Neutral polymer liquid bonding agent as well as preparation method and application thereof

Abstract

The invention relates to the technical field of solid propellants, and particularly discloses a neutral polymer liquid bonding agent as well as a preparation method and application thereof. A neutral polymer liquid bonding agent is characterized in that the structural formula is # imgabs0 #, x is the molar weight of a hydroxyethyl acrylate monomer, y is the molar weight of an acrylonitrile monomer, z is the molar weight of an undecyl acrylate monomer, and n is the structural polymerization degree of a segmented copolymer; r is-(CH2) 10 <-> CH3. The neutral polymer liquid bonding agent is in a liquid state and can be better and more fully dispersed in propellant slurry. The NPBA prepared by the method can be better adsorbed on the surface of a filler, solves the problem of solubility of NPBA, has large molecular weight, improves the bonding effect with nitramine explosives, improves the mechanical properties of the system, and achieves the effect of interface enhancement.

Description

Technical Field

[0001] The invention relates to the technical field of solid propellants, and in particular to a neutral polymer liquid bonding agent and a preparation method and application thereof. Background Art

[0002] Composite solid propellant is a heterogeneous composite material composed of solid filler (high-energy nitramine, oxidant, metal fuel), polymer adhesive, and plasticizer. HTPB (hydroxy-terminated polybutadiene) propellant and NEPE (nitrate plasticized polyether) high-energy propellant are the main products of composite solid propellant and have been widely studied and applied.

[0003] In order to increase the energy of solid propellants, solid oxidizers and fuel particles with a content of up to 70%-90% are used in the formula. Commonly used octogen (HMX), hexogen (RDX) and ammonium perchlorate (AP) are all non-reinforcing fillers, which makes the solid propellant prone to "dehumidification" when subjected to a certain load, which has a great impact on the mechanical properties of the propellant. If a suitable bonding agent is selected, a high-modulus tear-resistant layer can be formed around the filler particles. When the solid propellant is subjected to a load, the part with gaps will be pushed deeper into the adhesive matrix phase, and the filler particles will not "dehumidify" but continue to bear the load. Therefore, after the propellant formula is determined, the method of improving the mechanical properties of solid propellants mainly focuses on suitable bonding agents.

[0004] Neutral polymer liquid bonding agents are mainly suitable for nitrate ester plasticized polyether propellant systems. Due to the large polarity of nitrate ester plasticizers, plasticizers will compete with bonding agents for adsorption on nitramine fillers. Small molecule bonding agents are easily soluble in polar nitrate esters and cannot be adsorbed on the surface of ammonium nitrate particles, and thus cannot play a bonding role. At the same time, non-neutral bonding agents are not conducive to the curing and stabilization of nitrate ester-containing systems. In addition, ammonium nitrate is also slightly soluble in nitrate ester plasticizers, and a soft interface layer is formed on the surface of ammonium nitrate, resulting in weak interface bonding between the oxidant and the adhesive, resulting in poor mechanical properties of the propellant. Summary of the invention

[0005] The first object of the present invention is to provide a neutral polymer liquid bonding agent which is in liquid state and can be better and more fully dispersed in the propellant slurry.

[0006] The second object of the present invention is to provide a method for preparing a neutral polymer liquid bonding agent, which is stable, has a wide source of synthetic raw materials, is relatively low in price, and is easy to scale up and control in quality.

[0007] The third object of the present invention is to provide an application of a neutral polymer liquid bonding agent. It can be better adsorbed on the surface of the filler, solving the solubility problem of NPBA, and at the same time, the molecular weight is large, which also improves the bonding effect with nitramine explosives, improves the mechanical properties of the system, and achieves the effect of interface enhancement.

[0008] The technical solution for achieving the first object of the invention is a neutral polymer liquid bonding agent having the structural formula:

[0009]

[0010] Wherein, x is the molar amount of hydroxyethyl acrylate monomer, y is the molar amount of acrylonitrile monomer, z is the molar amount of undecyl acrylate monomer, n is the degree of polymerization of the block copolymer structure; R is -(CH2) 10 -CH3.

[0011] Preferably, the x:y:z is 1:0.1 to 0.3:0.1.

[0012] Preferably, the block copolymer structure has a degree of polymerization of 26-53.

[0013] The neutral polymer liquid bonding agent of the present invention reduces the intermolecular force by controlling the ratio of three monomers in the product, the degree of polymerization of the block copolymer structure of the final product and the molecular chain length in the undecyl acrylate monomer, thereby making the final copolymer product liquid.

