Electron beam effects on polymers. III. Mechanical and thermal properties of electron beam-irradiated poly(phenylene sulfide)

The effect of electron beam (EB) irradiation on the mechanical and thermal properties of initially amorphous and semicrystalline poly(phenylene sulfide) (PPS) films has been investigated. Irradiations were carried out either in a nitrogen or air atmosphere. Subsequent mechanical testing carried out at 23°C suggested that oxidative degradation occurs in air for high radiation dosages. However, modulus and tensile strength were not greatly affected by irradiation level. Moreover, it was found that elongation by yielding no longer occurs at doses higher than 1000 Mrad for initially amorphous materials and above 500 Mrad for the initially semicrystalline materials. Differential scanning calorimetry (DSC) measurements utilized to determine crystallinity and melting behavior suggest the likely occurrence of some crosslinking with high irradiation levels. Scanning electron microscopy (SEM) of the irradiated PPS surface suggest the possible occurrence of gas evolution—at least for high dosage levels.