Preparation and characterization of bionanocomposite films reinforced with nano kaolin

Effects of nano-kaolin incorporation into semolina films on the physical, mechanical, thermal, barrier and antimicrobial properties of the resulting bio-nanocomposite films were investigated. The properties included crystal structure (by X-ray diffraction), mechanical resistance, color, Fourier transform infrared spectra, decomposition temperature, water-vapor permeability (WVP), oxygen permeability (OP), and antimicrobial activity against Staphylococcus aureus and Escherichia coli. Kaolin was incorporated into biofilms at various amounts (1, 2, 3, 4, and 5 %, w/w total solid). All films were plasticized with 50 % (w/w total solid) combination of sorbitol/glycerol at 3:1 ratio. The incorporation of nanokaolin into semolina films decreased OP and WVP. The moisture content and water solubility of the films were found to decrease by nanokaolin reinforcement, and mechanical properties of films were improved by increasing nanokaolin concentration. Tensile strength and Young's modulus increased from 3.41 to 5.44 MPa and from 63.12 to 136.18, respectively, and elongation-at-break decreased. The films did not exhibit UV absorption. In conclusion, nanokaolin incorporation enhanced the barrier and mechanical properties of semolina films, indicating the potential application of these bio-nanocomposites in food-product packaging.