Abstract
In this study, we evaluated the probability process of devitrification and the moisture absorption rate for the
amorphous trehalose film that formed on a CaF2 glass surface. The film samples were left at longest, for 7
hours in the test chamber filled with 40 °C -relative humidity (Rh= 40-80 %) air. Using FTIR spectrometer,
the IR absorption spectrum of samples was measured at 0.5 or 1 hour intervals during the storage. The phase
change in the film was judged by the differential spectrum from the initial state, and the water content in a
film sample was evaluated by the area of 2 bend + libration combination peak. The results are summarized
as, 1) the devitrification process of amorphous trehalose film were stochastic, 2) the exposure of amorphous
trehalose film at Rh= 60 % induced the crystallization of trehalose dihydrate, while the exposure at Rh=
70 % induced the crystallization and the liquefaction of sample film, 3) the water absorption coefficient and
absorption flux of amorphous trehalose at 40 °C were calculated, 4) the equilibrium vapor pressure of
amorphous trehalose is 3.7 kPa.
