Effect of lignin-containing cellulose nanofibrils on the curing kinetics of polymeric diphenylmethane diisocyanate (PMDI) resin

Abstract

Abstract In order to increase the curing rate of polymeric diphenylmethane diisocyanate (PMDI) resin, different contents of lignin-containing cellulose nanofibrils (L-CNFs) were blended into the PMDI. Differential scanning calorimetry (DSC) was used to examine how the addition of L-CNFs influences the curing kinetics of PMDI resin. The activation energy (Ea ) of the curing reaction of PMDI/L-CNF systems was calculated using the Kissinger, Friedman and Flynn-Wall-Ozawa model-free methods. The results showed that Ea values calculated by the aforementioned three methods varied in a similar trend with the increase in the L-CNF content. Adding L-CNFs could decrease the Ea value of the curing reaction of PMDI and speed up the curing reaction. The acceleration of the cure rate of the PMDI resin upon the addition of L-CNFs may be attributable to the effective dispersion of the L-CNFs into the PMDI resin as well as the reaction between the hydroxyl (-OH) groups of the L-CNFs and the isocyanate (-NCO) groups of the PMDI.