Tecnologia em Metalurgia, Materiais e Mineração
https://tecnologiammm.com.br/article/doi/10.4322/tmm.00502009
Tecnologia em Metalurgia, Materiais e Mineração
Artigo Original

EFEITO DA INCORPORAÇÃO DE FIBRAS DE COCO NO COMPORTAMENTO DINÂMICO-MECÂNICO DE COMPÓSITOS COM MATRIZ POLIÉSTER

EFFECT OF COIR FIBER INCORPORATION IN DYNAMIC MECHANIC BEHAVIOR OF POLYESTER- MATRIX COMPOSITES

Monteiro, Sérgio Neves; Rodriguez, Rubén Jesus S.; Lopes, Felipe Perissé D.; Sores, Bluma Guenther

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Resumo

Realizou-se um estudo da variação com a temperatura dos parâmetros dinâmico-mecânicos de compósitos com matriz poliéster incorporada com fibras de coco. Diferentes percentagens em peso de fibras de coco, até 40%, foram misturadas com resina poliéster ortoftálica e, após prensagem, curada por 24 horas à temperatura ambiente. Ensaios dinâmico-mecânicos (DMA) foram realizados para se obter os módulos de armazenamento e perda, bem como a tangente delta para cada tipo de compósito com diferentes quantidades de fibra de coco. Os resultados desses parâmetros revelam que a incorporação de fibra de coco diminui a rigidez viscoelástica do compósito com matriz poliéster. Esta redução na rigidez está associada à baixa tensão interfacial, o que dificulta a transferência de esforços mecânicos da matriz para a fibra. Ocorrem também modificações na temperatura de transição vítrea e no pico α de relaxação com a incorporação de fibras de coco. Em particular, o amortecimento do compósito que está relacionado ao valor da tangente delta, diminui a quantidade de fibra incorporada pelo fato de somente parte da tensão aplicada deformar a interface fibra/matriz.

Palavras-chave

Fibra vegetal, Compósitos, Matriz poliéster, Comportamento, Temperatura de transição

Abstract

A study on the temperature variation of the dynamic-mechanical parameters of polyester matrix composites incorporated with continuous coir fibers was carried out. Different weight percentages, up to 40 wt.% of coir fibers, were mixed with orthophtalic polyester resin and, after press-molding, cured for 24 hours at room temperature. Dynamic-mechanical, DMA, tests were conducted to obtain the storage modulus and the loss modulus as well as the tangent delta for each type of composite with different amounts of coir fibers. The DMA results revealed that the incorporation of coir fiber decreases the viscoelastic stiffness of the composite with polyester matrix. This reduction in stiffness is associated with a low interfacial shear stress, which makes it difficult for the mechanical load transfer from the matrix to the fiber. Modifications in the glass transition temperature and in the a relaxation peak also occurred with the amount of incorporated coir fiber. In particular, the damping response of the composite, associated with the value of the tangent delta, decreases with the amount of incorporated fiber owing to the fact that only part of the applied stress was used to deform the fiber/matrix interface.

Keywords

Coir fiber, Polyester composites, Dynamic-mechanical behavior, Glass transition temperature

Referências

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