Produção e caracterização fisico-mecânica de compósitos de matrizes poliméricas e matrizes polímericas funcionalizadas com nanotubos de carbono reforçadas com fibras da Amazônia

Abstract

The development of new materials with distinctive characteristics such as good mechanical performance and biodegradability has increased considerably in recent years. In this sense, the production of polymer matrix composites reinforced with natural fibers from the Amazon and the addition of carbon nanotubes emerges as a viable alternative for these new materials. The Amazon region has a wide variety of species from which natural fibers can be extracted and used to reinforce composite materials. Among these species, the periquiteira (Cochlospermum orinocense) and envira (Bocageopsis multiflora) plants have shown potential for use as reinforcing agents in polymer matrices. In addition, the addition of carbon nanotubes can improve the mechanical properties of composites. Thus, this work aims to produce composite materials from polymer matrices (polyester and epoxy) reinforced with natural fibers and polymer matrix composites with the addition of carbon nanotubes (CNTs) and reinforced with natural fibers. Physical, chemical, and thermal characterizations were performed on the fibers. The composites were produced with the incorporation of 10, 20, 30, and 40% fiber by volume, and the nanocomposites with the addition of 0.1% CNTs. The mechanical properties of the composites were evaluated by tensile, flexural, and impact testing, performed following the guidelines of ASTM D 638, ASTM D 790, and ASTM 256 standards. The characterizations of periquiteira and envira fibers indicated values of density, crystallinity index, thermal stability, and functional groups characteristic of lignocellulosic fibers. In xiii addition, morphological analysis by SEM revealed that both periquiteira and envira fibers had fine bundles of fibrils and a rough surface along their entire length. The mechanical tensile strength values of the fibers indicated that these fibers have the potential to be used as reinforcement in polymer composites. The mechanical tensile characterization of composites with periquiteira fibers in an epoxy matrix showed an increase of 48% and with envira fiber 36% in relation to the matrix. For composites with a polyester matrix, the increase in the ideal fiber concentration was 70% for periquiteira and 36% for envira fiber. In relation to flexural strength, only the epoxy matrix composition with periquiteira fiber showed an increase in strength. For nanocomposites, there was no significant change in the results obtained for both tensile and flexural strength. Analyses of the fracture region indicated that, in general, the fracture occurred in a brittle manner. In relation to nanocomposites, areas of NTC agglomeration were observed, indicating that adequate dispersion did not occur.