Mechanical, thermal conductivity and water absorption behaviour of eco-friendly epoxy composites incorporating agro-waste powder as hybrid reinforcement

Eco-friendly epoxy composites were fabricated using Aervalanata stem fiber as reinforcement and fungal agro-waste powder as filler, both treated with a silane coupling agent to improve interfacial adhesion. The prepared composites were evaluated for their mechanical, thermal, and water absorption properties. The results indicated a clear improvement in performance with the addition of fiber and filler compared with the neat epoxy matrix. Among the developed specimens, AB3 containing 30 vol.% stem fiber and 2 vol.% fungal filler exhibited the best mechanical performance, with a tensile strength of 128 MPa, flexural strength of 148 MPa, impact energy of 5.8 J, and hardness of 82 Shore-D. This improved performance is attributed to the combined effect of fiber reinforcement and well-dispersed filler, which enhanced stress transfer, crack bridging, and energy absorption during loading. In contrast, specimen AB4 with 30 vol. % fiber and 4 vol. % filler demonstrated superior thermal and moisture resistance, showing a thermal conductivity of 0.51 W/mK and the lowest water absorption value of 1.23%. The higher filler content likely promoted better heat conduction pathways and reduced micro-void formation, thereby limiting moisture penetration. Overall, the findings indicate that the hybridization of natural fiber and agro-waste filler provides a sustainable approach for developing epoxy composites with improved multifunctional properties.