Influence of Alkaline Treatment Performance on the Mechanical, Thermal and Wettability Properties of Epoxy/Kenaf Fibre Composite

The development of eco-friendly composites with enhanced mechanical and thermal performance remains a challenge, particularly when using natural fibres. The studies on the mechanical and thermal properties of neat epoxy (EPX), EPX/KF and EPX/KF/NaOH at different kenaf fibre loading and at different NaOH treatment. This study investigates the effects of kenaf fibre (KF) loading and sodium hydroxide (NaOH) treatment on the properties of epoxy-based composites. Neat epoxy (EPX), EPX/KF, and EPX/KF/NaOH composites were fabricated via hand lay-up at varying fibre contents and treatment concentrations. Mechanical, thermal, and wettability analyses were conducted. Results showed that incorporating 30 wt % KF significantly improves tensile strength and Young’s modulus compared to neat epoxy, while additional NaOH treatment further enhances tensile strain and impact strength. The Impact strength improved across all formulations, with the highest value observed at 40 wt % KF loading (3960.38 ± 210.5 J/m2). Linear thermal expansion and viscoelastic parameters also improved, indicating better thermal stability and energy degeneracy. Wettability analysis showed reduced contact angle and wetting energy after fibre treatment, suggesting improved fibre– matrix adhesion. Largely, the kenaf fibre reinforcement combined with the best NaOH treatment yields composites with superior mechanical, thermal, and interfacial properties. Alkalization of kenaf fibre statistically improved interfacial interaction between epoxy and fibre, thermal stiffness and stability, alongside the effect increases with higher curing time. These findings support the use of chemically treated natural fibres in high-performance polymer composites for applications demanding improved durability and thermal stability.