共晶和共混对CL-20/DNB感度和热解机理影响的MD模拟

为了从分子水平进一步揭示共晶和共混对六硝基六氮杂异伍兹烷(CL-20)/1,3-二硝基苯(DNB)含能材料的感度、力学性能和热解机理的影响,采用分子动力学(MD)模拟方法在COMPASS力场条件下对CL-20、DNB、两者的共混物及共晶的感度、结合能和力学性能进行了模拟计算。在Reax FF/lg力场条件下对其热解机理进行了研究。结果表明,共晶和共混均会降低体系的感度,但共晶效果更加明显;与共混物结构相比,共晶结构更加稳定,共晶和共混均可以改变复合体系的力学性能,降低体系的刚度,增加体系的柔性和安全性,但共混会使体系的力学性能劣化。共晶分子间强的作用会促进体系中各组分的热解反应,NO_2、N_2、NO、H_2O、HONO、HON以及CO_2等是共晶和共混体系的主要热解产物。与共混相比,共晶是一种更加有效的含能材料改性方法,可为含能材料的配方设计提供理论指导。

Effect of Cocrystallizing and Mixing on Sensitivity and Thermal Decomposition Mechanisms of CL-20/DNB via MD Simulation

To further reveal the effect of cocrystallizing and mixing on the sensitivity, mechanical properties and thermal decomposition mechanism of hexanitrohexaazaowuetzitane(CL-20)/1,3-dinitrobenzene(DNB) energetic material from molecular level, the sensitivity, binding energy and mechanical properties of CL-20, DNB, CL-20/DNB cocrystal and CL-20/DNB mixture were simulated and calculated using molecular dynamics(MD) simulation method under the condition of COMPASS stress force field. Their thermal decomposition mechanisms were studied under the condition of ReaxFF/lg force field. Results show that the cocrystallizing and mixing can reduce the sensitivity of CL-20, increase that of DNB, but the cocrystallizing effect is more obvious. Compared with the mixture structure, the cocrystallizing structure is more stable. Cocrystallizing and mixing can change the mechanical properties of the system, reduce the stiffness, increase the flexibility and safety of CL-20 system, but mixing makes the mechanical properties of the system deteriorate. The strong effect between cocrystal molecules can promote the thermal decomposition of the components in the system. NO₂, N₂, NO, H₂O, HONO, HON and CO₂ are the main products of cocrystallizing and mixed systems. Considering that compared with mixing, co-crystallization is a mor effective modification way for energetic materials. which can provide theoretical guidance for the formulation design of energetic materials.