Tung Oil Based-Polyurethanes Reinforced With Wood Flour

U.M. CASADO; N.E. MARCOVICH; M.I. ARANGUREN; M. A. MOSIEWICKI

Río de Janeiro, Brasil

Conferencia; International Conference on Science and Technology of Composite Materials, COMAT 2007; 2007

COMAT

INTRODUCTION Polyurethane polymers can be used in different applications to offer a wide range of properties from those of flexible elastomers to rigid crosslinked polymers. Although the majority of polyols used for polyurethanes production are derived from the petroleum industry [1], 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. Vegetable oils are abundant and widely available; they are relatively low cost materials and offer potential biodegradability. 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 [2]. Tung oil is obtained from the seeds of the tung tree [4]. It is particularly interesting because its main constituent is elaeostearic acid with 3 conjugated unsaturations [5]. This characteristic makes it an excellent product to be used in paint and varnish industry as a drying oil due to its fast polymerization in presence of oxygen [6]. These multiple carbon-carbon double bonds are capable of being reacted to introduce hydroxyl groups through a hydroxylation reaction. On the other hand, the use of natural fibers as reinforcing material is an attractive alternative since they are obtained from renewable resources at relative low cost compared to that of synthetic fibers [7]. Lignocellulosic fibers have high strength and modulus, so they can impart good mechanical properties to the material, improving its performance and lowering its cost. Additionally, vegetable fibers present surface hydroxyl groups that can interact chemically with isocyanate groups during polyurethane synthesis, improving the fiber-matrix adhesion. Thus, the aim of this work was to synthesize and characterize a polyol derived from tung oil. This polyol was further used to prepare rigid reinforced polyurethanes, using wood flour and microcrystalline cellulose as fillers.