Polyurethanes from oil based polyols

MIRMA MOSIEWICKI; NORMA E. MARCOVICH; MIRTA I. ARANGUREN

Buenos Aires, Argentina

Congreso; XXII Interamerican Congress of Chemical Engineering. V Argentinian Congress of Chemical Engineering; 2006

Asociación Argentina de Ingenieros Químicos. Confederación Interamericana de Ingeniería Química

Polyurethanes can be manufactured to offer a wide range of properties from those of flexible elastomers to rigid crosslinked polymers and thus, they can find use in different applications. Although the main polyols used for polyurethanes production are derived from the petroleum industry , the use of renewable natural products as an alternative source for raw materials has gained increased importance in both basic research and industrial production during the last years. Natural products are abundant and widely available; they are relatively low cost materials and offer the possibility of biodegradation. Specifically, vegetable oils consist of triglyceride molecules, which are composed of three unsaturated fatty acid chains. These triglycerides present many reactive sites able to be reacted in order to obtain a product for the polymer industry.Natural polyols can be obtained by chemical modification of the vegetable oils introducing hydroxyl groups in an unsaturated triglyceride by hydroxylation of carbon-carbon double bonds and/or by alcoholysis of the triglyceride to obtain a monoglyceride. Tung oil is particularly interesting because it presents a high percentage of unsaturated acids capable to be converted through a hydroxylation reaction. The tung oil and the tung oil-based polyol were characterized, by measuring hydroxyl values and analyzing their infrared spectra. Both techniques indicate that the hydroxyl content increased significantly after the hydroxylation and alcoholysis reactions. The modified oil was subsequent used as the polyol component in the formulation of rigid polyurethane foams.On the other hand, the use of natural fibers as a reinforcement material is an attractivealternative since they are obtained from renewable resources and their cost is low compared to that of synthetic fibers . Lignocellulosic fibers have high strength and modulus, so they can impart better mechanical properties to the material, improving its performance and lowering its cost. Additionally, natural fibers present surface hydroxyl groups that can interact with the isocyanate group, improving the fiber-matrix adhesion. Although, some works have reported the use of oil based polyols in polyurethane formulations with good results; the study of these materials and their properties is still scarce.  The aim of this work is to synthesize and to characterize a polyol from tung oil. To obtain rigid polyurethanes using this synthesized polyol and to find the optimum isocyanate/hydroxyl ratio to be later used in the manufacture of reinforced rigid polyurethanes. The effect of the addition of natural fibers to the polymer will also be evaluated.