Frictional heating measurements in PBX 9501

Heating due to frictional processes is one of many proposed mechanisms for hot spot ignition in explosives during sub-shock, mechanical loading. Novel experiments were conducted to isolate this mechanism and measure the temperature rise due to frictional heating in PBX 9501. A rheometer was used to apply mechanical sliding loads at the interface between two explosive pellets with a controlled axial load, and the resulting coefficient of friction of the material sliding against itself and temperature rise using thermocouples along the pellet surface were measured. The measured coefficient of friction values are reported for three different axial loads, and these fall within the range of typical values for polymer against polymer. Measured bulk temperature rises were small, but showed a clear trend with increasing axial load. Such experiments provide valuable data that can be used to inform and/or validate model representations of frictional heating.