Rate of copolymerization of styrene and methyl methacrylate. II. The gel effect in copolymerization

An analysis of the rate data for the copolymerization of styrene with methyl methacrylate at 60° is given over a conversion range from 0 to 95%. A measure of the increase in rate observed over that to be expected from classical kinetics is calculated. It is termed the gel effect index, γ, and is used to systematize the observations. The results are interpreted in terms of three major developments which can be seen in γ, viz., the onset of translation diffusion control of termination, the onset of a strong decrease in initiator efficiency, and the practical cessation of polymerization.