Analysis of Palierne's emulsion model in the case of viscoelastic interfacial properties

The quantitative understanding of rheological experiments on compatibilized binary polymer blends requires the consideration of viscoelastic interfaci al properties. The Palierne model offers these capabilities but a systemati c analysis has not been performed yet. Starting from the Palierne model con taining a Maxwell ansatz for complex interfacial shear or dilatational modu li and which considers a particle-size distribution function, we find that this model combines parameter and material functions in an ambiguous way. C onsequently, a simplified version of the model-frequency-independent interf acial moduli and monomodal particle-size distribution-was introduced. Formu las have been derived for the relaxation times, the form relaxation time, a nd one additional still longer time which is associated with viscoelastic i nterfacial properties. We have found a good agreement between the predictio ns of the model and experimental data as well as the characteristic times i n the relaxation time spectrum and the derived time constants for a PS/PMMA blend compatibilized with different amounts of a corresponding symmetric b lock copolymer. These results reveal that from the rheological point of vie w, the interface is of almost elastic nature, either shear or dilatational. (C) 1999 The Society of Rheology. [S0148-6055(99)01406-6].