Structure and transport properties of polyvinyl chloride-based heterogeneous cation-exchange membrane modified by additive blending and sulfonation

Abstract

In this work, the structure-performance relationship of modified heterogeneous ion-exchange membranes (IEMs) was investigated by the microheterogeneous model. Polyvinyl chloride (PVC)-based IEM has been modified by introducing hydrophilic additive and immersing in sulfuric acid solution. The modified membrane has displayed a high degree of structural heterogeneity with inter-gel phase fractions (f2) of 0.28 to 0.43. The α value isaround 0.20–0.31 which indicates that the prepared membranes have a randomly distributed conductive phase. In general, the inter-gel phase fraction (f2) has a positive effect on membrane conductivity. However, membrane permselectivity decreases at higher inter-gel phase fraction. The addition of hydrophilic polymer increases the fraction of inter-gel phase while the sulfuric acid immersion increases the gel-phase conductivity (kg). Moreover, it has been found that the permselectivity is linearly correlated to kg/f2.