Extrudable polyvinyl alcohol compositions containing modified starches.

摘要

An extrudable polyvinyl alcohol composition useful for packaging and molding applications is prepared by melt blending polyvinyl alcohol and thermoplastic modified starch to provide a product which has reduced water sensitivity, improved modulus and reduced elongation at high relative humidity. A method for extruding the polyvinyl alcohol composition comprises: adding sufficient energy to the polyvinyl alcohol composition to both melt it and essentially eliminate the polyvinyl alcohol crystallinity in the melt, and simultaneously removing energy from the melt at a rate sufficient to avoid decomposition of the polyvinyl alcohol. The thermoplastic modified starch may be added to the polyvinyl alcohol before or during the melting of the polyvinyl alcohol and elimination of its crystallinity, or the starch may be blended with the thus treated polyvinyl alcohol and then melt extruding the polyvinyl alcohol/starch blend.