Kinetic study of a phenolic-novolac resin curing process by rheological and DSC analysis

Rheological isothermal curing runs of a novolac resin were performed in order to study its chemorheological behavior. In addition, DSC tests were carried out for the partially cured novolac resin to determine the curing degree reached at the end of each isothermal run. The Arrhenius and Kiuna empirical models were applied to establish the curing kinetic parameters of a novolac resin. The material curing process had an activation energy of 195.0 kJ/mol using the Arrhenius rheokinetic model. The activation energy obtained for the resin curing was 103.5 kJ/mol when the Kiuna model was applied. The profile of the resin's curing degree for all isothermal tests was obtained from rheological parameters: complex modulus (G*), elastic modulus (G′) and torque (Γ). Torque was the most suitable rheological variable of the resin for evaluating changes in the degree of cure during the curing process of the novolac resin. The Kamal and Markovic kinetic models were proposed to model the resin's curing behavior. Kamal's model was suggested as the best approach to predict the change in the mechanical degree of conversion during the material curing process.