(119a) Characterization of the Durability of Nafion Membranes and Nafion/Inorganic Oxide Nanocomposite Membranes

Selected results in the investigation of the chemical degradation of Nafion perfluorosulfonic acid membranes in the fuel cell environment will be presented. The topics will include a detailed explanation of the use of the powerful technique of modern broadband dielectric spectroscopy in monitoring the shift in the dynamics of Nafion macromolecular chains with degradation. In particular, long range main perfluorocarbon chain motions associated with the glass transition are revealed, the signature of which is the distribution of relaxation times (DRT). It will be explained how the DRT is related to the shift in Nafion molecular weight distribution with degradation in peroxide via the Fenton's reagant test. Also discussed will be the concept and rationale of the use of Nafion membranes that are inorganically modified with membrane - in situ - grown nanoscopic fillers that render the membrane more hydrophilic and possess greater hydration at higher temperatures.