Novel Kefiran-Polyvinyl Alcohol Composite Film: Physical, Mechanical and Rheological Properties

Kefiran (Kef) is a water-soluble polysaccharide that can form transparent film; however, it is brittle. Therefore, in order to improve the mechanical properties of kefiran film, a mixture with other polymers can be offered. The expansion of mixed systems can propose kefiran and polyvinyl alcohol (PVOH) as a new composite film. Solutions of 20 gram per liter kef and 40 gram per liter of PVOH were prepared. A mixture of film-forming solutions of different ratios of Kef/PVOH (100/0, 68/32, 50/50, 32/68) was prepared. In this study, different experiments including the physical properties (thickness, moisture content, and film solubility in water), water vapor permeability, and mechanical properties (tensile strength, elongation at break, puncture strength, and puncture deformation) of composite films as well as the rheological properties of film forming solutions were investigated. The results of physical properties such as thickness, moisture content, solubility in water and mechanical properties such as tensile strength, elongation at break, puncture deformation, puncture strength and water vapor permeability indicated that the mechanical properties, thickness and solubility in water increase with increase in PVOH content; however, moisture content and water vapor permeability decrease. Rheological characterization of different film forming solutions exhibited Newtonian fluid behavior. These results contribute to the establishment of an approach to optimize films’ composition based on the interactions between polymers, aiming at improving the properties of polysaccharide-based films.