A Kinetic Model for the Low Temperature Curing of an Unsaturated Polyester Resin with Single and Dual Initiators
A kinetic model has been developed for the prediction of reaction and gel time in the curing behaviour of an unsaturated polyester resin initiated by methyl ethyl ketone peroxide (MEKP), acetylacetone peroxide (AAP) and the MEKP/AAP dual initiator system. The curing behaviour was examined by gel time and pseudo-adiabatic exotherm measurements. We demonstrated that at room temperature and for a constant concentration of promoter, the logarithm of the reaction time (t) for each conversion can be described as a linear function of the logarithm of (Io% + R), namely ln t = a - b ln (Io% + R), where Io% is the initial content (wt%) of one of initiators and R is a constant dependent on the sum of the initial initiator contents, initiator molar masses and their kinetic parameters. It was also established that there is a linear relationship of the type ln((MEKP)o%/(AAP)o%)=A+Btgel between the ratio of the initial initiator contents and the gel time when MEKP and AAP mixtures were used as dual initiator systems for room temperature curing, with a constant concentration of promoter.