The Use of Chemiluminescence Nitrogen Oxides Analysis for the Study of the Decomposition of Nitrocellulose

Abstract

Understanding the decomposition of nitrocellulose (NC) and other nitrate esters within storage and usage temperature ranges is essential for managing the service life and safety of (NC)-containing formulations. High-temperature decomposition studies often fail to reflect typical storage conditions due to temperature-dependent mechanisms. This study uses chemiluminescence nitrogen oxides (NOx) analysers to examine NC decomposition, measuring NOx evolution across a wide temperature range. From 20°C to 135°C, decomposition modes include thermolysis, hydrolysis, and physical desorption. Results show NOx can desorb from NC at ambient temperatures, potentially misleading traditional stability tests. The quantity of NOx generated depends on material history and can be reduced by pre-test procedures. While thermolysis dominates at higher temperatures with an activation energy of 140 kJ.mol−1, hydrolysis is predominant at lower temperatures with an activation energy of 46 kJ.mol−1. This low activation energy should be considered in any life assessment predictions. In this lower temperature regime, moisture significantly affects decomposition rates, especially below 50°C. Whilst the rate increases in the presence of moisture, the activation energy for the hydrolysis process is unaffected. Chemiluminescence NOx analysis has proven to be a powerful tool for studying the low-temperature decomposition behaviours of NC and NC-containing formulations. This innovative approach not only enhances the understanding of NC decomposition but also offers a more efficient and accurate method for assessing the stability of NC-containing formulations.