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

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. •Kefiran/Al2O3 nanocomposite films were prepared by solution casting method.•Al2O3 caused to increase water barrier and mechanical properties of kefiran films.•Uniform distribution of Al2O3 nanoparticles at lower concentrations was approved.•Al2O3 had different effects on mechanical properties at different concentrations.•Kefiran films with up to 3% Al2O3 are suitable for food packaging applications.