Effect of nanomaterials on the combustion and pyrolysis characteristics of tear gas mixtures

Abstract To further optimize the overall combustion performance of combustion-type tear gas mixtures and improve the effective utilization rate of the tear gas agent OC, various nanomaterials and composite nanomaterials were incorporated into the combustion-type tear gas mixture system. Using specialized equipment for measuring physical property parameters and thermal analysis instruments, changes in the physical property parameters and thermal decomposition behavior of six modified mixtures were investigated. The microstructure of these mixtures was characterized and analyzed, and the mechanism by which nanomaterial addition influences the thermal decomposition process of the mixture system was explored via the Starink method, Flynn-Wall-Ozawa method, and Coats-Redfern method. The results revealed that the maximum decomposition temperature (T max ) of samples NP2, NP5, and NP6 exhibited the most significant reduction (approximately 40 °C), while the average combustion rate increased by nearly 17%. Correspondingly, the OC release efficiency (ω OC ) rose by 8.2% to 10.2%, and the smoke concentration increased by approximately 10%. Comprehensive analysis of sample pyrolysis behavior, calculation of kinetic parameters, fitting of reaction models, and examination of combustion residues demonstrated that the activation energy of the first-stage reaction for samples NP1–NP6 varied with the conversion degree (α). This indicates that the addition of nanomaterials transformed the reaction process at this stage from a single-step to a multi-step mechanism, which is consistent with the findings from pyrolysis behavior analysis.The most probable reaction models were predicted using the Coats-Redfern method, revealing that the reaction models corresponding to each stage of samples NP1–NP6 underwent certain changes. Notably, during the first two pyrolysis stages of the samples, the models shifted from the diffusion model (D3) and nucleation model (A4) to the reaction order model (F1/F2). Additionally, this study reproduced the pyrolysis process of the tear gas mixture as it enters the combustion zone through thermodynamic simulation. The reaction processes occurring within these specific temperature ranges provide a critical foundation for further investigating precise temperature control technologies and enhancing the overall combustion efficiency of such mixtures.