Poly (vinyl alcohol) and casein films: The effects of glycerol amount on the properties of films

The aim of the present work was to investigate the effect of glycerol (GLY) concentration on the properties of poly (vinyl alcohol) (PVA)/casein (CAS) blend films. The films were prepared by solution casting method at the different concentrations of GLY. The structural, mechanical, thermal, barrier and hydrophilic-hydrophobic properties of the films were determined by various methods. The structural analysis indicated that there were some interactions between the components. Tensile test results release that tensile strength of the film decreased with the addition of GLY while strain at break values increased. According to thermogravimetric analysis (TGA) results, the GLY included films exhibited lower thermal stability than GLY-0 film. The residual weight decreased by increasing GLY content. The contact angle measurements showed that all films were hydrophilic structure. Also, the water vapor barrier property of the GLY-0 film was developed with the addition of GLY.