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

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. (C) 2011 Elsevier B.V. All rights reserved.