Concerning the Shock Sensitivities of Certain Plastic Bonded Explosives Based on Attractive Cyclic Nitramines

Abstract

Plastic bonded explosives (PBXs) based on ε-2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (ε-HNIW), 1,3,5-trinitro-1,3,5-triazinane (RDX), β-1,3,5,7-tetranitro-1,3,5,7-tetrazocane (β-HMX) and cis-1,3,4,6-tetranitro-octahydroimidazo-[4,5-d]imidazole (BCHMX) were prepared using a hydroxyl-terminated polybutadiene as a binder (HTPB) and cured with hexamethylene di-isocyanate (HMDI). Recently published data for analogous PBXs with a polyisobutylene binder (i.e. a C4 matrix) are also included. All of these PBXs were tested using the Small Scale Water Gap Test according to STANAG 4490, the results of which are directly proportional to the impact and friction sensitivities of the PBXs studied. Reciprocal ratios between the shock sensitivity of these PBXs and their performance were found using the volume heat of explosion as a variable; a semi-logarithmic analogue, using a representative of the detonation pressure (product ρD2) as a variable, has shown an opposite trend for three of these PBXs. A semi-logarithmic relationship between the shock sensitivity of the PBXs and the impact sensitivity of their pure nitramine fillers has confirmed the higher shock reactivity of the C4 PBXs filled with both technical ε-HNIW and RS-ε-HNIW, while for the HTPB PBXs filled with technical grade ε-HNIW, the shock sensitivity found was as expected. The shape and size of the particles should not be a reason for the increased resistance to shock of HMX-C4.