A bio-plastic composite film based on nanocrystalline cellulose-zinc oxide reinforced poly (lactic acid) with enhanced UV-shielding effect and antibacterial activity for food packaging applications

This work reports the properties of composite films based on biodegradable poly (lactic acid) (PLA) incorporated with nanocrystalline cellulose (NCC) and nanocrystalline cellulose coated with zinc oxide (NCC-ZnO). The NCC was prepared from microcrystalline cellulose (MCC) by an acidolysis technique, and subsequently used as a supporting core for ZnO deposition via a hydrothermal process. The NCC and NCC-ZnO were characterized by various techniques, i.e., TEM, SEM, FTIR, XRD, and TGA. The results confirmed the successful fabrication of the NCC-ZnO, with approximately 41% weight of ZnO coated on the NCC surface. Both NCC and NCC-ZnO were later incorporated into PLA at various contents, and their properties, i.e., tensile properties, ultraviolet (UV) shielding efficacy, and antibacterial activity, were investigated. Compared with NCC, NCC-ZnO exhibited higher reinforcement because it provided greater tensile strength and Young's modulus at the same filler content. The addition of NCC-ZnO significantly improved the UV shielding efficacy (both UV-A and UV-B) and the antibacterial activity. The results reveal the potential of using NCC-ZnO as an alternative filler in active food packaging applications for enhanced performance.