Insight into the pyrolysis of 3,7-dinitro-1,3,5,7-tetraazabicyclo [3,3,1] nonan (DPT) based on ReaxFF MD simulations and TG-FTIR-MS techniques

ReaxFF molecular dynamics (ReaxFF MD) simulations in conjunction with TG-FTIR-MS (Thermogravimetric-Fourier transform infrared-Mass spectrometry) techniques were performed to illuminate the pyrolysis mechanism of 3,7-dinitro-1,3,5,7-tetraazabicyclo [3,3,1] nonan (DPT). The characteristics of DPT decomposition under different temperatures were explored by ReaxFF molecular dynamics. The simulation results show the evolution of primary intermedia products and final products of DPT decomposition varies with time. The complete dynamic process of DPT decomposition at the atomic level is revealed. The pyrolysis of DPT is primary triggered by N-NO2 rupture, which is confirmed by the bond dissociation energy (BDE) calculation. Subsequently, the intermedia products undergo a series of complex interactions and H2O, N2, NH3 and C network generate as final products. The volatile gas detected by ReaxFF molecular dynamics are all certified by the TG-FTIR-MS techniques, which demonstrating the reasonability of theoretical simulations. Thus, a full microscopic picture of the thermal decomposition of DPT is presented, which is a great help in the safe manufacture of octogen (HMX).