Fabrication of raw and chemically treated biodegradable Luffa aegyptica fruit fibre-based hybrid epoxy composite: a mechanical and morphological investigation

This study investigated the manufacturing and characteristics of luffa fibre reinforced epoxy composites with different stacking sequences and fibre treatments. The composites were created using a manual lay-up approach mixed with compression moulding. Three laminates were tested: L1 with untreated luffa fibres, L2 with HCl-treated fibres, and L3 with NaOH-treated fibres. Mechanical tests demonstrated that chemical treatments considerably increased tensile, flexural, interlaminar shear, and impact strengths when compared to the untreated L1 laminate. L3 with NaOH-treated fibres had the highest tensile strength of 16.47 N/mm², flexural strength of 11.205 N/mm², interlaminar shear strength of 4.105 N/mm², and improved impact energy absorption. The alkali treatment was more successful than the acid treatment at improving fibre-matrix adhesion by removing hemicellulose and lignin. Scanning electron microscopy analysis revealed enhanced interfacial bonding and decreased debonding in the treated fibre laminates. Water absorption experiments revealed that the NaOH-treated L3 laminate absorbed the least amount of moisture after 28 days of immersion, at approximately 6–7%. The results show that chemically treated luffa fibre reinforced composites can be tailored for medium load structural applications by adjusting the fibre surface characteristics.