Shear Stress‐Dependent Viscosity Master Curves for Practical Applications

Abstract

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

Kinetics for the Slip Motion of Ripple Dislocations on Gold-Coated Poly(dimethylsiloxane)

“…It is known that the viscosity (flow resistance) of polymer, η, is temperature-dependent and can be expressed by the Vogel–Fulcher–Tammann (VFT) equation − as with η 0 and B being constants depending on the materials, T being the absolute temperature, and T vf being an empirical constant. For a narrow range of temperature, eq reduces to the Arrhenius-type equation, which is supported by the results in Figure a,b. Increasing temperature decreases the viscosity and the viscous resistance accordingly.…”

Structural and Rheological Properties of Nonedible Vegetable Oil-Based Resin

“…Next, the master curve of shear stress–shear rate was constructed with the aim to simultaneously fit the data of different temperatures and to predict the flow behaviour. It offers accurate and practical results rather than fitting the data separately [ 37 ]. Based on the k and n value, the calculated shear rate was expressed based on Equation (4) [ 40 ].…”

“…This will also involve the correlation between the rheological properties with the chemical structure [ 36 ]. In addition, the establishment of a common master curve based on either viscosity or shear rate, which is measured at different temperatures, was reported to create practical information regarding fluid behaviour for future processing conditions [ 37 ].…”