The effect of the microstructure of the reaction system on the initiation step in DI- and oligoester acrylate systems

Abstract

The initiation rate constant and the rate consant of decomposition of AZBN in some oligoester acrylate and in solutions of the latter in chlorobenzene have been determined by two indepndent methods, namely from the length of the induction period and from the rate of decomposition of a stable radical. It was found that the initiation rate constants increase as the concentration of chlorobenzene in increased, reach a maximal value then decrease. This kind of variation is explained by the hypothesis that the molecular packing in the oligomer and in the solvent is of a different type. Each type of molecular packing gives rise to corresponding hindrance to diffusion at the stage escape of the initiating radical from the “cage”.