Below Tg: secondary relaxations
Amorphous and glassy states of molecular and pharmaceutical compounds: general properties

Figure 28 shows the evolution of the dielectric loss factor ${\epsilon }^{″}\omega \left(T\right)$ of amorphous maltitol as a function of temperature, for several frequencies from 100 to 200 kHz. The temperatures cover a range on either side of T_g. For T > T_g, we note the presence of the α relaxation peak, whose temperature at the peak changes little with frequency. In other words, its characteristic frequency decreases rapidly with decreasing temperature. This leads to an effective motion freeze corresponding to T_g. This rapid evolution reflects the high activation energy of the α process. For T < T_g, we note the presence of relaxation peaks,...