Investigation of the Thermomechanical Properties of a Polylactic Acid/ZnO Biocomposite Film Distained for Food Packaging

Studies have been conducted on how the structural, thermal, morphological, mechanical, and antibacterial properties of PLA polymer are affected by low filling concentrations of ZnO nanoparticles. This study proposes the fabrication of biodegradable PLA–ZnO films with ZnO filling percentages ranging from 2.5 to 40%, utilising a cost-effective process involving solvent casting combined with ultrasonication at room temperature. The films were characterised using XRD, FTIR, SEM, TGA testing, tensile testing, and antibacterial testing against E. coli and S. aureus. The integration of ZnO affects the structural semi-crystallisation of the PLA matrix and prefers an hkl crystallographic orientation as support. SEM images confirmed the efficient dispersion of nanoparticles in all films, which has a direct impact on thermal stability. Regarding mechanical properties, tests conducted according to the ATMD-882 standard demonstrated good properties even at the saturation point of 40%. Ultimately, this study demonstrates that biodegradable films exhibit effective antibacterial activity against E. coli and S. aureus, even at low filling ratios, thereby suggesting their potential applicability in the food packaging sector.