Measurement of transient and steady-state shear and normal stresses in filled polymers

Abstract

The flow behaviour of viscoelastic polymers filled with rigid particles was measured. The viscosity functions can be described with the viscosity of the basic liquid as a function of a shear stress equivalent shear rate. Using this concept of a representative internal shear rate and applying the “mirror relations” the transient zero shear viscosity of the suspensions can also be derived from the viscosity function of the basic liquid.

A similar application of the “mirror relations” including the concept of a representative internal shear rate was used to predict the suspensions’ first normal-stress coefficient from the viscosity function of the basic liquid. At low shear rates the calculations show good agreement with the measurements. With increasing shear rates normal stress differences that were too high were predicted.