Permeation behavior for mixed gases in poly (4-methyl-1-pentene) membrane near the glass transition temperature

Abstract

Permeabilities to CO 2 in an equimolar mixture of CO 2 and air for a homogeneous poly (4-methyl-1-pentene) membrane were measured at various upstream gas pressures. The permeability to CO 2 for the mixed gas was smaller than that for pure CO 2 at the same CO 2 upstream pressure. The permeability to O 2 for the mixed gas increased with increasing upstream gas pressure, although for pure O 2 the permeability was independent of pressure. Such experimental evidence is consistent with the free-volume model prediction. The increase in permeabilities for the coexisting O 2 might result from the membrane plasticization action of sorbed CO 2. The depression of CO 2 permeability in the gas mixture case might be ascribed to the hydrostatic pressure effect applied to the system, as suggested by the free-volume model.