Curing kinetics of poly(furfuryl alcohol) resin: a fractionation and molecular weight study

Polyfurfuryl alcohol (PFA) resin consists of low and high molecular weight oligomeric chains which are differently involved in cross-linking reactions. The dependence of PFA curing kinetics to its molecular weight was investigated by differential scanning calorimetry. To this end, PFA resin was synthesized by cationic polymerization of furfuryl alcohol in the presence of maleic anhydride and fractionated to four fractions by precipitation fractionation. The fractionation efficiency was then examined by software-based deconvolution of GPC chromatograms. Effect of molecular weight of the fractions on their curing kinetics was studied by determining the curing enthalpy and activation energy using Kissinger–Akahira–Sunose and Flynn–Wall–Ozawa isoconversional models. A reduction in molecular weight, e.g., 291.72 g.mol−1, resulted in a 20 kJ mol−1 drop in the cure activation energy and decreased the curing enthalpies, eq. 9.57, 7.97 and 9.87 J.g−1 at heating rates of 5, 10 and 15 °C.min−1, respectively. Taking such dependency into consideration, a curing mechanism was highlighted among different reported mechanisms for PFA cross-linking reactions.