ABSTRACT
The underpinning assumption adopted here is that the material functions (shear viscosity, elasticity, elongation viscosity and the derived characteristics) which originate from constitutive equations for the continuum are applicable to the multiphase melt flow description. The convenience of using the same description procedures for the component—polymers and for the polyblends—has to be compensated, therefore, by a number of strong simplifying assumptions and semiempirical correlations. Most of the simplifications follow from neglecting coupled effects of normal stresses and the interface tension on the concomitant phase structure (morphology) of a polyblend. Perhaps an equally crude approximation is in neglecting the effect of isotropic pressure: there is some evidence that the pressure dependence of the melt rheology of the polyblends [55] is even stronger than that observed for polymers [5-7].
