Author
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Lawton Jr, John |
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Submitted to: Satake Centre for Grain Process Engineering
Publication Type: Abstract Only Publication Acceptance Date: 6/6/1996 Publication Date: N/A Citation: N/A Interpretive Summary: Technical Abstract: Thermoplastic starch used alone and in combination with other biodegradable polymers can be processed into many useful articles. Starch is a hygroscopic polymer and will gain or lose water to achieve equilibrium with ambient air. Since water is a good plasticizer for starch, tensile properties of materials made with starch will change with relative humidity. Water can be a solvent for thermoplastic starch. Items that contain starch and come into direct contact with water can be severely altered or destroyed. To help alleviate the problems associated with starch's sensitivity to water, biodegradable water repellent coatings for starch have been evaluated. Hydrophobic polymers such as poly(hydroxybutyrate-co-valerate) when coated onto starch foam do a good job in protecting the foam from water. Because of their hydrophobic nature, these types of materials do well to ahere to starch. Peel tests done with starch foams and hydrophobic polymers indicate that peel strength is related to the surface energy of the coating. Peel strengths are in the order: Poly(hydroxybutyrate-co-valerate) is less than polycapralacton, is less than poly(lactic acid). Adhesion strength of coatings to substrate can be predicted from their interfacial tension. These predictions can be helpful in finding new coatings or possible compounds that can be used to lower the interfacial tension between starch and the hydrophobic coatings. |
