WO1998021168A1

WO1998021168A1 - High energy thermoplastic elastomer propellant

Info

Publication number: WO1998021168A1
Application number: PCT/US1996/018372
Authority: WO
Inventors: Thelma Manning; Joseph Prezelski; Sam Moy; Bernard Strauss; Jim Hartwell; Arpad Juhasz; Robert Lieb
Original assignee: Thelma Manning; Joseph Prezelski; Sam Moy; Bernard Strauss; Jim Hartwell; Arpad Juhasz; Robert Lieb
Priority date: 1996-11-13
Filing date: 1996-11-13
Publication date: 1998-05-22
Also published as: AU1159797A

Abstract

A high energy propellant, comprising an oxetane thermoplastic elastomer energetic binder admixed with a high energy explosive filler. The oxetane thermoplastic elastomer energetic binder preferably comprises from about five percent to about thirty percent by weight and the high energy explosive filler comprises from about seventy percent to about ninety-five percent by weight of the composition. A preferred propellant further includes an explosive plasticizer, preferably in an amount of about four percent to about seven percent of the plasticizer by weight of the propellant. The prefered filler is selected from the group consisting of CL-20, TNAZ, RDX and mixtures thereof. The preferred plasticizer is selected from the group consisting of TNAZ, BTTN, TMETN, TEGDN, BDNPA/F, methyl NENA, ethyl NENA and mixtures thereof. In a preferred embodiment, the propellant is actually a pair of high energy propellants comprising a mixture of first and second high energy propellants with the first propellant having a burning rate at least two times faster than the burning rate of the second propellant. The first propellant includes an oxetane thermoplastic elastomer energetic binder admixed with CL-20 high energy explosive filler. The second propellant including an oxetane thermoplastic elastomer energetic binder admixed with RDX high energy explosive filler. Plasticizers and relative amounts for each of the first and second propellants are the same as for the single propellant.

Description

HIGH ENERGY THERMOPLASTIC ELASTOMER PROPELLANT

The invention described herein may be manufactured, used, and licensed by or for the U.S. Government for U.S. Governmental purposes. ■

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FIELD OF THE INVENTION | j

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, - The present invention relates generally to a ihigh energy propellant composition. More particularly the invention relates to a propellant that includes an energetic thermoplastic elastomer as a binder and a high energy, high density filler. I ,

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BACKGROUND OF THE INVENTION

ancillary waste, especially in enhanced demil and recyclability.

Accordingly, one object of the present invention is to provide a pair of high energy propellants whose average impetus is at or above the 1300 J/g level. j| ii , ,

Another object of this invention is to provide a pair of high energy propellants whose burning rate differential is three or greater. An additional object of this invention is to provide new energetic materials and processes that eliminate or greatly reduce both volatile organic compound production and ancillary waste through demil and recyclability.

Other objects will appear hereinafter.

SUMMARY OF THE INVENTION

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TNAZ, Butane-trio-trinitrate or BTTN, Trimethylolethane Trinitrate or TMETN, Triethylene Glycol Dinitrate or TEGDN, Bis, 2,2 - Dinitro propyl acetal/Bis 2,2 - Diniro propyl formal or BDNPA/F, Methyl Nitrato ethyl nitramine or methyl NENA, ethyl NENA. These plasticizers may be used alone or in combination.

It has also been discovered that a pair of high energy propellants may be combined to produce a propellant mixture having a first propellant having a burning rate at least three times faster than the burning rate of the second propellant. In the preferred embodiment, the first propellant includes an oxetane thermoplastic elastomer energetic binder admixed with CL-20 high energy explosive filler. The second propellant including an oxetane thermoplastic | elastomer energetic binder admixed with RDX Λiigh energy explosive filler or RDX and TNAZ mixtures. The ratio of burning rates may I be varied from at least 2.0 times to as high as 4.8 times, or higher^ Of course, plasticizers and relative amounts for each of the first and second propellants are within the same ranges as for the single propellants.

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DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The present invention has many advantages over the prior art

OXETANE Only 166 1 229

1 1

OXETANE/TNAZ (l:l) 153 ! l ^{! |}211 6

OXETANE/CL-20 (1:1) 1 8 1 206

OXETANE/RDX (l:l) 196 222

1 j

In order to demonstrate the effectiveness of the propellants of this invention, a number of gun propellant formulations were mixed and extruded. The method of preparing the formulations comprised the O 98/21168

steps of mixing at about 95 °C and extruding at slightly lower temperatures. Processing at these temperatures provided a safe operating margin of at least 50 ° C because the self heat temperatures of the filler ranges from about 175 °C to 192 °C, but the preferred plasticizer TNAZ melts around 100 °C, so that as some of the TNAZ begins to melt during processing at 95 °C, a more fluid mix results that is easier to process. Presented below in Table II are seven formulations that have been prepared. All values for the composition are given in percent by weight, based on the total weight. ^!

TABLE π

Sample O etane FUler/a oftnt Impetus, j/g Flame, O.K. A 24 CL-20/76 1297 3412

B 24 TNAZ/76 1309 3321 C 20 TNAZ/76* 1335 3475 D 20 CL-20/76* 1324 3575 E 13.3 RDX/80** 1319 3395 F 1 8 RDX/76*** 1306 I [l348 G 20 CL-20**** 1348 I 3683

* Sample also included 4 % BDNPA/F as plasticizer ** Sample also included 6.7 ^τ% BDNPA/F as plasticizer *** Sample also included 6 % TNAZ as plasticizer **** Sample also included 4% TNAZ as plasticizer.

