Debye momentum cutoff of the critical binary mixture of carbon tetrachloride and coconut oil

Author(s): Yusur.H.Kittany, Issam.R.Abdelraziq

The dynamic shear viscosity coefficients of the binary liquid mixture carbon tetrachloride and coconut oil for different temperatures and concentrations are measured using digital viscometer with UL adapter. Shear viscosity anomaly is clearly observed near the critical temperature Tc= 22.2 C and the critical concentration xc= 0.732 by weight of carbon tetrachloride. Debye parameter L (the intermolecular force range) was calculated using a light scattering formula to be L = 5.5 Å. Mode Coupling Theory (MCT) of the dynamic shear viscosity is used to fit our experimental data above the critical temperature in the range 0.05  T-Tc 8C. It is found that the noncritical part of the dynamic shear viscosity (background viscosity) ç0 = 2.59 cP and the Debye momentum cutoff (the upper cutoff wave number) qD= 0.126 Å-1. The MCT universal constant A is measured to be A = 0.054 which is consistent with the theoretical value.

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