Analysis of the kinetics of vapor absorption/desorption in/from silicone rubber and cellulose acetate membranes in the presence of stagnant boundary layers
| Autor: | Matthias Wessling, H. Strathmann, J. H. Petropoulos, Dimitrios Stamatialis, Merope Sanopoulou |
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| Přispěvatelé: | Membrane Science & Technology, Faculty of Science and Technology |
| Rok vydání: | 1997 |
| Předmět: |
chemistry.chemical_classification
IR-11469 Analytical chemistry Filtration and Separation Sorption Polymer Silicone rubber Biochemistry Chloride Cellulose acetate Fick's laws of diffusion chemistry.chemical_compound Penetrant (mechanical electrical or structural) chemistry Desorption Polymer chemistry medicine General Materials Science Physical and Theoretical Chemistry METIS-106178 medicine.drug |
| Zdroj: | Journal of membrane science, 1997(1), 165-175. Elsevier |
| ISSN: | 0376-7388 |
| DOI: | 10.1016/s0376-7388(96)00265-7 |
| Popis: | The application of an interferometric technique (optical thickness meter, OTM) to the measurement of vapor sorption kinetics in both rubbery and glassy polymers is presented. In this technique, the membrane is formed by casting on a suitable glass surface and interferometry is applied in situ. The use of a carrier gas loaded with penetrant vapor introduced a stagnant boundary layer (SBL) effect which had to be corrected, in order to determine true sorption kinetics. The said SBL effect was estimated, on the basis of existing theory for the silicone rubber?methylene chloride (SR/MC) system and found to be more pronounced in the case of desorption. Upon correction for this effect, Fickian sorption curves were obtained; which yielded nearly constant values of the diffusion coefficient, not materially different for absorption and desorption, in line with theoretical expectation. Cellulose acetate?methylene chloride (CA/MC) was then studied as an example of a glassy polymer?vapor system, where the SBL effect distorts the absorption kinetic curve in the same way as the non-Fickian mechanism of sorption inherent in this kind of polymer?penetrant system. Here, the vapor sorption data were corrected using the results obtained from the Fickian SR/MC system. The corrected results were checked by comparison with independent data reflecting the true kinetic behavior of CA/MC, obtained with a vacuum balance apparatus (VBA), which is free of SBL effects. It is shown that this novel method of applying the SBL correction was reasonably successful in favorable circumstances, while a criterion is provided to identify cases where reasonably reliable correction is not possible |
| Databáze: | OpenAIRE |
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