Avaliação das propriedades mecânicas e térmicas de um compósito polimérico reforçado por particulados de sabugo de milho triturado

Abstract

The utilization of natural lignocellulosic fibers acquired through the vegetables and plants is increasingly recognized as an environmentally correct alternative to replacing non-recyclable materials. An example of this are the granules and bran of the corn cob, a type of waste that can be found in large quantities throughout the world and that are frequently used in animal feeding and/or fertilization of land. This lignocellulosic residue, the granules and the bran of the corn cob, has been studied as polymeric composites, reinforced by them. Due to the fact that the granules of corn cob can be found in large quantity, we aim, in this work, to study the feasibility of the use of crushed corn cob, employed as a filler particulate reinforcement in a composite material with a polyester resin polymeric matrix, so that it might be possible to determine its applicability in different areas of engineering. Three different particle sizes of this reinforcement were used: fine particles (PF) with 44μm, medium particles (MP) with 850 μm and large particles (LP) with 2360 μm, in percentages of 0%, 5%, 10% and 20% in weight. The reinforcements were selected through hand sieving and blending the resin manually to obtain the evidence specimens. Such dosages were important in order to investigate and compare the influence of reinforcements on mechanical and thermal properties of the composite material. The mechanical characterization of the composites were made by mechanical property testing (tensile, flexion and impact). Also, the morphological analyzes of pure resin (polyester) and the composites were performed by scanning electron microscopy (SEM). On the other hand, the thermal conductivity analysis was performed by the compensated hot plate device method, and the thermal characterization was performed by thermogravimetry (TGA). As observed in the results of mechanical property testing (tensile, flexion and impact), specimens with presence of 5% of fine particle of the corn cob show greater resistance than the ones with large particle and medium particle, which reinforces the relevance of the applicability of this material in the industry. Fractographic analyzes of the composites obtained through SEM indicated low mechanical adhesion load / matrix, with little evidence of transfer of effective tensions between phases. In terms of homogeneity of the mixture, the most viable particle size is the fine particle (FP). The composites obtained proved to be viable for thermal applications, with thermal conductivity lower than 0.25 W / m, being classified as thermal insulation of good quality. Thus, it can be emphasized that this composite showed a good thermal stability, can have its relevant applications, as thermal insulators, or as structural elements that are subject to light mechanical loading for composites with fine particle (FP) or medium particle (MP).