KR20100035522A - Gap/nitramine-based energetic propellant composition having excellent mechanical properties - Google Patents

Abstract

PURPOSE: A gap/nitramine based high energy propellant composition is provided to use a prepolymer in which both ends of the prepolymer is degenerated to the hydroxyl group to improve mechanical property of a GAP propellant. CONSTITUTION: A gap/nitramine based high energy propellant composition contains a polymer and an oxidizer of a binder. The polymer of the binder is prepared by mixing GAP and a component selected from the group consisting of PEG, PCL, polytetrahydrofuran and polyoxetane, in a ratio of 0.1~9.0:1. The oxidizer is selected from HNIW, RDX or their mixture. The propellant composition additionally contains a neutral polymer type binder. The propellant composition is consisted with 48~80wt% of oxidizer, 0.1~2wt% of binder composed of a prepolymer, a plasticizer and a hardener.

Description

GAP / NITRAMINE-BASED ENERGETIC PROPELLANT COMPOSITION HAVING EXCELLENT MECHANICAL PROPERTIES}

The present invention relates to a propellant composition for a rocket propulsion engine having excellent mechanical properties, and more particularly, to a glycidyl azide polymer (hereinafter referred to as GAP) / nitramine-based propellant having improved mechanical properties. According to the present invention, a single or mixed component selected from polyethylene glycol (PEG), polycaprolactone (PCL), polytetrahydrofuran, and polyoxetane is used in parallel as a prepolymer of a binder with GAP. In addition, a high energy-enhancing solid propellant composition comprising hexanitro hexaaza isowurtzitane (HNIW) and cyclotrimethylene trinitramine (RDX) alone or in combination as an oxidant is provided.

Polyether-type GAPs obtained by cationic living ring-opening polymerization were developed in the early 1980s and began to attract attention as prepolymers to lead the next generation of high energy mixed solid propellants. This azide group ^{(-N + = N = N -} ) bonded to the main chain of the GAP by, is of about 85 kcal / mol more energy dissipating during propellant combustion can enhance the specific impulse of the propellant burn rate, as well as Because there is.

The ongoing research on these GAP-applied propellants is due to oxidizing agents such as ammonium perchlorate (AP) or ammonium nitrate (AN) or RDX and HNIW, which are commonly used in solid propellants. This is because it is possible to manufacture lead-free propellants as well as environmentally friendly propellants without chlorine gas generated by AP using nitramine oxidants such as. In addition, since the GAP propellant has excellent thermal properties, it is possible to considerably increase the combustion rate of the propellant, and has the advantage that the air intake propulsion engine can be applied as a solid fuel.

However, the mechanical properties of the GAP propellant are not very satisfactory because of the low flexibility of the polymer main chain due to the bulky methylene azide groups present in the main chain of the GAP prepolymer. In addition, the GAP propellant is lower than other nitrate ester polyether (or polyester) propellants having different plasticizer contents due to the high free volume of the GAP itself. In the NEPE propellant, nitro ester type plasticizers such as butane triol trinitrate (BTTN) and trimethylolethane trinitrate (TMETN) are used alone or in combination.

As such, in order to improve the mechanical properties of the GAP propellant, there is also a method of using a high molecular weight GAP, but due to the high molecular weight of the GAP, the viscosity of the slurry during the propellant preparation may cause a lot of problems in the processability. In general, the properties of the polymeric binder, which govern the properties of the solid propellant, should be designed to be suitable for specific applications such as space launch vehicles, strategic missiles, and air-to-air tactical missiles. In fact, PBAA (Poly (butadiene- co -acrylic acid), PBAN (Butadiene, acrylic acid and acrylonitrile terpolymers), HTPE (Hydroxy-terminated polyether, poly (ethylene oxide- co -tetrahydro furane), and heterogeneous polymers It is used as a missile propellant by modifying the properties of the binder using a copolymer such as a segmented block copolymer.

