according to claim 1, characterized in that: The ratio of the total mass of the aluminum powder, HMX and the neutral macromolecular bonding agent to the mass of the solvent is 1: (1-1.1).

6. The method for preparing the Al / HMX / neutral macromolecular bonding agent composite according to claim 1, characterized in that: The solvent is selected from one of tetrahydrofuran, dimethyl sulfoxide and dimethylformamide.

7. The method for preparing the Al / HMX / neutral macromolecular bonding agent composite according to claim 1, characterized in that: The particle size of the aluminum powder is 50-100 nm.

8. The method for preparing the Al / HMX / neutral macromolecular bonding agent composite according to claim 1, characterized in that: The air inlet temperature of the spray dryer is 180-190° C., the feed rate of the spray dryer is 3-5 mL / min, and the high-purity nitrogen flow rate is 360-400 L / h.

9. An Al / HMX / neutral macromolecular bonding agent composite, characterized in that: The Al / HMX / neutral macromolecular bonding agent composite is prepared by the preparation method of the Al / HMX / neutral macromolecular bonding agent composite according to any one of claims 1 to 8.

10. The Al / HMX / neutral macromolecular bonding agent composite according to claim 9, characterized in that: The particle size of the Al / HMX / neutral macromolecular bonding agent complex is 1-43 μm.

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