this invention discloses a method of preparing and extruding biodegradable starch blends into biodegradable products in such a way that preprocessing steps , such as gelatinizing or destructurizing of the starch , are not required . unprocessed raw starch is combined with biodegradable copolymers such as polyvinyl alcohol , or ethylene vinyl alcohol , a nucleating agent , and a plasticizer . the combination may be processed using a twin - screw mixer , and blown into a film . the method described in this invention alleviates pre - preparation steps , reduces the cost and time required to prepare and extrude starch - based biodegradable materials , eliminates the need to use expensive pre - processed starch , and results in a substantially completely biodegradable product .