Rapid fragmentation contributing to the low heat resistance of energetic materials

Abstract

Heat resistance is a basic and crucial characteristic of energetic materials (EMs), and always accounted in development and application. Compared with the clear origin of the high heat resistance of EMs, the mechanism for the low heat resistance remains still unclear. This work reveals the mechanism by carrying reactive molecular dynamics simulations on heating six less thermally stable EMs of nitroforms and pentaerythritol tetranitrate (PETN), as well as a more thermally stable EM of 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) for comparison. Unexceptionally, all the nitroforms and PETN heated feature fast NO2 partition and further decomposition throng the oxidation of NO2 to form small fragments and final small stable product molecules, with fast heat release; while, the intermolecular reactions and the further clustering govern the initial steps in decomposing TATB. Therein the reactants also exhibit a rapid consumption; however, this fast consumption with clustering does not result in the low heat resistance of TATB. That is, some general indicators representative of thermostability, such as bond dissociation energy and the reactant consumption rate, are insufficient to assess it practically. Thus, the rapid fragmentation originally contributes to the low heat resistance. These insights are expected to present an overall perspective of understanding the thermal stability mechanism of EMs, and set a theoretical base and pave a way for designing EMs with desired heat resistance.