Mechanical Behaviour of Hybrid Natural Fibre Composites from Coir and Jute Reinforced Epoxy in Tropical Nigerian Conditions

This study investigates the mechanical behaviour of hybrid composites reinforced with coir and jute fibres in epoxy resin matrix, evaluated under simulated tropical Nigerian environmental conditions. Interest in hybrid natural fibre composites stems from the opportunity to combine the complementary mechanical attributes of different fibre types at lower environmental impact than synthetic fibre composites. Coir fibres are obtained from coconut husks in Cross River State and jute fibres sourced from commercial suppliers. Both fibre types are alkali-treated and surface-dried. Hybrid composites are fabricated by hand lay-up with coir-to-jute ratios of 100:0, 75:25, 50:50, 25:75, and 0:100 at a total fibre volume fraction of 30 percent. Specimens are tested in the as-fabricated state and after conditioning at 40 degrees Celsius and 85 percent relative humidity for 30 days to simulate Nigerian tropical exposure. Tensile strength, flexural strength, and impact energy are measured. Moisture absorption is tracked gravimetrically. Results indicate that the 25 percent coir and 75 percent jute hybrid achieves the best balance of tensile and flexural properties. All compositions show strength reduction after tropical conditioning, with coir-dominated composites showing greater moisture uptake and larger strength loss. Alkali treatment reduces but does not eliminate moisture-induced degradation. Keywords: hybrid composite, coir fibre, jute fibre, epoxy, tropical environment.