Effect of clay nanoparticle on structural and thermal properties of nano-biopolymer films based on kefiran

Kefiran is an exopolysaccharide produced by microorganisms present in the kefir grains that has several health promoting properties. In this research, physico-mechanical and thermal characteristics of nanocomposite film composed of kefiran-montmorillonite (MMT; 1, 3 and 5% w/w) were studied. Results showed that the thickness and the tensile strength of the films increased by increasing the nanoclay content but its effect on the elongation at break, glass transition temperature and melting temperature in various concentrations is different, so that these factors increase until concentration of 3% of the nanoclay and decrease in higher concentrations(5%). X-ray diffraction analysis showed that formation of an exfoliated structure with the addition of small amounts of MMT to the kefiran matrix. Scanning electron microscopy and the surface topography results showed ideal dispersion for MMT nanoparticles into the structure of the bio-nanocomposite films and a considerable increase in roughness parameters by incorporating the nanoparticles in kefiran matrix,respectively.