Ostwald-deWaele

Effective viscosity as a function of shear rate for 0.15 g/dL of copolymer 5 in distilled water is given in Figure 15 The Ostwald-DeWaele exponent for copolymer solutions is greater than that of matching hydrolyzed copolymer solutions at a given concentration. Thus, copolymer molecules are less compactable in solution than are their hydrolyzed derivatives, and pseudoplasticity of polymer solutions increases upon hydrolysis. 

Figure 13. Plot of the Ostwald—DeWaele exponent, sample 8.

Rheologically, the flow of many non-Newtonian materials can be characterized by a time-independent power law function (sometimes referred to as the Ostwald-deWaele equation)... 

If the data (either shear stress or viscosity) exhibit a straight line on a log-log plot, the fluid follows the power law (or Ostwald deWaele) model ... 

EFFECT OF PLASTICIZERS ON PRODUCT PROPERTIES Rheological properties of PVC pastes can be conveniently modelled by Ostwald-deWaele, ... 

Pseudoplastic fluids. The majority of non-Newtonian fluids are in this category and include polymer solutions or melts, greases, starch suspensions, mayonnaise, biological fluids, detergent slurries, dispersion media in certain pharmaceuticals, and paints. The shape of the flow curve is shown in Fig. 3.5-1, and it generally can be represented by a power-law equation (sometimes called Ostwald-deWaele equation). 

The most direct and least complex of all the constitutive equations is the previously described Ostwald-DeWaele power law. Although the equation does not describe the entire range of behavior shown in Fig. 3-8, it gives an excellent fit over useful ranges that are encountered in processing. As such, it can be widely utilized, as long as its limitations are borne in mind. 

Power Law n (Ostwald-deWaele model) The simplest representation of pseudoplastic flow, and characteristic of most polymer melts over several decades of shear rate. One versatile form of the model is... 

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