Schematic representation of n-octanoic acid (OA) and bis(2-ethylhexyl)amine (BEEA) molecular structures.
Density (upper panel) and refractive index at 546.1 nm (lower panel) of OA/BEEA system at 298 K as a function of volume fraction (ϕ OA).
Experimental number density values (ρ N ) as a function of XOA. The inset shows the excess molar volumes.
Molar refraction (R) of OA/BEEA system as a function of the OA molar fraction (XOA). The inset shows the excess molar refraction (ΔR) as a function of XOA.
Real (ɛ ′) and imaginary (ɛ ″) parts of dielectric spectrum of the mix at XOA = 0.35 (circles). Continuous lines are the overall fitting curves and the dashed ones are the single contributions.
Anti-Stokes side of the Brillouin spectrum for selected samples obtained at 25 °C. Solid lines are the fit results using Eq. (4). In the inset the full spectrum (Stokes and anti-Stokes sides) for a mixture (XOA = 0.67).
Normalized absorption, a/f 2, and hypersonic velocity as functions of temperature of some representative samples.
Relaxation time at 25 °C as a function of XOA.
Correlation between the relaxation times (found by both dielectric spectroscopy and Brillouin scattering) and the conductivity. For each point, the corresponding XOA value is shown as a label. Linear least squares fit to the data gives exponents (a) of 9 ± 1 for Brillouin data and (b) 4.2 ± 0.9 for dielectric ones.
Optimised fitting parameters derived from the analysis of dielectric data for all the samples.
Fitting parameters through the Cole-Cole model and Eq. (9) for the whole set of experimental data.
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