Caracterização mecânica e análise fractográfica de compósitos poliméricos com fibras naturais do epicarpo do coco babaçu (Orbignya Speciosa)

Abstract

The pressure exerted on natural resources, arising from the exponential growth of world demand, leads human activity to an unprecedented scenario. Researchers have been demonstrating numerous efforts for sustainable solutions, in this scenario there is a continuous growth in the development of composite materials with vegetable fibers. In this work, pure orthophthalic polyester matrix materials and composite materials with plant fibers from the babassu coconut epicarp were produced. The composites were manufactured manually using silicone molds. The fibers characterized according to their morphology, through scanning electron microscopy (SEM), were randomly inserted with mass fractions set at 3% and 5%, length varying between 10 mm and 20 mm. The composites produced were analyzed for their mechanical properties, through tensile and flexural tests according to ASTM D 638 and ASTM D 790 standards, and fractographic analysis of the fracture surface through scanning electron microscopy (SEM). The morphological analysis of the surface of the fibers showed its roughness and characteristics present in vegetable fibers. For composites with 3% of fibers, a tensile strength of 20.03 MPa was obtained, while for composites with 5% of fibers, the result was 14.16 MPa. of 32.34 MPa for the composites with 3% of fibers and 37.01 MPa for the composites with 5% of fibers, in both properties (tensile strength and flexural strength) there was a reduction of the same when compared to the matrix material pure. With regard to the modulus of elasticity, the composites had an increase in this mechanical property when compared to the pure matrix, confirming that the increase in the stiffness of the material is due to the increase in the fiber fraction, with the best results obtained in composites with 5 % of fibers, 0.486 GPa in tensile tests and 27.10 GPa in bending tests. The fractographic analyzes of the fracture surfaces showed satisfactory results regarding the identification of failure mechanisms and characteristics present in the composites, such as the presence of air bubbles, voids and the phenomenon of fibers pulled out of the matrix (pull out), indicating low adhesion at the interface matrix/fiber.