RESUMONos últimos anos tem surgido um grande interesse na utilização de fibras lignocelulósicas como material de reforço em compósitos poliméricos. Neste trabalho foram produzidos compósitos poliméricos de polipropileno com fibra de capim-elefante (Pennisetum purpureum Schum.) denominado (PP/Capim). O efeito do teor de carga e o envelhecimento acelerado sobre as propriedades mecânicas dos compósitos PP/Capim foram avaliados. Os compósitos foram preparados através do processo de extrusão de polipropileno com fibra de capim elefante na relação de 15 e 25% em massa. As amostras foram moldadas por processo de injeção de acordo com as normas American Society for Testing and Materials (ASTM). Na avaliação das propriedades de compósitos, os resultados obtidos mostraram que o aumento na quantidade de carga, resultou numa diminuição das propriedades mecânicas em tração e aumento do índice de fluidez, dureza Shore D e densidade. Quanto ao envelhecimento acelerado, os compósitos não apresentaram diferenças significativas são extremamente favoráveis quando comparado a outros sistemas comerciais reforçados por cargas inorgânicas. Palavras-chave:Fibras lignocelulósicas, Termoplástico, Capim-elefante. GRASS AS REINFORCEMENT OF POLYPROPYLENE ABSTRACTConsiderable interest has been generated in the use of lignocellulosic fibers as filler and reinforcements in polymeric composite. In this work polymeric composites were obtained from elephant grass fiber and polypropylene (PP/Grass). The effects of the content filler and accelerated aging on the mechanical properties of polypropylene composites reinforced with elephant grass fiber were evaluated. The composites were prepared through the extrusion process of polypropylene with grass fiber in ratio 15 and 25% wt. The specimens were injection molded according to American Society for Testing and Materials standards. In the evaluation of the composite properties, the obtained results noticed that increasing the filler amount resulted in a decrease of mechanical properties and increase in flow index, shore D hardness and density. The composites did not show significant differences as function of accelerated aging. The results showed that composite properties are extremely favorable when compared to other commercial systems reinforced by inorganic fillers.
The study of connections for timber structures has been the subject of intense research in Brazil. This work aimed to study the embedment strength of connections made by steel pins (dowels) in specimens of reforested woods. Analytical and experimental evaluations were considered in this study. Initially, tests on specimens made from Pinus elliottii (Class C30) and Eucalyptus salligna (Class C50) woods with dowels, type 1020, with diameter of 6.35 mm (1/4") were performed. The tests were performed according to the ANBT NBR 7190 (1997)
Wood sanding is one of the most expensive processes in the woodworking industry, and little is known about the factors that influence the final quality of wooden parts. For this reason, studies involving different wood treatments, such as thermal treatment, have been developed to produce better surface qualities. The objective of this work was to verify the influence of thermal treatment of the wood species Corymbia citriodora before the sanding process on the surface quality of the wood pieces. The surface finishes of the sanded natural and heat-treated wood were compared. Sanding was performed using two sandpaper grades, 80 mesh and 120 mesh, with abrasive grains of aluminum oxide. The sanding process was performed by flat horizontal sanding parallel to the fibers. Six specimens were used for each sandpaper grade. Initially the specimens were heat-treated at 120 °C, 160 °C, and 200 °C for 2 h, and then they were subjected to sanding. For the analysis of the surface quality of the wood pieces, the average roughness was used. From the obtained results, it was concluded that the heat treatment considerably reduced the roughness of the wood for both sandpaper grit sizes, and it facilitated the final finishing of the wood pieces.
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