Multi-aspect and comprehensive atomic insight: the whole process of thermolysis of HMX/Poly- NIMMO-based plastic bonded explosive

Abstract

Abstract Based on the reactive molecular dynamics, the whole process of thermolysis of HMX/Poly-NIMMO-based PBX was studied in detail at the micro scale, which provided a novel atomic insight into the thermolysis mechanism of HMX/Poly-NIMMO. Further, it was compared with the HMX single substance system to explore the influence of binder on thermolysis of HMX. According to the findings, the activation energy required by pyrolysis of HMX in the mixed system is much less than that required by the pure HMX system at both phases. From the point of view of reaction energy, Poly-NIMMO promoted the thermolysis of HMX. Especially, the mechanism analysis confirmed this point. The nitro and hydroxyl groups detached from Poly-NIMMO will react with HMX, and the generated HNO2 will further accelerate the decomposition process of nitrogen heterocycles. In addition, the number of the final products H2O and H2 in the two-component system increased greatly, but the number of CO2 and N2 molecules had not changed much, and C clusters were formed in the system. The evolution trend of bond number further verified the above analysis. While the maximum cluster number does drop with increasing temperature at first, after a particular temperature threshold is reached, it remains unchanged. In a nutshell, Poly-NIMMO will hasten HMX's thermolysis and reduce the system's stability when subjected to heat.