ELECTRON-BEAM IRRADIATION OF POLYPERFLUOROETHERS - EXPERIMENTAL-ANALYSIS OF MAIN-CHAIN DEGRADATION

The electron beam irradiation of polyperfluorinated ethers are investigated. Main-chain scissioning is the predominant effect, inducing a weight loss in the bulk materials caused by evolution of small gas molecules such as COF2 and CF4. The G values for main-chain scissioning, mass loss, and gas evolution are determined from experiment and correlated to structural differences. From these results we conclude that unbranched polyperfluoroethers degrade more efficiently and produce more COF2 than branched polymers when the monomer units contain -CF2-CF2-O- and/or -CF2O- in the main chain. With a pendant perfluoromethyl, -CF(CF3)-CF2-O-, or an additional carbon atom in the main-chain monomer unit, -CF2-CF2-CF2-O-, the electron beam induced degradation is comparatively less efficient; in the branched polymers, CF4 evolution competes with COF2 formation.