Synergistic Effects of ZnO Nanoparticles on the Structural and Antibacterial Performance of LLDPE Blown Films

Zinc oxide (ZnO) nanoparticles are antibacterial agents that have received attention from many researchers across the world as materials exhibiting excellent antibacterial activity, biocompatibility, and thermal resistance. In addition, ZnO nanoparticles have lower toxicity to human cells when compared with other antibacterial agents. This study explores the impact of ZnO nanoparticles as key fillers on the linear low-density polyethylene (LLDPE) structural, chemical, and functional properties, hypothesizing that LLDPE incorporation would enhance the mechanical and antibacterial properties. Styrene maleic anhydride (SMA) was also used as a compatibilizer agent. The nanocomposite film of LLDPE/ZnO was fabricated by the blown-film extrusion method, and the samples were characterized using FTIR, tensile testing, SEM-EDS, DSC, TGA, XRD, and antibacterial activity measurements. The results indicated that no chemical reaction occurred between the LLDPE chains and ZnO nanoparticles. The mechanical properties of the LLDPE/ZnO nanocomposite films increased compared to those of neat LLDPE films. Furthermore, the mechanical properties of the PEMB3 nanocomposite films were superior to those of the PEMB1 and PEMB2 films due to the presence of SMA and ZnST within the nanocomposite compositions. This indicates that the good distribution of ZnO nanoparticles in the presence of the SMA compatibilizer led to improved mechanical properties of the LLDPE/ZnO nanocomposite films. SEM images revealed that the agglomerate size of ZnO nanoparticles within the LLDPE matrix increased with increases in the ZnO concentrations. Increasing the ZnO nanoparticle loadings enhanced the thermal properties and crystallinity of the LLDPE/ZnO nanocomposite films. Among the nanocomposite films, the PEMB2-3 showed the highest melting temperature and the maximum degradation temperature at 123.13 and 434 °C, respectively. It can be concluded that LLDPE nanocomposite films with an optimum ZnO nanoparticle loading can be used in high-temperature applications. Finally, it was found that all LLDPE nanocomposite films incorporating ZnO nanoparticles exhibited antibacterial activity against Staphylococcus aureus and Escherichia coli. Additionally, all of the obtained LLDPE/ZnO nanocomposite films exhibited greater antibacterial activity against S. aureus than against E. coli. This is probably due to the difference in the structural characteristics of the bacterial cells. These results indicate that these nanocomposite films could be able to efficiently serve as a potential for advanced applications in antimicrobial packaging materials.