Preparation and Properties of Polyurethanes based on Castor Oil Chemically Modified with Yucca Starch Glycoside

We present novel polyurethanes from renewable materials of castor oil and starch. Castor oil is transesterified with pentaerythritol in order to obtain a wide range of polyols. Yucca starch is converted into glycoside through transglycosylation reactions with ethylene glycol and glycerol. The glycosides from starch are then chemically incorporated to the castor oil polyols by a second transesterification reaction to generate a sequence of polyol-glycosides with a high level of polyhydroxyl content. These products are characterized by the hydroxyl value, viscosity, and specific gravity as a function of the glycoside type content and the kind of castor oil polyol prepared. MALDI TOF mass spectroscopy is used to find the mass fraction of glycosides and polyol-glycosides. Polyurethanes are synthesized from the polyol-glycosides by reaction with isophorone diisocyanate, under different NCO/OH molar ratios. The polymer characterization is accomplished by Fourier transform infrared analysis, tensile stress-strain tests, Shore A hardness, thermogravimetric analysis, chemical resistance to solvents, scanning electron microscopy, and dynamic-mechanical thermal analysis.