Mechanical and Structural Evaluation of Biodegradable Cast Films from Plant-Based Polymers for Sustainable Packaging Applications

Biodegradable starch films are promising candidates for short-life packaging but often suffer from moisture sensitivity and limited strength. This study solvent-cast films made from two starch sources (potato, maize), two plasticizers (sorbitol, glycerol), and a natural reinforcer (yellow pea fiber) under identical processing, enabling direct, formulation-level structure – property evaluation. Across 16 formulations, nine yielded testable films; potato-starch systems dominated the successful set. Mechanical testing revealed that potato starch plasticized with sorbitol achieved the highest tensile performance (FH up to 58.45 N) with a Young’s modulus clustered near 1.0–1.14 GPa – within the range of polypropylene copolymers – while glycerol-rich systems favored ductility at the expense of strength. Contact-angle measurements confirmed high surface hydrophilicity (all < 71° per ASTM D5946 levels), underscoring moisture susceptibility relative to polyethylene. Optical/microscopic inspection exposed thickness variability and air-void defects arising from manual casting, highlighting scalability limits without controlled film forming. Overall, the results clarify how starch source and plasticizer choice govern the strength – ductility balance and surface wettability and identify sorbitol-plasticized potato starch as a promising baseline for sustainable packaging provided that barrier properties and processing uniformity are improved (e.g. through controlled extrusion and nanofiller strategies).