Thermal Decomposition Mechanism and Energy Release Law of Novel Cyclo-N5--Based Nitrogen-Rich Energetic Salt.

Abstract

Detonation energy of novel cyclo-N5--based nitrogen-rich energetic salts is expected to exceed 3 times the equivalent of TNT. PHAC([(N5)6(H3O)3(NH4)4Cl]) was selected as the prototype to investigate the thermal decomposition reaction of PHAC in the solid phase for the first time by the first-principles molecular dynamics method. At about 38 ps, the final state of the reaction was reached. It was found that there were mainly five final products, among which the proportion of N2 molecules was the maximum and accounted for 60% (mole fraction) of all final products. The reaction pathways of PHAC were analyzed, and more than 30 elementary reactions were found. The initial reaction of the PHAC thermal decomposition was the ring-opening of cyclo-N5- ion and proton transfer. The energy release of PHAC thermal decomposition is divided into two stages. The first stage is a slow release of energy before the formation of the HN3 molecule. The second stage is the rapid release of energy after the formation of HN3 molecules. The HN3 molecule is an essential junction, and the unimolecular dissociation of HN3 is the rate-determining step. Such an understanding of reaction mechanism and energy release law greatly promotes the application and synthesis of novel cyclo-N5--based nitrogen-rich energetic salts.