In the present invention, in order to improve the mechanical properties of the GAP propellant, unlike GAP, binders with one or more components selected from PEG, PCL, polytetrahydrofuran, and polyoxetane having a linear and flexible molecular structure together with GAP The properties of the binder were modified by using them in parallel as a prepolymer and by using HNIW and RDX alone or in combination as oxidants. Thus, the mechanical properties of the GAP propellant could be improved by using the prepolymer in which the sock end was modified with a hydroxyl group.

In addition, the propellant composition of the present invention further includes a neutral polymer binder in addition to a binder composed of a prepolymer, a plasticizer, and a curing agent and a nitramine-based oxidant.

The propellant composition of the present invention comprises 18 to 50% by weight of a binder composed of a prepolymer, a plasticizer and a curing agent, 48 to 80% by weight of an oxidizing agent, and 0.1 to 2% by weight of a neutral polymer binder.

At this time, when the maximum content of the binder exceeds 50% solid particles in the propellant may be precipitated, and in the case of the oxidant, when the maximum content exceeds 80%, it is known to adversely affect the propellant performance.

In addition, the mixing ratio of PEG, PCL, polytetrahydrofuran, or polyoxetanol to GAP to be used as a prepolymer in the binder is preferably 0.1 to 9.0: 1, particularly showing a good effect at 0.4 to 2.3: 1. The higher the content of PCL, PEG, polytetrahydrofuran or polyoxetanol mixed in the GAP, the better the mechanical properties but the lower the performance of the propellant, so that the GAP and GAP It is preferable to adjust the content ratio of PCL and the like mixed therewith. Here, since the effect of PCL, PEG, polytetrahydrofuran or polyoxetanol on the performance of the propellant is not so large compared to that of solid particles such as oxidants or metals, PCL, PEG, polytetrahydrofuran or poly Degradation of the propellant due to the increased content of oxetanol, etc. can be sufficiently offset by a small increase in the content of the high-energy oxidizing agent HNIW or RDX.

On the other hand, N-3 (Desmodur N-100 polyisocyanate), which is a trifunctional curing agent, and IPDI (Isophorone diisocyanate), which is a difunctional curing agent, are mixed at a constant magnification to improve tensile strength and elongation. At this time, the content of N-100 If too much, the strength of the propellant is increased, so that the elongation can not be improved. If the content of IPDI is too high, the hardness of the propellant is too low, and the mechanical strength is lowered. Therefore, it is required to use N-100 and IPDI in an appropriate mixing ratio. According to the experiment, it is preferable that the amount of N-100 is 2.5 times to 1.0 times that of IPDI.

In addition, triphenyl bismuth may be added in an amount of 0.05 to 0.2% by weight as a curing catalyst for promoting curing.

Meanwhile, the plasticizer component of the binder in the present invention uses a plasticizer containing nitro ester group, nitramine group or azide group, and the amount of plasticizer is preferably 1 to 4 times the amount of the prepolymer. If the content of the plasticizer is less than 1 times the content of the prepolymer, PCL or PEG, which is a solid at room temperature, will not melt in the plasticizer. If the content of the plasticizer is more than 4 times, the viscosity of the binder will be too low. Because it can. Here, as the plasticizer containing nitro ester group, BTTN, TMETN and diethylene glycol dinitrate (DEGDN) may be used alone or in combination, and as the plasticizer containing nitramine group, Nn-butyl-N-nitritoethylnitramine (BuNENA). Azide-containing plasticizer containing azido-modified azido-modified azido-modified Gazido-terminated GAP (GAP-A) or 1,5-diazido- 3-nitroaminopentane (DANPE) can be used.

In addition, HNIW and RDX are used alone or in combination as an oxidizing agent, and the amount thereof is preferably 48 to 80% by weight based on the total amount of the propellant composition.

