Heterogeneous Cation Exchange Membranes Made of Ground Powder of Cation Exchange Resins and Polypropylene

Abstract

Polypropylene resin composites, consisting of cation exchange resin particles (the diameter was less than 149, μ) and finely dispersing in polypropylene matrix, were formed into sheets. By treating the above sheets with hot water, the heterogeneous cation exchange membranes of good electrical and mechanical properties were obtained. The effects of crosslinking and particle diameter of cation exchange resins on the heterogeneous cation exchange membrane properties were investigated in detail. The higher the degree of crosslinking of cation exchange resins, the larger are the ion transfer coefficient and the specific resistance of the heterogeneous cation exchange membranes. On the other hand, the smaller the particle diameter of cation exchange resins, the lower is the specific resistance. These, phenomena were explained in terms of the presence of cavities which are formed between cation exchange resin particles and the polypropylene matrix by the hot water treatment. It was concluded that the preferable cation exchange resins to obtain the better heterogeneous cation exchange membranes are those whose degrees of crosslinking are as high as possible and whose particle diameters are as small as possible.