朱 伟a,b 肖继军a 郑 剑c 赵孝彬c 陈中娥c 肖鹤鸣*,a
(a南京理工大学分子与材料计算研究所 南京 210094)
(b嘉兴学院生物与化学工程学院 嘉兴 314001)
(c中国航天科技集团四院四十二所 襄樊 441003)
为了寻求高能复合材料的感度理论判据, 对高氯酸铵(AP)和HMX(环四甲撑四硝胺)所构成的不同质量比的二元混合体系, 用分子动力学(MD)方法和修正的PCFF力场, 作正则系综(NVT)下的周期性模拟计算, 求得其结合能和HMX热解引发键(N—NO2)的平均键长和最大键长. 结果表明, 结合能随质量比不同呈复杂变化趋势; HMX(N—NO2)引发键的最大键长随体系中HMX配比增加先增后减, 而当AP/HMX为1∶1时其值最大, 恰与此配比下感度最大的实验事实相一致. 选择质量比为1∶1的AP/HMX作不同温度下的NVT-MD模拟, 发现引发键(N—NO2)最大键长随温度升高而递增, 与感度随温度升高而增大的实验事实相符. 为此我们建议, 把高能复合材料中易爆燃组分引发键的最大键长作为其热和撞击等感度的理论判据, 借以阐明、比较或预示它们的相对安全性.
XIAO, He-Ming *,a
(b School of Biological and Chemical Engineering, Jiaxing University, Jiaxing 314001)
(c The 42nd Institute of the Fourth Academy of China Aerospace Science and Technology Corporation, Xiangfan 441003)
Molecular dynamics (MD) simulations have been performed to investigate AP (ammonium perchlorate)/HMX (octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine) composites at various concentrations and temperatures in NVT ensemble using the modified PCFF force field. The binding energies and the average and maximum bond lengths of pyrogenation trigger bond N—NO2 in the AP/HMX composites were obtained. It was shown that with the mass ratio of AP/HMX increasing the binding energy changed according to a complex mode, but the maximum bond length of N—NO2 changed according to a parabola mode, which means that the bond length increased first and then decreased, and the peak of the parabola was at the AP/HMX ratio of 1∶1. This agreed well with experimental fact that the sensitivity value was highest at this ratio. The maximum bond lengths of the N—NO2 trigger bonds of 1∶1 AP/HMX system were calculated and found to increase with increasing temperatures, which was consistent with the experimental fact of sensitivity increase with temperature increasing. Thus it was suggested that the maximum trigger bond length of the most sensitive component in energetic composites could be used as a theoretical criterion of thermal or impact sensitivity to judge or predict the relative safety of energetic composites.