Condensed-phase kinetics of cyclotrimethylenetrinitramine by modeling the T-jump/infrared spectroscopy experiment

During the combustion of solid propellants, explosives, or pyrotechnics, the condensed phase experiences heating rates that may exceed 20,000 K/s. At such high heating rates, the thermal decomposition behavior of the energetic material could be affected by its rate of decomposition. To simulate the high heating rate environment, the T-jump experiment was developed for use with Fourier-transform infrared spectroscopy. The T-jump experiment utilizes electrical resistance heating of a thin Pt filament on which a small amount of the energetic test sample is placed. This work describes a heat transfer model of the filament and sample, a model of the current's control circuit, and global decomposition and heat release mechanisms of cyclotrimethylenetrinitramine (RDX), which is an energetic ingredient used in propellants and explosives. Comparisons of model calculations with experimental data reveal an excellent agreement. Similarly, the predicted time to rapid heat release for the highly energetic RDX sample also shows a good agreement with experimental results. Thus the use of the developed model in conjunction with experiments should be a useful tool in studying the thermal decomposition behavior of energetic materials under combustion-like conditions.