An al / hmx / neutral macromolecular bonding agent composite and a method for preparing the same

Abstract

This invention proposes a method for preparing an Al / HMX / neutral macromolecular bonding agent composite. The method first involves dissolving HMX and a neutral macromolecular bonding agent in a solvent to obtain a mixed solution. Then, aluminum powder is added to the mixed solution and ultrasonically dispersed to obtain a dispersion. The dispersion is then spray-dried and granulated to obtain the final product. The neutral macromolecular bonding agent is a binary copolymer obtained by copolymerizing acrylonitrile and hydroxyethyl acrylate nitrate, or a ternary copolymer obtained by copolymerizing acrylonitrile, hydroxyethyl acrylate, and vinyltriethoxysilane. The Al / HMX / neutral macromolecular bonding agent composite proposed in this invention not only increases the contact area between the reducing agent aluminum powder and the oxidizing agent HMX, shortening the reaction mass transfer distance, but also effectively improves the complete combustion and efficient energy release of the aluminum powder. Simultaneously, assembling the solid bulk macromolecular bonding agent into a micron-sized composite material improves the dispersion uniformity of the solid bulk macromolecular bonding agent and increases the contact area between the solid bulk macromolecular bonding agent and HMX, significantly improving the mechanical properties of the propellant and the preparation process conditions.

Description

Technical Field

[0001] This invention belongs to the field of energetic materials technology, and relates to macromolecular bonding agent complexes, specifically to an Al / HMX / neutral macromolecular bonding agent complex and its preparation method. Background Technology

[0002] Solid propellants are the power source for missile and rocket engines, and are energetic composite materials with specific properties. Their components burn in the combustion chamber, converting chemical energy into heat energy to generate high-temperature, high-pressure gas. This gas expands and accelerates through the nozzle, converting heat energy into kinetic energy. The high-speed rearward ejection of this gas provides a reaction force to the engine, supplying thrust. The performance of solid propellants directly impacts the operational capability and survivability of strategic and tactical missiles.

[0003] High energy output has always been a research hotspot for solid propellants. To further improve propellant energy, high-theoretical-calorific-value aluminum powder has become an inevitable choice. The particle size and content of aluminum powder greatly affect the combustion performance and actual energy level of the propellant. Although numerous studies have confirmed that the application of nano-aluminum powder in propellants can significantly improve propellant energy and energy release efficiency, nano-aluminum powder faces problems such as poor dispersibility, difficulty in maintaining activity, and poor processing performance in practical applications.

[0004] The pyrolysis rate of HMX is 6200 kJ·kg⁻¹. -1 The detonation velocity is 9110 m / s. -1 High-energy-density, high-energy-density, and good thermal stability make HMX widely used in composite solid propellants. HMX can influence the energy performance, burning rate, flame structure, and mechanical properties of solid propellants, and can also significantly alter aluminum agglomeration on the propellant burning surface and the characteristics of condensed-phase combustion products. In composite propellants, the content of HMX is usually high. Due to its smooth crystal surface and near-chemical inertness, it is difficult to form effective physical and chemical bonds, and it partially dissolves in polar plasticizers, creating a soft interface layer between the nitramine filler and the binder matrix. This layer can lead to dewetting under external forces, reducing the mechanical and safety properties of the propellant. Adding an appropriate amount of bonding agent to the propellant can effectively improve the interfacial properties between the filler and binder system, reduce dewetting, and effectively improve the mechanical properties of the propellant.

[0005] Neutral macromolecular bonding agents (NPBA), containing multiple polar groups, can adsorb onto the filler surface and react with isocyanates to form a tough coating layer on the surface of solid particles. NPBA is generally copolymerized from acrylonitrile (AN), acrylate (MA), and hydroxyl acrylate. The cyano groups of NPBA can adsorb onto the surface of ammonium nitrate particles, while the hydroxyl groups can undergo cross-linking reactions with the curing agent.

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

[0007] To address the shortcomings of existing technologies, the present invention aims to provide an Al / HMX / neutral macromolecular bonding agent complex and its preparation method, thereby solving the problems of poor propellant mechanical properties and complex preparation processes caused by the difficulty in uniformly dispersing neutral macromolecular bonding agents in existing technologies.

[0008] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

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

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

[0011] Step 2: Add aluminum powder to the mixed solution and ultrasonically disperse to obtain a dispersion. Then, spray the dispersion on a spray dryer to granulate it, thus obtaining the 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 vinyltriethoxysilane.

[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 neutral macromolecular bonding agent to the mass of the solvent is 1:(1 to 1.1).

