Eco‐Friendly Poly(Lactic Acid)/Poly (Butylene Adipate‐Co‐Terephthalate) Films Loaded by Zinc‐Aluminum Layered Double Hydroxide Nanoparticles for Packaging Applications

In this study, a novel biodegradable nanocomposite film containing poly(lactic acid) (PLA)/poly(butylene adipate‐co‐terephthalate) (PBAT) as matrix and zinc‐aluminum layered double hydroxides(Zn‐Al LDH) nanoparticles, was prepared by the melt‐compounding method. First, the sol–gel process was applied to synthesize the Zn‐Al LDH nanoparticles. The nanocomposite films composed of 0.25, 0.5, 0.75, and 1 phr of the nanoparticles were then prepared. The morphological and thermal properties, mechanical behavior, as well as water vapor transmission in the nanocomposites were analyzed. Incorporation of nanoparticles improved interfacial adhesion of the two phases (PLA and PBAT) and their compatibility, as confirmed by the Field Emission Scanning Electron Microscopy. The sample loaded with 1 phr of Zn‐Al LDH exhibited higher miscibility than other samples. Structural properties in LDH crystals were investigated using x‐ray diffraction analysis. Improved tensile strength from the initial value (25.14 MPa in unloaded sample) to 35 and 31 MPa was obtained through incorporating 0.25 and 0.5 phr of nanoparticles in the matrix, respectively. Differential scanning calorimetry revealed enhanced crystallization ability of the polymer matrix, as well as a higher cold crystallization rate in the nanocomposite films. The measurement of Water Vapor Transmission Rate (WVTR) exhibited enhanced gas obstacle properties through embedding of Zn‐Al LDH nanoparticles. The PLA/PBAT nanocomposites containing 1 phr of nanoparticles displayed the lowermost WVTR with a 70% decrease compared to the unloaded one. These results confirm morphological findings, as well as improved crystallinity of the samples by loading of the Zn‐Al LDH nanoparticles, which endow them as a promising candidate for use as food packaging films.