Shear Rate

Figure 5-19. Consistency curve of a pseudoplastic fluid a logarithmic plot of shear stress versus shear rate is linear for a pseudoplastic fluid. As shown in Figure 5-20, the slope of the curve defines n, and the intercept on the stress axis at y = l defines K (since log 1 = 0)

K and n mav either be measured directly from the plot or calculated from two values of stress, as follows:

For example, if dial readings are taken at 600 and 300 rpm in direct-indicating viscometer, then

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