Free Volume and Ozygen Permeability in Polymers Related to Polymer Electrolyte Fuel Cells
The mechanism of gas permeation in sulfonated polymers such as Nafion and sulfonated polyethersulfone (SPES) for polymer electrolyte fuel cells has been investigated from the viewpoint of free volume. Free volume was quantified using the positron annihilation lifetime (PAL) technique and O2 permeability was measured as a function of temperature or ion exchange capacity (IEC). Good linear correlations between the logarithm of the permeabilities and reciprocal free volume indicate that gas permeation in the sulfonated polymers depends strongly on the free volume. Comparison of Nafion with SPES and other relatively flexible chain polymers showed that the stiff chains of the perfluoroethylene backbone in Nafion make the O2 permeability much smaller than the corresponding flexible chain polymer with a similar free volume size. The O2 permeability in the K+-form of Nafion is systematically smaller than the H+-form, showing that the chain stiffness is enhanced by the ion exchange.
free volume permeability Nafion polyethersulfone ozygen positron annihilation
Hamdy F.M.Mohamed A.Ohira Y.Kobayashi
FC-Cubic,National Institute of Advanced Industrial Science and Technology (AIST),Tokyo 135-0064,Japa FC-Cubic,National Institute of Advanced Industrial Science and Technology (AIST),Tokyo 135-0064,Japa NMIJ,AIST,Tsukuba,Ibaraki 305-8565,Japan
国际会议
第九届国际正电子与正电子素国际会议(9th International Workshop on Positron and Positronium Chemistry)(PPC–9)
武汉
英文
58-60
2008-05-11（万方平台首次上网日期，不代表论文的发表时间）