DSC monitoring of the cure kinetics of a castor oil-based polyurethane

Differential scanning calorimetry (DSC) has been used to monitor the reaction between castor oil and isophorone diisocyanate (IPDI), using a non-isothermal method, at different heating rates. The NCO/OH ratio in these systems was 1, so that the concentration of NCO and OH groups could be considered equivalent during all the experiments. Despite the complexity of the system, in which different order kinetics are possible, as well as physically controlled diffusion processes, data were fitted to a simple kinetic model, of apparent order n, apparent activation energy EA, and apparent frequency factor A0. The dependency of these parameters on heating rate was used to analyze kinetics of polymerization of these systems.