Exploration of the combustion characteristic based on the pyrolysis and combustion spectral analysis of single base propellant

The pyrolysis and combustion of gunpowder are inseparable. To explore the risk characteristics of single base propellant, the pyrolysis kinetics and spectral information of single base propellant during combustion were studied in this work. Notably, with an increased heating rate, the exothermic peak shifts to higher temperatures, and the exothermic rate intensifies during the pyrolysis process, resulting in an incomplete reaction and the formation of residues. The reaction of single base propellant encompasses decomposition stage and multiple level reactions, it is phase boundary reaction mechanism. NO is generated firstly at 441.108 K and is identified as the most influential substance in facilitating the transition from pyrolysis to combustion. It causes intensified molecular chain breakage, CO, NH₃, H₂O, HCN, C_xH_y, NO, CO₂ are generated. The combustion process results in the destruction of the flocculent structure and amorphous regions within single base propellant, leading to a relatively smooth particle surface, reduced porosity, and structural collapse. Moreover, the combustion optical spectrum of single base propellant has a distinct characteristic absorptions at 589 nm, 767 nm, and 770 nm, corresponding to Na and K, respectively. The spectrals can be effectively discerned within 15 ms. During the from pyrolysis to combustion of the single base propellant, the reaction mechanism, spectral band and intensity provide valuable indicators for anticipating potential accidental combustion hazards.