Deviations from the Einstein Model

The Einstein theory is based on a model of dilute, unsolvated spheres. In this section we examine the consequences on intrinsic viscosity of deviations from the Einstein model in each of the following areas  

In addition, we introduce one other major source of deviation discussed in more detail in Section 4.8, namely, effects of interparticle interactions due to charges on the particles and polymer additives. 

We consider each of these items as potential causes of deviation in the following subsections. 

To do this, we consider a dispersion of volume fraction 4 and examine the increment in viscosity dr) as a small amount of particles is added to the dispersion. If we take j to be small enough that the Einstein equation, Equation (41), holds, the increment dr) that accompanies the addition of particles is then given by 

11 The effect of particle crowding on viscosity. The solid line is drawn according to Equation (48) the points are experimental results. (Data from R. Roscoe, Br. J. Appl. Phys., 3, 267(1952).) 

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