Thermal decomposition mechanism of HMX/DNAN at high temperatures by reactive molecular dynamics simulations

This work investigated the thermal decomposition process of the HMX/DNAN melt-cast explosive system at high temperatures using reactive molecular dynamics. The initial reaction paths of the system and the effects of DNAN on the thermal decomposition of HMX were revealed. The findings indicated that the H atoms and nitro groups produced by the decomposition of DNAN were reacted with HMX and its intermediates, which in turn promoted the pyrolysis of HMX, while the OH radicals produced by the decomposition of HNO₂ continued to induce the decomposition of HMX. Calculations of activation energies showed that the addition of DNAN enhanced the sensitivity of HMX to thermal stimuli. In terms of products, the addition of DNAN significantly impacted the final product H₂O of HMX, while its impact on CO₂ is relatively small. At 2000 K–3500 K, the maximum number of clusters in mixed system showed a general decreased trend with increased temperature.