Thermal relaxation calorimetry on ethanol at low temperatures

Ethanol exhibits a very interesting polymorphism presenting different solid phases: a fully-ordered (monoclinic) crystal, a (bcc) plastic crystal which by quenching becomes an orientationally-disordered crystal with glassy properties, and the ordinary amorphous glass. Therefore, it appeared as a good model system to investigate low-temperature properties of glasses, including the role played by orientational vs translational disorder. In the present work, we extend and improve previous measurements by implementing higher-accuracy calorimetric methods at low temperatures (especially, two complementary versions of the thermal relaxation method). We have employed these new measuring methods to study the possible effect of water impurities on the calorimetric and thermodynamic behavior of the different solid phases of ethanol.