Sylwester J. Rzoska

Bio: Sylwester J. Rzoska is an academic researcher from Polish Academy of Sciences. The author has contributed to research in topics: Dielectric & Liquid crystal. The author has an hindex of 33, co-authored 216 publications receiving 3570 citations. Previous affiliations of Sylwester J. Rzoska include University of Silesia in Katowice & Silesian University.

Shear viscosity measurements near a critical endpoint

Abstract: The coordinates of the critical endpoint in a nitroethane–ethanediol–cyclohexane–methanol solution have been determined and measurements have been made of the shear viscosity in the vicinity of this point. Results can be well approximated with relations used to express the behavior of viscosity in the area of an ordinary critical point.

Consistency of the Vogel — Fulcher — Tammann (VFT) Equations For The Temperature-, Pressure-, Volume-and Density- Related Evolutions of Dynamic Properties in Supercooled and Superpressed Glass Forming Liquids/Systems

Abstract: A consistent set of temperature- (T), pressure- (P), volume- (V) and density- (ρ) related VFT-type equations for portraying the evolution of the structural relaxation time or viscosity is presented, namely: $$\begin{array}{rcl} \tau \left(P \right) & = & \tau _0 \,\exp \left[ {{{D_P \left({P - P_{SL} } \right)}/{\left({P_0 - P} \right)}}} \right] \\ \tau \left(T \right) & = & \tau _0 \,\exp \left[ {{{D_T \left({T_{SL} - T} \right)\left({{{T_0 }/{T_{SL} }}} \right)}/{\left({T - T_0 } \right)}}} \right],\\ \tau \left(\rho \right) & = & \tau _0 \,\exp \left[ {{{D_\rho \left({\rho - \rho _{SL} } \right)}/{\left({\rho _0 - \rho } \right)}}} \right]\\ \end{array}$$ andτ (V) = τ 0 exp[D T (V SL — V)(V 0 V SL )/(V — V 0)], where T 0,P 0,V 0 and ρ0 are VFT estimates of the ideal glass loci and T SL , P SL , V SL and ρ SL are estimates of the location of the absolute stability limit, partially hidden in the negative pressures domain (P<0). For these equations prefactors are well defined via ρ 0 = ρ (T SL ,P SL , V SL ,ρ SL ), ie. they are linked to the absolute stability limit loci (gas-liquid spinodal). Noteworthy is their smooth transformation into VFT-type equations, used so far, on approaching the glass transition, and into Arrhenius-type equations remote from the glass transition, on approaching the absolute stability limit. The latter may suggest the re-examination of experimental data suggesting the VFT-to-Arrhenius crossover far away from the glass transition. Novel VFT counterparts also lead to the consistent set of fragility strength coefficients (D T ,D P ,D V ,D ρ) and fragilities associated with the slope (steepness index) at appropriate “Angell plot” counterparts.

Polymer matrix ferroelectric composites under pressure: Negative electric capacitance and glassy dynamics.

Abstract: This report presents the results of high-pressure and broadband dielectric spectroscopy studies in polyvinylidene difluoride (PVDF) and barium strontium titanate (BST) microparticles composites (BST/PVDF). It shows that the Arrhenius behaviour for the temperature-related dynamics under atmospheric pressure is coupled to Super-Arrhenius/Super-Barus isothermal pressure changes of the primary relaxation time. Following these results, an explanation of the unique behaviour of the BST/PVDF composite is proposed. Subsequently, it is shown that when approaching the GPa domain the negative electric capacitance phenomenon occurs.

Temperature and pressure studies of the isotropic—mesophase transition discontinuity by static nonlinear dielectric effect

Abstract: Results of studies of static nonlinear dielectric effect (NDE) in the isotropic phase in the homologous series of nDBT: (5-n-alkyl-2-(4-isothio-cyanatophenyl)-1,3-dioxane) for n = 4, 6 and 8 exhibiting the I-SmA transition are presented. The strong pretransitional anomaly in the isotropic phase is similar to the one observed in nematogens. It has been found that the discontinuity of the I-N transition increases from 10.8 K to 18.8 K when moving from 4DBT to 8DBT. It has been also shown that pressure reduces the discontinuity of the I-SmA transitions. Results obtained are compared with similar studies in two other homologous series (Phys. Rev. E61 (2000) 5349 and Phys. Rev. E61 (2000) 5355).

Classification of secondary relaxation in glass-formers based on dynamic properties.

Abstract: Dynamic properties, derived from dielectric relaxation spectra of glass-formers at variable temperature and pressure, are used to characterize and classify any resolved or unresolved secondary relaxation based on their different behaviors. The dynamic properties of the secondary relaxation used include: (1) the pressure and temperature dependences; (2) the separation between its relaxation time τβ and the primary relaxation time τα at any chosen τα; (3) whether τβ is approximately equal to the independent (primitive) relaxation time τ0 of the coupling model; (4) whether both τβ and τ0 have the same pressure and temperature dependences; (5) whether it is responsible for the “excess wing” of the primary relaxation observed in some glass-formers; (6) how the excess wing changes on aging, blending with another miscible glass-former, or increasing the molecular weight of the glass-former; (7) the change of temperature dependence of its dielectric strength Δeβ and τβ across the glass transition temperature Tg; ...

Supercooled dynamics of glass-forming liquids and polymers under hydrostatic pressure

Abstract: An intriguing problem in condensed matter physics is understanding the glass transition, in particular the dynamics in the equilibrium liquid close to vitrification Recent advances have been made by using hydrostatic pressure as an experimental variable These results are reviewed, with an emphasis in the insight provided into the mechanisms underlying the relaxation properties of glass-forming liquids and polymers