Zhang Tiantian, Cheng Longjiu, Zhang Jianguo, Wang Kun
Department of Chemistry, Anhui University, Hefei, Anhui 230601, P. R. China.
State Key Laboratory of Explosion Science and Technology, Beijing 100081, P. R. China.
Phys Chem Chem Phys. 2020 Apr 8;22(14):7421-7429. doi: 10.1039/d0cp00050g.
1,3,5-Trinitroperhydro-1,3,5-triazine (RDX) and 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (CL-20) are the classic high energy nitramine compounds. Herein, we performed simulations of the overall decomposition pathways of condensed α-RDX and ε-CL-20 by applying the Car-Parrinello molecular dynamics (CPMD) method. Both of them appear to have similar distinct initial decomposition pathways, which are the bond cleavages of N-NO2 bonds. Interestingly, we find that the continuous explosion is nonspontaneous without the participation of self-produced hydrogen radicals of RDX or oxygen radicals of CL-20. Increased radicals are produced gradually with increasing temperature, which activates further entropy-increased steps, resulting in the uncontrollable transition of deflagration to detonation with the formation of NOx, COx and HCN. Herein, we provide a detailed and systematic description of the decomposition for unit-cell α-RDX and ε-CL-20 under increased temperature, which can be summarized as C3H6O6N6 (RDX) → NO + HNO + H2 + CO2 + HCHO + HNCN + N2O and C6H6O12N12 (CL-20) → NO + HONO + 5HCN + CO2 + N2O + 3NO2.
1,3,5-三硝基全氢-1,3,5-三嗪（RDX）和2,4,6,8,10,12-六硝基-2,4,6,8,10,12-六氮杂异伍兹烷（CL-20）是典型的高能硝胺化合物。在此，我们应用Car-Parrinello分子动力学（CPMD）方法对凝聚态α-RDX和ε-CL-20的整体分解途径进行了模拟。它们似乎都有相似的独特初始分解途径，即N-NO₂键的断裂。有趣的是，我们发现如果没有RDX自身产生的氢自由基或CL-20的氧自由基参与，连续爆炸是不会自发发生的。随着温度升高，自由基逐渐产生，这激活了进一步的熵增加步骤，导致爆燃到爆轰的不可控转变，并形成氮氧化物、碳氧化物和HCN。在此，我们详细且系统地描述了在温度升高情况下晶胞α-RDX和ε-CL-20的分解过程，其可总结为C₃H₆O₆N₆（RDX）→NO + HNO + H₂ + CO₂ + HCHO + HNCN + N₂O以及C₆H₆O₁₂N₁₂（CL-20）→NO + HONO + 5HCN + CO₂ + N₂O + 3NO₂ 。
