Hypersonic dispersion

Fig. 3. 73-function, (90R) and refractive index of poly(l,2-propandiol) "PPG 1000 versus temperature. This oligomer is known to exhibit a hypersonic dispersion near room temperature. 

Recently, Brillouin scattering has proved useful in this area for studying the frequency dependence of hypersonic (GHz zone) absorption and dispersion velocity in liquid sulphur dioxide [91] the effect of isotopes on hydrodynamic fluctuations in self-associated fluids [92] and the elastic properties of polyethylene glycol solutions in water, benzene and toluene [93]. 

Tornado dry powder system uses a hypersonic high shear system to ensure maximum dispersion without sample attrition. This system is stated... 

Another approach to determining the viscoelastic properties of dense microemulsions at high frequencies is to conduct ultrasonic absorption experiments. In such experiments it has been found that the percolation process is correlated to a shift of the ultrasonic dynamics from a single relaxation time to a distribution of relaxation times [121]. Other experiments showed an increase in the hypersonic velocity for samples at and beyond the percolation threshold. The complex longitudinal modulus deduced from such experiments is also correlated with the occurrence of the percolation phenomenon, which suggests that the velocity dispersion is clearly correlated with structural transformations [122]. 

Figure 3 displays the hypersonic speed dispersion curves of CCl, at four different temperatures. The complete dispersion curve contains additionally an experimental point corresponding to the ultrasonic velocity, i.e. lying at a comparatively low frequency which is located on the ordinate axis. The fit has been made with the classical dispersion relation with the relaxation time, and the amplitude of the dispersion curve as free fit parameters according to the equation ... 

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