Caracterização de compósitos de poliuretano de óleo vegetal com madeira de Pinus taeda e fibras de Agave sisalana

Abstract

Polymeric materials derived from petroleum because damages to the environment and to human health, are derived from non-renewable sources and have solvents in its composition. The polyurethane foam derived from castor oil is a renewable feedstock material, biodegradable and has no solvent in its composition. The sawdust of Pinus taeda is a timber sector‟s main residue, the sisal fiber, Agave sisalana, is cultivated on northeast of Brazil, and both can be used in sustainable constructions. The objective of this research is to prepare and characterize composites of polyurethane foam derived from vegetable oil with sawdust reinforcement of Pinus taeda and short fiber of dispersed sisal. The composites were produced in five different proportions of reinforcement, without treatment in the fibers. It was made the reinforcement chemical analyzes, the composites were analyzed by density profile, bending test, water absorption, swelling in thickness, perpendicular traction, X - ray and SEM images. The results were analyzed statistically. The composite with greater resistance was reproduced with sawdust treated in NaOH. Composites with 50% foam, 37.5% sawdust and 12.5% sisal without chemical treatment presented 11.31 MPa as bending test result. This value was superior than the composite with sawdust treated with NaOH. The increase in sisal: Pinus taeda sawdust adversely affected the mechanical and physical strength of the composites due to the reduction of chemical bonds between the NCO of the diisocyanate present in the polyurethane and the free OH present in the lignin, as well as the difficulty of packaging and homogenization components. Composites with 50% foam, 37.5% sawdust and 12.5% sisal without chemical treatment showed resistance to bending stress of 11.31 MPa, values higher than those found for the same composition with sawdust treatment. The composites were considered suitable for handcrafted use and decorations.