Effect of Fiber Content, Fiber Length and Alkali Treatment on Properties of Kenaf Fiber/UPR Composites Based on Recycled PET Wastes

Kenaf fibers were mixed with unsaturated polyester resin (UPR), which was prepared by recycling of polyethylene therephthalate (PET) waste bottles. Grinded PET waste bottles were subjected to recycle by glycolysis which was used to prepare unsaturated polyester resin. The resin was then mixed with kenaf fibers in two different lengths (2.5 and 5 mm) at different fiber loading (2.5 and 5 phr of kenaf in UPR resin). The effects of fiber content, fiber size and surface treatment on the mechanical properties, density and water absorption of the composite were studied. The SEM and FTIR analysis were used to analyse the influence of alkali treatment on fibers and interfacial interaction between fibers and matrix. The results show that the optimum values of the stiffness properties and impact strength is at 2.5 phr, whereas tensile strength decreases with increasing fiber content. The length of fiber played a significant role in some of the mechanical properties of the composites with 5 mm fiber length has higher mechanical properties than 2.5 mm length. The results also showed that alkali treatment causes a better adhesion between the fiber and UPR matrix and improves the mechanical properties of the composites. Furthermore, surface treatment reduced the water absorption of composites.