Valorization of agro-industrial residues for PLA-based biocomposites: Role of MAPP compatibilization in mechanical and thermal optimization

Mechanical, thermal, and structural improvements of natural fiber (Aloe vera and Eucalyptus) reinforced polylactic acid (PLA) composites with agro-waste fillers (Rice Husk and Wheat Husk) without and with maleic anhydride grafted polypropylene (MAPP) as a compatibilizer are reported in the present study. The composites comprise 70% PLA and 30% reinforcements, fillers, and MAPP. In hybrid composites, 70% PLA is combined with 10% fiber reinforcement, 10% fillers, and 10% MAPP. Ten formulations were produced and systematically investigated through measuring surface roughness, hardness, tensile, and flexural properties, impact strength, density, creep, fatigue, and thermal conductivity. The incorporation of MAPP had a substantial effect on fiber–matrix interface, contributing to the enhanced load transfer ability, dimensional stability, and energy dissipation. APWM and APRM had better tensile strength, fatigue performance was better, and flexural and thermal properties of EPWM and EPRM were good. Tensile, impact strength and creep resistance were also significantly improved in MAPP-modified composites. Composites with hybrid reinforcement were always better than those with either type of reinforcement or no reinforcement, indicating synergy in hybrid reinforcement. Although uncompatibilized and particulate-only composites showed moderate increase, they were still inferior to those of MAPP-modified counterparts. The results highlight the potential of lignocellulosic fiber–filler systems for the sustainable development of high-performance PLA composites. Morphological analysis of fractured surfaces was performed using scanning electron microscopy (SEM) to evaluate interfacial adhesion between the reinforcements and the polymer matrix.