PLA/PHBV/SEP/ZnO Hybrid Composites for Antimicrobial Multifunctional Packaging

The development of multifunctional packaging addresses the demand for solutions that combine protection, sustainability, and functionalities such as antimicrobial activity. In this context, films of hybrid composites (HC) based on a poly(lactic acid)/poly(3-hydroxybutyrate-co-3-hydroxyvalerate) blend - PLA/PHBV (70/30 wt/wt), sepiolite nanoparticles (SEP, 5 phr), and different contents (3 and 5 phr) of micrometric zinc oxide (ZnO) were produced via melt mixing and compression molding. The influence of ZnO content on rheological, thermal, mechanical, and water vapor permeability properties, as well as its role as an antimicrobial agent, was evaluated. Despite ZnO acting as a catalyst for PLA degradation during processing, the HC with 3 phr of ZnO demonstrated significant improvements, including a 16% in elastic modulus and a 21% increase in tensile strength (compared to PLA/PHBV blend), an 85% reduction in water vapor permeability (compared to PLA/PHBV/SEP nanocomposite), good processability, and effective inhibition of bacterial growth on the film surface. These results highlight the potential of HC with 3 phr of ZnO for producing multifunctional packaging using conventional melt-processing techniques.