Development and characterization of kefiran - Al₂O₃ nanocomposite films: Morphological, physical and mechanical...

Biodegradable kefiran films, containing different concentrations of Al₂O₃ (alumina) (1, 3 and 5% w/w), were prepared by casting method and their physical, mechanical, and thermal properties were studied. Based on the results, the increase of the nano-Al₂O₃ content led to a decrease in the water vapor permeability, moisture content, moisture absorption, and water solubility. The addition of nanoparticles did not affect the lightness of the films significantly (P > 0.05). The mechanical tests revealed that the addition of Al₂O₃ nanoparticles to the kefiran films significantly increased both tensile strength and elastic modulus, while had no effect on the elongation at break (P > 0.05). Thermogravimetric analysis (TGA) indicated the improvement of the films' thermal stability by adding alumina. The results of X-ray diffraction (XRD) confirmed the effect of Al₂O₃ on the semi-crystalline structure of kefiran. Scanning electron microscopy (SEM) images approved a uniform distribution of nanocomposites containing 1 and 3% w/w of Al₂O₃. The obtained results suggested that Al₂O₃ was able to improve the characteristics of the kefiran-based films for using as food packaging material.