Enhancement of Starch-Based Biodegradable Films Through Single and Multiple Crosslinking Agents for Potential Packaging Applications

Abstract In this study, the suitability of starch as a biodegradable packaging material was enhanced through single and multiple applications of three cross-linking agents (CLA) (citric acid, boric acid, glutaraldehyde). 12 film formulations containing 2–8% CLA were prepared using the casting method. The films were characterized for molecular structure, optical properties, thickness, mechanical properties, water vapor permeability (WVP), and crystallinity. The mechanical and barrier properties, which are critical for packaging performance, were evaluated using the multi-criteria decision-making method (TOPSIS), and 4 formulations with the most favorable properties were selected. The selected films were subjected to further analyses, including surface topography, microstructural properties, water contact angle (WCA) and puncture resistance. While the incorporation of CLA did not significantly influence the optical properties of the films, it resulted in a reduction in WVP and an increase in crystallinity. Films containing boric acid exhibited enhanced tensile strength. According to TOPSIS, the application of CLA generally decreased the WCA, indicating modified surface wettability, whereas puncture resistance properties were strongly dependent on both the type of CLA and the cross-linking strategy employed. The use of multiple CLA led to significant improvements in puncture strength and elongation, while single citric acid application reduced these parameters. Cross-linking reduced the granular surface structure observed in the control film, yielding a more homogeneous surface with increased roughness. Overall, the findings demonstrate that a multiple cross-linking strategy effectively enhances the mechanical, barrier, and surface properties of starch-based packaging films, highlighting its strong potential for biodegradable packaging applications.