Density scaling and decoupling in o-terphenyl, salol, and dibutyphthalate

Abstract

We present new viscosity and equation of state (EoS) results extending to high pressures for oterphenyl, salol, and dibutylphthalate. Using these and data from the literature, we show that the three liquids all conform to density scaling; that is, their reduce viscosities and reorientational relaxation times are a function of the ratio of temperature and density with the latter raised to a constant. Moreover, the functional form of the dependence on this ratio is independent of the experimental probe of the dynamics. This means that there is no decoupling of the viscosities and relaxation times over the measured range of conditions. Previous literature at odds with these results were based on erroneous extrapolations of the EoS or problematic diamond anvil viscosity data. Thus, there are no exceptions to the experimental fact that every non-associated liquid complies with density scaling with an invariant scaling exponent.

Corroborative evidences of TVγ-scaling of the α-relaxation originating from the primitive relaxation/JG β relaxation

“…(3) to a wide range of glass-forming liquids and polymers with values of  within the range 0.138.5 by dielectric spectroscopy. There are confirmations from measurements using light scattering, 21 , molecular dynamics simulations [23][24][25][26][27] , static ambient-pressure quantities 28,29 , and viscosity [30][31][32] . In polymers, TV  -scaling was found for both   (T,P) and the relaxation time n(T,P) of the chain normal modes with the same  by simulations 23 and by dielectric relaxation [33][34][35] , i.e.…”

Glass Transition Temperature and Density Scaling in Cumene at Very High Pressure

“…where x is τ α or η, F is an unknown function, and γ is a material-dependent scaling exponent [10,[13][14][15][16][17][18]. This scaling, known as density scaling, allows dynamic measurements taken over a broad range of T and ρ to collapse onto a single master curve when plotted vs. ρ γ /T .…”

Nano-viscosity of supercooled liquid measured by fluorescence correlation spectroscopy: Pressure and temperature dependence and the density scaling

“…The scaling exponent obtained for all the OTP data in Fig. 9 using the new equation of state (EoS) [6] amounts to  = 5.35. Thus, for OTP the density scaling works not only for rotational relaxation and viscosity, as it was shown in [6] but also for translational diffusion at temperatures T > 1.2 T g .…”

“…9 using the new equation of state (EoS) [6] amounts to  = 5.35. Thus, for OTP the density scaling works not only for rotational relaxation and viscosity, as it was shown in [6] but also for translational diffusion at temperatures T > 1.2 T g . In our previous publication [5] we have shown that the nanoviscosity calculated from the translational tracer diffusion coefficient of the fluorescent probe using the SE relation measured by means of FCS not only scales with the macroscopic viscosity, but these two viscosities are equal.…”

“…the reduced reorientational relaxation time and viscosity can be scaled to a single curve when plotted versus T -5.35 when the correct equation of state (EoS) is used to calculate the T and P dependence of the density [6]. In the previous studies on OTP [7] when another equation of state was used a successful scaling of the same data was achieved with the exponent  equal to about 4.…”