In-situ investigations of the curing of a polyester resin

Quasi-isothermal curing of a polyester resin was studied at different catalyst concentrations and temperatures in-situ by ¹H-NMR relaxometry and NIR spectroscopy simultaneously. Sample and probe temperatures were also recorded. An autocatalytic kinetic model, optionally including a diffusion term, was successfully applied to describe and predict the curing kinetics of the polyester resin as a function of temperature and catalyst concentration, although the diffusion effect is relatively weak in the investigated system under the experimental conditions. The corresponding kinetic coefficients and the reaction activation energy were obtained by fitting the models to the data, assuming an Arrhenius relation.