Aromatic polymers for advanced alkaline water electrolysis. Part I: Polyphenylene sulfide and its sulfonated derivatives

Two types of thin (0.055 cm) diaphragms, asbestos-polyphenylene sulfide and asbestos-sulfonated polyphenylene sulfide, have been obtained respectively by imbibing asbestos cardboard with polyphenylene sulfide dissolved in diphenyl sulfide and by sulfonating the polyphenylene sulfide-asbestos diaphragm with sulfur trioxide at low temperature (< 10°C). The diaphragms have been found stable in boiling KOH (30–40 w/w%) up to the end of the test period (180 h). The voltage drop across the diaphragms (Ωcm2 in 43% w/w KOH: 0.21-0.5 at 30° and 0.08–0.21 at 80°C follows the order: asbestos < asbestos-sulfonatedpolyphenylene sulfide < asbestos-polyphenylene sulfide.