无定形PET中小分子扩散系数的分子动力学模拟  

Molecular dynamics simulation of diffusion coefficients of small molecules in amorphous PET

作　　者：王平利[1] 王志伟[1] 胡长鹰[2] 陈默[1,3] 

机构地区：[1]暨南大学包装工程研究所,广东珠海519070 [2]暨南大学食品工程系,广东广州510632 [3]江南大学包装工程系,江苏无锡214122

出　　处：《化工学报》2009年第8期1920-1925,共6页CIESC Journal

基　　金：广东省自然科学基金项目(07005952);北京市重点实验室开放实验室课题基金项目(KF060402);珠海市科技计划项目(PB20051013)~~

摘　　要：采用分子动力学模拟研究了相对分子质量在32～339范围内小分子在无定形PET中的扩散过程。基于Einstein关系式计算了扩散系数,讨论了模拟时间、密度对扩散系数的影响。结果表明:在较高的温度下,较短的模拟时间内就能观察到均方位移曲线的线性区;而在较低的温度下,需更长的模拟时间。扩散系数随密度增加而降低,聚合物密度越大,所需的模拟时间越长。通过比较扩散系数的计算值与实验值,发现两者的比值在一个数量级范围内,表明建立的聚合物模型可接受且能正确描述小分子在无定形PET中的扩散过程,为获得迁移模型中关键参数——扩散系数提供了一种近似的计算方法。Diffusion of molecules with molecular weights ranging from 32 to 339 in amorphous polyethylene terephthalate （PET） was examined by using molecular dynamics simulation. The diffusion coefficients were calculated based on Einstein relation and the influence of simulation time and density on diffusion coefficients was discussed. The results showed that for a higher temperature a shorter simulation time was needed in order that the linear area in mean square displacement （MSD） curves could be observed while for a lower temperature a longer simulation time was needed. Diffusion coefficients decreased with increasing density of the polymer and a higher density required a longer simulation time. Comparison of the calculated diffusion coefficients with experimental values found in the literature indicated thatthe calculated and experimental values were in the same order of magnitude. It suggested that the polymer model was acceptable and could describe correctly the diffusion process of small molecules in PET. This work can provide an approximate method of calculating diffusion coefficient, which is the key parameter in the migration model.

关 键 词：分子动力学模拟 扩散系数 小分子 

分 类 号：TQ021.4[化学工程]