Strength-toughness balanced, high UV-shielding PBAT/PLA-based films by incorporating biodegradable epoxy-based...

Both polybutylene adipate-co-terephthalate (PBAT) and polylactic acid (PLA) show strong potential as replacements for conventional petroleum-based plastics. However, their intrinsic immiscibility leads to weak interfacial interactions, limiting practical applications. To overcome this issue, lignin was chemically modified using an acetic anhydride-pyridine system to produce acetylated lignin (AcAL), serving as a functional filler. AcAL and a biodegradable epoxy-based terpolymer (SHG) were then incorporated via melt blending to achieve balanced mechanical properties and UV-shielding performance in PBAT/PLA-based films. The results showed that SHG played a dominant role in improving the mechanical properties of the PBAT/PLA blend through reactive compatibilization, while AcAL mainly contributed to UV-shielding performance and a modest improvement in thermal stability. The combined incorporation of SHG and AcAL enabled PBAT/PLA-based films with balanced mechanical performance and improved UV-shielding performance. When 1.5 wt% AcAL and 0.7 wt% SHG were incorporated, the elongation at break and tensile strength of the composite increased by 210.5% and 63.2%, respectively, as compared to the unmodified PBAT/PLA blend. This composite also exhibited the highest T_10% value among all samples, indicating a slight enhancement in thermal stability. Additionally, at a 3.0 wt% AcAL loading, the UV transmittance of the obtained composite neared zero, demonstrating excellent UV-shielding performance. This work presents an effective and scalable approach for developing sustainable, low-cost, high-performance biodegradable composites, having potential for UV-shielding packaging applications.