[0014] The technical solution for achieving the second object of the invention is a method for preparing a neutral polymer liquid bonding agent, comprising:

[0015] Step 1: weighing hydroxyethyl acrylate monomer, acrylonitrile monomer and undecyl acrylate monomer;

[0016] Step 2: adding an organic solvent, an initiator and a chain transfer agent to the hydroxyethyl acrylate monomer, the acrylonitrile monomer and the undecyl acrylate monomer;

[0017] Step 3: Use one-pot reaction and post-treatment to obtain a neutral polymer liquid bonding agent.

[0018] Preferably, the molar ratio of the hydroxyethyl acrylate monomer, the acrylonitrile monomer and the undecyl acrylate monomer is 1:0.1 to 0.3:0.1.

[0019] Preferably, the organic solvent is acetone, the initiator is AIBN, and the chain transfer agent is 2-mercaptoethanol.

[0020] Preferably, in the synthesis method, the mass ratio of hydroxyethyl acrylate monomer, acetone, AIBN and 2-mercaptoethanol added is: 116:50:4:6.

[0021] Preferably, the one-pot reaction is carried out at 60° C. for 6 h.

[0022] Preferably, the post-treatment includes using ethanol for sedimentation washing, removing the supernatant after stratification, and drying the turbid liquid to obtain a neutral polymer liquid bonding agent.

[0023] The preparation method provided by the invention is simple in that the reaction is carried out by a one-pot method, the solvent acetone used has a low boiling point and is easy to be evaporated, the post-processing is relatively convenient, the synthetic raw materials have a wide source, the price is relatively low, and it is easy to scale up and control the quality.

[0024] The technical solution for achieving the third invention objective is to use a neutral polymer liquid bonding agent in PEG propellants and GAP propellants.

[0025] The degree of polymerization n of the block copolymer structure is controlled to be 26 to 53, thereby increasing the molecular weight of the final product and improving the bonding effect between the bonding agent and the nitramine explosive.

[0026] Beneficial effects of the above technical solution:

[0027] (1) The neutral polymer liquid bonding agent provided by the present invention is in a liquid state and can be dispersed better and more fully in the propellant slurry, thereby solving the technical problem that the neutral polymer bonding agents in the prior art are mostly in a powdery solid state and are not conducive to dispersion in the propellant slurry.

[0028] (2) The neutral polymer liquid bonding agent of the present invention can be better adsorbed on the surface of the filler, which solves the solubility problem of NPBA. At the same time, the molecular weight is relatively large, which also improves the bonding effect with nitramine explosives, improves the mechanical properties of the system, and achieves the effect of interface enhancement. Solve the contradiction between the molecular weight, solubility and interface enhancement of the neutral polymer bonding agent in the prior art. For the neutral polymer bonding agent NPBA in the prior art, the solubility parameter and molecular weight determine the solubility of NPBA molecules in the slurry. The closer the solubility parameter is to the slurry and the smaller the molecular weight is, the better the solubility of NPBA in the slurry is. NPBA dissolves more in the slurry, improving the network structure of the matrix, but cannot be adsorbed on the filler surface and does not play a role in interface enhancement. If the molecular weight or solubility parameter is too large, NPBA is difficult to dissolve in the slurry and cannot be adsorbed on the filler surface through phase separation. In this way, NPBA can neither improve the matrix network nor enhance the adhesion of the interface. DETAILED DESCRIPTION

[0029] The technical solutions in the embodiments of the present invention will be clearly and completely described below in combination with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0030] Examples of the embodiments, wherein the same or similar symbols throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below are exemplary and intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0031] The purpose of the present invention is to improve the mechanical properties of NEPE propellant and provide a novel neutral polymer liquid bonding agent. The bonding agent has a stable synthesis method, a wide range of synthetic raw materials, a low price, is easy to scale up and control quality, and can significantly improve the mechanical properties of polyether propellant.

[0032] The neutral polymer liquid bonding agent provided by the present invention is prepared by reacting hydroxyethyl acrylate, acrylonitrile and methyl acrylate in a certain proportion, and its structure is:

[0033]

[0034] Wherein, x, y, and z are the proportions of the three monomers hydroxyethyl acrylate, acrylonitrile, and undecyl acrylate in the block copolymer structure. R is -(CH2) 10 -CH3.

