PHYSICOCHEMICAL CHARACTERIZATION OF NATURAL AND ACETYLATED THERMOPLASTIC CASSAVA STARCH CARACTERIZACIÓN FISICOQUÍMICA DE ALMIDÓN TERMOPLÁSTICO DE YUCA NATURAL Y ACETILADA

摘要: th , 2009, accepted April 22 2010, fi nal version April, 30 2010 ABSTRACT: Thermoplastic starch (TPS) was obtained from natural and acetylated cassava using a twin screw extruder then con- ditioned at 25 oC 54 % of relative humidity. It found that the crystallinity index, calculated as ratio IR peaks 1047 (crystalline phase) 1022 cm- 1 (amorphous phase), decreases due to effect plasticization process. Also, expected, SEM micrographs show process destroyed granular structure almost completely an amorphous mass obtained. The TGA results indicated activation energy, Ea, also reduced by TPS shows decrease in Tg, tensile strength percentage moisture absorption compared but larger strain breaking point. This behavior suggests chemical modifi cation reduces secondary interactions between chains substitution hydroxyl groups acetates.