LINEAR VISCOELASTIC BEHAVIOR OF SOME INCOMPATIBLE POLYMER BLENDS IN THE MELT - INTERPRETATION OF DATA WITH A MODEL OF EMULSION OF VISCOELASTIC LIQUIDS

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 maybe 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.