Mechanical and Microstructural Properties of Epoxy Composites Hybridized with Bio-Waste Particulates

Clement Nworji Obiora (Department of Industrial and Production Engineering, Faculty of Engineering, Nnamdi Azikiwe University Awka, Anambra State, Nigeria)
Callistus Nkemjika Chukwu (Department of Industrial and Production Engineering, Faculty of Engineering, Nnamdi Azikiwe University Awka, Anambra State, Nigeria.)
Ugochukwu Richards Orji (Department of Industrial and Production Engineering, Faculty of Engineering in Nnamdi Azikiwe University Awka, Anambra State, Nigeria)
Sunday Chimezie Anyaora (Department of Mechanical Engineering, Faculty of Engineering, Nnamdi Azikiwe University Awka, Anambra State, Nigeria)
Nwekeoti Arinze Chukwunakueze (Solar Unit, Nnamdi Azikiwe University Awka, Anambra State, Nigeria.)
Fakiyesi Oladapo Babafemi (Department of Industrial and Production Engineering, Faculty of Engineering in Nnamdi Azikiwe University Awka, Anambra State, Nigeria)

Nexus: Journal of Cross-Disciplinary Insights
Vol. 2 No. 2 (2026): Science for a better life

Developing sustainable structural materials from agricultural and industrial bio-waste remains critical for mitigating environmental impacts and replacing non-biodegradable synthetic reinforcements. Unreinforced epoxy resins exhibit inherent brittleness and low impact resistance, whereas un-optimized bio-filler additions frequently induce particulate agglomeration and weak interfacial bonding. In this study, EPOCHEM epoxy resin was hybridized with eco-friendly particulates derived from Anambra cow bones and Mangifera indica (mango) seed shells. The bio-wastes were synthesized through controlled carburization, hydrothermal treatment, and calcination processes to yield fine particulate ash. Hybrid composites were fabricated using a hand lay-up technique with a standard resin-to-hardener ratio. Response Surface Methodology (RSM) based on a Central Composite Design (CCD) was employed to optimize the chemical treatment parameters—specifically sodium hydroxide (NaOH) concentration and soaking duration—to maximize the ultimate tensile strength of the bio-waste hybrid composites. Mechanical testing (tensile and hardness), thermal stability, dry sliding wear, FTIR functional group analysis, and SEM-EDS microstructural characterization were conducted. Analysis of Variance (ANOVA) confirmed high statistical model significance () with a non-significant lack of fit (). Optimal processing conditions were established at 6.5 wt.% NaOH concentration and a 4.2-hour soaking duration, yielding a peak experimental tensile strength of 68.45 MPa with a desirability score of 0.985. The SEM microstructural evaluation verified a homogeneous particulate dispersion and improved interfacial adhesion, preventing early matrix cracking. Overall, the hybridization of Mangifera indica shell ash and cow bone ash provides a cost-effective, environmentally friendly reinforcement strategy that significantly enhances the mechanical and microstructural performance of epoxy composites for lightweight semi-structural automotive and industrial paneling applications.