Studies on ion-exchange membranes.: II.: Measurement of the anisotropic conductance of Nafion®

Measurements of the conductivity of Nafion(R)117 in the tangential and the normal directions are reported in this paper. These measurements were made using the coaxial probe method described in an earlier paper. The tangential component of the conductivity of the swollen membrane at 100% humidification was 8.56 x 10(-2) S cm(-1), while the normal component of the membrane under the same conditions was 2.4 x 10(-2) S cm(-1). This anisotropy is examined in the light of current knowledge of the morphology and structure of swollen Nafion(R). The normal component of the conductivity depends strongly on the pressure applied on the membrane, and therefore must be corrected to zero pressure. Our experiments show that the membrane resistance is linear with regard to the applied pressure. (C) 1998 Elsevier Science S.A. All rights reserved.