Effects of Endothermic Binders on Times to Explosion of HMX- and TATB-Based Plastic Bonded Explosives

Abstract

Plastic-bonded explosives (PBXs) based on octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) or 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) formulated with the endothermic binders Estane, Viton, or Kel-F exhibit longer times to thermal explosion than do pure HMX and TATB in the one-dimensional time to explosion (ODTX) and in other thermal experiments. Previous chemical kinetic thermal decomposition models for HMX- and TATB- based PBXs assumed that the binders decomposed independently of and at lower temperatures than the explosives. Recent chemical decomposition rate measurements showed that Estane, Viton, and Kel-F are more thermally stable than HMX and TATB. Thus, the longer thermal explosion times for these PBXs are most likely due to endothermic decompositions of the binders by reactions with the gaseous decomposition products of HMX and TATB. New PBX chemical decomposition models are developed using the global HMX and TATB models, measured binder kinetics, and cross-reactions between gaseous explosive products and binders. These new models accurately predict ODTX time to explosion and other experimental data.

Keywords:

• endothermic binders
• HMX
• TATB
• thermal explosion

Acknowledgments

The authors thank all the experimentalists who generated the ODTX and STEX data, as well as Alan Bunrham and Randall Weese for many interesting discussions. The authors also thank Dr. Melvin Baer of Sandia National Laboratories for the original suggestion of cross-reactions between explosive decomposition products and the surrounding binders. This work was performed under the auspices of the United States Department of Energy by the Lawrence Livermore National Laboratory under contract no. W-7405-ENG-48.

Notes

^a 38.23 for fine HMX particles

^b 28.53 for fine HMX particles.

^a 30.8 for ultrafine TATB particles

^b 27.8 for ultrafine TATB particles.

^a For fraction reacted > 0.42, ln Z = 28.13

^b For fraction reacted > 0.42, Ea = 43.74.