THERMOPHYSICAL PROPERTIES OF TREHALOSE AND ITS CONCENTRATED AQUEOUS-SOLUTIONS

Purpose. To address the lack of fundamental thermophysical data for tr ehalose and its aqueous systems by measuring equilibrium and nonequili brium properties of such systems. Methods/Results. Differential scanni ng calorimetry (DSC) and dynamic mechanical analysis were used to meas ure glass transition temperatures of trehalose and its solutions. X-ra y diffractometry was used to verify the structure of amorphous trehalo se. Controlled-stress rheometry was used to measure viscosity of sever al aqueous trehalose systems at ambient and sub-ambient temperatures. Over this temperature range, the density of these solutions was also m easured with a vibrating tube densimeter. The equilibrium phase diagra m of aqueous trehalose was determined by measuring the solubility and freezing point depression. Conclusions. Our solubility measurements, w hich have allowed long times for attainment of chemical equilibrium, a re substantially different from those reported earlier that used diffe rent techniques. Our measurements of the glass transition temperature of trehalose are higher than reported values. A simple model for the g lass transition is presented to describe our experimental observations .