Effect of alkali treatment on moisture absorption and mechanical properties of mokolwane fiber reinforced polyester composites

This study aims to investigate the influence of alkali treatment on moisture absorption and mechanical properties of Mokolwane fibre reinforced polyester composites. Composite specimens were fabricated by varying fibre loading and NaOH concentration. The Optimum tensile strength, flexural strength, and impact energy of 76.5 MPa, 124 MPa, and 3.83 J, respectively, were obtained with composites with 50wt. % fibre loading and alkali treatment of 4%NaOH. The positive effect of alkali treatment is substantiated by SEM and FTIR results, indicating enhanced fiber-matrix interfacial adhesion due to the removal of hydrophilic amorphous surface components. However, excessive alkali concentration damages the fiber surface, harming mechanical properties. Additionally, inadequate fiber loading hampers stress transfer, while excessive loading causes cracks, voids, and fiber agglomerations.