Evaluation of the physico-mechanical/chemical properties of corncob-groundnut shell hybrid composite

Abstract

This study investigates the development and characterization of sustainable hybrid bio composites reinforced with groundnut shell (GNS) and corncob (CC) particulates in an unsaturated polyester resin (UPR) matrix. Lignocellulosic analysis revealed that GNS contains a high cellulose content (61.537%), while CC exhibits higher hemicellulose (36.434%) and oil content (8.489%), influencing mechanical strength and moisture behavior. Water absorption tests showed a progressive increase with time, with values ranging from 0.338-0.474 wt.% for 100% GNS composites and up to 1.326-1.987 wt.% for 100% CC composites after 5 hours, confirming higher hydrophilicity of CC-rich composites. Mechanical evaluation indicated an ultimate tensile strength of approximately 59 MPa, a Tensile's modulus of 7.9 GPa, and strain at break of 0.892%, demonstrating good stiffness but limited ductility. BET analysis showed a high surface area of 266.971 m²/g with a strong correlation coefficient (r = 0.99297), indicating significant porosity and adsorption potential. SEM analysis confirmed uniform particle dispersion with localized porosity, while EDX revealed dominant silicon content (57.0%) alongside carbon (19.5%) and oxygen (10%). FTIR spectra identified key functional groups at 665.3, 1718.3, 2871.9, and 3347.1 cm⁻¹, indicating the presence of silicate, carbonyl, alkyl, and hydroxyl groups. The novelty of this study lies in the hybridization of CC and GNS to achieve tunable moisture and mechanical properties. The results demonstrate the potential of agro-waste composites for sustainable structural and functional applications.