Each of the above batches was formulated into a propellant by mixing and then extruding at a lower temperature. Selection and control of the precise extrusion parameters ₍was important to obtain proper grain dimensions without excessive swelling or deformation, Table III below identifies the barrel temperature, die temperature and ram speed for each sample batch. ! ' 98/21168

TABLE III

Sample arrel temp, _°c_ Die temp, °£ Ram speed, in/min.

A 82 70 0.14

B 95 86 0.14

F n/a n/a n/a ne,g neg

G n/a n/a n/a n< 1& neg

The next evaluation of these samples was to determine the burn rate at various_^ conditions. The data for the burn rates, presented i h i O 98/21168

below in Table VI, represent closed bomb data. As can be seen, RDX containing samples E and F have the slowest burning rates, which is comparable to the LOVA type M43 formulations. The CL-20 samples A, D and G have much faster burn rates, the improvement being about 2.7 times at 10,000 psi and 4.8 at 25,000 psi. The TNAZ filled samples B and C have intermediate burning rates and sample G is the fastest. Based upon this data, a combination of a first propellant having burning ratios at least three times faster than a second combined propellant is now possible. ι

TABLE VI

Sample 10 kpsi 15 kpsi 25 kpsi Exponent Friςtion

(inch/sec) (inch/sec) (incji/scc) ( 10-3)

A 4.5 6.9 1 1 .8 1 .04 0.30 B 3.1 4.7 7.9 1 .02 0.25 C 3.5 5.1 8.4 0.97 0.46 D 4.5 6.8 1 1.2 0.98 0.54 E 1.7 2.6 4.4 1 .03 0.14 F 1.7 2.7 4.5 1 .04 0. 12 G 4.6 9.0 21.0 1 .65 0.001

To complete the evaluation of the samples, some mechanical behavior tests were performed, the results of which are below in Table VII. Tests were done on an Instron test machine at low strain.

TABLE VII

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10

The symbols for the failure data in the last column of Table VII are as follows: B = barrel, P = pancake, SC = slight crumble, and S = split

The data shows that high energy gun propellants at an energy level of 1300 J/g can be formulated with an Oxetane binder in combination with high energy fillers. Desirable burning rates with burn rate differential by a factor of 3 or more can be obtained from these formulations. ,

While particular embodiments of the present invention have been illustrated and described herein, it is not intended that these illustrations and descriptions limit the invention. I Changes and modifications may be made herein without departing from the scope and spirit of the following claims.

Claims

98/2116811CLAIMS

1. A high energy propellant, comprising: an oxetane thermoplastic elastomer energetic binder admixed with a high energy explosive filler.

2. The propellant of claim 1 , wherein said oxetane thermoplastic elastomer energetic binder comprises from about five percent to about thirty percent by weight of the propellant.

3. The propellant of claim 1, wherein said high energy explosive filler comprises from about seventy percent to about ninety-five percent by weight of the propellant.

4. The propellant of claim 1, wherein said filler is selected from the group consisting of CL-20, TNAZ, RDX and mixtures thereof.

5. The propellant of claim 1 which further includes an explosive plasticizer.

6. The propellant of claim 5 wherein said plasticizer is selected from the group consisting of TNAZ, BTTN, TMETN, TEGDN, BDNPA/F, methyl NENA, ethyl NENA and mixtures thereof.

7. A high energy propellant, comprising: about five percent to about thirty percent by weight of an oxetane thermoplastic elastomer energetic binder admixed with from about seventy percent to about ninety-five percent by weight of a high energy explosive filler selected from the group consisting of CL-20, TNAZ, RDX and mixtures thereof.

8. The propellant o^τf claim 7, which further includes an explosive plasticizer selected from the group consisting of TNAZ, BTTN, TMETN, TEGDN, BDNPA/F, methyl NENA, ethyl NENA and mixtures thereof. O 98/21168

12 9. The propellant of claim 8, which includes about four percent to about seven percent of said plasticizer.

10. A pair of high energy propellants, comprising: a mixture of first and second high energy propellants with said first propellant having a burning rate at least three times faster than the burning rate of said second propellant , comprising: a first propellant including an oxetane thermoplastic elastomer energetic binder admixed with CL-20 high energy explosive filler; and a second propellant including an oxetane thermoplastic elastomer energetic binder admixed with RDX high energy explosive filler; whereby the burning rates of the first propellant is at least three times faster than the burning rate of said second propellant.

1 1. The propellant pair of claim 10 in which each propellant further includes an explosive plasticizer.

12. The propellant pair of claim 11 wherein said plasticizer is selected from the group consisting of TNAZ, BTTN, TMETN, TEGDN, BDNPA/F, methyl NENA, ethyl NENA and mixtures thereof.

13. The propellant pair of claim 11, in which each propellant includes about four percent to about six percent of said plasticizer.

14. The propellant pair of claim 10, wherein said oxetane thermoplastic elastomer energetic binder comprises from about five percent to about thirty percent by weight of each of the propellants.

15. The propellant pair of claim 10, wherein said high energy explosive filler comprises from about seventy percent to about ninety-five percent by weight of each of the propellants.