Influence of moisture content on the thermal decomposition kinetics of smokeless gunpowders

The present work investigated the effect of moisture content on the thermal decomposition of two smokeless powders. First, the main ingredients of the studied gunpowder formulations were identified using gas chromatography-mass spectrometry (GC-MS) and Fourier Transform Infrared (FTIR) spectroscopy. The investigated gunpowders were stored in three different humid environments and then analyzed using a C80 microcalorimeter and a thermogravimetric analyzer. The obtained heat flow curves showed a major exothermic peak within the 140–230 °C temperature range, corresponding to the main gunpowder thermal decomposition. This degradation phase shifted to lower temperatures as the sample moisture content increased. Based on non-isothermal TG experiments, two model-free iterative methods (it-KAS and it-FWO) were applied to estimate the kinetic triplet of this main degradation phase for the stored specimens. It was found that the mean value of the activation energy decreased as the water content of the sample increased. This finding may be explained by the accelerated hydrolysis process of water on the thermal degradation of nitrocellulose-based smokeless powders.