Compatibilizer-Induced performance changes in sustainable apricot kernel shell powder reinforced polypropylene biocomposites

This study demonstrates the successful valorization of apricot kernel shell (AKS), a lignin-rich agricultural byproduct, as a sustainable reinforcing filler in polypropylene (PP) biocomposites. The inherent incompatibility between hydrophilic AKS and hydrophobic PP was effectively mitigated using maleic anhydride-grafted polypropylene (MAPP) as a compatibilizer, which forms covalent ester linkages with AKS hydroxyl groups while maintaining molecular compatibility with the PP matrix. The compatibilized composites exhibited substantial property enhancements, including a significant increase in crystallinity from 15% in neat PP to 47% in PP-15AKS-MAPP, superior thermal stability with degradation onset temperatures up to 100 °C higher, and recovered mechanical performance where tensile strength reached 31 MPa—closely approaching neat PP and substantially exceeding uncompatibilized composites. Morphological analysis confirmed uniform filler dispersion and improved interfacial adhesion, correlating with the enhanced macroscopic properties. With minimal water absorption (~ 0.08%) confirming structural integrity, these biocomposites present viable, eco-friendly alternatives for packaging, automotive, and construction applications, while establishing a strategic framework for optimizing biomass-polymer composites through targeted compatibilization.