A kinetic study of the acceleration effect of substituted benzyl alcohols on the cationic photopolymerization rate of epoxidized natural oils

The rate of the cationic photopolymerization of epoxidized natural oils was enhanced by the addition of several mono, di and trisubstituted benzyl alcohols. The epoxidation of vegetable oils was achieved by using 30% hydrogen peroxide with methyl trioxo rhenium (MTO) as a phase transfer catalyst. Then, the effect of different methoxy-substituted benzyl alcohols on the curing rate was evaluated, using the real-time FT-IR technique. The overall result was an increase in the curing rate. The acceleration effect was explained on the basis of synergistic effects of two mechanisms, namely, the radical induced cationic photopolymerization and the activated monomer mechanism. Epoxidized oils with 2,5-dimethoxybenzyl alcohol as an accelerator exhibited the highest photopolymerization rate. Higher conversions were obtained using electron-transfer photosensitizers.