Concerning the shock sensitivity of cyclic nitramines incorporated into a polyisobutylene matrix

Two types of plastic bonded explosives (PBXs) based on ε-2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (ε-HNIW, CL-20), and PBXs based on 1,3,5-trinitro-1,3,5-triazinane (RDX), ß-1,3,4,7-tetranitro-1,3,5,7-tetrazocane (ß-HMX) and cis-1,3,4,6-tetranitro-octahydroimidazo-[4,5-d]imidazole (bicyclo-HMX, BCHMX) were prepared using a polyisobutylene binder with dioctylsebacate (DOS) as plasticizer, i.e. a C4 matrix. One version of the e-HNIW PBX is a product with reduced sensitivity (RS-ε-HNIW). All these PBXs, referenced respectively as RS-ε-HNIW-C4, ε-HNIW-C4, RDX-C4, HMX-C4 and BCHMX-C4, were tested using the Small Scale Gap Test according to STANAG 4488. The results of the gap test on the PBXs with RDX, ß-HMX and BCHMX correspond to the impact sensitivities of the original crystalline nitramines. This is not entirely valid for e-HNIW. In other words, PBXs with RS-ε-HNIW cannot achieve as low a shock sensitivity as would be expected from the differences obtained from the impact sensitivities between RDX, ß-HMX and BCHMX, on the one hand, and RS-e-HNIW on the other. It is shown that the morphological stability of RS-ε-HNIW in the C4 matrix is insufficient. However, further development and use of RS-ε-HNIW as a filler of PBXs would seem to be both desirable and beneficial. Despite the relatively high impact sensitivity of crystalline BCHMX, the shock sensitivity of its analogous C4 PBX is already good, and comparable with that of RS-ε-HNIW.