Unraveling of Poly(lactic acid) (PLA)/Natural Wax/Titanium Dioxide Nanoparticle Composites for Disposable Plastic Applications

The present research is a comprehensive study that developed poly(lactic acid) PLA/natural wax (Wx)/non-functionalized titanium dioxide nanoparticles (TiO₂-NF) and PLA/Wx/titanium dioxide nanoparticles functionalized with triethoxysilane (TiO₂-F) composites by melt blending. This research systematically investigated their hydrolytic degradation, antibacterial properties, oxygen permeability, and optical transparency. The TiO₂-NF or TiO₂-F (0.1, 0.5, or 1 wt%) were added to a PLA/Wx (85:15) blend using a Brabender internal mixer at 180 °C. Hydrolytic degradation was carried out in distilled water at 50 °C and an initial pH of 6.2 for 9 months. Changes in weight, morphology, and the rheological behavior of the blends were evaluated at different times during the hydrolytic degradation of the PLA/Wx/TiO₂-NF and PLA/Wx/TiO₂-F composites. The antibacterial properties of PLA/Wx, PLA/Wx/TiO₂-0.1-NF, and PLA/Wx/TiO₂-0.1-F were assessed by testing them against both <i>E. coli</i> (Gram-negative) and <i>S. aureus</i> (Gram-positive) bacteria. Their oxygen permeability and optical transparency are comparable to those of LDPE films. These composites, produced by melt blending, show potential for application as disposable plastics, which could significantly impact the fields of materials science and polymer engineering.