Mechanical and Thermal Enhancement of Polylactic Acid/Poly(Butylene Adipate‐Co‐Terephthalate) Composites by Modified Chitin Micro‐Nanofibers

ABSTRACT Enhancing the mechanical properties and thermal stability of polylactic acid (PLA) remains a critical challenge in developing high‐performance biodegradable materials. Although incorporating biofiber can improve the tensile strength of PLA, achieving satisfactory toughness is still difficult. The introduction of poly(butylene adipate‐co‐terephthalate) (PBAT) offers a promising solution for toughening; however, ensuring the ideal dispersion of both PBAT and reinforcing fibers within the PLA matrix continues to pose significant technical challenges. Herein, we present an effective strategy for fabricating PLA/PBAT‐based composites with high strength, high toughness, thermal stability, and biodegradability. Chitin micro‐nanofibers were produced via energy‐efficient stirring and chemically treated to yield modified chitin micro‐nanofibers (KCHs). The obtained KCHs were subsequently melt‐blended with PBAT and PLA to prepare the ternary KCH/PLA/PBAT composites. The KCHs synergistically combined the advantages of chitin nanofibers (e.g., high specific surface area and aspect ratio) with those of chitin microfibers (energy‐saving properties and processability). Notably, the surface modification of KCHs significantly enhanced interfacial compatibility, resulting in improved properties of KCH/PLA/PBAT. As a result, the developed KCH/PLA/PBAT composites exhibited good mechanical properties (tensile strength: ~35.0 MPa, toughness: ~8.47 MJ/m ³ ), improved thermal stability (the linear coefficients of thermal expansion: ~171.5 × 10 ⁻⁶ /K), and biodegradability. Additionally, KCH/PLA/PBAT could be easily molded into packaging products, such as spoons and knives, which can be considered promising biodegradable alternatives to disposable plastics.