改进的Vrentas-Duda扩散模型及其应用 (Ⅰ)预测弱极性分子在聚合物膜中的扩散系数

A modified Vrentas-Duda diffusion model and its applications (Ⅰ) Prediction of the diffusion coefficient of weak-polar diffusants in polymer membrane

在膜分离过程中,渗透物分子在聚合物膜内的扩散过程,是影响聚合物膜分离性能的关键因素.详细考察了目前被广泛使用的Vrentas-Duda扩散模型,对其进行改进,提出了新的计算ζ的公式.根据新提出的公式,对聚苯乙烯/甲苯(PS/toluene)、聚苯乙烯/乙苯(PS/ethylbenzene)、聚乙酸乙烯酯/甲苯(PVAc/toluene)3种体系中弱极性渗透物分子的扩散系数进行了预测,其较之原Vrentas-Duda扩散模型、Ju改进的Vrentas-Duda扩散模型有更好的预测结果.

The diffusion of diffusants within the membranes greatly affects the membrane separation performance.A widely used diffusion model,VrentasDuda model,is investigated,and a new ζ expression is proposed in this work.The diffusion coefficients of weak-polar permeation molecule in polymers for PS-toluene,PS-ethylbenzene,PVAc-toluene systems with different temperatures are predicted by the new ζ expression.Compared the calculation results of diffusion coefficients with original Vrentas-Duda model and with Ju's modified Vrentas-Duda model,the model modified in this paper can offer more precise prediction not only for the rigid but also for the soft diffusion molecule.