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

[0018] The aluminum powder has a particle size of 50–100 nm.

[0019] The inlet temperature of the spray dryer is 180-190℃, the feed rate of the spray dryer is 3-5 mL / min, and the flow rate of high-purity nitrogen 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 this invention has low sensitivity, which not only increases the contact area between the reducing agent aluminum powder and the oxidant HMX and shortens the reaction mass transfer distance, but also effectively improves the complete combustion of aluminum powder and the efficient release of energy. At the same time, the solid bulk macromolecular bonding agent is assembled into a micron-sized composite material, which improves the dispersion uniformity of the solid bulk macromolecular bonding agent and increases the contact area between the solid bulk macromolecular bonding agent and HMX, which can significantly improve the mechanical properties and preparation process conditions of solid propellants.

[0024] (II) The spray drying method proposed in this invention is simple to operate, has a short cycle, is easy to remove solvent and mass-produce, and the Al / HMX / neutral macromolecular bonding agent complex prepared has good dispersibility. Attached Figure Description

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

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

[0027] The specific content of the present invention will be further explained in detail below with reference to the embodiments. Detailed Implementation

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

[0029] In this invention, the acrylonitrile-hydroxyethyl acrylate nitrate copolymer and the acrylonitrile-hydroxyethyl acrylate-vinyltriethoxysilane terpolymer are all known products.

[0030] The molecular structure of the copolymer of acrylonitrile and hydroxyethyl acrylate nitrate is shown below:

[0031]

[0032] The number-average molecular weight is 9550.

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

[0034]

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

[0036] Following the above technical solutions, 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 modifications made based on the technical solutions of this application fall within the protection scope of the present invention.

[0037] Example 1:

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

[0039] Step 1: Add 480g of HMX, 2g of acrylonitrile and hydroxyethyl acrylate nitrate copolymer obtained by copolymerization to 570mL of 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 any known and commonly used copolymerization method can be used for the copolymerization of the binary copolymer.

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

[0042] SEM images of the Al / HMX / acrylonitrile and hydroxyethyl acrylate nitrate copolymer composite are shown below. Figure 1 As shown, from Figure 1 As can be seen, the Al / HMX / acrylonitrile and hydroxyethyl acrylate nitrate binary copolymer composite prepared in this embodiment has a particle size of 1.95 μm, a uniform and controllable particle size distribution, good particle dispersibility, and does not clump.

[0043] The performance of the Al / HMX / acrylonitrile and hydroxyethyl acrylate nitrate binary copolymer composite prepared in this embodiment was tested. The Al / HMX / acrylonitrile and hydroxyethyl acrylate nitrate binary copolymer composite prepared in this embodiment was added to the composite solid propellant formulation. The propellant formulation was as follows: the mass fraction of Al / HMX / acrylonitrile and hydroxyethyl acrylate nitrate binary copolymer composite was 65%, the mass fraction of AP (ammonium perchlorate) was 10%, and the binder system (GAP (polyazidoglycidyl ether) / PEG (polyethylene glycol) / BuNENA (N-butylnitrooxyethyl nitrate) / N-100 (polyfunctional isocyanate)) was 25%.

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

[0045] The mechanical properties of solid propellants were tested using the method specified in section 413.1 of the publicly known Chinese 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 complex. This comparative example uses the components and proportions disclosed in Example 1. The difference is that in this comparative example, the above-mentioned HMX, aluminum powder and the 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 Comparative Example 1 was added to the composite solid propellant formulation, which had the following composition: 9.27% ​​aluminum powder, 55.5% HMX, 0.23% acrylonitrile and hydroxyethyl acrylate nitrate copolymer, 10% AP, and 25% binder system (GAP / PEG / BuNENA / N-100).

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

[0050] Table 1 Experimental results of composite solid propellants

[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] As can be seen from Table 1, 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, when the Al / HMX / acrylonitrile and hydroxyethyl acrylate nitrate binary copolymer composite is applied to the composite solid propellant, the tensile strength of the composite solid propellant increases from 0.76 MPa to 0.97 MPa, and the elongation at break increases from 82.3% to 95.1%.

[0053] Example 2:

[0054] This embodiment provides a method for preparing an Al / HMX / neutral macromolecular bonding agent complex. This method is essentially the same as the method for preparing the Al / HMX / neutral macromolecular bonding agent complex in Example 1, except that the neutral macromolecular bonding agent in this embodiment is a terpolymer obtained by copolymerizing acrylonitrile, hydroxyethyl acrylate, and vinyltriethoxysilane, with a number-average molecular weight of 20,500. The copolymerization method for the terpolymer can be any known and commonly used copolymerization method.

