The influence of different fiber sizes on the flexural strength of natural fiber-reinforced polymer composites

This experiment aimed to investigate the impact of varying fiber lengths on the flexural strength of coconut fiber composites with epoxy resin. Coconut fiber composite panels were produced using rectangular molds. The effects of various fiber sizes, especially 2, 4, and 6 mm, respectively, were compared with fiberless and continuous fiber polymer composites on the flexural strength of Natural Fiber-reinforced Polymer Composites (NFPC). The lowest flexural strength is 10.04 MPa, was obtained for the NFPC sample with a fiber length of 2 mm, while the highest flexural strength value was 10.70 MPa with a fiber length of 6 mm. Generally, flexural strength is influenced by variations in fiber size but not significantly. The flexural modulus and flexural strength values exhibit the same trend. Fiber pullouts are visible on the fracture surface of the sample, and voids in the form of trapped gas are also apparent on the sample surface. Short fiber size is one of the causes of fiber pullout, which can reduce the flexural strength of short fiber polymers.