Poly(lactic acid)-based composite film reinforced with acetylated cellulose nanocrystals and ZnO nanoparticles for active food packaging

Poly(lactic acid) (PLA)-based composite films reinforced with acetylated cellulose nanocrystals (ACNC) (1 wt%) and ZnO nanoparticles at different content (1, 3, 5 and 7 wt%) were prepared by solution-casting method. The surface acetylation of cellulose nanocrystals improved its dispersion in the PLA matrix. The morphologies, optical, mechanical, barrier, thermal and antibacterial properties of PLA/ACNC/ZnO ternary composite films were investigated. SEM images showed that ACNC and ZnO were evenly distributed in the PLA matrix to form homogenous film when the content of ZnO was ≤5 wt%. The PLA/ACNC/ZnO composite films showed improved UV blocking, mechanical strength, oxygen and water vapor barrier. This ternary composite also exhibited excellent antibacterial activity against E. coli and S. aureus. The migration amounts of Zn2+ from PLA/ACNC/ZnO composite film to food simulants were below the specific migration limit (5 mg/kg). Overall, the desirable properties of the resulting PLA/ACNC/ZnO ternary composite film highlighted the potential application as a promising option for active food packaging materials.