Neutral polymer binder which is a copolymer of hydroxyethyl acrylate (2-Hydroxyethyl acrylate, 2-HEA) and acrylonitrile having a molecular weight of 10,000 to 50,000 g / mol to enhance the interface adhesion between the oxidizing agent and the binder, In other words, NPBA (Neutral Polymeric Bonding Agent) is used. The neutral polymer binder is used in an amount of 0.1 to 2.0 wt% based on the total amount of the propellant composition. If the content is less than 0.1% by weight, the binding effect of the binder may not be seen, and if the content is more than 2.0% by weight, the viscosity of the propellant may be too high to make the manufacturing process considerably lowered, and the hardness of the propellant itself may be too high after curing, thereby significantly increasing the elasticity of the propellant. Falls. Here, it is preferable that the molar ratio of 2-HEA: acrylonitrile polymer is 5: 5-9: 1. In the neutral polymer type binder, the hydroxyl value of 2-HEA has the greatest influence on the properties of the propellant, but the amount of 2-HEA cannot be increased indefinitely to increase the hydroxyl content. This is because 2-HEA is acidic, which may seriously affect the aging of the propellant in the future. Therefore, the copolymer can be prepared by adding acrylonitrile having a high basicity together to lower the acidity of the copolymer, and the acidity of the copolymer can be appropriately adjusted in the above molar ratio range.

In addition, N-methyl para-nitroaniline (NMA) and 2-nitrodiphenylamine (2-NDPA) may be used alone or in combination as a stabilizer, and used in an amount of 0.1 to 2% by weight based on the total amount of the propellant composition. It is preferable.

In addition, aluminum, boron, zirconium, titanium, and magnesium may be used in amounts of 0.5 to 20% by weight of the propellant composition to increase the thrust of the propellant. The particle size of the metal particles to be added is appropriately 0.1 to 50 ㎛ size considering the porosity with other solid particles contained in the propellant. When the content of the metal particles exceeds 20% by weight, not only precipitation may occur in the propellant but also deterioration of the propellant may occur, so that the content of the metal should not exceed 20% by weight.

The present invention will be described in detail below with reference to Examples, but the present invention is not limited to these Examples.

According to the present invention, by using PEG, PCL, polytetrahydrofuran, polyoxetane, etc., which have a linear and flexible structure in the GAP, as a prepolymer, it is possible to improve the mechanical properties of the GAP such as tensile strength and elongation.

Example

Comparative Example 1

Material and method:

HNIW (5㎛) 30%, RDX (30㎛) 35%, GAP (2,400 g / mol) 14.9%, N-100 / IPDI (2/1 mix ratio) 2.1%, BTTN 12.7%, TMETN 4.3%, neutral polymer Type binder (2-HEA: molar ratio of acrylonitrile = 8: 2, 28,000 g / mol) 0.4%, Stabilizer (N-methyl para-nitroaniline) 0.5%, Curing catalyst (triphenyl bismuth) 0.1%

Propellants were prepared using a 1 pint vertical flannery mixer. The remaining components except the oxidizing agent, the neutral polymer binder, and the curing agent were placed in a mixer and stirred at 60 ° C. for about 20 minutes under vacuum. RDX, an oxidant, was added thereto, stirred for 5 minutes at atmospheric pressure, and stirred for 5 minutes under vacuum. Neutral polymer binder and HNIW were also stirred in the same manner as RDX, respectively. Stir for 20 minutes under vacuum before adding the curing agent. A propellant was prepared by adding a curing agent and a curing catalyst and stirring for 5 minutes at 50 ° C. under atmospheric pressure. The propellant in the form of a slurry was cured for 1 week in an oven at 50 ° C. The mechanical properties of the hardened propellant were measured using a universal testing machine (Model 5567, Instron) with a crosshead speed of 50 mm / min at room temperature.

As a result, the tensile strength was 3.9 bar, the strain was 20%, the hardness was 53, and the elastic modulus was 21.9 bar.

Example 1

A propellant was prepared in the following composition by the same method except that PEG was used in GAP as a prepolymer.

material:

HNIW (5 μm) 30%, RDX (30 μm) 35%, GAP (2,400 g / mol) 7.7%, PEG (4,500 g / mol) 7.7%, N-100 / IPDI (2/1 mix ratio) 1.6%, BTTN 12.7%, TMETN 4.3%, neutral polymer binder 0.4%, stabilizer (N-methyl para-nitroaniline) 0.5%, curing catalyst (triphenyl bismuth) 0.1%.

