Slow relaxations in salicylsalicylic acid studied by dielectric techniques

The dielectric techniques of Thermally Stimulated Depolarization Currents (TSDC) and Dielectric Relaxation Spectroscopy (DRS) were used in order to study the low frequency molecular motions in salicylsalicylic acid. Since this substance is a very effective glass-former, the molecular mobility was analyzed in the glassy state, in the metastable supercooled liquid state, and in the crystal. Four different kinds of motion have been detected and characterized: one in the crystal, two in the glass (α and β-relaxations) and one in the metastable liquid. Salicylsalicylic acid appears as a very strong glass former (fragility index m = 31 on the Angell scale). In addition, the thermally stimulated depolarization current technique used in the study proved to be a very powerful tool to study slow molecular motion in this particular system.