Abstract:
The present work reports the first synthesis of biobased polyurethanes utilizing soy-based polyols that are synthesized by epoxy ring opening of epoxidized soybean oil with chemicals bearing two different functionalities. Apart from polyols, the syntheses of which are described in our previous report where thioglycolic acid (TGA) and methyl ester of TGA (MTGA) were utilized for ring opening, a new polyol that was prepared by epoxy ring opening with glycolic acid (GA) was used for the synthesis of the polyurethanes. GA, which has both hydroxyl and carboxyl functionality, was used to open epoxy ring for the first time. The soybean oil-based polyurethanes (PUs) were formed by the reaction of 4,4 '-methylenebis(phenyl isocyanate) (MDI) with the polyols that were synthesized using TGA (polyol-1), GA (polyol-2) and MTGA (polyol-3) to open epoxy rings, in bulk. The PUs were characterized using DSC, FTIR, XRD, SEM and thermogravimetric analysis. New polyurethanes demonstrated a wide range of tensile properties ranging from very flexible to rigid (from 3.44 to 39.7 MPa) as the molar ratio of OH to NCO was changed from 1.85/1 to 2.12/1. With the same polyol/MDI ratio, the best tensile properties were obtained with polyol 1 which has the highest OH functionality.
