Method for Forming a Thermoplastic Composition that Contains a Plasticized Starch Polymer

A system for forming a thermoplastic starch-based composition, the system comprising:

• a supply of a starch polymer and a plasticizer;
• an extruder and a die, wherein the starch polymer and plasticizer are capable of being melt blended within the extruder and through the die to form an extrudate;
• at least one water-cooling stage located downstream from the extruder and die, the water-cooling stage comprising a water bath within which the extrudate is immersed upon exiting the die;
• and
• at least one air-cooling stage located downstream from the water-cooling stage that is configured to supply a stream of air into contact with the extrudate upon exiting the water bath.

A method for forming a thermoplastic starch-based composition, the method comprising:

• melt extruding a thermoplastic composition through a die to form an extrudate, wherein the thermoplastic composition comprises a starch polymer, plasticizer, biodegradable polymer, polyolefin, and a compatibilizer;
• subjecting the extrudate to at least one water-cooling stage in which the extrudate is contacted with water for a first period of time;
• and
• thereafter, subjecting the water-cooled extrudate to at least one air-cooling state in which the extrudate is contacted with air for a second period of time, wherein the air-cooled extrudate has a moisture content of from about 500 to about 20,000 parts per million.