The effect of sodium hydroxide treatment and fiber length on the tensile property of coir fiber-reinforced epoxy composites

The aim of this study is to investigate the effect of surface modification through sodium hydroxide (NaOH) treatment and fiber length on the tensile strength of coir fiber of reinforced epoxy composites. The coir fibers were treated with 2%, 4%, 6%, 8%, and 10% concentration of NaOH separately for 10 days. The tensile strength of untreated and alkali-treated fiber was measured. For each group of the coir fiber, experiments were conducted on different fiber lengths, namely, 10, 20, and 30 mm. The experimental results showed that increasing the NaOH concentration leads to a decrease in fiber diameter in a linear fashion. This reduction in diameter naturally ends up with reduced tensile strength. The treated coir fiber was used as a reinforcement and epoxy as a matrix to fabricate the composites. The tensile strength of different samples of composites was measured. Increased NaOH concentration (up to 4%) in fiber treatment was found to increase the tensile strength, and further increase in NaOH concentration reduces the tensile strength; also, increased fiber length was found to increase in tensile strength. The maximum tensile strength of the composite was observed at 4% NaOH-treated samples. On the basis of the nonlinear regression analysis, the tensile strength equation was proposed for coir fiber-reinforced epoxy composites.