Combined kinetic analysis of overlapping multistep thermal decomposition of 5-nitro-2,4,6-triaminopyrimidine -1,3-di-N-oxide (ICM-102)

Abstract

In this work, we studied the thermal decomposition of a promising novel energetic compounds, 5-nitro-2,4,6-triaminopyrimidine -1,3-di-N-oxide (ICM-102), in an inert atmosphere. This energetic compound with a high measured density, high thermal decomposition temperature, high detonation velocity, and extremely low mechanical sensitivities has the widely application prospect in military and civilian fields. Therefore, a reliable description of the thermal decomposition kinetics is important to prevent or control the decomposition in such applications. While previous kinetic studies published on this system use simplified methods that avoid the fact that the entire process cannot be described by a single kinetic doublet. Here, we have studied the decomposition process by first separating the overall reaction into its two constituent steps which were subsequently analysed independently. The deconvolution was carried out using Fraser-Suzuki function that is capable of fitting an asymmetric peak fitting function. The resulting kinetic models and parameters proved to be able to reconstruct the original experimental curves but are also capable of producing accurate predictions of curves recorded at heating schedule different from those employed to record the experimental data used in the kinetic analysis. Finally, we have simulated three types of major decomposition reactions of ICM-102: the hydrogen transfer reactions and the C-NO2 homolysis theoretically. The direct C-NO2 homolysis prevails with the activation barrier at 188.8 kJ mol−1. The hydrogen transfer intramolecular or intermolecular with the activation barriers at 187.3 and 190.9 kJ mol−1, respectively. The reduced activation barriers than experimental results are due to that the simulation is carried out in monomolecular or bimolecular reaction systems.