NON-LINEAR VISCOELASTIC PROPERTIES OF RUBBER-LIKE POLYMERS

(PART III) SHEAR-RATE DEPENDENCE OF APPARENT VISCOSITY AND FREQUENCY DEPENDENCE OF DYNAMIC VISCOSITY

Abstract

Steady-flow viscosities of various rubber samples were measured at relatively high rates of shear (10^-110⁺¹ sec^-1.) in a range of temperature of 50100 °C.
The real part and the absolute magnitude of the complex dynamic viscosity were calculated with appropriate approximations for each sample from the data on the stress relaxation measurements.
Those two dynamic viscosities were then graphically compared with the apparent steady-flow viscosity of the same sample by plotting against the logarithm of rate of shear, γ for the latter and the logarithm of angular frequency, ω for the former upon the same abscissa.
It was found in general that among those three viscosities there exists a well-known formal similarity which can be written in the form,
η's(ω)≅η_app(γ)|γ=Cω,
|η^*s(ω)|≅η_app(γ)|γC^*ω.
Here η's(ω), |η^*s(ω)| and η_app(γ) represent the real part, the absolute magnitude of the complex dynamic viscosity and the apparent steady-flow viscosity, respectively. The value of the factor, C ranged from 3 to 5.