Compósitos De Polipropileno Reforçado Com Capim-Elefante

Abstract

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.

Composites based on low-density polyethylene combined with PETcoated SBS paperboard shavings

“…This can be attributed to the amount of cellulosic fiber present in the composites, that is, the higher the percentage of cellulose fibers (APPET) the higher the density will be. A study by Caraschi et al [29] on the production and characterization of polypropylene containing composites reinforced with elephant grass fibers showed no significant difference between the density of pure polypropylene and the composite reinforced with 15% fibers (0.88 g.cm -3 ). However, when the elephant grass fiber reinforcement was 25%, the composite density increased significantly to 0.91 g.cm -3 , indicating that the increase in the percentage of cellulosic fibers causes density to increase [29].…”

“…A study by Caraschi et al [29] on the production and characterization of polypropylene containing composites reinforced with elephant grass fibers showed no significant difference between the density of pure polypropylene and the composite reinforced with 15% fibers (0.88 g.cm -3 ). However, when the elephant grass fiber reinforcement was 25%, the composite density increased significantly to 0.91 g.cm -3 , indicating that the increase in the percentage of cellulosic fibers causes density to increase [29]. The same phenomenon can be explained by the effect of the filling load on the density of the palm tree reinforced polyester composites [15].…”

“…According to Garcia et al [35], a lack of adequate compatibility between the fibers and the matrix leads to insufficient interfacial adhesion, which affects the mechanical properties. For deformation, it is important to increase its percentage in relation to the intensification of APPET content, since this parameter is inversely proportional to the modulus of elasticity [29]. On comparing the rupture strength results for the specimens obtained with the two methods (pressing and extruding) a significant difference is observed (p = 0.00).…”

“…The decrease in the tensile strength and elasticity values of the composites studied in this work, due to the increase in the content of APPET, can be explained, in part, to the hydrophobic behavior of the LDPE. The opposite is observed with the lignocellulosic fibers, which show hydrophilic behavior, resulting in low interfacial adhesion between the polymer phase and the fibrous phase [29]. According to Garcia et al [35], a lack of adequate compatibility between the fibers and the matrix leads to insufficient interfacial adhesion, which affects the mechanical properties.…”

“…In this study with APPET, another explanation for the decrease of the modulus of impact resistance in relation to the increase of fiber concentration in the composite is the low affinity between the matrix and the reinforcement. This is due to the hydrophilic character of the cellulose in the APPET, reducing adhesion with the LDPE matrix [22,29]. Mirmehdi et al [34] carried out a study with the objective was to evaluate the influence of the amount and aspect of the lignocellulosic reinforcement on the mechanical properties of LDPE matrix composites.…”