Enhancing the Functional Properties of Polylactic Acid by Incorporation of Esterified Lignin

ABSTRACT Incorporating lignin as an additive is a promising strategy to overcome the limitations of PLA‐based composites. This study investigates the effects of adding esterified lignin from banana pseudostem and sugarcane bagasse into a PLA matrix. Composites were produced via melt‐compounding followed by compression molding, using two lignin concentrations: 5 wt% and 10 wt%. Thermal analyses revealed a reduction of up to 14.4°C in the glass transition temperature, particularly in samples containing modified lignin. Mechanical properties were also influenced by lignin addition, with the lowest tensile strength (approximately 10.76 MPa) observed in composites containing modified banana pseudostem lignin. However, elongation at break remained unchanged. All lignin‐PLA composites exhibited enhanced hydrophobicity compared to neat PLA. Improved cohesion between unmodified sugarcane bagasse lignin and PLA resulted in lower surface roughness, while chemical modification led to more homogeneous banana lignin‐based composites. Furthermore, all lignin‐containing samples demonstrated a significant enhancement in antioxidant activity, reaching up to 84.9%. Lignin addition also provided complete UV‐blocking efficiency, regardless of source, content, or chemical modification. These findings confirm that esterified lignin effectively enhances the performance of PLA, particularly in terms of hydrophobicity, antioxidant capacity, and UV‐shielding properties, which is advantageous for non‐load‐bearing applications where functional performance is prioritized over mechanical reinforcement.