高聚物扩散体系中的“超调”现象

“OVERSHOOT”PHENOMENON IN POLYMER DIFFUSIVE SYSTEM

利用在EIT理论基础上的Jou模型研究了高聚物扩散体系中的“超调”现象 .经过对Jou模型的简化处理 ,得到了双曲型的扩散动力学方程 ,通过对模型中 3个组合参数的仿真分析 ,研究了参数的变化可能导致的不同的扩散行为 .结果表明 ,Jou模型成功描述了长时间吸附中发现的“超调”现象 ,从理论上说明了引起“超调”现象的原因 :扩散的瞬态过程引起的滞后是导致“超调”扩散行为的必要条件 ,而在扩散滞后存在的情况下 ,松弛时间大于扩散时间是引起“超调”的充分条件 .

Non-Fickian diffusion is one of the important phenomena often observed in chemical processes) especially in polymer-related diffusion, and of which overshoot is interesting. The Jou model based on the EIT theory was used to study overshoot behavior observed in polymer diffusive system. After simplification of the Jou model, a diffusion dynamic equation, which was characterized with hyperbolic type, was obtained, then simulative analysis for three combined dimensionless parameters was done to research various diffusion behavior resulted from the change of model parameters. Results indicate that, the equation can describe overshoot phenomenon, so that the cause of overshoot can be interpreted theoretically/mathematically. The existence of the intrinsic relaxation time for diffusion is a necessary requirement, and with appropriate existence of diffusive retardance, that diffusion time greater than relaxation time is a sufficient requirement for overshoot behavior.