PREPARATION, THERMAL-PROPERTIES, AND EXTRUSION OF HIGH-AMYLOSE STARCHACETATES

Starch acetates having degrees of substitution (DS) 1.5, 2.0 and 2.5 w ere prepared by the reaction of high-amylose cornstarch with acetic an hydride and aqueous sodium hydroxide. Differential scanning calorimetr y studies revealed that water was an effective plasticizer for the sta rch acetates. Glass transition temperatures (T-g) of dry starch acetat es (165-185 degrees C) were lowered to 95-35 degrees C in the presence of excess moisture. Extrusion of DS 2.5 starch acetate containing 15% moisture at 150 degrees C gave an expanded, water-resistant foam. The foam had a higher bulk density, higher compressive strength and lower resiliency than polystyrene foam. Little degradation of the starch ac etate occurred during extrusion. Possible uses for starch acetate foam include seedling containers, soil drainage aids and food packaging/se rving. Published by Elsevier Science Ltd