Bio-Based Starch Films from Ripe Plantain Peels: Kinetic Modelling and Physicomechanical Assessment

The growing environmental impact of traditional plastics has driven research toward more sustainable, biodegradable alternatives. In this study, ripe plantain peel (RPP), a common agricultural waste, was used to synthesize biodegradable films using thermal casting with glycerol, honey, and Arabic gum. The films were thoroughly studied using FTIR, XRD, TGA, SEM, and EDX to determine their structural, thermal, and morphological properties. FTIR investigation verified the existence of hydroxyl, carbonyl, and starch-related functional groups, whilst XRD revealed a significant amorphous content, compatible with a starch-based matrix. TGA indicated that substantial thermal degradation occurs between 200–350°C, where 67% mass loss is detected, and SEM/EDX investigation revealed a rough, compact, and heterogeneous surface with fused granular structures and micro-voids. The films were hydrophilic, with a moisture content of 15.93 ± 0.48%, water absorption capacity of 38.78 ± 1.55%, and low solubility (9.34 ± 0.16%), facilitating microbial colonization and polymer chain breakdown. Mechanical tests revealed a soft and flexible matrix (Young's modulus 0.27 ± 0.08 MPa, elongation at break 13.7 ± 1.69%) and tensile strength of 3.64 ± 0.40 MPa, making it ideal for light-duty packaging. Soil burial experiments assessed biodegradation kinetics, and the results were fitted to zero-order, first-order, second-order, and Korsmeyer-Peppas models. The zero-order model (R²= 0.9849) best describes degradation, demonstrating a consistent mass-loss rate caused by moisture transport and enzyme activity. This study shows that RPP can be converted into useful, biodegradable films, offering a sustainable substitute for traditional plastics and a circular economy solution by turning agricultural waste into environmentally friendly packaging materials that degrade naturally.