The impact of esterified nanofibrillated cellulose content on the properties of thermoplastic starch/PBAT biocomposite films through ball-milling.

To enhance the mechanical properties and interfacial compatibility of thermoplastic starch (TPS) highly filled poly(butylene adipate co-terephthalate) (PBAT) composite films, esterified NFC was innovatively fabricated and introduced into the composite system. The influences of NFC content and ball-milling treatment were thoroughly investigated. Interestingly, the amphiphilic esterified NFC provided a "bridge-like" effect between TPS and PBAT interfaces, which significantly improved the interfacial compatibility and mechanical properties. Notably, the tensile properties of the composite films reached their maximums at a 7 wt% NFC content, displaying a tensile strength of 6.2 MPa and an elastic modulus of 263 MPa. These values corresponded to a 59 % and 180 % increase, respectively, compared to the composition without NFC. More importantly, ball-milling contributed to uniform dispersion and surface activation of NFC, preventing starch retrogradation, and enhancing the tensile strength and elastic modulus by 30.3 % and 56.6 %, respectively. Additionally, the film exhibited excellent UV-blocking, foldable, writable, and transparent performance. These findings provide valuable data supporting the expanded applications of starch-based composite films.