Coupling effect on the thermal hazard assessment of hazardous chemical materials via calorimetric technologies and simulation approaches

The coupling effect of heat absorption and release exists in the thermal decomposition of a few chemical materials. However, the impact of the above coupling on thermal hazard assessment is not considered in the literature studies. In this work, nitroguanidine (NQ) and 1,3,5-trinitro-1,3,5-triazine (RDX) are selected as representative materials to explore the influence of the coupling effect on the thermal hazard assessment of chemical materials. The linear heating experiments of NQ and RDX are carried out by a microcalorimeter and synchronous thermal analyser. The thermal decomposition curves are decoupled by advanced thermokinetics software. The thermal decomposition and kinetic parameters before and after decoupling are calculated. The results of TG experiment show that both NQ and RDX began to lose mass during the endothermic stage. The endothermic melting and exothermic decomposition of NQ and RDX are coupled within this stage. The coupling effect has different degrees of influence on its initial decomposition temperature and safety parameters. Compared with the parameters in the coupling state, the initial decomposition temperature and adiabatic induction period after decoupling decrease. The self-accelerating decomposition temperature increases, and internal thermal runaway time decreases. In the thermal hazard assessment of chemical materials with coupling effects, the calculated parameters after decoupling should be taken as an important safety index.