Potato peel-based PBS/PBAT biocomposites: influence of composition and filler content on injection molded properties

Abstract

The growing demand for sustainable materials has intensified interest in bio-based and biodegradable polymers as alternatives to fossil-based plastics. This study investigated the development of injection-molded biocomposites based on poly(butylene succinate) (PBS), poly(butylene adipate-co-terephthalate) (PBAT), and their blends, reinforced with 30–70 wt% potato peels (PP), an abundant by-product of food processing. The effects of filler content and polymer composition on thermal, mechanical, and moisture-related properties were systematically evaluated. All composites remained thermally stable below 228 °C, confirming the suitability of PP for melt processing. FTIR spectroscopy showed no evidence of chemical bonding between filler and polymer matrices, although weak physical interactions were observed, particularly in PBS-rich systems. In contrast, blending PBS with PBAT indicated polymer–polymer interactions, suggesting partial compatibilization, as reflected in a 1.8-fold increase in elongation at break. PP addition consistently altered composite structure and significantly enhanced stiffness, with the elastic modulus increasing from 698 to 1825 MPa for PBS (+162%) and from 77 to 1161 MPa for PBAT (+1418%) at 70 wt% PP. Conversely, tensile strength decreased from 35.0 to 10.6 MPa (PBS) and from 17.1 to 6.5 MPa (PBAT), and elongation at break dropped below 3% for all composites containing ≥40 wt% PP. Overall, PBS/PBAT-potato peel composites exhibited more balanced mechanical performance compared to neat PBS or PBAT composites. DSC analysis revealed that PP acted as a nucleating agent in PBS and PBS-rich blends, increasing crystallization temperature with only minor impact on overall crystallinity. Collectively, these findings demonstrate the feasibility of producing high-filler-content biocomposites for sustainable packaging and agricultural materials.