It has been shown that the temperature behavior of dielectric permittivity ($\varepsilon$) in the isotropic phase of nematogens can be described in the same way as in critical binary solutions. Hence, using a relation with the critical exponent $\phi =1-\alpha =0.5\mathrm{}\pm 0.03$ it was possible to portray the results of $\varepsilon \mathrm{}\left(T\right)\mathrm{}$ measurements in the isotropic phase of 5-heptyl-2-(4′-cyanobiphenyl)-pyrimidine and 4,4-$n$-octylcyanobiphenyl. The influence of the position of the permanent dipole moment on the results was tested by additional measurements in $n$-($p$-methoxybenzylidene)-$p^{\prime }$-butylaniline. It also has been shown that a fluidlike analogy can be applied to the nonlinear dielectric effect (NDE), which describes changes of dielectric permittivity induced by a strong electric field. Measurements were conducted for the lowest frequency used in NDE studies ($f=67\mathrm{}$ kHz), so the condition $\tau f\ll 1$ (with $\tau$ the relaxation time) was always fulfilled. Values of discontinuities of the isotropicnematic phase transition from both the analysis of $\varepsilon \mathrm{}\left(T\right)\mathrm{}$ measurements and NDE studies are in good agreement.

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.

We discuss the phenomenology related to the pressure behavior of viscosity in low-molecular-weight glass-forming liquids. We show that the effect of pressure on viscosity in two examined glass-forming systems, salol and ortho-terphenyl, can be satisfactorily described, over considerable ranges of pressure (up to 1 GPa) and temperature (300–425 K), by the two-parameter pressure law which has been proposed previously for the relaxation time shift. The presented analysis indicates that one of the parameters (the pressure counterpart of the Vogel-Fulcher-Tammann law parameter D, which accounts for the fragility of a glass former) is independent of temperature in salol and ortho-terphenyl. As a consequence, the scaling plot which normalizes data collected for different temperatures can be constructed for a given glass former. On the basis of the presented considerations, a general form of the temperature-pressure viscosity “equation of state” is proposed.