Abstract The nitramines 1,3,5,7-tetranitro-1,3,5,7-tetrazoctane (HMX), and 1,3,5-trinitro-1,3,5-triazinane (RDX) are energetic materials commonly used in solid propellants and explosives. In order to predict ignition and deflagration of propellants containing these ingredients, their thermal decomposition behaviors must be thoroughly understood. In this study, the thermal decomposition of HMX was investigated using synergetic application of experimental and computational methods. Mole fraction profiles of the gaseous decomposition products evolving from the liquid-phase HMX were obtained using Fourier transform infrared (FTIR) spectroscopy for two types of thermolysis experiments – thermogravimetric analysis (TGA) and confined rapid thermolysis (CRT). Four heating rates (5, 10, 15, and 20 K/min) in TGA experiments and four set temperatures (290, 300, 310 and 320 °C) in CRT experiments were considered. In the TGA and differential scanning calorimetry (DSC) results, steep mass loss and rapid decomposition were observed after the melting of the HMX at 280 °C. CH2O and N2O were identified as the major decomposition products. Smaller quantities of H2O, HCN, NO and NO2, CO and CO2 were also formed. In the complementary computational study, liquid-phase elementary reactions were investigated using quantum mechanics calculations at B3LYP/6-311++G(d,p) level of theory with the conductor-like polarizable continuum model (CPCM). A zero-dimensional model was developed to simulate the TGA and CRT experiments based on conservation of mass and species in the condensed-phase and the gas-phase control volumes. The predicted mass loss and gas-phase mole fraction profiles of the decomposition products are in good agreements with the corresponding experimental results, indicating that the comprehensive mechanism proposed here captures the important reactions occurring during liquid-phase decomposition of HMX.

中文翻译：

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1,3,5,7-四硝基-1,3,5,7-四氮辛烷 (HMX) 液相分解的综合机制：热解实验和详细的动力学模型

摘要 硝胺 1,3,5,7-四硝基-1,3,5,7-四氮辛烷 (HMX) 和 1,3,5-三硝基-1,3,5-三嗪烷 (RDX) 是常用的含能材料。在固体推进剂和炸药中。为了预测含有这些成分的推进剂的点火和爆燃，必须彻底了解它们的热分解行为。在这项研究中，使用实验和计算方法的协同应用研究了 HMX 的热分解。使用傅里叶变换红外 (FTIR) 光谱仪进行两种类型的热解实验——热重分析 (TGA) 和受限快速热解 (CRT)，获得了从液相 HMX 演化出的气态分解产物的摩尔分数分布。TGA 实验中的四种加热速率（5、10、15 和 20 K/min）和四种设定温度（290、300、310 和 320 °C) 在 CRT 实验中被考虑。在 TGA 和差示扫描量热法 (DSC) 结果中，HMX 在 280 °C 熔化后观察到急剧的质量损失和快速分解。CH2O 和 N2O 被确定为主要的分解产物。还形成了少量的 H2O、HCN、NO 和 NO2、CO 和 CO2。在补充计算研究中，使用类导体极化连续介质模型 (CPCM) 在 B3LYP/6-311++G(d,p) 理论水平上使用量子力学计算研究液相基本反应。基于凝聚相和气相控制体积中的质量和物种守恒，开发了一个零维模型来模拟 TGA 和 CRT 实验。