Elastic aftereffect viscosity

At lowest shear stresses the behavior of bentonite clays may be the same as that of a solid-like system with high viscosity, which is consistent with the Kelvin model and corresponds to region I. The investigation of relaxation properties of coagulation structures forming in these moderately concentrated dispersions of bentonite clays revealed the existence of an elastic aftereffect at low shear stresses. This aftereffect is related to mutual coorientation of anisometric particles that are capable of taking part in rotational Brownian motion without any rupture of contacts. Consequently, the nature of elastic aftereffect is entropic. In such systems high viscosities are related... 

As seen in Figure 3.21, a complete rheological curve contains four characteristic regions. Region I corresponds to low stresses under which the system may demonstrate a solid-like behavior with high viscosity (Kelvin model). This case is characteristic of the already mentioned bentonite clays. The studies of relaxation structures in moderately concentrated suspensions of bentonite clays indicated the appearance of elastic aftereffect at low shear stresses. This effect has an entropic nature, as it is associated with the... 

The deformabilities at these two stages, which corresponding to the different viscous elements, Hf and are different and amonnt to V4 and respectively (Figure 3.32b). Since the time constant of the elastic aftereffect is defined as the ratio of the viscosity to the corresponding elasticity modnlns, the two corresponding viscosities are... 

The analysis of the elastic aftereffect also requires that a particular model be introduced. Let us first examine the first stage of the elastic aftereffect the fast elastic strain related to the appearance of the viscosity, tif (10 -10 )q , where q is the viseosity of water. 

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