Novel antimicrobial bioplastic based on PLA-chitosan by addition of TiO₂ and ZnO

The purpose of this study was to develop antimicrobial bioplastics based on Poly Lactic Acid (PLA) with the addition of chitosan-ZnO, and chitosan-TiO₂ to improve antimicrobial properties.

For the preparation of the bioplastics, PLA with chitosan-ZnO or chitosan-TiO₂ were used. The antimicrobial activity, mechanical and thermal properties, and water vapor permeability of bioplastics were evaluated.

PLA-chitosan-ZnO indicated a robust antimicrobial activity against bacteria such as Salmonella typhi, Bacillus subtilis, Escherichia coli, Staphylococcus aureus, yeast such as Candida albicans, and fungus Aspergillus niger. No formation of new functional groups in PLA-chitosan-ZnO composites. In comparison to other PLA-based bioplastics, this bioplastic has medium tensile strength, tensile modulus, and elongation percentages with low barrier ability to water vapor. Chitosan-ZnO itself has a greater tensile strength compared to chitosan-TiO₂. These two compounds undergo 2 stages of decomposition in a temperature range of 43 °C to 265 °C. The addition of PLA into chitosan-ZnO or chitosan TiO₂ causes the bioplastics decomposed in a single stage. It also increases the decomposition temperature of bioplastic. However, compared to chitosan-ZnO or TiO₂, the PLA-chitosan-ZnO or TiO₂ bioplastics tend to produce a fragile composite indicating by decrease in their tensile strength.

In general, the addition of chitosan-ZnO into in PLA-based bioplastic produces better antimicrobial properties compared to TiO₂.