Our solubility measurements, which have allowed long times for attainment of chemical equilibrium, are substantially different from those reported earlier that used different techniques. Our measurements of the glass transition temperature of trehalose are higher than reported values. A simple model for the glass transition is presented to describe our experimental observations.
The glass transition temperature (T
g) and viscosity of aqueous trehalose and its mixtures with either NaCl or
Na2B4O7 (borax) have been measured over a wide range of concentration. Borax and sodium chloride increase
the viscosity and T
g‘ of aqueous trehalose. Although the presence of ionic charges may partly explain some
of the observed effects, it is clear that ionic solutes that form complexes with trehalose lead to a greater
increase in T
g. The viscosity of supercooled aqueous mixtures was measured at several temperatures, most of
them above the so-called crossover temperature, T
g‘, where a change in the dynamics of relaxation processes
is expected. The viscosities of all the binary and ternary mixtures exhibit the same temperature dependence
when the temperature is scaled according to the T
g values; a change in the slope of the linearized WLF
representation is observed at a temperature close to 1.2T
g. Above this temperature, a power law expression
provides a similar description of the temperature dependence of viscosity as the WLF equation, the former
having a physical justification in the mode coupling theory.
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