Antioxidant and antibacterial PBAT/lignin-ZnO nanocomposite films for active food packaging

In present works, the lignin-zinc oxide (LZn) hybrid particles composed with lignin nanoparticles (LNP) and zinc oxide (ZnO) were prepared by a simple hydrothermal method under different pH conditions. Results from infrared spectra, thermogravimetric analysis, and elemental analysis evidenced the successful synthesis of LZn hybrids. The bacterial survival rate of LZn-9 (pH=9) against E. coli and S. aureus decreased to 9% and 49%, while the value of LNP was 69% and 80%, respectively. Then glyceryl methacrylate (GMA) was grafted on poly (butyleneadipate-co-terephthalate) (PBAT), following by the addition of LZn hybrid to prepare the master batches. Finally, the master batches were catalyzed by trimethylamine, and the PBAT-G-xLZn composite films were produced. The tensile modulus and yield strength of PBAT-G-3LZn increased by 35.2% and 28.6% compare with pure PBAT, respectively. The PBAT/LZn composite films were found to have obvious UV shielding, antioxidant and antibacterial activities. Composites belong to the contact type antibacterial, the bacterial adhesion rates of PBAT-G-xLZn were obviously reduced compare with pure PBAT. The transmittance at λ = 320 nm of PBAT-G-3LZn film was only 0.16%, and the radical scavenging activity (RSA) value was 11.6%. The Zn2+ migration concentration of PBAT-G-3LZn was only 3.3 μg/L. Therefore, the PBAT/LZn composite films were believed to be applied for active food packaging.