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

A novel permeation apparatus was developed which can make the on-line measu rements of both flux transient and permeate composition in gas permeation. The measurement with the permeation apparatus was based on the continuous-f low technique employed in the permeation apparatus which had been built pre viously for liquid permeation. The transient measurement allowed the simult aneous determination of permeation characteristics, such as, permeability, diffusion and solubility coefficient, and activation energies with one expe riment. The apparatus performance was illustrated by conducting the permeat ion of pure gases through the glassy 2,2-bis(3,4-dicarboxyphenyl) hexafluor opropane dianhydrade (GFDA)-based polyimides and the rubbery poly(dimethyls iloxane) membranes, respectively. A comparison of the permeation characteri stics determined from the flux transients was made with the literature valu es 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 confirm ed that the on-line measurement with the new apparatus provides the accurat e and quick determination of permeation characteristics and is of a practic al value in investigating gas permeation. (C)2000 Elsevier Science B.V. All rights reserved.