Pure- and mixed-gas carbon dioxide/ethane permeability and diffusivity in a cross-linked poly(ethylene oxide) copolymer

► CO2 permeability in XLPEO does not change in the presence of ethane at T ≥ 25 °C. ► CO2 permeability in XLPEO increases with increasing ethane content at T ≤ 0 °C. ► The presence of CO2 always increases ethane permeability in XLPEO considerably. ► Diffusivity of both gases increases with increasing concentration of CO2 in XLPEO. ► Permeability data are well correlated with a simplified free volume model.