Environmental Effects on Tung Oil based Polyurethanes

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

Los Cocos, Argentina

Simposio; V Argentine-Chilean Polymer Symposium, Archipol 2009; 2009

In general, polyols used for polyurethane (PU) production are derived from the petroleum industry (Cihan and Gan, 1998), but the use of bio-based oils as alternative natural raw materials is gaining growing attention. Vegetable oils that are widely available at low cost consist of triglyceride molecules with three unsaturated fatty acid chains able to be chemically modified to obtain resins for the polymer industry (Khot et al, 2001). Tung oil is obtained from the tung oil tree (largest growing regions are in China, Argentina, Paraguay, and parts of Africa). The oil is known as a drying oil, which main component is elaeostearic acid with 3 conjugated unsaturations (Formo et al, 1985) capable of being reacted to introduce hydroxyl groups through a hydroxylation reaction. On the other hand, wood flour (WF) as reinforcing material in polymers increases the content of renewable materials of low cost in the composites. It is well known that a good compatibility between the matrix and reinforcement improve significantly the mechanical properties in the materials, and this is to be expected in the tung oil-PU composites reinforced from tung oil. Although the polymers and composites based on tung oil can present good structural stability during storage at low relative humidity (Mosiewicki et al, 2008; Casado et al, 2008), the evaluation of changes produced under humid conditions, as well as the effect of microbial attack on these composites have not been analyzed previously. The aim of this work is to evaluate the changes occurred on PU based on tung oil and the derived WF composites exposed to humid and biological aggressive environments.