A combined ReaxFF simulation and TG-MS study on the thermal decomposition mechanism of 5,5ʹ-dinitramino-3,3ʹ-bi[1,2,4-triazolate] carbohydrazide salt (CBNT)

Thermogravimetry coupled with mass spectrometry (TG-MS) and ReaxFF molecular dynamics (MD) simulations are firstly applied to study the thermal decomposition mechanism of 5,5ʹ-dinitramino-3,3ʹ-bi[1,2,4-triazolate] carbohydrazide salt (CBNT). ReaxFF MD simulations are applied to investigate the primary chemical reactions, decomposition products and decomposition rate, respectively. Experimentally, TG-MS techniques are adopted to identify the final gaseous products decomposed by CBNT. Both TG-MS measured results and ReaxFF MD simulated results show that the final stable gaseous products are mainly NH₃, H₂O, N₂ and CO₂. The main intermediates and chemical reactions during the decomposition process are obtained by ReaxFF MD simulations as well. According to the simulation and experimental results, the most probable thermal decomposition path of CBNT is obtained. The initial decomposition step of CBNT is the dissociation of N−NO₂ and N−NH₃ bonds to generate NO₂ and NH₃, followed by the cleavage of the C−N bonds, and resulting in the formulation of the ring structure. After the main reactions of carbazide cations and bistriazole anions, high-frequency reactions primarily occur between the unstable intermediate products and finally produces small stable molecules such as NH₃, H₂O, N₂ and CO₂.