Guar Gum/Alkali-Treated PALF Nanohybrid Composites: Optimization of Tensile Behaviour via CCD–GRA

This study optimizes the tensile behavior of chemically treated pineapple leaf fiber (PALF)-reinforced epoxy–guar gum hybrid nanocomposites using CCD-integrated Grey Relational Analysis (GRA). PALF is sequentially treated with 5% NaOH, 1 M HCl and 2% NaOH (2 h, 60–80 °C) and reinforced with 1 wt.% nano-fillers (h-BN, MWCNT, Al2O3) at 1–5 wt.% PALF loading. Tensile strength is ranged from 10.05–16.32 MPa, yield strength 0.78–1.28 MPa, Young’s modulus 7.99–12.84 GPa, resilience 0.201–0.326 J and toughness 0.85–1.39 J. The optimized combination (AA2515–Al2O3–1 wt.% PALF) exhibits 16.32 MPa tensile strength, 12.84 GPa Young’s modulus, 1.28 MPa yield strength, 0.326 J resilience and 1.39 J toughness, achieving a GRG of 1.00 compared to the mean GRG of 0.5615, with a predicted improvement of 59.8% (GRG = 0.897). ANOVA confirms fiber type as the most significant factor (F = 402.03, p < .001), and the regression model shows high adequacy (R2 = 98.59%, prediction error < 3%). SEM of the optimized composite reveals strong fiber–matrix adhesion, crack deflection and uniform nano-Al2O3 dispersion.