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5.7 Ternary system nitroethane-3-methylpentane-cyclohexane

Figure 5.49: Frequency normalized ultrasonic attenuation spectra of the ternary mix- ture of col point composition:◦correspond to data close to consolute point ≃Tc, and □ represent ultrasonic data at temperature 23 oC.

of the binary as well as ternary mixtures of critical composition are displayed close to the consolute point. With respect to the main results of Mistura and D’Arrigo [139], [140], another conclusions has to be drawn in the case of the ternary mixture (NE-3MP-CH). The sound attenuation does not change in dependence on the number of components. The low frequency ultrasonic data displayed in Fig.(5.51) rather follow the behavior of the fluctuation correlation length ξ0 amplitude (small right plot in Fig.(5.51)). According to the Bhattacharjee-Ferrell dynamic scaling model the low frequency ultrasonic measure- ments, with the relaxation rate from dynamic light scattering have been evaluated for the α′, the col point and the α′′ ternary mixtures, with the critical amplitude SBF as the only adjustable parameter, according to Eq.(4.26), with respect to the Debye relaxation term. The data nicely fit to the empirical scaling function FBF, Fig.(5.52). The scaling function data in the case of the ternary mixture α′′ exhibits a remarkable scatter, due measurement problems, caused by rather high sound attenuation. Within the limits of this scatter, how- ever, the data from different runs and different temperatures of measurement fall on one curve and agree with the empirical scaling function. Unfortunately, the critical amplitude in all three mixtures demonstrates a dependence on temperature, with smaller magnitude but similar to that of the binary system (NE-CH). However, the additional relaxation con-

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