A method is described. The method comprising inputting starch into an extruder, inputting a plasticizer into the extruder, outputting an extrudate from the extruder, and chopping the extrudate output from the extruder into pellets. The extrudate includes the starch and the plasticizer. A pellet for manufacturing a biodegradable product is described. The pellet comprises starch and a plasticizer. A composition of the pellet, by weight percent, includes a starch weight percent representative of the starch included in the pellet and a plasticizer weight percent representative of the plasticizer included in the pellet. The starch weight percent is greater than the plasticizer weight percent and a density of the pellet is at least 0.5 g/cm.sup.3.

A thermoplastic packaging material composition is provided. The thermoplastic packaging material composition includes from about 30 wt % to 96 wt % of a starch, from about 1 wt % to 60 wt % of a plasticizer, and from about 0.05 wt % to 10 wt % of an adhesion promoter. The adhesion promoter may comprise an amine functional polymer, such as polyethylenimine (PEI). A multilayer packaging article may also be provided. The multilayer packaging article comprises at least a first layer formed from the thermoplastic packaging material composition described above. The multilayer packaging article further may include a second layer adhered to the first layer. The second layer may comprise a thermoplastic resin. The multilayer packaging article may further include a third layer adhered to the second layer. The third layer may comprise a thermoplastic resin such as polyester.