Effect of Oxygen Balance on the Pyrolysis and Kinetics of Guanidine Nitrate/Basic Copper Nitrate‐Based Airbag Gas Generant

ABSTRACT Sodium azide has long been employed as a gas generant in airbag inflators; however, concerns regarding its environmental impact, toxicity, and disposal have prompted the development of alternative formulations, notably ammonium nitrate (AN) based gas generants and, more recently, guanidine nitrate (GN) and basic copper nitrate (BCN) gas generants. In this study, differential scanning calorimetry (DSC) and thermogravimetry (TG) experiments were performed to analyze their redox decomposition of GN/BCN gas generants. Three samples were prepared based on the oxygen balance. The overall redox reaction was initiated by the local thermal decomposition of GN, while the fuel‐rich mixture exhibited behavior more akin to pyrolysis. The highest mass loss rate from the derivative thermogravimetry (DTG) plots was observed for the sample with 0% oxygen balance. Kinetic parameters were obtained using the Friedman isoconversional method. The average activation energies of 156.5 ± 44, 207.6 ± 65, and 233.4 ± 102 kJ/mol were calculated for 0%, +10%, and ‐10% oxygen balance samples, respectively. Deconvolution was performed on the DTG curves to discern individual steps using the Lorentz function. The simulated curves derived from the kinetic parameters and reaction models of each step were in good agreement with the experimental data, thus validating the results. Flame propagation velocity studies imparted further insights into flame propagation and its dependence on the oxygen balance. The results demonstrate how oxygen balance influences the multistep redox mechanism, including pyrolysis and the performance of energetic gas generants.