Polymer solutions and concentration

However, for more complex fluids such as high-polymer solutions and concentrated ionic solutions, where the range of intemiolecular forces is much longer than that for simple fluids and Nq is much smaller, mean-field behaviour is observed much closer to the critical point. Thus the crossover is sharper, and it can also be nonmonotonic. 

In conformity with the literature, dilute polymer solutions and concentrated polymer solutions will be discussed separately in this chapter. 

It is seen to contain two parameters m referred to as the consistency index with units of Pa s" and the dimensionless power law exponent . If = 1, the fluid is Newtonian and m = fi. For < 1, the fluid is shear thinning and the shear stress—shear rate slope decreases monotonically with increasing shear rate for > 1, the fluid is shear thickening and the stress-shear rate slope increases with increasing shear rate. We have already indicated that most macromolecular non-Newtonian fluids are shear thinning, however, shear thickening behavior is also observed over some ranges of shear rate with a number of polymer solutions and concentrated particle suspensions (Barnes et al. 1989). 

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