Particle Size Effects on Thermal Decomposition of Energetic Material

This work refers to a study of the thermal decomposition of octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) by differential scanning calorimetry (DSC) under nonisothermal conditions, with heating rates from 5 to 20°C min−1. The influence of the particle size in the thermal decomposition of HMX was verified. The activation energy for the decomposition of each sample was calculated using the peak temperature shift methods, proposed by Kissinger and Ozawa. A significant variation in the results was observed according to the range of the particle size used. The results showed that, as the particle size of HMX increased, the thermal decomposition temperature of HMX and the decompositional activation energies ranges enhanced. At the same time, at a constant heating rate, the decomposition temperatures of the smaller particles were lower than those of larger ones. The critical temperature for thermal explosion of each sample was calculated. Also, the values of ΔS#, ΔH#, and ΔG# of reaction for each particle size were computed.