Unusual thermal decomposition kinetics of a dihydroperoxide polymerization initiator. Experimental results and theoretical calculations

Abstract

Peroxides and azo compounds are the most important initiator systems for free-radical vinyl polymerization. Studies on the thermal decomposition kinetics of dihydroperoxides are limited. The thermal decomposition of 2,5-dimethyl-2,5-dihydroperoxyhexane in toluene at 80-100 °C showed a two-step reaction. This was due to the formation of intramolecular hydrogen bonding in this system. The first step consisted of a first-order reaction with a very low activation energy due to the decomposition of H-bonded hydroperoxide groups. The second step consisted of a higher activation energy due to the decomposition of the remaining peroxide groups.