Effect of Structure on Properties of Soy-Based Polyols and Polyurethanes

A series of polyols with different structure, suitable for rigid foams and cast polyurethanes, was synthesized from soybean oil. One polyol prepared by hydroformylation of soybean oil contained primary hydroxyl groups while the others, prepared from epoxidized soybean oil, had secondary OH groups and different side groups at the adjacent C-atoms. On the average these polyols contained four OH groups per molecule. The hydroxyl group content strongly affects viscosity of the polyols, which is higher for polyols with a higher hydroxyl content. The side groups were chlorine, bromine, methoxy and hydrogen. Polyol density, viscosity, melting points and stability are affected by their structure. Halogen containing polyols are more viscous, less thermally stable, have higher density, and have melting points above room temperature. Mechanical properties of polyurethanes from halogenated and the methoxy polyols were comparable, while hydrogenated polyol and one prepared by hydroformylation gave lower modulus and lower Tg polyurethanes.