Model for explosive sensitivity using enthalpy of explosion and effective trigger linkage kinetics

A simple and physically transparent model for the origin of explosive sensitivity has been developed from gas-phase enthalpies of explosion and the kinetics of trigger linkage rupture. These properties parameterize an Arrhenius rate law that connects energy release and bond strengths to the stability of explosive molecules. The effective trigger linkage kinetics are computed using gas-phase reactive molecular dynamics simulations that rapidly and automatically sample all possible decomposition pathways on the potential energy surface of each molecule. The model is parameterized to the results of drop weight impact testing, where H₅₀ is the height from which a 2.5 kg mass is dropped onto small, 40 mg samples such that they react with 50% probability, for a set of 24 primary, conventional, and insensitive explosives from a number of distinct chemical families with sensitivities that span H₅₀ = 0.7 cm to greater than 320 cm. Our results indicate that insensitive explosives (those with high H₅₀ values) generally derive their properties from a combination of strong trigger linkages and a small enthalpy of explosion while the most sensitive explosives (with small H₅₀ values) exhibit both weak trigger linkages and large enthalpies of explosion.