The Promise Of Energetic TPE Gun Propellants From Notebook To Full Scale Verification

Transcription

1 The Promise f Energetic TPE Gun Propellants From Notebook To Full Scale Verification Prepared For: NDIA 37 th Annual Gun And Ammunition Symposium Panama City, Florida April 15-18, 2002 P. Braithwaite, G. Dixon, M. Rose, and R. Wardle Thiokol Propulsion

2 Acknowledgements Advances in these new propellants are the results of cooperative efforts with many organizations including: ARL TACM-ARDEC DTRA NSWC/IH NR GD SAIC United Defense 2

3 utline Background Typical ETPE propellant ingredients Propellant processing Propellant characterization Gun testing Summary and conclusions 3

4 Background The potential advantages of TPE gun propellants were seriously discussed in the early 1980 s Performance Environmental benefits - R3 Superior burning rate control No plasticizers are used No sensitivity to moisture Early feasibility studies were successfully performed in coordination with ARL/NR and others Identified areas of critical technical needs Developed initial data to verify attractiveness Recent efforts have demonstrated these propellants on a larger scale 4

5 Background (cont.) Early calculations using ETPE propellant formulations indicated they had performance advantages when compared with NC based compositions Burning rate tailorability suggested by early low pressure tests indicated these propellants could be used in conventional and layered geometries Flame Temperature (K) Impetus vs Flame Temperature NC/NE Propellants Advanced TPE Propellants Impetus (J/g) 5

6 xetane Thermoplastic Elastomers Below Tm of Hard Block Hard Block Crystalline Sphereulites Soft Block Elastomers Above Tm of Hard Block Hard Block Melts Blocks phase separated Flows and Mixes under Shear Hard and Soft Blocks Mix Annealing needed for phase separation Melting materials behavior critical to energetic processing need narrow transition from hard to processible m.p. too low and won't survive environment (<65 C) m.p. too high and energetic solids can't be processed safely (>90 C) dynamic viscosity data show attractiveness of crystalline hard block oxetane TPE (green line) Novel TPEs allow continuous processing and recycling production scrap can be well below 1 percent TPE nature allows unusual geometries better energy management maximizes performance Eta (poise) Temperature (C)

7 TPE s ffer Formulation Flexibility BAM/NMM CH 2 N 2 H H 2 C C CH 2 CH 2 C CH 2 H BAM/BAM-AMM x CH 3 y most energetic H H 2 C C CH 2 x CH 2 C CH 2 CH 2 C CH 2 x CH 3 y y H BAM/AMM H H 2 C C CH 2 x CH 2 C CH 3 CH 2 y H H BEM/AMM CH 2 Et H 2 C C CH 2 CH 2 Et x CH 2 C CH 2 CH 3 y H least energetic 7

8 New Energetic Solids Thiokol Propulsion Energetic solids provide additional burning rate and energy tailoring capability Burning rates at 40 kpsi from less than 4 in/sec to over 15 in/sec Impetus levels above 1350 J/g CL-20 TEX 8

9 Twin Screw Extrusion Thiokol Propulsion Twin screw extrusion has been found to be the best way to mix and extrude pilot scale lots of ETPE based propellants No solvents are required during mixing and extrusion Multiple formulations have been extruded into a wide range of geometries 9

10 Multiple Geometries Have Been Successfully Manufactured 10

11 SEM Evaluation Careful examination indicates excellent adhesion between solid ingredients and ETPE 11

12 Gun Testing ETPE propellants have been tested in multiple gun systems 30 mm 35 mm 40 mm 60 mm 120 mm 5-inch 155 mm 12

13 120 mm Firings ETPE propellants have been tested in 120 mm gun systems using advanced geometries Results were great!!! Pressure Pressure Time PA0 PA270 PB0 PB90 PB180 PB270 PC0 Current Perforated Propellant PA0 PA270 PB0 PB90 PB180 PB270 PC0 Advanced TPE Propellant Time 13

14 Summary ETPE propellants have matured significantly during the past several years Formulation Processing Testing and characterization Quality control Recycle and reclamation Grain design Multiple gun test firings unequivocally demonstrated the performance potential of these promising new propellants 14