Properties of Biodegradable Films Prepared from Blends of Poly(Vinyl Alcohol) and Plasticized Casein with Glycerol
AbstractAbstract Recently, there has been an increasing interest in biodegradable packaging materials because of the increasing of the environmental damage of plastic waste. Among the various natural sources, proteins have been used as a packaging material because of their abundance and renewability [1]. Casein is a commercially available protein obtained from cow’s milk. Casein can be used several application areas due to its good film-forming properties, high O2, CO2 barrier and transparency. On the other hand, there are some drawbacks of casein-based films. Such as high water permeability, poor mechanical properties and stiffness compared to the synthetic polymer films. To improve these properties, proteins can be blended with other polymers and plasticizers [2,3]. Plasticizers such as glycerol increased the free volume and flexibility of casein. Poly (vinyl alcohol) (PVA) is the water-soluble synthetic polymer and it is convenient to biodegradation with enzymes and microorganisms. PVA can be blended with natural polymers and proteins. It provides good mechanical properties, chemical resistance, biodegradability and barrier properties to O2 and aroma [4,5].