Reaction Kinetics of Polyurethane Formation Using a Commercial Oligomeric Diisocyanate Resin Studied by Calorimetric and Rheological Methods

Reaction rate and kinetics of cure between PMDI and castor oil, a tri-functional polyol, for stoichiometric and off-stoichiometric mole ratios, were studied through isoconversional. analysis of DSC data and through gelation times and viscosity build up obtained through rheological techniques. The cure kinetics of the polyurethane reaction as monitored using different techniques gave similar activation energies for the stoichiometric ratio. Isoconversional analysis of DSC data showed a competitive reaction scheme for the stoichiometric system, suggesting the presence of isocyanate groups with different reactivities in the PMDI which was further substantiated in rheological investigations.