[0035] The neutral polymer liquid bonding agent of the present invention contains cyano groups in its structure, which produce strong polar interactions with -NO2 of ammonium nitrate explosives. The active hydrogen of the hydroxyl groups on the side chains can react with the curing agent to enter the adhesive network, forming a "chemical bridge" between the ammonium nitrate explosive particles and the adhesive matrix network, which can greatly improve the interface bonding strength between the ammonium nitrate explosive particles and the adhesive matrix, thereby improving the mechanical properties of the solid propellant.

[0036] The ratio of hydroxyethyl acrylate, acrylonitrile and methyl acrylate was adjusted to prepare neutral polymer liquid bonding agents according to Examples 1 to 3 respectively.

[0037] Embodiment 1

[0038] One embodiment of the present invention provides a neutral polymer liquid bonding agent, and the synthesis method comprises the following steps:

[0039] To a 500ml four-necked flask, three copolymer monomers of hydroxyethyl acrylate, acrylonitrile and undecyl acrylate were added in a molar ratio of 1:0.3:0.1. 50g acetone, 4g AIBN (azobisisobutyronitrile), and 6g 2-mercaptoethanol were reacted at 60°C for 6h using a one-pot method. The product was poured into a large beaker, ethanol was added and stirred, the supernatant was poured out, and the lower viscous liquid was dried to obtain a neutral polymer liquid bonding agent, recorded as BAG-M1.

[0040] The product was analyzed and identified to contain cyano, hydroxyl and ester groups.

[0041] Embodiment 2

[0042] One embodiment of the present invention provides a neutral polymer liquid bonding agent, and the synthesis method comprises the following steps:

[0043] To a 500ml four-necked flask, three copolymer monomers, hydroxyethyl acrylate, acrylonitrile and undecyl acrylate, were added in a molar ratio of 1:0.2:0.1. 50g acetone, 4g AIBN and 6g 2-mercaptoethanol were reacted in one pot at 60°C for 6h. After discharging, the product was poured into a large beaker, ethanol was added and stirred, the supernatant was poured out, and the lower viscous liquid was dried to obtain a neutral polymer liquid bonding agent, recorded as BAG-M2.

[0044] The product was analyzed and identified to contain cyano, hydroxyl and ester groups.

[0045] Embodiment 3

[0046] One embodiment of the present invention provides a neutral polymer liquid bonding agent, and the synthesis method comprises the following steps:

[0047] To a 500ml four-necked flask, three copolymer monomers, hydroxyethyl acrylate, acrylonitrile and undecyl acrylate, were added in a molar ratio of 1:0.1:0.1. 50g acetone, 4g AIBN and 6g 2-mercaptoethanol were reacted in one pot at 60°C for 6h. The product was poured into a large beaker, ethanol was added and stirred, the supernatant was poured out, and the lower viscous liquid was dried to obtain a neutral polymer liquid bonding agent, recorded as BAG-M3.

[0048] The product was analyzed and identified to contain cyano, hydroxyl and ester groups.

[0049] Application effect evaluation

[0050] (I) Application in PEG propellants

[0051] The neutral polymer liquid bonding agents BAG-M1, BAG-M2 and BAG-M3 prepared in Examples 1 to 3 were respectively used in PEG propellants. The propellant composition is shown in Table 1. The mechanical properties of the PEG propellant after the neutral polymer liquid bonding agent provided by the present invention was used to replace the original bonding agent BAG-1 are shown in Table 2. Propellant standard samples were prepared according to GJB770B-2005 "Test Methods for Gunpowder" and uniaxial tensile tests were carried out. Each batch of samples was repeated for 5 pieces, the test temperature was 25°C, and the tensile rate was 100 mm·min -1 ; 70℃, stretching rate 2mm·min -1 ; -50℃, stretching rate 100mm·min -1 σ mis the tensile strength, and is the elongation at break.

[0052] The functional components in Table 1 are all commonly used functional components in the prior art, including the bonding agent BAG-1, which accounts for 0.2% of the propellant composition. The bonding agent BAG-1 is replaced by the three neutral polymer liquid bonding agents BAG-M1, BAG-M2 and BAG-M3 provided by the present invention, and PEG propellants are prepared and the performance is tested.

[0053] Table 1 PEG propellant composition

[0054]

[0055] Table 2 Performance of PEG propellant

[0056]

[0057]

[0058] As can be seen from Table 2, the neutral polymer liquid bonding agent provided by the present invention can greatly improve the normal, high and low temperature mechanical properties of the PEG propellant. In particular, when the neutral polymer liquid bonding agent BAG-M3 is used, the comprehensive performance of the PEG propellant is optimal. The molar ratio of the three copolymer monomers of hydroxyethyl acrylate, acrylonitrile and undecyl acrylate in BAG-M3 is 1:0.1:0.1.

