Desenvolvimento de compósito poliéster insaturado/fibras vegetais (caroá e coco).

Abstract

In addition to improving the physical and mechanical properties of composites, the use of vegettable fibers minimizes environmental pollution and production costs of these materials. In this work, caroá and coconut fibers were used as reinforcement of a commercial, natural source polymer, known as biopoli. Composites containing 13, 23, 30 and 40% w/w caroa or coconut fibers were manufactures and their mechanical, flexural and impact performances were determined. A study on the thermal aging of the composites at a constant temperature (110 °C) was also performed. Fibers and composites were characterized by thermogravimetric analysis (TGA), X-ray diffraction (XRD) and scanning electron microscopy (SEM). It was found that the best mechanical properties were achieved for composites containing between 30 and 23%(w/w) fiber (caroa or coconut). For example, the tensile strength was higher for the composite containing 30% caroá fiber (36.94 MPa) and for the one with 23% (13.3 MPa) coconut fiber. Thermal aging test showed that there was significant loss on the tensile strength of the composites as a function of thermal exposure. Flexural strength, tensile and flexural moduli were hardly affected by thermal exposure, whereas the impact strength values showed a gradual decrease of up to 65 and 85.33% for composites made with coconut and caroa fibera, respectively, after 40 days of thermal exposure. Matrix and composites made with 23% w/w of fibers (caroa or coconut) with and without synthetic enamel coating subjected to accelerated aging cycles by exposure to ultraviolet (UV) light/humidity/temperature. The results show a reduction in tensile strength and in impact resistance with exposure time. The surface coating minimized the damage caused by aging in all samples (matrix and composites). Water sorption studies were conducted on boiling water and at room temperature on samples coated and uncoated with resin and or enamel. Our data suggests that resin coating reduced water pick up but enamel coating was ineffective and actually increased water pick up kinetics and content, which was attributed to the enamel chemical composition. Finally, we performed the acoustic emission test in the matrix and composites made with 13 and 40% caroá fiber and 40% coconut fiber, the results showed a higher number of hits in the composites compared to the polymer matrix, assigned the detachment of the interface, delamination and also because the largest number and route of cracks occurred in the composites. Given the set of properties obtained it can be concluded that the composites containing 23% fiber caroá and coconut are options to be used in furniture, panels and partitions environments, mainly because these composites having less environmental impact, since they are made from renewable plant sources and.