Shear Stress‐Dependent Viscosity Master Curves for Practical Applications

It was shown using several examples that the ratio of apparent viscosity and Newtonian viscosity at the same temperature as function of shear stress is independent of temperature. It means that viscosity curves for different homogeneous polymer systems measured in various temperatures create a commo...

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Bibliographic Details
Published in:Polymer engineering and science 2020-01, Vol.60 (1), p.44-54
Main Authors: Steller, Ryszard, Iwko, Jacek
Format: Article
Language:English
Subjects:
Polymer industry
Polymers
Shear stress
Temperature effects
Viscosity
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Summary:It was shown using several examples that the ratio of apparent viscosity and Newtonian viscosity at the same temperature as function of shear stress is independent of temperature. It means that viscosity curves for different homogeneous polymer systems measured in various temperatures create a common master curve, which is very convenient for practical calculations of many technically important flows. It was also shown that for such systems, the stress dependence can be often very well described by simple function of Kohlrausch type. Moreover, it was found that for small‐amplitude oscillatory shear, similar master curves can be created by representing the absolute value of complex viscosity or its components as functions of absolute value of complex modulus. For nonhomogeneous systems, second‐order temperature effects may appear. They were taken into account by additional rule based on the so‐called no‐flow temperature. It was also shown that the first normal stress difference as function of shear stress is temperature independent. POLYM. ENG. SCI., 60:44–54, 2020. © 2019 Society of Plastics Engineers
ISSN:0032-3888
1548-2634
DOI:10.1002/pen.25257