Avaliação da morfologia e propriedades mecânicas de compósitos de estrutura sanduíche a base de epóxi e cortiça

Abstract

Among the various possible design forms in composite structures, the idea of sandwich construction has become popular due to the development of artificial cell core materials, since they have different characteristics than those obtained in traditional solid materials. In this work polymeric sandwich composites were developed, using cork powder as core reinforcement. As a performance parameter, samples of pure resin and sandwich composites with the incorporation of hollow glass microspheres as core were used, having their composition tested in some iterations until the composition selected was 55% by volume of filler and 45% of resin. For the manufacture of the composites was used the technique of simple layer superposition, individually preparing each layer by means of casting the pure or composite resin into molds. The epoxy resin, matrix of the composites, was used as an adhesive between the layers. Morphological characteristics were determined by means of the scanning electron microscope. The influence of the filler on the density of the composite was also evaluated. The mechanical characteristics were observed by tensile, flexural and impact tests. Good dispersion of both cork powder and hollow glass microspheres was observed in the sandwich cores. However, it was possible to verify that in the cores the cork base had better adhesion of the filler to the matrix. At some points in the core the microspheres appeared supernatant in the matrix, with little adhesion. It was also observed a reduction in the density of all the composites with respect to the pure matrix. According to the presented results, it can be affirmed that for this concentration range and conditions of applied methodology, the use of cork powder as reinforcement of the core of sandwich structure presents results similar to the reinforcement of hollow glass microspheres. In all scenarios with the sandwich composites, the ductility of the specimens was reduced in relation to the pure matrix. Composite core sandwiches with cork incorporation may be applied where there is an expectation of weight reduction and/or higher tensile and flexural stresses than those supported by pure resin, especially where the concern with impact situations is not decisive.