The steady-state shear viscosity is also always needed. When possible, it should also be measured using capillary rheometry, and the data for shear viscosity vs. true shear rate should be obtained. If such an experiment is not feasible, you can instead extract information about shear viscosity from the empirical Cox-Merz rule [4], assuming that the modulus of the complex viscosity can be obtained from dynamic data. Alternatively, you can extract information about shear viscosity from the empirical mirror relationship of Gleissle [6], which suggests that the steady shear viscosity curve is a mirror image of the transient shear viscosity measured at a low shear rate. This assumes that transient viscosity measurements are indeed possible. See Empirical Rules and Principles for details.

Even though the knowledge of the shear viscosity is not important for all processes, the automatic fitting procedure requires it. Extrapolating from measured quantities can provide additional data, but data should not be extrapolated over more than one decade.