[0055] SEM images of the Al / HMX / acrylonitrile, hydroxyethyl acrylate and vinyltriethoxysilane terpolymer composite are shown below. Figure 2 As shown, from Figure 2 As can be seen, the Al / HMX / acrylonitrile, hydroxyethyl acrylate and vinyltriethoxysilane terpolymer composite of this embodiment has a particle size of 2.16 μm, uniform particle size distribution and no agglomeration.

[0056] The performance of the Al / HMX / acrylonitrile, hydroxyethyl acrylate, and vinyltriethoxysilane terpolymer composite prepared in this embodiment was tested. The Al / HMX / acrylonitrile, hydroxyethyl acrylate, and vinyltriethoxysilane terpolymer composite prepared in this embodiment was added to the composite solid propellant formulation. The propellant formulation was as follows: the mass fraction of Al / HMX / acrylonitrile, hydroxyethyl acrylate, and vinyltriethoxysilane terpolymer composite was 65%, the mass fraction of AP was 10%, and the binder system (GAP / PEG / BuNENA / N-100) was 25%.

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

[0058] The mechanical properties of solid propellants were tested using the method specified in section 413.1 of the publicly known Chinese 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 complex. The method uses the components and proportions disclosed in Example 2. The difference is that in this comparative example, the terpolymer obtained by copolymerizing acrylonitrile, hydroxyethyl acrylate and vinyltriethoxysilane in Example 2 is directly physically mixed to obtain an Al / HMX / acrylonitrile, hydroxyethyl acrylate and vinyltriethoxysilane terpolymer mixture.

[0061] The Al / HMX / acrylonitrile, hydroxyethyl acrylate, and vinyltriethoxysilane terpolymer mixture of Comparative Example 2 was added to the composite solid propellant formulation, which had the following composition: 9.27% ​​aluminum powder, 55.5% HMX, 0.23% terpolymer obtained by copolymerization of acrylonitrile, hydroxyethyl acrylate, and vinyltriethoxysilane, 10% AP, and 25% binder system (GAP / PEG / BuNENA / N-100).

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

[0063] Table 2 Experimental Results of Composite Solid Propellants

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

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

[0066] Tables 1 and 2 illustrate that the neutral macromolecular bonding agent proposed in this invention increases the contact area between the reducing agent aluminum powder and the oxidant HMX, shortens the reaction mass transfer distance, and effectively improves the complete combustion of aluminum powder and efficient energy release. At the same time, assembling the solid bulk macromolecular bonding agent into a micron-scale composite material improves the dispersion uniformity of the solid bulk macromolecular bonding agent, increases the contact area between the solid bulk macromolecular bonding agent and HMX, and significantly 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 complex, characterized in that, The method includes the following steps: Step 1: Dissolve HMX and a neutral macromolecular bonding agent in a solvent to obtain a mixed solution; Step 2: Add aluminum powder to the mixed solution and disperse it by ultrasonication to obtain a dispersion. Then, spray the dispersion on a spray dryer to granulate it, thus obtaining the Al / HMX / neutral macromolecular bonding agent complex. 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 vinyltriethoxysilane.

2. The method for preparing the Al / HMX / neutral macromolecular bonding agent complex as described in 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).

3. The method for preparing the Al / HMX / neutral macromolecular bonding agent complex as described in claim 1, characterized in that, The mass ratio of the aluminum powder, HMX, and neutral macromolecular bonding agent is 8:48:0.

2.

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

5. The method for preparing the Al / HMX / neutral macromolecular bonding agent complex as described in claim 1, characterized in that, The solvent is selected from one of tetrahydrofuran, dimethyl sulfoxide, and dimethylformamide.

6. The method for preparing the Al / HMX / neutral macromolecular bonding agent complex as described in claim 1, characterized in that, The aluminum powder has a particle size of 50–100 nm.

7. The method for preparing the Al / HMX / neutral macromolecular bonding agent complex as described in claim 1, characterized in that, The inlet temperature of the spray dryer is 180-190℃, the feed rate of the spray dryer is 3-5 mL / min, and the flow rate of high-purity nitrogen is 360-400 L / h.

8. An Al / HMX / neutral macromolecular bonding agent complex, characterized in that, The Al / HMX / neutral macromolecular bonding agent complex is prepared by the method described in any one of claims 1 to 7.

9. The Al / HMX / neutral macromolecular bonding agent complex as described in claim 8, characterized in that, The particle size of the Al / HMX / neutral macromolecular bonding agent complex is 1–43 µm.

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