2005/10/4 · The latter was used to prepare Nafion solutions with specified solvents. A porous polytetrafluoroethylene membrane (PTFE membrane, Yue-Ming-Tai Chemical Ind. Co., Taichung, Taiwan) with a thickness of 18 ± 3 μm, pore sizes of 0.5 ± 0.1 μm, and a porosity of