ARS | Publication request: MORPHOLOGY/PROPERTY RELATIONSHIPS IN THERMOPLASTIC STARCH/POLY(HYDROXY ESTER ETHER) BIODEGRADABLE BLENDS

Submitted to: Society of Plastics Engineers Proceedings
Publication Type: Proceedings
Publication Acceptance Date: May 12, 2000
Publication Date: N/A

Interpretive Summary: Increase in U.S. agricultural production has resulted in commodity abundance and lower prices. New value-added products must be found to give more profit to the farmer. Starch, particularly from corn, can be used to produce starch-based biodegradable plastics which would not only give value-added products but reduce the waste associated with petroleum-based plastics. Disposable plastic use in the U.S. is an 18 billion pounds per year industry. Better knowledge of the relationship between structure and properties in starch-poly(hydroxy ester ether) (PHEE) blends is needed to design products which can successfully meet the required properties. The blend structure was strongly dependent on the processing conditions, especially the moisture level. Different moisture level during processing resulted in different structures, which possessed different mechanical properties. The blends processed at high moisture levels (25%) had elongated starch structures (fiber and sheet- like) which improved the strength and stiffness of the blends. Hence an understanding was developed which would help determine the manner in which these blends should be processed to tailor the end properties. The benefit would be to farmers, especially corn producers, and the environment, since these products would replace petroleum-based plastics.

Technical Abstract: The effect of moisture level during processing on the mechanical properties of biodegradable blends of thermoplastic starch and poly (hydroxy ester ether)(PHEE) was studied. The morphology of the blends changed with the moisture content of starch. The dispersed phase was significantly deformed under high moisture conditions, leading to fibrillar and laminar types of morphologies at 50-80% starch level. A low moisture level produced a more dispersed morphology. Improved tensile properties were observed for the blends processed at high moisture levels due to the presence of elongated morphologies.