Synthetic and thermal studies of four insensitive energetic materials based on oxidation of the melamine structure

Oxidation of nitrogen-rich aromatic heterocycles has a significant impact on the development of energetic materials. 2,4,6-Triamino-1,3,5-triazine-1,3-dioxide (MDO) is a promising insensitive energetic backbone obtained from melamine under strong oxidation conditions with impressive thermal behaviors and detonation performances. In this paper, MDO was prepared with improved yields of 85% and its thermal behavior, non-isothermal decomposition kinetics and gas products were investigated in detail. The corresponding decomposition mechanism was also deduced by applying the TG-DSC-FTIR-MS technique for the first time. The decomposition temperature of MDO reaches 300 °C and the apparent activation energy of MDO (E) calculated by the Kissinger and Ozawa method proved to be 303.63 and 279.95 kJ mol⁻¹, indicating great thermal stability. Three new monoanionic energetic salts with impressively improved properties were achieved based on the basicity of MDO with yields of >80%. Their thermal decomposition temperatures proved to be higher than 230 °C and their densities are in the range of 1.75-1.89 g cm⁻³. The calculations and experiments show that their detonation velocities (v_D: 8711-9085 m s⁻¹) are comparable to or exceed those of RDX (D: 8795 m s⁻¹) while the sensitivities to impact (IS: 23-27 J) and friction (FS: >240 J) are much lower.