MOLECULAR WEIGHT DISTRIBUTION AT HIGH CONVERSIONS IN FREE RADICAL POLYMERS

The effects of conversion on molecular weight distribution were examined in isothermal, batch polymerizations of styrene and vinyl acetate. The influence of termination reactions, known to depend anomalously on the extent of conversion, were minimized in both systems by the choice of experimental conditions. In styrene polymerization the relatively moderate changes in molecular weight with conversion compare favorably with calculations based on literature values of the radical transfer constants. In vinyl acetate polymerization the formation of branches during polymerization causes a substantial broadening in distribution with conversion. The transfer constants appear to be independent of conversion in both systems. © 1969, American Chemical Society. All rights reserved.