Ostwald-de Waele equation

Power-law dependence of consistence factor on temperature. The experiments described [286] dealt with water solutions of carboxymethylcellulose, whose flow curve is well described by the power-law Ostwalde-de Waele equation. It was shown that the index n is virtually invariable in the temperature interval 15 to 60°C, whereas the medium consistence factor can be approximated by the expression... 

The log-log plots of apparent shear stress versus apparent shear rate for STR5L/ EPDM and STR5L/BEPDM blends with various blend compositions are shown in Figs. 15.12 and 15.13, respectively (71). Flow curves of all the blends show reasonably straight hnes, whose intercept K and slope n correspond to the power law equation (the Ostwald-de Waele equation) (72). Table 15.4 shows the power law index and the consistency of flow of STR5L/EPDM and STR5L/BEPDM blends. The values of n n < 1) indicate the pseudoplastic nature of STR5L, EPDM, BEPDM, and their blends. 

In many cases the experimental curves for both dilatant and pseudoplastic fluids can be reasonably well represented by the power law, also called the Ostwald-de Waele equation. ... 

The rheological data are given in Table 1. The second column of the table is the evaporation state of the oil in mass pereentage lost. The third column is the assessment of the stability of the emulsion based on both visual appearance and rheological properties. The power law constants, k and n, are given next. These are parameters from the Ostwald— de Waele equation which describes the Newtonian (or non-Newtonian) characteristics of the material. The viscosity of the emulsion is next and in column 7, the complex modulus which is the vector sum of the viscosity and elasticity. Column 8 lists the elasticity modulus and column 9, the viscosity modulus. In column 10, the isolated, low-shear viscosity is given. This is the viscosity of emulsion at very low shear rate. In column 9, the tan 5, the ratio of the viscosity to the elasticity component, is given. Finally, the water content of the emulsion is presented. 

Flow curves of all the blends showed reasonably straight lines, whose intercept K and slope n correspond to the power law equation (the Ostwald-de Waele equation) ... 

B. Cmnpounding Shear-Rate Determination In order to establish flie most suitable shear rate for compounding of polymer blends, the modified Ostwald-de Waele equation in the form given by Eq. (8.Q is used. For the two component polymers, Pi and Pj, at the temperature of blending and melt flow index of MFIb, we can write... 

Ostwald-de Waele equation A simplified power law relaflonshlp used to describe non-Newtonian fiulds as T=ay ". Depending on the value of the power index, n, the fluid can be classified as being pseudoplastic (n < 1), Newtonian (n= 1), or dilatant (n> 1). It is named alter German chemist Friedrich Wilhelm Ostwald (1853 1932) and British chemist Armand de Waele (1887-1966). 

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