COMPÓSITOS POLIMÉRICOS REFORÇADOS COM POLPA DE MADEIRA

Abstract

The use of reinforcement from cellulosic fibers in composites is advantageous when compared to inorganic materials, because they have a lower density, are less abrasive and less expensive, and present themselves as a raw material from renewable resources. The objective of this study was to evaluate the influence of the bleached and unbleached cellulosic pulp obtained by the chemical process, mechanical process pulp and wood-flour, of Pinus taeda as reinforcement in low density polyethylene (LDPE) matrix, virgin and recycled, together with a maleic anhydride coupling agent, in the properties of wood-plastic composites. The composites were produced by extrusion and the specimens molded by compression. The samples were characterized by thermal analysis (TGA and DTG), density, mechanical properties and scanning electron microscopy (SEM). It was found that when the pulp and flour were incorporated into the matrix the composites mechanical properties were improved. Thermal analysis showed that the addition of reinforcement to the matrix reduced the rate of material degradation. It was found that all reinforcement types acted as nucleating agents because the composites had better mechanical properties than pure LDPE. In this study, the tensile strength and flexural strength was influenced by all parameters studied and the interactions were significant. In general, the highest values of strength and stiffness were obtained with the use of thermo-mechanical process pulp as reinforcement and the lowest values with the use of unbleached chemical process pulp. Photomicrographs analysis showed that the coupling agent was effective for compatibilizing the reinforcement with the matrix in the composites. It was possible to produce composite materials with good physico-mechanical properties and improved thermal stability.