A systematic investigation into the influence of particle size of HMX on micromeritic parameters and the characteristic properties of its explosive formulations

The characteristics of particles, encompassing their morphology and precise size distribution, play pivotal roles in attaining superior performance, diminished shock sensitivity, substantial solid loading, and optimal fluidity of mixtures during the processing of explosive materials. In the present investigation, octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) with a defined mean particle size of 875 µm, 427 µm, 175 µm, and 20 µm, alongside their bimodal and trimodal mixtures, were explored for micromeritic properties. The findings reveal that the trimodal amalgamation of coarse 875 µm, medium 175 µm, and fine 20 µm particles in 50:30:20 ratio yielded optimal packing density coupled with relatively lower sensitivity. Explosive formulations were crafted from uni-, bi-, and tri-modal particle compositions, incorporating a blend of differently sized HMX particles amalgamated by Estane as a polymer binder system, with the investigation aimed at elucidating their impact on the distinctive properties. The explosive formulation derived from the trimodal mixture exhibited enhanced detonation velocity and reduced sensitivity in comparison to both the bimodal and unimodal explosive formulations. The tapped density of the trimodal PBX molding powder was superior to monomodal explosive formulations. Furthermore, the trimodal explosive formulations manifested diminished mechanical sensitivity, superior charge density, and enhanced performance relative to the monomodal formulation.