TIME-DEPENDENT PERMEATION OF CARBON-DIOXIDE THROUGH A POLYIMIDE MEMBRANE ABOVE THE PLASTICIZATION PRESSURE

The Lime-dependent permeation behavior of a glassy polyimide is studie d above and below the plasticization pressure with carbon dioxide as t he permeating gas. The work particularly focuses on the quantification of the slow increase in permeability at feed pressures above the plas ticization pressure. Significant differences in permeation behavior we re found for membranes with and without permeation history. Introducin g the quantity ''conditioning time'' allows one to compare the results obtained for membranes with different permeation history. The concept of conditioning time furthermore allows one to quantify the aging of a membrane plasticized during previous permeation. (C) 1995 John Wiley & Sons, Inc.