Glass transition temperature of perfluorosulfonic acid ionomers

The glass transition temperature of Perfluorosulfonic acid Ionomers, H +-form of Nafion through correlations of relaxation behavior was probed by Dynamic Mechanical Analysis (DMA) and dielectric spectroscopy. The results show the glass transition temperature of the Nafion is assigned to the weak β-relaxation centered at -20°C and the neutralized ionomers have a similar molecular origin. Vogel temperature and magnitude of the frequencies above β transition coupled with DMA results suggest that the β-relaxation is a glass transition and not short range. The results also show that mechanical segment motions are significant at temperatures between -20°C and 100°C. It is found that at temperatures above the α-relaxation, the hydrogen-bonded network becomes dynamic resulting in considerable molecular mobility.