Soy-castor oil based polyols prepared using a solvent-free and catalyst-free method and polyurethanes therefrom

Bio-based polyols from epoxidized soybean oil and castor oil fatty acid were developed using an environmentally friendly, solvent-free/catalyst-free method. The effects of the molar ratios of the carboxyl to the epoxy groups, reaction time, and reaction temperature on the polyols’ structures were systematically studied. Subsequently, polyurethane films were prepared from these green polyols. Properties of the new, soy-castor oil based polyurethane films were compared with two other polyurethane films prepared from castor oil and methoxylated soybean oil polyol, respectively. Thermal and mechanical tests showed that the polyurethane films prepared from the new polyols exhibited higher glass transition temperatures, tensile strength, Young's modulus, and thermal stability because of the higher degree of cross-linking in the new polyols. Moreover, the novel polyols, prepared using the solvent-free and catalyst-free synthetic route, were 100% bio-based and facilitate a more environmentally friendly and economical process than conventional soy-based polyols used for polyurethane production.