Avaliação microestrutural e mecânica das fibras de cotia e dos compósitos de matriz poliéster

Abstract

The search for sustainable and low-cost materials has driven the use of natural fibers in the development of polymer composites, due to their mechanical and sustainable properties. The aim of this work is to study and characterize a new natural fiber, as well as to study the mechanical properties of composites made with in natura fibres (FC) and mercerized fibres (FM) in volumetric percentages of 10, 20 and 30%. The fibres and composites were characterized using Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), Thermogravimetry (TGA), Scanning Calorimetry (DSC), Energy Dispersive Spectroscopy (EDS) and Raman Spectroscopy, as well as mechanical characterization. The physical characterization of the fiber indicated an average density of around 0.34 g/cm3. The FTIR of the FC and FM fibers indicated chemical structural changes, which were confirmed with Raman, SEM and EDS. The thermal stability of Cotia fiber in natura was close to 145 and 272 ºC. The mechanical properties of the FC and FM fibers showed average strengths of around 151.32 and 99.98 MPa, respectively. The FTIR and Raman scans of the composites showed few changes related to the variation in chemical treatment, but differences when percentages of fibers were added. The tensile and flexural results indicated that the CF fibers were stronger and stiffer in relation to the matrix than the modified fibers. The SEM confirmed the existence of defects and flaws that caused early rupture of the composites with FM fibers. The single and double F ANOVA confirmed that both factors, chemical modification and increase in volume percentage, had an impact on the final properties. Although the results of the FM fibers did not have a positive impact, the properties of the in natura fibers stand out as efficient reinforcements for engineering applications.