Chain scission efficiency of some polymers in γ-radiation

The G values of poly(methyl methacrylates) (PMMA), polycarbonates, and a polylactone for γ-radiation were determined by using a computer-assisted GPC as the primary tool for the measurement of the number-average molecular weights Mn. The accuracy and precision of the automated GPC were found to have a normalized standard deviation (σ/Mn) of less than 7%. The G value of PMMA was determined to be essentially independent of molecular weight. For low molecular weight polymers, some nonlinearity in the I/Mn versus dosage plot was observed at low dosage, i.e., about 1 Mrad.