氧气在 PVDF 片材中扩散的分子动力学模拟

Molecular Dynamic Simulation for Diffuse Characterization of Oxygen in PVDF Sheet

中文关键词: PVDF 片材  扩散  分子动力学模拟

英文关键词: poly vinylidene fluoride sheet  diffuse  molecular dynamic simulation

中文摘要:

      目的 研究气体在 PVDF 片材中的扩散。 方法 采用分子动力学模拟方法研究了氧气在其片材中的扩散行为,得到氧气在 PVDF 片材中的扩散系数,并讨论了时间、聚合度、温度及残余压力对扩散系数的影响。 结果 模拟时间太短对模拟结果不利,应以大于 1000 fs 为宜。 当聚合度由 400 增加到 800 时,扩散系数由 4 . 77 X10^-6cm²/ s 下降到 1 . 78 X10^-6cm²/ s;当温度从 298 K 提高到 303 K 时,扩散系数由 1 . 06 X10^-6cm²/ s 增加到 1 . 42 X10^-6cm²/ s;当残余压力由 60 kPa 增大到 100 kPa 时,扩散系数由 7 . 07 X10^-6cm²/ s 下降到 3 . 06 X10^-6cm²/ s。 结论 氧气在 PVDF 片层中的扩散系数随聚合度和残余压力的增大而变小,随温度的提高而变大。

英文摘要:

      Objective To study the diffusion behavior of gas in poly( vinylidene fluoride) ( PVDF) sheet material. Methods The diffusion behavior of oxygen in this sheet material was studied by molecular dynamics simulation method and the diffusion coefficient of oxygen in PVDF sheets was obtained, meanwhile, the effects of time, polymerization degree, temperature and residual pressure on the diffusion coefficient were also discussed. Results Short period of simulation time was unfavorable for the simulation results, and it should be more than 1000 fs. When the degree of polymerization increased from 400 to 800, the diffusion coefficient of oxygen in PVDF declined correspondingly from 4. 77 X10^-6( cm²·s^-1) to 1. 78 X10^-6( cm²·s^-1); when the temperature was elevated from 198 K to 303 K, the diffusion coefficient increased from 1. 06 X 10^-6( cm²·s^-1)to 1. 42X10^-6( cm²·s^-1)and when the residual pressure varied from 60 kPa to 100 kPa, the diffusion coefficient declined from 7. 07 X10^-6( cm²·s^-1)to 3. 06 X10^-6( cm²·s^-1). Conclusion The diffusion coefficient of oxygen in PVDF declined with the increase of polymerization degree and residual pressure, while increased with the increase of temperature.