[0059] (II) Application in GAP propellants

[0060] The neutral polymer liquid bonding agents BAG-M1, BAG-M2 and BAG-M3 prepared in Examples 1 to 3 were respectively applied to GAP propellants. The propellant composition is shown in Table 3. The performance results of the GAP propellants after using the neutral polymer liquid bonding agent provided by the present invention are shown in Table 4. Propellant standard samples were prepared according to GJB770B-2005 "Test Methods for Propellant" and uniaxial tensile tests were performed. Each batch of samples was repeated for 5 pieces, the test temperature was 25°C, the tensile rate was 100 mm·min -1 ; 70℃, stretching rate 2mm·min -1 ; -50℃, stretching rate 100mm·min -1 σ m is the tensile strength, and is the elongation at break.

[0061] The functional components in Table 3 are all commonly used functional components in the prior art, including the bonding agent BAG-1, which accounts for 0.2% of the propellant composition. The bonding agent BAG-1 is replaced by the three neutral polymer liquid bonding agents BAG-M1, BAG-M2 and BAG-M3 provided by the present invention, and GAP propellants are prepared and their performance is tested.

[0062] Table 3 GAP propellant composition

[0063]

[0064] Table 4 Performance results of bonding agent in GAP propellant

[0065]

[0066] From the performance data of GAP propellant in Table 4, it can be seen that the neutral polymer liquid bonding agent provided by the present invention can greatly improve the normal, high and low temperature mechanical properties of GAP propellant, especially BAG-M3 with a molar ratio of hydroxyethyl acrylate, acrylonitrile and undecyl acrylate of 1:0.1:0.1 has the best comprehensive performance.

[0067] In summary, the viscosity of BAG-M3 provided in Example 3 of the present invention is the smallest among the three bonding agents, which helps to increase the contact area between the bonding agent and the solid filler in the propellant and improve the effect of the bonding agent. The PEG and GAP propellant charges show that the bonding agent effect of BAG-M3 is the best, making the mechanical properties of the propellant perform best.

[0068] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit it. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A neutral polymer liquid bonding agent, characterized in that: The structural formula is: Wherein, x is the molar amount of hydroxyethyl acrylate monomer, y is the molar amount of acrylonitrile monomer, z is the molar amount of undecyl acrylate monomer, n is the degree of polymerization of the block copolymer structure; R is -(CH2) 10 -CH3.

2. The neutral polymer liquid bonding agent according to claim 1, characterized in that: The x:y:z is 1:0.1 to 0.3:0.

1.

3. The neutral polymer liquid bonding agent according to claim 1, characterized in that: The block copolymer structure has a degree of polymerization of 26 to 53.

4. A method for preparing a neutral polymer liquid bonding agent as claimed in any one of claims 1 to 3, characterized in that: include: Step 1: weighing hydroxyethyl acrylate monomer, acrylonitrile monomer and undecyl acrylate monomer; Step 2: adding an organic solvent, an initiator and a chain transfer agent to the hydroxyethyl acrylate monomer, the acrylonitrile monomer and the undecyl acrylate monomer; Step 3: Use one-pot reaction and post-treatment to obtain a neutral polymer liquid bonding agent.

5. The method for preparing the neutral polymer liquid bonding agent according to claim 4, characterized in that: The molar ratio of the hydroxyethyl acrylate monomer, the acrylonitrile monomer and the undecyl acrylate monomer is 1:0.1 to 0.3:0.

1.

6. The method for preparing the neutral polymer liquid bonding agent according to claim 4, characterized in that: The organic solvent is acetone, the initiator is AIBN, and the chain transfer agent is 2-mercaptoethanol.

7. The method for preparing the neutral polymer liquid bonding agent according to claim 4, characterized in that: The mass ratio of hydroxyethyl acrylate monomer, acetone, AIBN and 2-mercaptoethanol added in the synthesis method is 116:50:4:

6.

8. The method for preparing a neutral polymer liquid bonding agent according to claim 4, characterized in that: The one-pot reaction was carried out at 60° C. for 6 h.

9. The method for preparing a neutral polymer liquid bonding agent according to claim 4, characterized in that: The post-treatment includes using ethanol for sedimentation washing, removing the supernatant after stratification, and drying the lower turbid liquid to obtain a neutral polymer liquid bonding agent.

10. An application of the neutral polymer liquid bonding agent as claimed in any one of claims 1 to 3, characterized in that: Application in PEG propellants and GAP propellants.

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