Optimization of Formulation Parameters for Tensile Strength of Powdered Pentaclethra Macrophylla Pod–Gum Arabic Bio-composites

Abstract

The tensile behaviour of powdered Pentaclethra macrophylla pod–gum Arabic bio-composites was optimized using response surface methodology based on a Central Composite Design (CCD). Pentaclethra macrophylla pods, an underutilized agro-waste, were cleaned, dried, pulverized and fractionated into 150μm and 210μm size classes, with part of the powder subsequently carbonized at 950°C. Composite plates were produced via pre-impregnation and hot pressing, varying pod content between 10 and 50 wt. % at fixed processing conditions, while maintaining constant levels of other additives. Tensile tests were performed in accordance with ASTM D638. Maximum tensile strength occurred at 10 wt. % reinforcement and 150μm particle size for both carbonized and un-carbonized systems, with peak values of 14.2MPa and 16.4MPa, respectively. Analysis of variance showed that reinforcement content, particle size and surface condition (carbonized vs. un-carbonized) significantly affected tensile strength (p ≤ 0.05). The developed quadratic CCD model exhibited excellent agreement between predicted and experimental values (R² = 0.9957), comparable to optimized natural-fibre systems reported for kenaf, bamboo and banana fibre composites using response surface methodologies. The results define an optimal formulation window for Pentaclethra pod–gum Arabic composites and corroborate broader evidence that moderate filler loadings and fine particle sizes are required to avoid agglomeration, void formation and interfacial debonding in agro-waste reinforced bio-composites. These findings support the potential of Pentaclethra macrophylla pod and gum Arabic as sustainable constituents for low to-moderate load engineering applications.