Mechanical, morphological and thermal analysis of biochar-filled polymer bio-composites

ABSTRACT This study investigates the mechanical and morphological characteristics of biochar-filled polymer bio-composites fabricated using a polypropylene matrix reinforced with rice husk-derived biochar. The composites were prepared through melt blending with varying biochar loadings (5–25 wt%) to analyze their influence on tensile, flexural, and impact properties. The results reveal that biochar incorporation significantly enhanced the mechanical performance of polypropylene, with optimum properties achieved at 15 wt% biochar loading. At this composition, tensile strength and tensile modulus increased by approximately 28% and 34%, respectively, while flexural strength and flexural modulus improved by 31% and 38% compared to neat polypropylene. Impact strength also exhibited an improvement of about 18%, indicating effective energy absorption and improved toughness at moderate filler content. Beyond 15 wt% biochar loading, mechanical performance declined due to filler agglomeration, increased stress concentration, and restricted polymer chain mobility. Scanning Electron Microscopy (SEM) analysis confirmed uniform biochar dispersion and strong interfacial bonding at optimal filler content, whereas higher loadings showed particle clustering and micro-void formation. These findings demonstrate that rice husk-derived biochar acts as an effective reinforcement, enhancing the stiffness and structural integrity of polypropylene composites and offering a viable route for utilization of agricultural waste in eco-friendly engineering materials.