Dielectric relaxation and $PVT$ measurements were carried out on propylene carbonate. From these, we show that thermal energy exerts a stronger influence than volume on the temperature dependence of the dynamic properties. Data obtained at all temperatures and pressures superimpose, when expressed as a function of $T^{-1}{V}^{-3.7}$. The scaling exponent is consistent with more thermally governed dynamics, and can be interpreted as a reflection of the soft nature of the potential. The change of dynamics observed in the conductivity and relaxation data transpires at a fixed value of either quantity, independent of temperature and pressure.

• Received 12 August 2004

DOI:https://doi.org/10.1103/PhysRevE.70.061501