Characterization of Continuous Gradient Functionally Graded Natural Fiber Reinforced Polymer Composites

In this study, cylindrical tubes of functionally graded natural fibre reinforced polymer (FGNF/epoxy) composite are fabricated using horizontal centrifugal casting method. Natural fibres (NF) used in this research are coconut coir and oil palm empty fruit bunch (OPEFB). Natural fibres are mixed with epoxy at four different compositions which is at 0%, 5%, 10% and 15%. The study aims to determine the mechanical properties and microstructure of the FGNF/Epoxy composites. In this method, a homogenous mixture of epoxy liquid and natural fibres is inserted into mould simultaneously. Then, the mould is rotated at a constant speed for 4 hours. Effect of this process, the natural fibres particles in epoxy liquid move radial during mould rotation. Hardness and compression test are carried out to characterize the FGNF/epoxy cylindrical tubes. The microstructures of the composites are observed using optical microscope (OM) and scanning electron microscope (SEM). From the microstructural observation, it is found that the natural fibres particles can be graded from inner to outer surfaces of the FGNF/epoxy cylindrical tubes. The hardness value of the outer part of the FGNF/epoxy fabricated is higher than the middle and inner parts. Besides, from the compression test it shows that epoxy reinforced NF give a better result in strength compared to specimen without reinforced NF. However, the strength value decrease when the fibres percentage increase more than 5%. FGNF/epoxy with 5% NF content gives a balanced composition to have high hardness value and strength.