Pressure and Polymorph Dependent Thermal Decomposition Mechanism of Molecular Materials: A Case of 1,3,5,-Trinitro-1,3,5,-triazine
Pressure and Polymorph Dependent Thermal Decomposition Mechanism of Molecular Materials: A Case of 1,3,5,-Trinitro-1,3,5,-triazine
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DOI：
10.1021/acs.jpca.1c08171
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发表时间：
2022-01-21
影响因子：
2.9
通讯作者：
Xue, Xianggui
中科院分区：
文献类型：
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作者：
Wang, Chaoyu;Zhang, Chaoyang;Xue, Xianggui
1，3，5-三硝基-1，3，5-三嗪（RDX）是一种重要的含能材料，广泛用作各种固体推进剂和炸药。了解不同晶型RDX在高温高压下的热分解行为对安全储存和处理具有重要意义。通过ReaxFF反应分子动力学模拟和CI-NEB静态计算，揭示了RDX两种晶型（α-和e-晶型）在高温高压下的早期热衰变机理。结果表明，α-RDX和e-RDX的热分解速率分别对压力有正、负影响。这种差异源于两种多晶型物的分子间H转移上的压力效应的差异，因为我们确认双分子H转移而不是NO2分区以显着较低的能垒启动衰变。这一发现有助于理解压力和晶型对RDX衰变的影响，并有助于建立固体RDX燃烧的动力学模型。
1,3,5,-Trinitro-1,3,5,-triazine (RDX) serves as an important energetic material and is widely used as various solid propellants and explosives. Understanding the thermal decomposition behaviors of various polymorphs of RDX at high pressure and high temperature is significantly important for safe storage and handling. The present work reveals the early thermal decay mechanisms of two polymorphs (alpha- and e-forms) of RDX at high pressure and high temperature by ReaxFF reactive molecular dynamic simulations and climbing image nudged elastic band (CI-NEB) static calculations. It is found that the thermal decomposition rate has positive and negative effects on the pressure for alpha- and e-RDX, respectively. This difference originates from the difference of pressure effect on the intermolecular H transfer of the two polymorphs, as we confirm that the bimolecular H transfer rather than the NO2 partition initiates the decay with a significantly lower energy barrier therein. This finding may be beneficial to understand the pressure and polymorph dependent effect on the decay of RDX and to develop a kinetic model for the combustion of solid RDX.