Kinetic effect of radiation intensity and thermal after‐treatment in the photopolymerization of diallyl oxydiethylene dicarbonate

The influence of radiation intensity (from 1,08 · 10−7 to 2,48 · 10−4 einstein.s−1 · 1−1) on the photopolymerization of diallyl oxydiethylene dicarbonate was investigated systematically not only in the initial stages of reaction, but also at high monomer conversion (x), in order to detect possible variations in the polymerization mechanism. In some of the runs irradiation was stopped at x = 0,55–0,65 and thermal after‐treatments were carried out both in the presence and absence of air by following kinetically x‐values during the self‐decelerating cross‐linking. To rationalize experimental data a model is proposed which assumes two basically different mechanisms occurring simultaneously (bimolecular termination and radical trapping), but with different “weights” as a function of time. Long living radicals produced by irradiation continue to react in the dark. The rate of this reaction, which is enhanced in the presence of oxygen, is fitted by a relaxation model that considers double bonds, particularly of pendant groups, as traps, with increasing lifetimes, able to transfer to radical sites. The role of oxygen is also discussed.