银团簇在聚乙烯表面及内部的扩散分子动力学模拟研究

目的通过分子动力学模拟方法对聚乙烯(polyethylene,PE)中银团簇的扩散行为进行研究。方法采用分子动力学模拟方法研究银团簇在PE膜中的扩散行为,并分析了不同温度下银团簇的密度、自由体积、运动轨迹、均方位移以及扩散系数。结果通过运动轨迹分析发现,银团簇在343 K下在PE中移动范围较在293 K、313 K下大;由均方位移曲线计算不同温度下银团簇在PE中的扩散系数:D_(293K,Ag)=6.78×10~(-9)cm~2·s~(-1),D_(313 K,Ag)=4.38×10~(-9) cm~2·s-1,D_(343 K,Ag)=2.02×10~(-8) cm~2·s~(-1)。在PE和水接触界面上,银团簇的扩散系数为7.71×10~(-5) cm~2·s~(-1),比银团簇在PE内部的扩散系数大很多。结论在迁移过程中,银的迁出可能主要是材料表面银的溶出。

Molecular dynamics simulation for diffusion behavior of silver nanocluster in polyethylene and on the surface of polyethylene

Objective To study the diffusion behavior of silver nanocluster in polyethylene (PE) by molecular dynamics simulation method. Methods The diffusion behavior of silver nanocluster in PE was studied by molecular dynamics simulation method, and the density, free volume, trajectory, mean square displacement (MSD) and diffusion constant of PE/silver cluster under different temperatures were discussed. Results The figures of trajectory showed that the moving range at 343 K was larger than that at 293 K and 313 K. The diffusion constant of silver nanocluster in PE at different temperatures were as follows: D293 K,Ag=6.78×10-9 cm2?s-1, D313 K,Ag=4.38×10-9 cm2?s-1, D343 K,Ag=2.02×10-8 cm2?s-1. The diffusion constant of silver nanocluster on the interface between PE and distilled water was 7.71×10-5 cm2?s-1, which was larger than the diffusion constant of silver nanocluster in PE. Conclusion It can be inferred that the migration of silver from package into food stimulants mostly come from the surface of PE.