Influence Mechanism of PA on the Thermal Decomposition of RDX Based on ReaxFF MD and DFT

To elucidate the physicochemical mechanisms underlying the violent explosion triggered by nylon (PA) jet penetration into explosive reactive armor, the thermal decomposition behavior of RDX and the influence mechanism of PA on its thermal reaction were studied by reaction molecular dynamics simulation and quantum chemical calculation, which were compared with experimental research. The study reveals that the decomposition of RDX is primarily initiated through pathways such as N-NO₂ homolysis, HONO elimination, and concerted ring-opening. The addition of PA reduces the energy barrier for N-N bond homolysis and provides hydrogen atoms to initiate HONO elimination via a heterogeneous pathway with a lower energy barrier, thereby promoting the initial decomposition of RDX. The free radicals produced by the decomposition of PA and RDX participate in a synergistic reaction, efficiently yielding stable products and significantly altering the distribution of intermediate species. The introduction of PA lowers the activation energy barrier for RDX decomposition and supplies hydrocarbon fragments as fuel for the reaction, facilitating rapid decomposition and initiation. This work clarifies the dual mechanism by which PA promotes RDX detonation from the perspective of microscopic reaction kinetics, providing theoretical insights for understanding and modulating the response of explosives under complex impact conditions.