Experimental evaluation and optimization of mechanical and wear properties of plant fiber epoxy composites with bio fillers

This study investigates the mechanical and tribological performance of sustainable epoxy composites reinforced with alkali-treated hybrid plant fibers and bio-fillers. The composites were fabricated using sisal, hemp, flax, and bamboo fibers as hybrid reinforcements, all subjected to NaOH treatment, and incorporated bio-fillers derived from coconut shell, eggshell, and nutshell powders. Response Surface Methodology (RSM) combined with a Box–Behnken Design was employed to optimize three key parameters: fiber orientation (0°, 45°, and 90°), NaOH treatment duration (2–4 h), and bio-filler content (2–4 wt%). The novelty of this work lies in the integrated statistical optimization of a four-fiber hybrid system with multiple bio-fillers, together with a combined evaluation of mechanical properties and wear resistance. The optimized composite exhibited enhanced tensile strength (72.6 MPa), flexural strength (118.4 MPa), compressive strength (103.8 MPa), impact strength (8.7 KJ/m), and hardness (84.1 Shore D), along with an ultra-low specific wear rate of 0.0042mm 3 /N.m. Analysis of variance (ANOVA) confirmed the statistical significance of all input paramet 2 ers ( p < 0.05), Scanning electron microscopy (SEM) revealed improved fiber–matrix interfacial bonding and uniform dispersion of bio-fillers within the epoxy matrix. Overall, the results demonstrate that hybridized natural fiber epoxy composites can effectively sustain mechanical loads while offering superior wear resistance, highlighting their potential for applications in automotive, construction, and consumer product sectors.