Analysis of permeation transients of pure gases through dense polymeric membranes measured by a new permeation apparatus

Abstract

A novel permeation apparatus was developed which can make the on-line measurements of both flux transient and permeate composition in gas permeation. The measurement with the permeation apparatus was based on the continuous-flow technique employed in the permeation apparatus which had been built previously for liquid permeation. The transient measurement allowed the simultaneous determination of permeation characteristics, such as, permeability, diffusion and solubility coefficient, and activation energies with one experiment. The apparatus performance was illustrated by conducting the permeation of pure gases through the glassy 2,2-bis(3,4-dicarboxyphenyl) hexafluoropropane dianhydrade (GFDA)-based polyimides and the rubbery poly(dimethylsiloxane) membranes, respectively. A comparison of the permeation characteristics determined from the flux transients was made with the literature values for verifying the validity of the measurement. Also, the analysis of the permeation transients obtained was carried out for the close investigation of the permeation behaviors of gases through membrane. It could be confirmed that the on-line measurement with the new apparatus provides the accurate and quick determination of permeation characteristics and is of a practical value in investigating gas permeation. (C)2000 Elsevier Science B.V. All rights reserved.