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Pervaporation of alcohols in PBT near the glass temperature: An analysis of the concentration‐dependent diffusion
Author(s) -
Huber K.,
Nowack J.,
Göritz D.
Publication year - 1998
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/(sici)1097-4628(19980531)68:9<1503::aid-app13>3.0.co;2-#
Subject(s) - pervaporation , diffusion , chemical engineering , materials science , chemistry , polymer chemistry , chromatography , membrane , polymer science , thermodynamics , permeation , biochemistry , physics , engineering
Differential pervaporation measurements with alcohols in poly(butylene terephthalate) (PBT) in the range of its glass transition temperature were performed. The applied apparatus is based on a gas‐chromatographic detection system. The concentration dependency of the diffusion coefficient prevents solving the diffusion equations analytically. Therefore, a method was developed using finite differences in space and time to obtain numerical permeant fluxes under the assumption of certain concentration dependencies D ( c ). The results of this procedure were compared with the measured permeant fluxes, and intrinsic diffusion coefficients D 0 and explicit functions D ( c ) were attained. In addition, the concentration profiles of the liquids in the membrane for all times of the pervaporation process could be displayed. The evaluation of the temperature dependency of D ( c ) shows maxima for the plastification effect of the alcohol molecules at a temperature near T g . © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68: 1503–1515, 1998