Читать книгу The Rheology Handbook - Thomas Mezger - Страница 74

For polymer solutions the high-shear range may begin at around γ ̇ = 1000 s-1, however, for some of them γ ̇ = 10,000 s-1 has to be exceeded. Finally, all macromolecules are almost fully oriented and disentangled. Flow resistance is reduced to a minimum value now and cannot be decreased any further, corresponding to the friction between the individual disentangled molecules gliding off each other. Viscosity is measured then as a constant value which is referred to as the infinite-shear viscosity η∞.

Infinite-shear viscosity is occurring as a constant limiting value of the viscosity function towards sufficiently high shear rates which are “close to an infinitely high shear rate”. Sometimes here, rheologists are speaking of the plateau value of the limiting high-shear viscosity.

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