Emulsions of incompressible viscoelastic materials are considered, in which the addition of an interfacial agent causes the interfacial tension to depend on shear deformation and variation of area. The average complex shear modulus of the medium accounts for the mechanical interactions between inclusions by a self consistent treatment similar to the Lorentz sphere method in electricity. The resulting expression of the average modulus includes as special cases the Kerner formula for incompressible elastic materials and the Oldroyd expression of the complex viscosity of emulsions of Newtonian liquids in time-dependent flow.

The linear viscoelastic behavior of two-phase polymer blends in the melt has been analyzed by an emulsion model, with takes into account the viscoelasticity of the phases. In this paper, we have studied two types of blends: PS/PMMA and PDMS/POE-DO. For PS/PMMA blends, the model leads to values of relaxation times and secondary plateau modulus in accordance with experimental data. This supports the assumption that long-time relaxation mechanisms are due to geometrical relaxation of the droplets of the dispersed phase. For a quantitative comparison, further experiments have been carried out on PDMS/ POE-DO blends for which the distribution of size of the dispersed POE-DO inclusions may be easily determined.The data confirm the validity of the model and show that dynamic shear measurements can be used as a method to determine the interfacial tension between two polymer melts.

The elastoplastic behavior of silica–silicone compounds has been characterized by a yield stress σs and an elastic modulus G0. Scaling laws have been established for the changes in rheometrical parameters with the volume fraction Φv of silica: σs∝(Φv)3.3 and G0∝(Φv)4.2 and single master curves have been obtained whatever the silica type used. The mesoscopic structure of the compounds has been studied using x-ray and light scattering and a semidilute fractal structure has been observed, with a fractal dimension D≈1.8 and a characteristic length scale 4 μm. In this paper, a formulation of the nonfluctuating semidilute fractal concept allows us to relate the fractal dimension to the rheological scaling laws: σs∝(Φv)4/(3−D) and G0∝(Φv)5/(3−D).