Assessment of the Mechanical Properties of Agro-Waste Filled Epoxy Composites Using Groundnut Shell Particles from Katsina State

Groundnut shell is an abundant agricultural waste generated in large volumes in Katsina State and the wider North West geopolitical zone of Nigeria, representing an untapped resource for polymer composite production. This study assesses the mechanical properties of epoxy composites filled with groundnut shell particles at varying filler loadings of 5, 10, 15, and 20 percent by weight. Groundnut shells were collected, cleaned, dried, and milled to particle sizes below 250 micrometres. Surface modification using silane coupling agent was applied to half the filler samples to evaluate the effect of interfacial treatment on composite performance. Composite specimens were fabricated by casting and assessed for tensile strength, flexural strength, hardness, and impact energy absorption following standard ASTM test methods. Results demonstrate that untreated filler composites achieved maximum tensile strength of 42.3 MPa at 10 percent loading, declining beyond this loading due to agglomeration effects. Silane-treated filler composites at 15 percent loading outperformed untreated counterparts by 18 percent in tensile strength and 24 percent in flexural strength, confirming the efficacy of surface treatment in improving filler-matrix compatibility. Hardness increased progressively with filler content across all series. Impact energy absorption declined with filler addition for both treated and untreated composites. The study concludes that groundnut shell particles from Katsina State offer a cost-effective particulate filler for medium-strength epoxy composite applications and recommends further optimisation of coupling agent concentration and particle size distribution for structural applications. Keywords: groundnut shell, epoxy composite, filler, surface treatment, Katsina State