Читать книгу The Rheology Handbook - Thomas Mezger - Страница 59

Preset: γ ̇ = 0.01 to 1000 s-1 with 25 measuring points. The shear rates are increased in logarithmic steps, now showing the same distance in between neighboring points, but of course, only when using a logarithmic scale. Here, a variable logarithmic measuring point duration should be preset, for example, beginning with t = 100 s and ending with t = 5 s. Therefore, when using this method, longer measuring point durations are occurring at lower shear rates, and shorter durations at the higher ones. As a consequence, for each single measuring point in the low-shear range the transient effects of the sample will be either reduced to a minimum or they have already completely decayed at the end of the prolonged duration of each measuring point.

For “Mr. and Ms. Cleverly“

Figure 3.5: Viscosity functions of a dispersion, occurrence of time-dependent effects in the low-shear range such as the “transient viscosity peak”, when presetting too short measuring point duration: (1) clearly too short; (2) better, but still too short; (3) sufficiently long