Nanoscale Effect on Thermal Decomposition of 2,2′,4,4′,6,6′-Hexanitrostilbene by Dynamic Pressure Measuring Thermal Analysis

2,2′,4,4′,6,6′-Hexanitrostilbene (HNS) was prepared into nano- and microscale particles. The thermal decomposition behaviors were investigated using dynamic pressure measuring thermal analysis. The released gas amount and apparent activation energy show that the nanoparticles (NPs) have higher reaction activity and faster reaction rate and experience more drastic autocatalytic reaction than the microparticles (MPs). A reduction in particle size to nanoscale decreases the energy barrier of thermal decomposition and influences the reaction mechanism. The “trinitrotoluene mechanism,” which is the homolysis via hydrogen transfer to form a six-membered transition state, corresponds to the initial decomposition of HNS. The nanoscale effect is attributed to the surface properties of NPs, including high surface energy, rapid mass and heat transfer, and numerous active reaction sites on the reactant interface.