Radiation degradation of graft-type polymer electrolyte membranes

Sawada, Shinichi; Iwai, Yasunori; Yamanishi, Toshihiko; Maekawa, Yasunari

In the polymer-electrolyte-membrane (PEM) water electrolysis system in the international thermonuclear experimental reactor (ITER), the PEM material with high radiation resistivity is required. In this study, we investigated the radiation degradation behavior of the PEMs synthesized by radiation grafting method based on poly(ethylene-co-tetrafluoroethylene) (ETFE) and poly(etheretherketone) (PEEK) films. The PEMs were irradiated by 500-kGy -ray at 300 K, and then characterized in terms of their remaining weight, ion exchange capacity (IEC), proton conductivity, and breaking tensile strength (BTS). The ETFE-based PEM was significantly degraded in all the properties. Contrary to the ETFE PEMs, the PEEK PEM after irradiation did not lose their properties, probably because its aromatic hydrocarbon backbones were very resistant against irradiation. This result makes us expect that the PEEK PEM can be employed in the practical electrolyzer in ITER.