Reactive Molecular Dynamics Simulations of the Thermal Decomposition Mechanism of 1,3,3-Trinitroazetidine

1,3,3-Trinitroazetidine (TNAZ) has a molecular formula of C₃H₄N₄O₆ and the characteristics of low melting point, low impact sensitivity and good thermal stability. It is suitable for melt casting and pressed charges, and it has broad prospects for applications in low-sensitivity ammunition. In this study, the thermal decomposition of TNAZ crystals at high temperature was calculated by molecular dynamics simulation with the ReaxFF/lg reactive force field. The change in the potential energy of TNAZ, the formation of small-molecule products and clusters, and the initial reaction path of TNAZ were analysed. The kinetic parameters of different reaction stages in TNAZ thermal decomposition were obtained. The primary thermal decomposition reaction of TNAZ was found to be as follows: N−NO₂ and C−NO₂ bonds broke; a H atom on the quaternary ring was transferred to the nitro group; and the C-HNO₂ and N-HNO₂ bonds broke. The main decomposition products of TNAZ were thus NO₂, NO, N₂, H₂O, CO₂ and HNO₂, as well as macromolecular clusters. The size of the cluster structure was related to the reaction temperature, and the higher the temperature was, the smaller the cluster size was.