ELECTRICAL RELAXATION IN IN-SITU DRIED ACID-FORM NAFION

Electrical relaxation studies have been carried out on dried, acid-form Nafion 117 (copolymer of tetrafluoroethylene and perfluoro 3,6-dioxa-4-methyl-7-octenesulfonic acid and which has an equivalent weight of 1100). Significant electrical conductivity is found and the data are found to be non-Arrhenius. The results are converted to the electrical modulus representation and a conductivity relaxation is observed. A stretched exponential is best-fit to the conductivity relaxation and again, non-Arrhenius behavior is observed for the peak position. Finally, at low temperatures, a new dielectric relaxation peak is found which has an activation enthalpy of about 0.57 eV (13 kcal/mol). This relaxation is analogous to the gamma-relaxation observed in mechanical relaxation studies. (C) 1994 John Wiley & Sons, Inc.