Heterogeneous Cation Exchange Membranes Prepared from the Sulfonated Graft-polymers of Titanium(IV) Oxide/Styrene and Polypropylene

Abstract

Polypropylene resin composites, comprised of fine particles of sulfonated graft-polymers of titanium(IV) oxide (average diameter of particles being O.4, μ) / styrene dispersed in a polypropylen e matrix, were shaped into sheets. By treating the sheets with hot water, the heterogeneous cation exchange membranes of excellent electrical and mechanical properties, were obtained. The effects of concentrations of poly ( styrenesulfonic acid), bonded to surfaces of titanium(IV)oxide particles, on the properties of heterogeneous cation exchange membrane were investigated in detail. This kind of heterogeneous cation exchange membrane has low specific resistance and high ionic transport number, despite the low concentration of poly (styrenesulfonie acid) in this membrane (salt splitting capacity being 0.64 meq. /g-dry membrane). This result was quite surprising when considering the fact that only the surfaces of cation exchange resins are effective for migration of cation through the heterogeneous cation exchange membrane. These facts may give another proofs against the effective roles of the cavities, which are formed between the cation exchange resin particles and the interface of polypropylene matrix as a result of hot water treatment, and of the surfaces of cation exchange resins in these heterogeneous cation exchange membranes.