Abstract
Cation-exchange membranes for application to electrodialysis were prepared from commercially available polyethylene films using electron-beam-induced（EB-induced）graft polymerization. Three kinds of polyethylene, namely, low-density（LDPE）, high-density（HDPE）, and ultra-high molecular weight polyethylene（UHMWPE）, were adopted as the starting films. Styrene was graft-polymerized onto the film by immersing EB-preirradiated PE film in a styrene/xylene solution before sulfonation of the styrene-grafted membrane with a chlorosulfone/dichloroethane solution. The ion-exchange capacity, water content, membrane resistance, and tensile strength were measured, and the performance of electrodialysis of seawater was evaluated. The tensile strength of a cation-exchange membrane prepared using an LDPE or HDPE film（2000 ～ 3000 N/cm2）was found to be comparable to that of a commonly used cation-exchange membrane, Selemion® CSO, whereas a UHMWPE-based cation-exchange membrane was found to have twice the tensile strength of Selemion® CSO（4000 ～ 5000 N/cm2）. An electrodialyzer fabricated using a membrane pair consisting of the developed cation-exchange membrane and the commercial anion-exchange membrane, Selemion® ASA, exhibited a higher concentration of chloride in the concentration chamber than a pair of Selemion CSO and ASA. For example, the chloride concentration rose by 20 ％ at an identical membrane resistance of 1.5 Ωcm2.
