Mechanical properties of composites reinforced with lignocellulosic fibers have been researched in recent decades. Jute and mallow fibers are reinforcement alternatives, as they can contribute to increase the mechanical strength of composite materials. The present work aims to predict the Young’s modulus with application of continuous and aligned lignocellulosic fibers to be applied as reinforcement in polyester matrix. Fibers were manually separated and then arranged and aligned in the polyester matrix. Composites with addition 5, 15, and 25 vol% jute and mallow fibers were produced by vacuum-assisted hand lay-up/vaccum-bagging procedure. Samples were tested in tensile and the tensile strength, elasticity modulus, and deformation were determined. Results showed that the intrinsic Young’s modulus of the fibers was set at values around 17.95 and 11.72 GPa for jute and mallow fibers, respectively. Statistical analysis showed that composites reinforced with 15 and 25 vol% jute and mallow presented the highest values of tensile strength and Young’s modulus. The incorporation of 25 vol% of jute and mallow fibers increased the matrix Young’s modulus by 534% and 353%, respectively, effectively stiffening the composite material. Prediction models presented similar values for the Young’s modulus, showing that jute and mallow fibers might be used as potential reinforcement of polymeric matrices
Natural lignocellulosic fibers (NLFs) have in recent decades appeared as sustainable reinforcement alternatives to replace synthetic fibers in polymer composite material applications. In this work, for the first time, the periquiteira (Cochlospermum orinocense), a lesser known NLF from the Amazon region, was analyzed for its density and, by X-ray diffraction (XRD), to calculate the crystallinity index as well as the microfibrillar angle (MFA), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), scanning electron analysis (SEM) and tensile strength. The apparent density found for the periquiteira fiber was 0.43 g/cm3, one of the NLF’s lowest. XRD analysis indicated a crystallinity index of 70.49% and MFA of 7.32°. The TGA disclosed thermal stability up to 250 °C. The FTIR analysis indicated the presence of functional groups characteristic of NLFs. The SEM morphological analysis revealed that the periquiteira fiber presents fine bundles of fibrils and a rough surface throughout its entire length. The average strength value of the periquiteira fiber was found as 178 MPa. These preliminary results indicate that the periquiteira fiber has the potential to be used as a reinforcing agent in polymeric matrices and can generate a lightweight composite with excellent mechanical properties that can be used in various industrial sectors.
Composite materials stand out for enabling the development of new materials that are environmentally friendly, whose manufacturing processes and waste are increasingly less harmful, associated with good mechanical properties. In this context, this work sought to investigate the mechanical behavior in flexural and impact of polyester matrix composites with the inclusion of short fibers of sisal, piassava, raffia, mallow and jute arranged randomly. The mechanical properties of flexural were evaluated according to ASTM D 790 and the impact toughness Charpy with the ASTM D 6110 standard. The results showed that when subjected to flexural stresses, the composites presented resistance of 112 .12 MPa for the neat matrix and 35.21; 34.45; 27.29; 25.89 and 20.56 MPa with the inclusion of sisal, piassava, raffia, mallow and jute fibers, respectively. As for the impact test, they showed values of 31.50 kJ/m² for the neat matrix and 57.06; 52.52; 48.03; 38.02; 37.65 kJ/m² with the inclusion of sisal, piassava, raffia, mallow and jute fibers, respectively. Then, the fracture surface of the composites was analyzed with a microscope in order to correlate the fracture aspects with the mechanical properties.
Neste trabalho foram desenvolvidos e caracterizados materiais compósitos de matriz poliéster insaturada, na presença de resíduo de madeira (maracatiara, marupá e angelim pedra) e fibra natural (juta) na forma de tecido plano. Os processos de fabricação utilizados neste trabalho foram os de laminação manual e compressão a frio. Foram fabricados corpos de provas de materiais compósitos com poliéster/resíduos de madeira e as combinações de compósitos híbridos poliéster/tecido de juta/resíduos de madeira. Avaliou-se o comportamento mecânico dos compósitos em tração de acordo com os procedimentos da ASTM e micrografias em MEV da superfície de fratura. A metodologia de fabricação utilizada mostrou-se satisfatória principalmente em função das propriedades da matriz e para a carga na forma de lascas (maravalha).
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