Chain length dependence of radical - Radical termination in free radical polymerization: A pulsed laser photolysis investigation

Abstract

A new method for analyzing the chain length dependence of termination rate coefficients (kt(i,j) where i and j are the chain lengths of the reacting radicals) in low conversion free radical polymerizations is described. The method involves comparing experimental molecular weight distributions of polymers formed in pulsed laser photolysis experiments with those predicted by kinetic simulation. The method is enabled by direct measurements of the concentration of radicals generated per laser pulse. Knowledge of the radical concentrations should mean that the only unknowns in the simulations are the termination rate coefficients. The analysis demonstrates the need for chain length dependent term..