HIGH-PRESSURE STUDIES OF HYDRATED NAFION MEMBRANES - DIELECTRIC-RELAXATION AND DEUTERON NMR

Audio frequency electrical conductivity/dielectric relaxation and nucl ear magnetic resonance studies of NAFION-117 have been carried out at pressures up to 0.3 GPa (3 kbar). For some samples, the electrical con ductivity exhibits dispersion typical of hopping conductivity in an am orphous material, sigma = sigma0omega(m). The values of m are sample d ependent and vary from about 0.55 to 0.75. In addition, the values of m are not strongly pressure sensitive. At a given frequency, the elect rical conductivity tends to decrease as pressure increases and yield a ctivation volumes on the order of 5 to 10 cm3/mol. The activation volu me determined from the NMR spin-lattice relaxation time measurements a re also sample dependent. The data shown correspond to an activation v olume of about 8.6 cm3/mol. The results of the high pressure electrica l conductivity studies also yield activation volumes on the order of t hat determined via NMR.