As a result of measuring mechanical properties in the same manner as in Comparative Example 1, it was found that the tensile strength was 5.4 bar, the strain 73%, the elastic modulus 18.9% bar.

Example 2

A propellant was prepared with the following composition by the same method except that PCL was used in parallel with GAP as a prepolymer.

material:

HNIW (5 μm) 30%, RDX (30 μm) 35%, GAP (2,400 g / mol) 7.5%, PCL (3,000 g / mol) 7.5%, N-100 / IPDI (2/1 mix ratio) 2.0%, BTTN 12.7%, TMETN 4.3%, neutral polymer binder 0.4%, stabilizer (N-methyl para-nitroaniline) 0.5%, curing catalyst (triphenyl bismuth) 0.1%.

As a result of measuring mechanical properties in the same manner as in Comparative Example 1, it was found that the tensile strength is 7.6 bar, the strain 45%, the elastic modulus 40.3% bar.

From the above results, it can be seen that the mechanical properties of the propellants according to Examples 1 and 2 of the present invention are superior to those of Comparative Example 1. However, in the case of the GAP / PEG (Example 1) propellant, the hardness was lower than that of the GAP propellant, resulting in a low initial modulus, that is, a modulus of elasticity, which is due to a difference in reactivity of the curing agent between polymers. That is, since the reactivity of the polymers to the curing agent having an isocyanate group is in the order of PEG, PCL, GAP, when the GAP and PEG are mixed, the uniformity of the network (formed by the polymer and the curing agent) is lower than that of PCL. The elastic modulus is also somewhat lower. However, this does not mean that the modulus of the propellant consisting of GAP and PEG is always lowered. In this case, increasing the content of a highly functional hardener such as N-100 may improve the modulus of elasticity.

In addition, in order to more clearly determine the effect of PEG or PCL, through the following Comparative Examples 2, and Examples 3 and 4 to prepare a propellant in a composition without adding a neutral polymer binder was measured mechanical performance. That is, unlike Comparative Example 1, Example 1, and Example 2 described above, instead of adding the neutral polymer-type binder, 0.4% of the equivalent amount was increased by 0.4% of the binder to form a propellant to test mechanical properties.

Comparative Example 2

A propellant was prepared using the following composition in the same manner as in Comparative Example 1 without adding a neutral polymer binder.

material:

HNIW (5 μm) 30%, RDX (30 μm) 35%, GAP (2,400 g / mol) 15.2%, N-100 / IPDI (2/1 mix ratio) 2.0%, BTTN 12.7%, TMETN 4.3%, stabilizer (N-methyl para-nitroaniline) 0.5%, curing catalyst (triphenyl bismuth) 0.1%.

As a result of measuring the mechanical properties in the same manner as in Comparative Example 1, it was found that the tensile strength of 1.3 bar (burst point), strain 182% (burst point), hardness 15, elastic modulus 8.5 bar (initial).

Example 3

A propellant was prepared in the following composition by the same method as Comparative Example 1, except that PEG was used in GAP as a prepolymer and no neutral polymer binder was used.

material:

HNIW (5 μm) 30%, RDX (30 μm) 35%, GAP (2,400 g / mol) 7.8%, PEG (4,500 g / mol) 7.8%, N-100 / IPDI (2/1 mix ratio) 1.6%, BTTN 12.9%, TMETN 4.3%, stabilizer (N-methyl para-nitroaniline) 0.5%, curing catalyst (triphenyl bismuth) 0.1%.

As a result of measuring mechanical properties in the same manner as in Comparative Example 1, it was found that the tensile strength was 4.1 bar (burst point), strain 910% (burst point), hardness 13, and elastic modulus 7.5 bar (initial).

Example 4

A propellant was prepared in the following composition by the same method as Comparative Example 1, except that PCL was used in parallel as a prepolymer and a neutral polymer binder was not used.

material:

HNIW (5 μm) 30%, RDX (30 μm) 35%, GAP (2,400 g / mol) 7.7%, PCL (4,500 g / mol) 7.7%, N-100 / IPDI (2/1 mix ratio) 1.8%, BTTN 12.9%, TMETN 4.3%, stabilizer (N-methyl para-nitroaniline) 0.5%, curing catalyst (triphenyl bismuth) 0.1%.

