ELECTRICAL-IMPEDANCE STUDIES OF ACID FORM NAFION(R) MEMBRANES

Electrical conductivity/dielectric relaxation studies of acid form NAF ION-117 have been carried out at frequencies from 10 to 10(8) Hz. By d irect measurement, it is shown that when ''standard'' two terminal mea surements are made across the thickness of a 0.18 mm film, it is neces sary to use frequencies in excess of 10(7) Hz in order to observe the bulk conductivity of the sample. As a consequence, previous reports of a power law dependence for the electrical conductivity are not associ ated with the bulk electrical conductivity but rather are due to elect rode effects and space charge. As confirmation, it is shown that by ch anging the geometry of the electrodes, the low frequency electrical re sponse of the material is significantly changed.