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