MOSIEWICKI mirna Alejandra
congresos y reuniones científicas
Polymers and Composites from Vegetable Oils and Plant Fibers/Fillers
Santiago, Chile
Conferencia; X Internacional Conference on Frontiers of Polymers and Advanced Materials; 2009
The continuous rising of public environmental concerns and decreasing fuel sources has pushed companies and academy to redirect their efforts to the investigation and development of new materials based on renewable resources, in order to replace (or partially replace) ubiquitous synthetic polymers. The 90´s saw the appearance and dramatic increase of wood plastic composites, broadly speaking composites that incorporate wood flour/fibers and other agro-industrial (or waste) natural fibers into polymer matrices. In more recent years, additional efforts have been focused in the production of polymer matrices from available biomass. In this area, traditional natural polymers that had been previously replaced by synthetic ones made a new come back; such is the case of cellulose-derived polymers, starches, proteins and fats. In particular, the results obtained in the production and characterization of composites made from plant oil-based polymers and lignocellulosic reinforcements will be discussed in this presentation. Vegetable oils are abundant, widely available and relatively low cost materials. These compounds, formed by triglyceride molecules, have different reactive chemical groups that can be modified to be used in the preparation of polymers, which can be further used to prepare biocomposites, also reinforced with plant fibers/fillers. These types of fillers/reinforcements are very interesting because of their availability, low cost and frequently good compatibility with the plant derived polymers considered here. They can also show acceptably good mechanical properties, which are largely due to the presence of cellulose, the naturally reinforcing polymer in the structure of the plants. Composites prepared from a tung oil-based polyurethane (PU) and wood flour have proved to present an outstanding balance of properties. The addition of 30 wt.% of wood flour improved tensile modulus (to more than three times the modulus of the PU) and strength of the polyurethane, which is the common behavior of rigid particles added to a polymer, but without reducing the elongation to rupture. The uncommon improvement in toughness of the polyurethane was further demonstrated by impact testing the composites, which showed an increase of 70 % of the fracture resistance at the concentration mentioned above. Polyurethanes derived form other plant oils, such as castor oil, also proved to be adequate in the production of rigid polyurethane foams, or partially foamed panels of low density that incorporate agro industrial fibers (ex: hemp).