Vapour Pressure above the Glassy Trehalose Solution and Glass Relaxation

Data are scarce on thermophysical properties of the glassy trehalose solution at low temperatures.

Water vapor pressure above the glassy trehalose solution and the relaxation behavior were studied at temperatures from -57°C to -40°C and at concentrations from 71% to 78% (w/w).

Glassy trehalose solutions were prepared by quenching in liquid nitrogen. Vapour pressure was measured using the static method.

Vapour pressure above the glassy trehalose solution was slightly lower than above the glassy sucrose solution. The relaxation of the glassy state can be described by the stretched exponential Kohlrausch-Williams-Watts (KWW) function. The characteristic times of water relaxation (Τ_p) were compared with those of enthalpy relaxation (Τ_e). When the difference (∆T) between the glass transition temperature (T_g) and ageing temperature was relatively small, i.e. ∆T ≤ 10 K, Τ_p is close to Τ_e. If ∆T ≥ 15 K, Τ_e will be much greater than Τ_p.

The difference of water vapor pressure above the trehalose glassy solution and sucrose glassy solution could lead to significant distinction between their drying kinetics.