Structure‐Property Relationships in Cross‐Linked Starch Bioplastics Derived From Banana Peel, Corn, and Potato Sources

ABSTRACT

The increasing environmental burden of non‐biodegradable plastics has accelerated the development of sustainable alternatives derived from renewable resources. In this study, biodegradable bioplastics were synthesized from agro‐waste sources, namely banana peel, corn starch, and potato starch, using glycerol as a plasticizer and acetic acid as a cross‐linking agent. A systematic comparison between native and cross‐linked films was performed to evaluate the influence of chemical modification on physicochemical, mechanical, thermal, and biodegradation properties.

The incorporation of acetic acid significantly enhanced mechanical performance. For instance, the tensile strength of banana peel‐based films increased from 0.30 ± 0.03 MPa (native) to 0.45 ± 0.05 MPa (cross‐linked), representing an improvement of approximately 50%. Similarly, potato starch films exhibited the highest tensile strength of 1.20 MPa among all samples. Water absorption behavior showed strong dependence on starch origin, with corn starch films exhibiting maximum uptake (∼164%) compared to potato (∼131%) and banana peel (∼60%) films, indicating differences in structural compactness and hydrophilicity.

Thermogravimetric analysis revealed moderate thermal stability, with onset degradation temperatures ranging from ∼80°C to ∼300°C, which showed slight improvement upon cross‐linking due to reduced polymer chain mobility. Furthermore, soil burial tests demonstrated progressive biodegradation, with partial degradation observed within four weeks and complete degradation estimated within 90–180 days depending on the formulation.

These findings demonstrate that acetic acid cross‐linking plays a crucial role in enhancing the performance of starch‐based bioplastics, while the intrinsic composition of different starch sources governs their final properties. The developed materials show strong potential for low‐load, short‐lifecycle applications such as biodegradable packaging and agricultural films.