Polyurethanes from Solvent-Free Vegetable Oil-Based Polyols

The catalytic effects of 1,8-diazabicydo[5.4.0]-undec-7-ene (DBU) and pyridine on the ring-opening reaction between epoxidized soybean oil and fatty acids from castor oil in a solvent free process were investigated using differential scanning calorimetry and were analyzed using both model-free and model-fitting methods. The resulting biopolyols from this reaction with epoxidized soybean oil, and similarly prepared polyols from epoxidized linseed oil, were characterized by proton nuclear magnetic resonance, Fourier transform infrared spectroscopy, and gel permeation chromatography. Polyurethane films were prepared by step-growth polymerization of the biopolyols with isophorone diisocyanate and were characterized by dynamic mechanical analysis, thermogravimetric analysis, and tensile tests. Polyurethanes from polyols manufactured with DBU as catalyst exhibited higher glass transition temperatures, tensile strength, and Young's modulus than polyurethanes from polyols manufactured using a catalyst-free method, which was attributed to the more homogeneous structure of their cross-linked network.