Effects of nitric acid and sulfuric acid on the thermal behavior of nitrocellulose by slow heating experiments

Sulfuric acid and nitric acid are two typical additives in manufacturing, storage, processing, and transportation of nitrocellulose. This paper performed a comparative study of the decomposition behavior of nitrocellulose supplemented with nitric acid or sulfuric acid using a micro calorimeter under slow heating condition. Different from the single heat flow peak of nitrocellulose, two exothermic peaks were observed after adding 30 wt% acids into nitrocellulose. The kinetics parameter of pure nitrocellulose and its mixture with acids were obtained by isoconversional kinetics method and compared to that by other methods. The self-heating property was analyzed by isothermal experiments. The involvement of nitric acid and sulfuric acid influenced thermal behavior with different mechanisms. The involvement of nitric acid highly reduced the onset temperature by 44% ~ 50%, and decreased the activation energy from over 110 kJ/mol to less than 80 kJ/mol. Both onset temperature and activation energy for the mixture involving sulfuric acid were not slightly improved. Comparing to sulfuric acid, nitrocellulose mixed with the same amount of nitric acid is more likely to undergo self-accelerating decomposition and cause thermal hazards. Graphical abstract