Enhancing the Physicochemical Properties of Starch/Epoxidized Soybean Oil‐Based Bioplastics via Oxidation

ABSTRACT This work comprehensively examined the impact of NaClO treatment on the physicochemical properties of starch/epoxidized soybean oil (ESO)‐based bioplastics. A steaming step was introduced to enhance starch oxidation. Starch oxidation was verified by FTIR detection of carbonyl groups and the increased carboxyl content of modified starch (0.10–0.40 mmol/g). The optimum NaClO level for starch oxidation was 60 wt% based on the carboxyl content. The bioplastics exhibited improved morphology and transparency after steaming and oxidation treatment, indicating enhanced compatibility between modified starch and ESO. The oxidized starch‐based bioplastics exhibited greater flexibility due to the plasticizing effects of ESO and moisture in the bioplastics. Oxidation also reduced the molecular mass of starch, accompanied by decreased thermal stability and increased hydrophilicity of both starch and the corresponding bioplastics. Steaming and oxidation of starch caused a significant reduction in the swelling degree of the bioplastics. The bioplastics maintained desirable biodegradability following steaming and oxidation treatments. Overall, the bioplastics prepared in the study demonstrated superior microstructure, transparency, flexibility, and biodegradability, highlighting the potential for packaging applications.