Investigation of Mechanical and Wear Properties of Coconut Sheath and Fly Ash Powder Reinforced Epoxy Composites

The present work has conducted a comprehensive experimental examination of the mechanical and tribological performance of coconut sheath fibre– and fly ash–reinforced epoxy composites across a range of reinforcement proportions. The principal conclusions drawn from the results are as follows: 1.  Coconut sheath fibre serves as an effective reinforcing agent for epoxy matrices, delivering progressive gains in tensile and flexural strength up to a fibre loading of 35 vol% (C4 grade, 63.91 MPa tensile strength), beyond which agglomeration effects reduce performance. 2.  Fly ash hybridisation uniformly elevates all mechanical properties examined. The HC-series surpasses the C-series at every reinforcement level, providing direct experimental evidence of synergistic reinforcement from the dual-constituent system. 3.  Hybrid grade HC4 (17.5 wt% coconut sheath fibre + 17.5 wt% fly ash) represents the optimal trade-off between reinforcement content and fibre–matrix interfacial quality, attaining the highest tensile strength (65.89 MPa), tensile modulus (7.28 GPa), and peak flexural response among all grades tested. 4.  Impact toughness and Vickers hardness increase without interruption from the lowest to the highest reinforcement compositions, confirming that these properties are not adversely affected by particle agglomeration and continue to benefit from maximum filler content even at HC5. 5.  Taguchi S/N analysis establishes applied normal load (Factor A) as the dominant tribological variable, followed in influence by sliding velocity (Factor C) and sliding distance (Factor B). The parameter set A1B2C3 yields the minimum wear rate. 6.  Under optimised sliding conditions, hybrid composites achieve wear rates up to 27% lower than their single-reinforcement counterparts. This reduction is ascribed to a thin protective tribofilm that develops at the sliding interface, sustained by hard fly ash ceramic particles acting as load-bearing micro-asperities. 7.  Coconut sheath fibre and fly ash are both eco-compatible, low-cost reinforcing constituents derived from agricultural and industrial waste streams, respectively. Their successful deployment in high-performance epoxy composites positions these hybrid materials as a genuinely sustainable alternative to conventional synthetic-fibre composite systems. On the basis of these conclusions, HC4 is recommended as the preferred composition for lightweight structural applications — including automotive panels, interior trim components, and protective packaging — where a well-balanced combination of tensile strength, bending stiffness, surface hardness, and tribological durability is demanded.

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