Effects of acetylated lignin and its oriented lamellar structures on the crystallization and rheological properties of polylactic acid

This paper investigated modified alkaline lignin for enhancing the crystallization and rheology of polylactic acid (PLA). Alkaline lignin (AL) was acetylated (ACAL) to reduce hydrophilicity and improve compatibility. Bidirectional freezing created oriented structures (FDAL/FDACAL). Results showed that lignin incorporation reduced melt viscosity, improving processability. While all variants influenced crystallization, FDACAL exhibited the most enhancement, as the synergy between acetylation and oriented structure optimized interfacial adhesion and nucleation. Melt properties were tuned by lignin type and structure. This research highlights the importance of synergistic chemical-physical lignin modification for high-performance PLA composites. • Oriented lamellar structures were fabricated from acetylated lignin by bidirectional freezing. • Acetylation improved lignin's polymer compatibility. • Oriented-nucleating lignin regulates PLA crystallization. • Reveals the synergistic effect of acetylation and oriented structure in lignin fillers. • Achieves simultaneous enhancement of crystallization and processability.