Showing papers by "Sylwester J. Rzoska published in 2004"

Temperature and volume effects on the change of dynamics in propylene carbonate.

Abstract: 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.

Liquid–liquid phase equilibria in nitrobenzene–hexane critical mixture under negative pressure

Abstract: A new method has been presented in this paper on the determination of the liquid–liquid critical locus of a binary liquid mixture (nitrobenzene/n-hexane) under negative pressure, using experimental data obtained from measurements performed on positive pressures. The method is based on the pre-transitional anomaly of the dielectric permittivity and enables us to determine the liquid–liquid locus down to −20 MPa without actually going below P = 0.

Effect of pressure on dynamic heterogeneity in dendrimeric alkyd resin.

Abstract: Broadband dielectric spectroscopy is employed to investigate the non-Debye relaxation behavior in a dendrimeric alkyd resin. From temperature-dependent measurements at ambient pressure, we found a very broad distribution of relaxation times. This is attributed to the complex geometrical topology of the molecule. However, compression significantly reduces the non-Debye character of the dielectric response; thus, pressure induces dynamic homogeneity in the dendrimeric alkyd resin.