Comprehensive study on thermal decomposition mechanism and interaction of 3-Nitro-1,2,4-Triazol-5-One/Poly-3-nitromethyl-3-methylox- etane plastic bonded explosives

XF Yuan and QJ Guo and SH Zhang and RJ Gou and Y Huang, JOURNAL OF ANALYTICAL AND APPLIED PYROLYSIS, 168, 105753 (2022).

DOI: 10.1016/j.jaap.2022.105753

In this paper, the thermal decomposition process of 3-Nitro-1,2,4-Triazol-5-One (NTO)/Poly-3-nitromethyl-3-methyloxetane (Poly-NIMMO) based Plastic Bonded Explosives (PBXs) at five temperatures from 2500 K to 3500 K was simulated based on the reactive molecular dynamics, and some related analysis contents were supple-mented and verified by first-principles and quantum chemistry methods. In particular, given the strong acidity of NTO explosive, the interaction between NTO and Poly-NIMMO was analyzed. The analysis results of the atoms in molecules (AIM) method and Independent gradient model based on Hirshfeld partition (IGMH) method show that there are some relatively strong hydrogen bonds between them. The activation energies of the initial decomposition stage and the intermediate decomposition stage of the mixed system are 60.37 kJ center dot mol-1 and 98.37 kJ center dot mol-1. Compared with the pure NTO system, the activation energies of the two stages decrease to a different extent. Poly-NIMMO in the mixed system brings a lot of NO2 and OH groups, these molecular fragments and groups will have chemical reactions with NTO and decomposition products of NTO, resulting in the reduction of the number of hydrogen transfer reactions between NTO molecules. By comparing the quantity of products, it can be found that the content of H2O is greatly increased. The curve reaches the peak in a shorter time, and the decomposition reaction rate of the system is faster. The amount of CO2 did not increase too much, and more C atoms gathered to form clusters. The changes of the number of bonds verify the above analysis. In addition, in a certain temperature range, the relationship between the maximum number of clusters and tem- perature is positively correlated, but the excessive temperature can inhibit the maximum number of clusters. The ratio of O, N, H atoms to C atoms in the cluster after equilibrium at five temperatures is H/C > N/C > O/C. There is no doubt that Poly-NIMMO will reduce the acidity of the system, but it will promote the thermal decompo-sition of NTO and reduce the insensitivity of PBXs to thermal stimulation.

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