知识与财富的链接
针对钝感剂在发射药贮存期间的扩散迁移影响发射药服役寿命的问题,采用分子动力学模拟(MD模拟)比较了小分子邻苯二甲酸二丁酯(DBP)、聚新戊二醇己二酸酯(NA)在发射药体系中的扩散系数,探究了温度和硝化甘油(NG)含量对DBP、NA在双基发射药中扩散的影响,并分析了扩散机理.结果表明:5℃时DBP和NA在NC基体中的扩散能力相当,扩散系数均在10-12 m2·s-1数量级,25℃时DBP与NA的扩散系数分别为1.13×10-11 m2·s-1和5.13×10-12 m2·s-1,65℃时DBP与NA的扩散系数分别为1.88×10-11 m2·s-1和7.57×10-12 m2·s-1,85℃时DBP与NA的扩散系数分别为3.42×10-11 m2·s-1、1.11×10-11 m2·s-1,在相同温度下,钝感剂扩散系数的大小顺序为DBP>NA,这说明NA具有较好的抗迁移特性,该特性在高温时更为凸显;从微观角度分析温度对扩散机理的影响为:高温使原子间氢键作用峰值减小,即DBP、NA与NC的相互作用力减弱,并且体系的自由体积分数也变大,增大了分子运动的有效活动空间,更有利于DBP、NA扩散.DBP、NA的扩散能力随着增塑剂NG含量的增加而增强,添加NG使得DBP、NA与NC的相互作用减弱,因此DBP、NA运动更活跃,扩散能力增强.
As the diffusion and migration of the deterrents affect the service life of gun propellants during the storage period, the molecular dynamics simulation （MD simulation） was applied to compare the diffusion rate of the small molecule dibutyl phthalate （DBP） and polyneopentyl glycol adipate （NA） in gun propellants. Meanwhile, the effect of nitroglycerin （NG） content on the diffusion of DBP and NA in double base gun propellants was explored and the diffusion mechanism was analyzed. The results indicate that the diffusivity of DBP and NA in nitrocellulose （NC） is equivalent at 5 ℃ and the diffusion coefficients are both in the order of 10-12 m2∙s-1. The diffusion coefficients of DBP and NA are 1.88×10-11 m2∙s-1 and 7.57×10-12 m2∙s-1 at 65 ℃, respectively. The diffusion coefficients of DBP and NA are 3.
42×10-11 m2∙s-1 and 1.11×10-11 m2∙s-1 at 85 ℃, respectively. At the same temperature, the order of the diffusion coefficient of the deterrents is DBP>NA, which shows that NA has better anti-migration properties, which are more prominent at high temperatures. Owing to the high temperature, the peak value reduces, thus weakening interaction between DBP, NA and NC, meanwhile, the fractional free volume of system increases, which is conducive to the diffusion of DBP and NA. The diffusion capacity of DBP and NA increases with the increase of NG content. Adding NG weakens the interaction between DBP, NA and NC, so DBP and NA move more actively and the diffusion ability increases. The molecular dynamics simulation method is used to study the diffusion properties of the deterrents in gun propellants, which provides important theoretical guidance for predicting the life of gun propellants.
