Nowadays, the world is facing a crisis in regards to renewable resources and rising carbon footprint. In the microscopic scale of engineering, this is where natural fibers come into play. Natural fibers comprise of considerable advantages that include being lightweight, inexpensive and renewable in comparison to their synthetic counterparts. The fibers are being used as reinforcement in composite matrices, including hybrid composites. The main issue with natural fibers is the high disparity of its mechanical properties, especially tensile strength. In this study, Weibull statistical analysis is utilised in order to quantify the variation of the probabilistic strength of banana fibers. Single fiber tensile test was performed after the fiber diameters were measured at 1mm intervals along its length. The modified Weibull distribution with conical frustum model can predict the gauge length effect more accurately than the conventional Weibull distribution with cylindrical model.

Oil palm fiber (OPF) extracted from empty fruit bunches is proven as a good raw material for bio-composites. The statistical variability in single fiber strength was observed due to the randomly distributed flaws along the fiber. In this study, the effect of gauge length on tensile strength of OPFs has been investigated. The Weibull/ weakest link distribution model was applied to analyse the statistical strength of OPFs. The modified Weibull distribution can predict the gauge length effect more accurately than the conventional Weibull distribution. In addition, the failure strength of the OPF was less sensitive to gauge length compared to coir fiber even though the OPF has a similarity in structures to coir fiber.

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In this work, interfacial fracture toughness between treated fiber and matrix was investigated by using double shear test method. Susrface treatment on the oil palm empty fruit bunch (OPEFB) fibers was performed to improve the interfacial bosnding properties of natural fiber reinforced Poly(L-lactide acid) composites. Three fibers model composite and four fibers model composite were prepared for the double shear test. The interfacial fracture toughness of both model composites is dependent on matrix length. In addition, the interfacial fracture toughness and the critical interfacial shear stress were increased with increasing the concentration of NaOH and the duration of surface treatment.