Potreck Jens, Uyar Fuat, Sijbesma Hylke, Nijmeijer Kitty, Stamatialis Dimitris, Wessling Matthias
Membrane Technology Group, University of Twente, Institute of Mechanics, Processes and Control Twente, P.O. Box 217, 7500 AE, Enschede, The Netherlands.
Phys Chem Chem Phys. 2009 Jan 14;11(2):298-308. doi: 10.1039/b810638j. Epub 2008 Nov 26.
This paper presents an analysis of the sorption kinetics of water vapor and liquid water in the glassy polymer sulfonated poly(ether ether ketone) (S-PEEK). Sorption isotherms are determined experimentally using a gravimetric sorption balance, and the relative contributions of Fickian diffusion and relaxational phenomena are quantified as a function of the water concentration in the polymer using the model of Hopfenberg and Berens.Analysis of the sorption isotherms and determination of the sorption kinetics prove the occurrence of both Fickian sorption behavior and relaxational phenomena already at very low water concentrations in the polymer. With increasing water concentration, the relative importance of relaxation phenomena increases, whereas the relative contribution of Fickian diffusion decreases.Based on the water vapor sorption kinetics only, the Fickian diffusion coefficient increases over two orders of magnitude with increasing water vapor concentration. Taking also the diffusion kinetics from liquid water sorption experiments into account reveals a change of even three orders of magnitude of the Fickian diffusion coefficient when the water concentration in the polymer increases.
本文对玻璃态聚合物磺化聚醚醚酮（S-PEEK）中水蒸气和液态水的吸附动力学进行了分析。使用重量吸附天平通过实验测定吸附等温线，并根据霍普芬伯格（Hopfenberg）和贝伦斯（Berens）模型，将菲克扩散和松弛现象的相对贡献量化为聚合物中水浓度的函数。对吸附等温线的分析以及吸附动力学的测定证明，在聚合物中极低的水浓度下就已经同时出现了菲克吸附行为和松弛现象。随着水浓度的增加，松弛现象的相对重要性增加，而菲克扩散的相对贡献减小。仅基于水蒸气吸附动力学，随着水蒸气浓度的增加，菲克扩散系数增加超过两个数量级。同时考虑液态水吸附实验的扩散动力学表明，当聚合物中的水浓度增加时，菲克扩散系数甚至会发生三个数量级的变化。
