Influência de variáveis de processo nas propriedades mecânicas dos compósitos PEAD/pinus e PEAD/algarobeira.

Abstract

This work investigates the feasibility of using post mesquite the wood (hard wood, not marketed) in the preparation of composite plastic/wood, and compares the properties of these composite systems related to manufactured with powder of pine (soft wood, marketing). We assessed the following effects on mechanical properties: a) concentration changes in the matrix residue incorporated b) melting temperature, rotor speed, processing time, c) influence of the dust of wood mesquite as the longitudinal (eg, means and top) and transverse (bark, and sapwood or white and durâmen) from where the powder was removed. The pure HDPE and the composites were PEAD/Pine to compression and injection molded and PEAD/Mesquite composites were injection molded. It also investigated the water sorption of composites and pure HDPE, HDPE/Pine, HDPE/Mesquite. It was found that more severe processing conditions (time, temperature and speed of the rotor) led to a reduction of mechanical properties, although not significant, for both composites, attributed to a slight degradation of the matrix. Best result was obtained by the composite HDPE/Pine processed to 150 oC, 50 rpm for 10 minutes. The tensile strength and modulus of elasticity of the composite HDPE/Mesquite were slightly lower than that of the composite HDPE/Pine. The compression molded composites also showed properties inferior to those obtained by injection, because of defective parts and not homogeneous because of poor dispersion, poor compression molding and inefficient. It was found that the sorption of water in the composite was rapid in the early stages, tending to equilibrium in times longer exposure (up to 980 hours) due to the dust timber is very hygroscopic, ie more dense showed lower sorption of water. This study indicates that the fibers act as inert cargo, which could promote an economy of material used for polymer composites, which can use the mixed powder of wood due to no significant difference in their mechanical properties in relation to its position in log.