Gas transport through integral‐asymmetric membranes: A comparison to isotropic film transport properties

摘要

AbstractPressure‐normalized gas fluxes for defect‐free integral‐asymmetric membranes prepared according to a dry/wet phase inversion process were measured as a function of temperature and pressure and compared to measurements on thick isotropic films. Asymmetric membranes were prepared from polysulfone, polycarbonate, and poly(ester carbonate). The activation energies of permeation for O2and N2in the range of 25–55°C were higher for the asymmetric polysulfone membranes than for a thick isotropic film. O2/N2selectivities of the asymmetric membranes are higher than those for isotropic films. The asymmetric membranes did not show the typical dualmode behavior for the CO2flux as a function of pressure as determined for thick films. Differences in the free volume and its distribution in the ultrathin skin layer of the asymmetric membranes compared to isotropic films may be responsible for these results. © 1993 John Wiley