Preparation and Characterization of PVA/ZnO Nanocomposite

ZnO nanoparticles were synthesized by the sol-gel method. The nanoparticles were added to polyvinyl alcohol (PVA) biopolymer to compare the microstructural, mechanical, antibacterial and physical properties of bionanocomposite films reinforced with various loading contents (1, 3 and 5 wt %) and thicknesses (70, 100 and 130 μm). Results showed that with increasing ZnO content to 3 wt %, the tensile strength and Young's modulus increased by 64 and 72%, respectively. The least amount of water vapor permeability was also observed in the sample containing 5 wt % ZnO nanoparticles. Moreover, the antibacterial properties of the films improved with ZnO addition and increased by increasing nanoparticle content up to 5 wt %. However, the transparency of the PVA-based films decreased by ZnO addition. Practical Applications A suitable food packaging can increase the shelf life of a food product in addition to sustain its initial quality. The majority of materials used for food packaging are made of undegradable fossil fuel products which have led to the serious environmental problems. On the other hand, the biodegradable films that have been developed suffer from several limitations such as frangibility due to low mechanical strength and weak gas exchange inhibition. Because of very high “surface to volume ratio” of nanostructured materials, their properties are drastically different from common conventional materials. Zinc oxide (ZnO) nanostructured materials have exhibited fascinating properties which have led to wide variety of applications including biomaterial applications. In this regard, the production of the hydrogen peroxide at their surface results in outstanding antibacterial activity. Furthermore, because of ZnO biocompatibility, it is a promising candidate for substitution of silver-based nanoparticles in food packaging applications. Polyvinyl alcohol (PVA), a degradable polymer, is easily dissolved in water, and combination of ZnO nanoparticles and PVA results in improved electrical, mechanical and optical properties. This no poisoning biodegradable nanocomposite should be used as a more effective and environmentally friendly material for food stuff packaging.