Preparation and Characteristics of Films Based on Polyvinyl Alcohol and Starch for Environmentally Friendly Packaging

The following article represents the research on the elaboration of biodegradable films for environmentally friendly packaging based on polyvinyl alcohol, corn starch, glycerin, and borax. Growing consumption of packaging results in greater waste; the biggest part of which comprises problematic plastic packaging that is difficult and expensive to recycle. The majority of biodegradable packaging materials have insufficient technological characteristics. It is due to that the development of composite compositions based on inexpensive raw materials is a necessary condition to extend the range of high-quality safe packaging capable of minimizing environmental impact. The objective of the study is to obtain film materials based on polyvinyl alcohol, corn starch, and glycerin with the addition of sodium tetraborate and to study its mechanical and surface properties. The compositions for the film samples are prepared by an aqueous solution of Polyviol 6 04/140 polyvinyl alcohol to which water-soluble corn starch is added. The mixture is gelatinized, cooled, and glycerin and borax are added under stirring. Films are obtained by casting onto a glass substrate. The films obtained are almost transparent to the sight, soft and flexible by touch, showing good stretchability. The values of tensile strength for the films containing polyvinyl alcohol-starch, as measured by a dynamometer on a universal testing machine, are 1.5-1.7 times higher than that of samples without starch. The values for elongation at break of the films tested fall between 280 and 425%. Surface property testing of the obtained films is performed with an instrument for the determination of the wetting contact angle. Distilled water and ethylene glycol are used as test liquids for wetting. Wetting kinetics analysis of the films by water and ethylene glycol shows the possibility to make high-quality marking with necessary consumer information on them. Biodegradable films with a polyvinyl alcohol-starch mass ratio of 5:2 exhibit the best mechanical and surface properties. From a performance point of view, PVA, starch, and borax-containing films could be used as biodegradable packaging.