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This research is primarily based on the search for alternative natural reinforcements to polymeric composites. This study begins with a complete characterization of the licuri fiber as an alternative reinforcement to polymeric composites. It then investigates the development of a composite laminate made solely from licuri fibers to understand the behavior of the fiber when impregnated in thermosetting resin (orthophthalic unsaturated polyester resin). The composite was developed as a lamina (a sheet with a single reinforcement layer) and industrially manufactured. The fibers were studied to determine their physical, chemical, and mechanical properties. The mechanical properties of the lamina were determined by uniaxial tensile and three-point bending tests. Macroscopic and microscopic (SEM) studies of the fracture were carried out to determine the influence of fiber/matrix interfacial adhesion on the final composite for both loads.

The gradual replacement of conventional materials with composite materials has become a concern due to their response to adverse environmental conditions, such as ultraviolet radiation, high temperature, and humidity. In this context, composite laminate using ortho-terephthalic polyester resin as matrix, reinforced with two layers of unidirectional woven licuri fiber, was submitted to accelerated environmental aging in order to study the influence of environmental degradation on mechanical properties, morphology, and fracture characteristics. Age-related morphological degradation of composite laminate was studied based on microscopic analysis of the microstructure and mass loss. In general, the licuri fiber reinforced plastics exhibited certain advantages in its responses to environmental aging. These advantages are evident in behavior related to photo-oxidation and microstructure degradation. Losses were recorded in the mechanical properties of the aged laminate when compared to the original condition; however, the structural integrity was little affected.

Increasing non-biodegradable plastic consumption is a great factor that contributes to worldwide pollution and global warming. Mechanochemistry provides a clean, solvent-less, route for chemical reactions such as polymerization based on the absorption of mechanical energy. Urea polymers have several applications in industrial and medical area, such as paints, resins, plastic, wood glue, separating aliphatic hydrocarbons, coating, and pharmaceutical drugs. In this study, a copolymer of urea and citric acid was synthesized using a planetary ball mill as grinder with fixed reaction time and rotational speed, varying the number and material of the planetary ball mill sphere to find the effects of those two conditions in the yield percentage of the copolymer. The purified polymer was characterized by Infrared spectroscopy (FTIR) and Nuclear Magnetic Resonance – NMR. Results confirmed that polymeric material is formed by the reaction between citric acid and urea without any catalyzer using mechanochemistry. NMR results showed that the reaction occurred between urea and the acid groups at the ends of the chain, while the central COOH remained intact.

Natural fiber reinforced plastics (NFRP) have awakened considerable interest in the area of polymer composites, because of the need to develop new, environmentally friendly materials. One of the most complex ways of manufacturing this type of material is in the form of ultrathin laminar layers; however, this process hinders mechanical testing, mainly three and four-point bending. The present investigation faces this challenge and shows the influence of parameters, such as the grammage of reinforcing fabric and lamination process, on strength, stiffness and fracture characteristics for three-point bending in this type of structural element. The industrially manufactured laminas were composed of orthophthalic polyester resin reinforced with licuri fibers. Macromechanical and micromechanical analyses were conducted in the study of fracture characteristics for all the parameters. The mechanical behavior in the three-point bending of the laminar composite showed that the use of licuri fiber to obtain natural fiber-based plastic is completely viable.

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