Compuestos Basados en Fibras Vegetales y Poliuretanos Derivados de Aceite de Tung

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

San Nicolás, Buenos Aires, Argentina

Congreso; 7º Congreso Binacional de Metalurgia y Materiales, SAM-CONAMET 07; 2007

SAM-CONAMET

RESUMEN Tung oil was the raw material selected for the synthesis of a polyol, to be further used in the formulation of rigid polyurethane polymers and composites. The synthesis of the polyol was carried out in two steps: hydroxylation of the double bonds in the fatty acid chains of the unsaturated oil and then, alcoholysis of the hydroxylated oil with triethanolamine. The unmodified tung oil (TO), the hydroxylated tung oil (HTO) and the alcoholized hydroxilated tung oil (AHTO) based polyols were characterized by analytical techniques (ex: hydroxyl value) and infrared spectroscopy. It was found that the hydroxyl value increased significantly after the hydroxylation and alcoholysis reactions. To produce the polyurethane matrix, the AHTO was mixed with MDI (groups ratio NCO to OH = 1.1) in THF solution (to decrease the initial viscosity). The same procedure was used to prepare the composites, but in this case the MDI was previously mixed with the filler. Neat and reinforced samples were cured at 75ºC under a pressure of 4 MPa. Wood flour (WF) and microcrystalline cellulose (MCC) were used as reinforcements. Physical, thermal and mechanical properties of the neat and reinforced polyurethanes were measured and analyzed. Although the wetting of both fillers by the matrix was good, the dispersion of WF particles into the polymeric matrix was better than that of the MCC, as it was confirmed by scanning electronic microscopy. Thus, the mechanical and dynamic-mechanical properties of composites based on WF resulted superior to those of the MCC based samples. Storage modulus, as well as tensile modulus and strength increase as WF concentration increases, indicating that WF is acting as a reinforcement of the polyurethane matrix.