Light shear viscosity

Mori et al. s results for three PBLG samples in m-cresol. For every sample, Dr decreases monotonically with increasing c, in a way resembling the simulation results shown in Fig. 16b. These Dr data, as well as the dynamic light scattering data, will be compared with Eqs. (50)- (52) in Sect. 8 together with zero-shear viscosity data. 

Here pg and p f are the mass densities of the gel and the solvent, respectively, K is a bulk modulus, c0 is the speed of sound, and i s is the solvent shear viscosity. The solvent bulk viscosity has been neglected. The terms proportional to / arise from an elastic coupling in the free energy between the density deviation of gel and that of solvent The p in Eq. (6.1) coincides with the shear modulus of gels treated so far. We neglect the frequency-dependence of the elastic moduli. It can be important in dynamic light scattering, however, as will be discussed in the next section. 

Abbreviations C, coexistence curve S, static light scattering D, dynamic light scattering T, turbidity N, coherent neutron scattering V, shear viscosity E, electrical conductance I, interfacial phenomena (ellipsometry). d Deuterated 1-octanol. 

Interfacial Viscosity. In a clean system in which two pure liquids produce an interface, the viscosity of the interface should be the same as the bulk solution viscosity. However, surfactant or impurity adsorption at an interface can cause a resistance to fiow to occur that can be measured as the interfacial shear viscosity. This viscosity is defined as the ratio between the shear stress and the shear rate in the plane of the interface (12), Methods used to make these measurements include a viscous traction surface viscometer (J2), droplet-droplet coalescence (J3), the rotating ring viscometer (14), and surface laser light scattering (9). 

Stegeman (1968) and Stegeman and Stoicheff (1968) have made an extensive experimental study of the doublet in the depolarized light-scattering spectrum for several liquids and claim reasonable agreement with the Rytov theory with the exception that an essential requirement for the validity of the theory does not hold—namely that the shear viscosity rjs, shear modulus ps, and shear relaxation time r must satisfy the relation... 

Despite the fact that here one has the typical composition of a microemulsion, i.e., surfactant-water-oil, one does not find a low viscosity microemulsion but instead a highly viscous system. The addition of water results in the formation of flexible cylindrical reverse micelles that form a transient network of entangled micelles and has been characterized by means of dynamic shear viscosity measurements [73,74]. Light scattering experiments on systems with cyclohexane as the oil have demonstrated that a water-induced micellar growth occurs and that these systems may be described analogously to semidilute polymer solutions [75-77]. 

Optohydrodynamics Fluid Actuation by Light, Fig. 5 (a) Fluid velocity profile in a two-layer system in presence of an interfacial tension gradient notations are also illustrated, (b) Analytical resolution of the steady flow pattern and the interface deformation in a double-layer conflguration with same shear viscosities and Hi = 5 2 = 5w. (c) Interface deformation in a three-layer system composed of a thin Aim of thickness 2Hi bounded by two external liquid layers of same thickness H2 for Hi = O.lw and H2 = 2w. Top. The dald T > 0 case leads to the formation of a dimple. Bottom. The dat I < 0 case leads to the formation of a nose... 

Callaghan and Neustadter [31] have made a study of the foam stabilities of air-crude oil and natural gas-crude oil systems using a variety of light crude oils of viscosities 14 mPa s. This study, at ambient temperature using a sparging method, concerned so-called dead oils from which natural gas had been separated. It also involved a comparison of the foam behavior with critical film rupture thicknesses, bulk phase, and surface shear viscosities together with dilatational surface properties. 

Figure 12.19 Derived parameters from surface quasi-elastk light scattering as a function of concentration of polymethyl methacrylate spread on water (a) surface tension (b) surface shear viscosity (c) dilational modulus...

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