Permeabilities of methanol, ethanol and dimethyl ether in new composite membranes: A comparison with Nafion membranes

New composite membranes were prepared by solution casting from sulfonated poly(ether ether ketone), poly(vinylidene fluoride) and phosphotungstic acid. Their structures were characterized using XRD, DSC and FT-IR. The permeability of methanol, ethanol and dimethyl ether in composite membranes ranged from 1.9 to 3.7 × 10−7, 7.4 to 20 × 10−8 and 1.6 to 3.2 × 10−8 cm2/s, respectively. These values were about or more than one order of magnitude lower than those of Nafion® 117 membrane measured under the same condition. The water uptake and the swelling ratio of composite membranes were also studied, and composite membranes showed good water stability within measurement range of temperature. Higher selectivity values were observed for composite membranes compared with Nafion® 117 membrane.