Desenvolvimento de compósitos poliméricos de matriz epóxi reforçados com partículas do caroço de Euterpe edulis Martius tratadas quimicamente

Abstract

The industrial sector has an interest in developing products that can be manufactured using less energy and with low environmental impact. In this regard, polymeric composite materials stand out due to their versatility in obtaining products with different structures and properties. The use of agricultural residues to reinforce polymeric matrices reduces the handling of petrochemical raw materials in the generation of new products. In this context, the juçara seed, a byproduct of the fruit of the Euterpe edulis Martius palm, discarded after extracting the pulp for consumption, is a promising agro-industrial waste. In light of the above, aiming for innovation in the field of renewable materials, the objective of this research is the reuse of juçara seeds as reinforcement in epoxy polymeric matrices and the study of the influence of chemical treatments with 7% sodium hydroxide (NaOH) and acetylation (acetic anhydride and acetic acid). Therefore, this study produced and characterized composites with epoxy matrix reinforced with 50, 60, and 70% natural, alkaline, and acetylated juçara seed fibers and particles. Lignocellulosic characterization, particle size distribution, scanning electron microscopy (SEM), thermogravimetry (TG), Fourier-transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD) were carried out on the three types of juçara seed fibers and particles (JSFP). These were mixed with epoxy resin and inserted into a metal mold to be pressed at 4.72 MPa for 24 hours. For the characterization of the composites, analyses of water absorption, tensile strength, flexural strength, Charpy impact, TG, SEM, FTIR, and XRD were performed. In the flexural and Charpy impact tests, the composites with 50% acetylated JSFP and 60% natural JSFP obtained the highest resistance. In the tensile test, no composite achieved a strength equal to or higher than pure resin. In the water absorption test, the composite with 50% acetylated JSFP was the only one with low absorption. SEM, XRD, TG, and lignocellulosic analysis confirmed an increase in the hydrophobicity of acetylated JSFP and a better interaction between them and the epoxy matrix in the acetylated composites. Overall, aiming for mechanical performance and sustainability, natural composites are most suitable for industrial applications.