The kinetics of thermal decomposition and hot-stage microscopy of selected energetic cocrystals

With the increased interest in cocrystals, there is a need to quantify the decomposition characteristics of these new materials. The thermal decomposition of four energetic cocrystals composed of 4-amino-3,5-dinitropyrazole (ADNP)/diaminofurazan (DAF), 2,4,6-trinitrotoluene (TNT)/2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (CL20), 1,3,5,7-tetranitro-1,3,5,7-tetrazacyclooctane (HMX)/CL20, and 1-methyl-3,5-dinitro-1,2,4-triazole (MDNT)/CL20 was studied using simultaneous differential scanning calorimetry (DSC), thermogravimetry analysis (TGA), and hot-stage microscopy. The kinetic parameters of their thermal decomposition reaction were determined using both the Kissinger and Ozawa kinetic analyses methods. Each cocrystal’s peak exothermic temperature (decomposition temperature), activation energy, and pre-exponential constant are reported and compared to the corresponding stoichiometric physical mixture. The results showed that cocrystallization clearly affects the thermal decomposition and reaction kinetics of these materials, and importantly can make the material more, or less, susceptible to decomposition.