端羟基聚丁二烯/增塑剂共混物相容性的分子动力学模拟

固体推进剂和炸药的力学性能在很大程度上依赖于配方中高分子粘结剂与增塑剂的相容性. 本文对相容和非相容两种体系进行了分子动力学(MD)模拟, 以考察分子模拟方法的实用性. 为预测固体推进剂中端羟基聚丁二烯(HTPB)与增塑剂癸二酸二辛酯(DOS)、硝化甘油(NG)的相容性, 采用MD模拟方法在COMPASS力场下, 对HTPB、DOS、NG和共混物HTPB/DOS、HTPB/NG的密度、内聚能密度及溶度参数等进行了模拟计算. 通过比较溶度参数差值(△δ)的大小、分子间径向分布函数和模拟前后体系密度变化情况均可以预测HTPB/DOS属于相容体系,而HTPB/NG属于不相容体系, 与实验结果一致. 径向分布函数分析同时揭示了HTPB/增塑剂组分之间的相互作用及本质. 本文的模拟方法可以作为预测聚合物与增塑剂相容性的有利工具, 也可以为固体推进剂和炸药的配方设计提供理论指导.

Molecular Dynamics Simulation on Compatibility of Hydroxyl-Terminated Polybutadiene/Plasticizer Blends

It has been found that the mechanical properties of solid propellants and plastic bonded explosives (PBX) depend heavily on the compatibility of the polymer binder and plasticizer used in their formulation. Two systems, one miscible and the other immiscible, were simulated by molecular dynamics (MD) simulations to test the usefulness of this molecular simulation technique. Density, cohesive energy density, and solubility parameters of hydroxyl-terminated polybutadiene (HTPB), dioctyl sebacate(DOS), nitroglycerine (NG), HTPB/DOS blend and HTPB/NG blend were calculated by MD simulations with the COMPASS force field for the prediction of polymer binder and plasticizer compatibility. Results show that HTPB/DOS is a miscible system but HTPB/NG is not miscible by comparing the difference in the solubility parameter value (△δ), pair correlation function and the change of density. The predictions agreed well with experimental observations. By calculating the pair correlation function the HTPB/plasticizer interaction was clarified. Therefore, the method used in this work is a useful tool to provide information on miscibility and other properties of a given polymer/plasticizer blend. In addition, it is a promising technique to help to design formulations for screening solid propellants and PBX before experimental tests.