|Lawton jr, John|
|Willett, Julious - J l|
Submitted to: Society of Plastics Engineers Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 5/12/2000
Publication Date: N/A
Citation: Interpretive Summary: Biodegradable plastics can be made from corn starch alone but these tend to be brittle and have poor water resistance. Starch can be coated to improve water resistance but most polymer coatings do not adhere well to starch. Thin film coatings of poly(hydroxyester-ethers)(PHEE)'s were found to adhere well to starch sheets and foams and provided resistance to cold water over short periods of time (hours- days). In the case of foam peanuts, the coating forms spontaneously during extrusion of a starch/PHEE blend, making an additional coating step unnecessary. Starch films and foams having a PHEE coating could have a number of uses such as mulch film, biodegradable packaging, clammshells, and plates. This technology will benefit companies which compound and process plastics, those which use plastic articles in their products, as well as other scientists in academia and government.
Technical Abstract: Poly(hydroxyester-ethers) (PHEE) were added to a variety of thermo- plastic starch composites in order to improve the mechanical and water- resistant properties of these systems. Thin film coatings of PHEE's were found to adhere well to starch sheets and foams and provided resistance to cold water over short periods of time (hours-days). Adhesion was decreased by high water or glycerol contents in the starch and was increased by addition of partially hydrolysed polyvinyl alcohol. Extruded starch foam peanuts containing 5-10% PHEE were found to have a thin surface layer consisting mainly of PHEE. This probably explains, at least in part, why the starch/PHEE foams have a higher expansion ratio, greater water resistance, and reduced friability compared to foams made from starch alone.