Glass transition
Amorphous and glassy states of molecular and pharmaceutical compounds: general properties

Figure 13 shows the evolution of the specific heat C_p of indomethacin during melting by heating a crystal and during supercooling, by cooling the liquid. The increase in C_p after melting (at T_m) is associated with the dynamic release of the large-amplitude molecular degrees of freedom that characterize the liquid state. By cooling the liquid quickly enough (at a rate of around 10°C/min) below T_m, crystallization can be avoided. C_p retains a value higher than that of the crystal until a temperature of T_g where it decreases quite sharply (but continuously). C_p...