RDX及其衍生物高温热解的反应分子动力学模拟

发布时间：2018-11-18 19:07

【摘要】：本文采用ReaxFF反应分子动力学方法,研究了RDX及其衍生物晶体在高温条件下(2000、2500和3000 K)的热分解机理以及主要产物随时间的变化情况。结果表明:RDX及其衍生物晶体热解的第一步反应均为N NO_2键断裂生成NO_2分子,随后反应由于六元环上和侧链基团的不同导致侧链脱除或开环反应的顺序不同。在这四种单胞体系热解中,NO_2和NO分子为共同的中间产物,形成之后迅速发生次级反应并最终生成N_2。各体系热解终产物一致,均为N_2、H_2O和CO_2,其中N_2分子数最多,大于20个。由于原始分子结构和组成中C/N比、H/O比的不同,各体系热解后H_2O和CO_2分子数目相差较大。不同温度下,各单胞体系热分解生成的最大含碳团簇中C原子数均较小。在进一步超胞体系的模拟中,RDX和RDX-D2体系生成的含碳团簇中C原子数分别达到约30和16个,远高于单胞模拟,且受温度影响较大;而RDX-D1和RDX-D3单胞或超胞模拟结果相近,均未生成含碳团簇,仅存在小分子含碳碎片。因此,初始分子的结构和元素比对含碳团簇的生成有明显影响。
[Abstract]:In this paper, the mechanism of thermal decomposition of RDX and its derivative crystals at high temperature (2000.2500K and 3000 K) and the changes of main products with time have been studied by means of molecular dynamics method of ReaxFF reaction. The results show that the first step of pyrolysis of RDX and its derivatives is the breaking of N NO_2 bond to form NO_2 molecule, and then the order of side chain removal or ring opening reaction is different due to the difference of six member ring and side chain group. In the pyrolysis of these four cell systems, the NO_2 and NO molecules are the common intermediate products, and the secondary reactions occur rapidly after the formation of the molecules, and finally N2s are formed. The end products of pyrolysis of each system are the same, which are N _ 2H _ 2O and CO_2, among which the number of N _ (2) molecules is the most, which is more than 20. Due to the difference of C / N ratio and H / O ratio in the original molecular structure and composition, the number of H _ 2O and CO_2 molecules after pyrolysis of each system is quite different. At different temperatures, the maximum number of C atoms in the carbon-containing clusters generated by thermal decomposition of each unit cell system is smaller. In the further simulation of the supercellular system, the number of C atoms in the carbon-containing clusters generated by RDX and RDX-D2 systems is about 30 and 16 respectively, which is much higher than that of the single cell simulation, and is greatly affected by temperature. However, the simulation results of RDX-D1 and RDX-D3 were similar, and no carbon-bearing clusters were formed, only small molecular carbon fragments were found. Therefore, the structure and element ratio of the initial molecule have a significant effect on the formation of carbon-bearing clusters.
【作者单位】：四川大学空天科学与工程学院;四川大学化学学院;四川大学化学工程学院;
【基金】：国家自然科学基金(91441132) 教育部新世纪优秀人才支持计划(NCET-13-0398)资助项目~~
【分类号】：O643.1

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