Studies on ion‐exchange membranes. XXXII. Heterogeneity in ion‐exchange membranes

Abstract Twelve kinds of cation‐exchange membranes were treated with hydrogen peroxide. Some of them (Selemion CMV, Nepton CR‐61, Scrion C‐100, SAM‐1) were completely destroyed. Heterogeneity is believed to be present in that part of their chemical structures that is decomposable by the treatment. The other membranes were converted into porous membranes by the decomposition of the resinous part. Water permeabilities and electric resistances of the porous membranes were examined to evaluate the pore radius. It was concluded that the “paste method” membranes have a heterogeneity or localized distribution of the resinous part under 50 mμ. The “paste method” membranes seemed to resemble the “graft method” membranes in chemical structure and to be much different from the mosaic‐type membranes such as Permaplex and MC‐3142. These results were also supported by extraction of the membranes with appropriate solvents and observation by electron microscopy.