Solution casting, characterization, and performance evaluation of perfluorosulfonic sodium type membranes for chlor‐alkali application

Abstract

AbstractThis investigation describes solution casting, characterization and performance evaluation of perfluorosulfonic sodium (PFSS) type membranes prepared by three different methods from Nafion solution and Nafion‐117 for Chlor‐Alkali (CA) application. A Chlor‐Alkali experimental set‐up was designed and constructed for performance evaluation of the recast membranes. The chemical structure of solution cast films was studied and confirmed by FTIR (Fourier Transform infrared spectroscopy) and ATR (Attenuated total reflection) techniques. The physical properties of solution cast films including mechanical strength, thermal behavior, water sorption, ion‐exchange capacity (IEC), morphology, and crystallinity were also evaluated. All the recast polymeric films behave like elastomers with low modulus but high elongation at break. Differential scanning calorimetric (DSC) thermograms of solution cast films showed two endothermic peaks at 180°C and 250°C attributed to matrix glass transition (Tgm) and ionic cluster glass transition (Tgc) of the Nafion polymer, respectively. The water uptake of polymeric films was reasonable in comparison with Nafion‐117. Solution casting has no significant effect on ion exchange capacity of the recast films. The scanning electron microscope (SEM) micrograph showed that the morphology of recast films is reasonably similar with Nafion‐117. However, the as‐cast films have some micro pores, which are produced during solution casting. The crystallinity of annealed film, because of the heat treatment was slightly high due to local ordering. According to the experimental results, which obtained from performance evaluation in CA cell, the properties of recycled films are similar to commercial membranes such as Nafion‐117 and can be used in CA process. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011