Stoichiometric interpretation of thermoplastic starch water sorption and relation to mechanical behavior

The characterization of glycerol plasticized starch by water sorption was interpreted in terms of interaction stoichiometry. The saturation of starch was found to correspond to a 2:1 anhydroglucose unit/glycerol stoichiometric ratio. The introduction of cellulose into the formulation of plasticized starch (TPS) decreased the quantity of bonded glycerol, due to the strong interaction between cellulose and starch. The systematic study of the TPS properties in the whole range of relative humidities showed transitions which were not connected to the “saturation transition” or to the glass transition. Breaking properties probably depended on a complex combination of different system characteristics.