Radiation stability of electron beam irradiated high degree sulfonated poly(ether ether ketone) membranes for the applications in nuclear facilities.

• Response tolerance to the high dose (500 kGy) irradiation in air and water of highly sulfonated SPEEK is demonstrated. • Thermal and mechanical properties for SPEEK with degree of sulfonation up to 70 % remain stable after high dose irradiation compared to nonirradiated SPEEK membranes. • Irradiation in water enhances reduction of molecular arrangement at the DS > 70 % causing membrane dissolution in water. • Improved molecular arrangement due to the physical interaction of sulfonated groups affects mechanical stiffness of SPEEK60-70 membranes after irradiation in water. Sulfonated poly(ether ether ketones) (SPEEK) have raised interest as a replacement of Nafion® proton exchange membranes (PEM) for the application in harsh environments involving material exposure to ionizing radiation, for example, radioactive hydrogen isotope separation from water. This study is dedicated to evaluate the effects of high dose (500 kGy) electron beam irradiation on the physico-chemical and thermomechanical properties of highly sulfonated (degree of sulfonation 60–90 %) SPEEK membranes irradiated in air and water. Spectrometric and thermogravimetric analysis indicated slight changes in the material properties after irradiation with increase of the degree of sulfonation (DS). Tensile tests and thermomechanical analysis of irradiated samples indicated notable deterioration of properties at higher DS values. Results demonstrate that SPEEK membranes with DS around 70 % could be a replacement of the traditional PEM for the applications where exposure to ionizing radiation occurs. [ABSTRACT FROM AUTHOR]