Surface‐modified chitin micro‐nanofibers endow polylactic acid‐based composites with good mechanical performance and thermal stability

Abstract Despite biodegradability, the weak mechanical properties and poor thermal stability remain the main challenges for polylactic acid (PLA). The addition of biofibers is an approach to enhance the PLA materials while unpromising interfacial compatibility hinders their further development. Herein, we report a facile method to fabricate fiber‐reinforced‐PLA composites with improved tensile performance and thermal stability. The modified chitin micro‐nanofibers (KCHs) were mixed with PLA and processed via co‐extrusion to prepare KCH/PLA composites. Specifically, the interfacial compatibility between chitin and PLA was significantly increased due to the surface modification of KCH, thus contributing to the enhanced properties. As a result, compared with PLA (tensile strength: ~17.36 MPa, Young's modulus: ~1230.9 MPa), the developed KCH/PLA composites were endowed with good mechanical performance (tensile strength: ~36.07 MPa, Young's modulus: ~1647.6 MPa) and reduced thermal expansion coefficient (~134.4 × 10 −6 /K). Moreover, the KCH/PLA could be molded into tableware such as forks and knives. So, it has great potential as a biodegradable candidate to replace petroleum‐based plastics in packaging applications. Highlights Polylactic acid (PLA)‐based composites were reinforced by the modified chitin micro‐nano fibers. Chitin micro‐nanofiber (KCH)/PLA composites combined improved tensile properties and thermal stability. The interfacial compatibility was improved by the hydrophobic modification. Biodegradable KCH/PLA was molded into packaging products (fork and knife). KCH/PLA are promising candidates for replacing non‐biodegradable plastics.