High-speed photographic study of the drop-weight impact response of ultrafine and conventional PETN and RDX

This paper describes a series of drop-weight experiments performed on pentaerythritol tetranitrate (PETN) and cyclotrimethylene trinitramine (RDX). Both chemicals were available in a conventional grain size (10-200 mum for PETN, 30-500 mum for RDX) and in a novel ultrafine particle size (<1 mum). The aim of the study was to determine the relative sensitivity of the four materials and to investigate the mechanisms by which ignition occurred in the samples. Heat sensitive film and high-speed photography revealed adiabatic shear bands in all four materials. However, trapped gas appeared to be the main reason for ignition. Because ultrafine powders have smaller interstices between grains, this could explain why the ultrafine samples were less susceptible to drop-weight impact. (C) 2002 by The Combustion Institute.