Study on the non-isothermal curing kinetics of a polyfurfuryl alcohol bioresin by DSC using different amounts of catalyst

Abstract

The curing kinetics of a biomass-based polyfurfuryl alcohol resin with three different amounts of catalyst was studied by DSC non-isothermal measurements using seven heating rates. The change of the activation energy of the curing process was obtained by the isoconversional methods of Kissinger–Akahira–Sunone, Flynn–Wall–Ozawa and Vyazovkin. The latter method provided maximum values of the activation energy of about 115, 95 and 80 kJ mol −1 before the gelation point for 2%, 4%, and 6% (w/w) amounts of catalyst, respectively. Based on a purely kinetic criterion, the most suitable amount of catalyst is assessed to be 4% (w/w). The change of the activation energy during curing was found to consist of three stages: an initial stage, where the activation energy increases due to accumulation of reaction intermediates; a main stage, where the activation energy slowly decreases due to the increasing viscosity and gelling of the resin which leads to a constrained mobility of the polymer chains; and a final stage, where the activation energy decreases more rapidly due to the formation of a rigid molecular network that restricts diffusion processes. Altogether, the obtained knowledge of the curing kinetics will form a valuable contribution to the design of improved cure cycles for manufacturing of composite materials with a polyfurfuryl alcohol matrix.