As a result of measuring mechanical properties in the same manner as in Comparative Example 1, it was found that the tensile strength was 4.7 bar (burst point), strain 511% (burst point), hardness 27, and elastic modulus 17.4 bar (initial).

Figure 2 is a solid propellant consisting of the GAP propellant according to Comparative Example 2 and Examples 3 and 4, that is, a GAP propellant without the addition of a neutral polymer binder, GAP-based copolymer binders containing 50% by weight of PEG and PCL, respectively Their mechanical properties are shown. From Figure 2 it can be seen that the tensile strength and elongation at break of the propellant added PEG and PCL is significantly higher than the propellant consisting of GAP only. The knee phenomenon shown in FIG. 2 is completely eliminated when the neutral polymer binder is added, as shown in FIG. 1.

1 is a diagram showing elongation-stress of GAP / nitramine-based propellant compositions according to Comparative Example 1, Example 1 and Example 2. FIG.

2 is a diagram showing elongation-stress of the GAP / nitramine-based propellant compositions according to Comparative Example 2, Example 3 and Example 4. FIG.

Claims (14)

GAP / nitramine-based propellant characterized in that at least one component selected from PEG, PCL, polytetrahydrofuran and polyoxetane as a prepolymer is used in combination with GAP and HNIW and RDX alone or in combination as an oxidizing agent. Composition. The propellant composition according to claim 1, wherein the mixing ratio of one or more components selected from PEG, PCL, polytetrahydrofuran and polyoxetane to GAP is 0.1 to 9.0: 1. The propellant composition of claim 1 further comprising a neutral polymeric binder. The method of claim 3, wherein the oxidizing agent 48 to 80% by weight; 18-50% by weight of a binder consisting of a prepolymer, a plasticizer and a curing agent; And 0.1-2% by weight of the binder. The propellant composition according to claim 4, which contains a mixture of N-100 and IDPI as a curing agent. The propellant composition according to claim 4, wherein the plasticizer is selected from a plasticizer containing nitro ester group, nitramine group or azide group, and the content of the plasticizer is 1 to 4 times the amount of the prepolymer. The propellant composition according to any one of claims 1 to 6, wherein the molecular weight of GAP is 2,000 to 4,000 g / mol, the molecular weight of PEG is 4,000 to 6,000 g / mol, and the molecular weight of PCL is 2,000 to 4,000 g / mol. . The amount of 0.1 to 2% according to any one of claims 1 to 6, wherein N-methyl para-nitroaniline (NMA) and 2-nitrodiphenylamine (2-NDPA) are used alone or in combination as a stabilizer. Propellant composition to contain. The propellant composition according to claim 6, which contains BTTN, TMETN and diethylene glycol dinitrate (DEGDN) alone or in combination as a plasticizer containing nitro ester groups. The propellant composition according to claim 6, which contains N-n-butyl-N-nitritoethylnitramine (BuNENA) as a plasticizer containing a nitramine group. The azido-terminated GAP (GAP-A) or 1,5-diazido- modified plastic azide group according to claim 6, wherein the end of the GAP having a molecular weight of 500 to 1,000 g / mol is modified as an azide group. A propellant composition containing 3-nitroaminopentane (DANPE). The air according to any one of claims 1 to 6, wherein the neutral polymeric binder comprises 2-HEA and acrylonitrile in a molar ratio of 5: 5 to 9: 1 and has a molecular weight of 10,000 to 50,000 g / mol. A propellant composition containing coalescing. The propellant composition according to any one of claims 1 to 6, wherein the metal fuel contains 0.1 to 50 µm in size of aluminum, boron, zirconium, titanium, and magnesium in an amount of 0.5 to 20% by weight. The composition according to any one of claims 1 to 6, which contains triphenylbismuth in an amount of 0.05 to 0.2% by weight as a curing catalyst.

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