Analysis of Nafion~R Fuel Cell Membrane Chemical Durability Using Broadband Dielectric Spectroscopy

摘要

Changes in macromolecular dynamics associated with the T_g - related β relaxation of Nafion~R, with chemical degradation, were investigated using broadband dielectric spectroscopy. Loss permittivity vs. frequency spectra showed peak splitting reflecting microstructural heterogeneity. Spectra were analyzed using the conductivity-modified Havriliak-Negami equation and the Kramers-Kronig integral transform, both of which showed broadening and peak splitting for degraded samples. Peak broadening and bi and tri-modal character of the spectra of degraded samples was also manifest in distributions of relaxation times which reflected a broadening of molecular weight distribution and related microstructural heterogeneity induced by chemical degradation.