ISSN:
1572-9567
Schlagwort(e):
critical phenomena
;
shear viscosity
;
diffusivity
;
dynamic scaling
Quelle:
Springer Online Journal Archives 1860-2000
Thema:
Physik
Notizen:
Abstract Results of measurements of the temperature dependence of the shear viscosity and the mutual diffusion coefficient of a 2-butoxyethanol/water mixture of critical composition are reported. The shear viscosities are measured with a capillary viscometer, and the diffusion coefficients by dynamic light scattering. The viscosity data are used to determine the regular (background) and the singular (critical) part of the viscosity $$[\eta _b ;\eta = \eta _b (Q_0 \xi )^{z_\eta } ]$$ and to analyze the crossover regime.Q 0 has a value ofQ o = (1.54 ± 0.60) × 106 cm−1, which is small for a binary mixture of components of small molar mass. The viscosity is dominated by singular contributions in a narrow temperature range (T c − T) ≤ 1.2 K. The singular contributions can be neglected for temperatures (Tc−T) ≥ 11 K. The function η=ηb expz η H, given in the literature, represents the viscosity data in the temperature range 3 mK ≤ (T c − T) ≤ 25 K using the asymptotic form of the functionH for (q d/q c) → 0 (q d,q c, parameter of the theory). This limit corresponds to the case in which the background diffusion coefficient Lib can be neglected. The reduced diffusion coefficient D* calculated from the light-scattering data as a function of the scaling variable x(=qζ) is represented by the approximation of the dynamic scaling function proposed in the literature.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1007/BF01439247
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