聚氨酯弹性体中NG和BTTN迁移的介观模拟

为在介观尺度下研究聚氨酯弹性体中的硝酸酯增塑剂硝化甘油(NG)和1,2,4-丁三醇三硝酸酯(BTTN)的迁移扩散现象,运用分子模拟软件Materials Studio进行了耗散粒子动力学DPD模拟计算。搭建了粗粒化的介观模型,用此模型计算了NG和BTTN在聚氨酯弹性体中的扩散系数。计算得到NG的介观扩散系数为1.80×10-12m2·s-1,BTTN的扩散系数为0.21×10-12m2·s-1,与文献报道NG的微观扩散系数0.65×10-12~11.10×10-12m2·s-1处于同一数量级上。预聚物分子量提高、温度升高后扩散系数增大,但硝酸酯含量提高后扩散系数降低,同等条件下NG的扩散系数大于BTTN。介观分子模拟计算结果与文献报道值和理论趋势较为符合,说明搭建的硝酸酯/聚氨酯粗粒化模型可以用于考察NG和BTTN在聚氨酯中扩散的情况。

Mesoscopic Molecular Simulation of Migration of NG and BTTN in Polyurethane

To study the migration and diffusion phenomena of nitrates nitroglycerine(NG) and 1, 2, 4-butanetriol trinitrate (BTTN) as plasticizers in polyurethane elastomer under mesoscopic scale, the dissipative particle dynamics(DPD)simulation calculation was performed by molecular simulation software Materials Studio. A mesoscopic model of coarse graining was established. The diffusion coefficient of NG and BTTN in polyurethane elastomer was calculated by this model. Mesoscopic diffusion coefficient obtained by calculation is 1.80×10^-12 m²·s^-1 for NG, 0.21×10^-12 m²·s^-1 for BTTN, which is at the same level with microscopic results reported in literature, i.e. 0.65×10^-12-11.10×10^-12 m²·s^-1 for NG. After rising of molecular weight of prepolymer and temperature, the diffusion coefficients of nitrates increase. But the diffusion coefficient decreases with increasing the nitrate content. The diffusion coefficient of NG is bigger than that of BTTN under same conditions. The mesoscopic molecular simulation results agree with the reported values in literature and theoretical trend, indicating that the established coarse graining model of nitrate/ polyurethane can be used to investigate the diffusion case of the two nitrates in polyurethane.