Surface Modification Strategies for Improved Performance of PLA-Tapioca Starch Bio-composites: A Comparative Study

The increasing demand for sustainable and eco-friendly materials has driven the development of biodegradable biocomposites with improved mechanical and thermal properties. However, the mechanical performance of hydrophilic starch fillers and hydrophobic polymer matrices is limited due to their low compatibility, which makes the development of durable bioplastics for real-world applications challenging. This study investigated the effects of acetylation and ultraviolet/ozone (UV/O₃) surface modification on the performance of polylactic acid (PLA) reinforced with tapioca starch (TS) as a biodegradable filler. The modified and unmodified composites were characterized by using Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and Field Emission scanning electron microscopy (FESEM) to evaluate chemical, thermal, and morphological changes. The acetylation process introduced ester linkages, while UV/O₃ treatment enhanced surface hydroxyl groups, leading to improved compatibility and adhesion between the PLA matrix and tapioca filler. Thermogravimetric analysis revealed enhanced thermal stability, with both modifications delaying the onset of degradation. Mechanical testing showed that UV/O₃-treated PLA/TS achieved a tensile strength of 48 MPa, showing a 45.4% increase over untreated composites, while acetylated PLA/TS demonstrated superior elongation at break, reaching 1.81 mm. These findings highlight that targeted surface modification significantly enhances the mechanical properties of hard bioplastics, making them suitable for applications in sustainable food packaging such as plates, cutlery, and lunch boxes. This study provided a foundation for developing high-performance biodegradable composites by leveraging surface engineering strategies, contributing to the broader goals of environmental sustainability and reduced reliance on petrochemical-based materials.