Kinetic Study of Polyurethane Reaction between Castor Oil/TMP Polyol and Diphenyl Methane Diisocyanate in Bulk

Polyols as precursors of crosslinked polyurethanes were prepared by alcoholysis between castor oil (CO) and Trimethylol propane (TMP). The alcoholysis reaction produced an equilibrium mixture of monoglycerides, diglycerides, and triglycerides of TMP and some free TMP. The polyol thus prepared was characterized using FTIR, Atmospheric Pressure Chemical Ionization (APCI) under positive ion mode and various analytical techniques. A series of bulk polyurethane polymerization reactions were then carried out using the polyol and Diphenyl methane diisocyanate (MDI) at 25°C, and were investigated using Fourier transform Infrared (FTIR) spectroscopy with different NCO/OH ratios, that is, 0.75, 1.0, and 1.25. All the reactions obeyed second order kinetics. Second order rate constants were calculated and found to be 2.49 × 10−4 lit/eq. sec., 3.4 × 10−4 lit/eq. sec. and 2.38 × 10−4 lit/eq. sec. for NCO/OH ratio 1.25, 1.0, and 0.75, respectively.