Insights into pyrolysis and combustion mechanism of green energetic agent 5-amino-1 h-tetrazole with different particle sizes

5-amino-1H-tetrazole (5AT), a novel high-nitrogen energetic compound, has garnered increasing interest due to its high energy density, low sensitivity, and environmental friendliness. In this study, the influence of particle size on the thermal oxidative degradation process of 5AT was investigated using TG-DSC and infrared spectroscopy in an air atmosphere. We calculated the activation energy for each sample and analyzed how particle size affects the activation energy. The entire reaction comprises two distinct stages, with stage-1 being the primary process. We found that smaller particle sizes correspond to lower activation energy in stage-1, making the reaction easier to initiate. Using the Trache–Abdelaziz–Siouani (TAS) method, the kinetic model and the pre-exponential factor for 5AT samples with different particle sizes were calculated. The optimal kinetic models shift from the second-order model to the three-dimensional diffusion model as particle size decreases. Based on the results of the infrared analysis, we proposed the most likely decomposition pathway and mechanism for 5AT. It is suggested that 5AT begins to decompose through an amino structure, with the pyrolysis process primarily occurring in two stages. This study provides a valuable reference for further exploration of the pyrolysis behavior of tetrazole materials in an air atmosphere.