On Impact Resistance and Sensitivity to Electric Spark in Selected Cyclic Nitramine Coagglomerates

Abstract

Cocrystallization via VPSZ coagglomeration have emerged as promising strategies to modulate this sensitivity without sacrificing performance, however, the structural drivers that govern these effects still demand systematic exploration to unlock their full potential. This study focuses on the impact sensitivity (IS) and electric spark sensitivity (EES) of co-agglomerated crystals/co-crystals (CACs) of the cyclic nitramines RDX, β-HMX, δ-HMX, BCHMX, and β-CL-20. The impact-sensitivity values were determined using the BAM method, whereas the EES values have been evaluated in accordance with the Czech Defense Standard ČOS137601 (incorporated into STANAG 4490). All correlations of the IS and EES data with molecular-structure characteristics have confirmed that both types of sensitivities are intrinsic properties of energetic materials. Converting these nitramines into cocrystals/CACs leads to the entering coformer generally exhibiting higher shock sensitivity than it does in its pure state. However, it is also possible to prepare cocrystals with lower shock sensitivity than that of both of their pure coformers. In the conformer PANi the sensitivity of nitramine CACs to electric sparks is higher than the sensitivity of the pure nitramine coformer the composite. The principles of the sensitivity behaviour of the CACs investigatedare explained based on the FTIR analysis of symmetric N−O bond stretching vibrations and changes in the mesomeric equilibrium in the nitramine grouping. Further established - the linear correlations between IS and EES. New linear correlations are identified between the values of both sensitivity types and the specific surface areas of CACs - microcrystals, providing a practical, spectroscopic structure-based framework for anticipating and ultimately crystal engineering through crystal design the safety profile of nitramine-based energetic cocrystals.