Sueo Machi

Radiation synthesis of ion-exchange carboxylic fluorine containing membranes

Abstract Copolymerization of methyl 2,3,3-trifluoropropenoate (MTFP) and tetrafluoroethylene (TFE) with propylene (P) and/or ethylene (E) in bulk at room temperature was induced by γ-irradiation at a dose rate ranging from 5 × 10 5 rad/hr to 1 × 10 6 rad/hr. The initial monomer molar ratio of MTFP/TFE was 25 25 and the P/E molar ratio was varied from 0 50 to 50 0 with different polymerization times (1–6 hr). An alternating copolymerization between both electron acceptors (MTFP and TFE) and electron donors (alkenes) takes place. Hydrolysis of polymers was carried out by sodium hydroxide methanol aqueous solution. IR spectra and physical properties of the ester and acid type polymers such as molecular weight, glass transition and decomposition temperatures, chemical resistance, as well as carboxylic group concentrations, degree of hydrolysis, swelling of hydrolysed copolymers were determined. Films of 50–100 μm thickness were prepared from the acid type copolymers and they were crosslinked by electron beam irradition. Thermal, mechanical, electrical, chemical and ion-exchange properties of MTFP-TFE-alkenes crosslinked membranes were studied. The basic characteristics of the obtained carboxylic fluoropolymer membranes are considered to be very promising for practical use in chlor-alkali electrolysis.