Non-ideal polymerization. A new analysis and its application to vinyl chloride

Abstract

A new method is presented for analyzing non-ideal polymerizations in which retardation by degradative chain transfer and primary termination participate. It involves the measurement of reaction rates ω over a wide range of rates of primary radical formation ∮. The properties of the plot of log ω against log ∮ are described; its experimental realization enables the kinetic parameters to be evaluated. This approach offers the possibilities of separating the non-ideal components and allowing their contributions to be assessed, and does not require a knowledge of the rate of the unretarded reaction.

The method has been applied to the polymerization of vinyl chloride in three solvents, with initiation by AZDN (thermal and photochemical) and by the Mn₂(CO)₁₀+ CCI₃COOEt system (photochemical). Non-ideality decreases in the order chlorobenzene, tetrahydrofuran, ethylene dichloride; in each case the kinetic parameters have been calculated. Primary termination is significant at higher rates of initiation by AZDN; with manganese carbonyl initiation it is much less. Our treatment is shown to offer a satisfactory explanation of results obtained by other workers. The geometric mean assumption does not agree well with our observations, particularly those on polymer molecular weights.