Development of an Epoxy Matrix Hybrid Composite with Astrocaryum Aculeatum (Tucumã) Endocarp and Kaolin from the Amazonas State in Brazil

Abstract

Composites with natural lignocellulosic fillers are being cited as a viable and sustainable alternative to conventional materials, as they combine lower costs with lower weight. In many tropical countries, such as Brazil, there is a considerable amount of lignocellulosic waste that is improperly discarded, which causes pollution of the environment. The Amazon region has huge deposits of clay silicate materials in the Negro River basin, such as kaolin, which can be used as fillers in polymeric composite materials. This work investigates a new composite material (ETK) made of epoxy resin (ER), powdered tucumã endocarp (PTE), and kaolin (K), without coupling agents, with the aim of producing a composite with lower environmental impact. The ETK samples, totaling 25 different compositions, were prepared by cold molding. Characterizations of the samples were performed using a scanning electron microscope (SEM) and a Fourier-transform infrared spectrometer (FTIR). In addition, the mechanical properties were determined via tensile, compressive, three-point flexural and impact tests. The FTIR and SEM results showed an interaction between ER, PTE, and K, and the incorporation of PTE and K reduced the mechanical properties of the ETK samples. Nonetheless, these composites can be considered potential materials to be used for sustainable engineering applications in which high mechanical strength is not a main requirement of the material.

Amazon Natural Fibers for Application in Engineering Composites and Sustainable Actions: A Review

“…As noted in Table 5, most natural fibers have a maximum density close to 1.60 g/cm 3 , making them heavier than water. Although some natural fibers, such as vakka, bamboo, and rachila abaca, among others, are hollow and have low densities in their natural state, they are often densified during processing.…”

“…These fibers are lignocellulosic in nature and have an elliptical shape with an average thickness of 130 µm and a length of about 18 mm. They have a slightly higher density than water, approximately 1.11 g/cm 3 . Generally, açaí fibers are underutilized due to their toxic residues, leading to various environmental issues, and the extracted fiber yield is low [176][177][178].…”

“…The buriti fibers exhibit a comparatively low density ranging from 0.63 to 1.12 g/cm 3 , coupled with a moderate tensile strength within the range of 129 to 254 MPa. This characteristic renders them suitable as reinforcement for polymer composites characterized by lower density yet relatively weaker strength [213].…”

“…Junio et al [222] studied the influence of the average diameter of carnauba fiber. When conducting studies with fibers with an average of 0.765 ± 0.22 mm, the author observed that the average density of the fibers was 1.13 ± 0.22 g/cm 3 , and there was a 54.5% reduction in density with increasing fiber diameter compared to the beginning and end of the fiber, as well as an 87.3% reduction in Young's modulus and 83.4% in tensile strength.…”

“…Nature has provided a comprehensive diversity of natural fibers throughout the ages. With a remarkably extensive history, these fibers have roots that date back to prehistoric times, unquestionably meeting human needs throughout history [1][2][3]. Vegetable fibers have been used for various purposes in different eras and regions of the world.…”