HEAT-CAPACITIES AND GLASS TRANSITIONS OF 1-PROPANOL AND 3-METHYLPENTANE UNDER PRESSURE - NEW EVIDENCE FOR THE ENTROPY THEORY

The heat capacities of 1-propanol and 3-methylpentane were measured in the temperature range 50-180 K (50-130 K for the latter) and at three different pressures (0, 108, 198 MPa) using an adiabatic high-pressure calorimeter. For both substances, the glassy state was readily realized by cooling the liquid and glass transitions were observed calorimetrically at every pressure. Thermodynamic quantities associated with the fusion of the crystalline phase were measured at three pressures for 1-propanol and at 108 MPa for 3-methylpentane. Pressure dependences of the glass transition and fusion were accurately determined. Experimental data for the entropy of fusion and the heat capacity difference between the glass and the liquid were combined to calculate the temperature dependence of the configurational entropy, S(c), at each pressure. The pressure dependence of the Kauzmann temperature, T0, at which S(c) tends to vanish, was also determined. It was found that the quantity TS(c) was almost constant at T(g) for respective pressures, indicating the validity of the entropy theory proposed by Adam and Gibbs.