Wang Chaoyu, Zhang Chaoyang, Xue Xianggui
Institute of Chemical Materials, China Academy of Engineering Physics (CAEP), P.O. Box 919-311, Mianyang, Sichuan 621999, China.
Department of Materials Science and the Advanced Coatings Research Center of the China Educational Ministry, Fudan University, Shanghai, 200433, China.
J Phys Chem A. 2022 Feb 3;126(4):463-472. doi: 10.1021/acs.jpca.1c08171. Epub 2022 Jan 21.
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 (α- and ε-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 α- and ε-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 NO 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.
1,3,5-三硝基-1,3,5-三嗪（RDX）是一种重要的含能材料，被广泛用作各种固体推进剂和炸药。了解RDX各种多晶型物在高压和高温下的热分解行为对于安全储存和处理至关重要。本工作通过ReaxFF反应分子动力学模拟和爬山图像推挤弹性带（CI-NEB）静态计算揭示了RDX的两种多晶型物（α-和ε-型）在高压和高温下的早期热分解机理。研究发现，热分解速率对α-RDX和ε-RDX的压力分别有正向和负向影响。这种差异源于压力对两种多晶型物分子间氢转移的影响不同，因为我们证实双分子氢转移而非NO分解引发了分解，其中能垒显著更低。这一发现可能有助于理解压力和多晶型对RDX分解的依赖性影响，并建立固体RDX燃烧的动力学模型。
