DYNAMIC VISCOELASTIC BEHAVIOR OF POLYMER BLENDS IN THE MELT - EXPERIMENTAL RESULTS FOR PDMS POE-DO, PS PMMA AND PS PEMA BLENDS

In the frame of a rheological model for concentrated emulsions of viscoelastic liquids, the linear viscoelastic behaviour of three kinds of polymer blends in the melt could be accounted for quantitatively. For the PDMS/POE-DO (polydimethylsiloxane/polyethylene-diol) and PS/PMMA (polystyrene/polymethylmethacrylate) blends, all required parameters are known and the rheological data ascertain the validity of the model. The observed long-time relaxation process could thus be assigned to the relaxation of the shape of the droplets forming the dispersed phase. In the frame of this analysis, dynamic shear measurements can also be used for determining the interfacial tension between the phases as the value leading to the best agreement between the model prediction and experimental data. This has been done for PS/PEMA (polystyrene/polyethylmethacrylate) blends, and values of interfacial tension determined from viscoelastic measurements have been found to be in good agreement with results obtained from the pendant drop method.