PHASE INVERSION AND DUAL-PHASE CONTINUITY IN POLYMER BLENDS - THEORETICAL PREDICTIONS AND EXPERIMENTAL RESULTS

In this work, the point of phase inversion for several polymer blends is investigated experimentally. Four different blends were studied: po lystyrene/polyethylene, poly(methyl methacrylate)/polyethylene, polyst yrene/poly(methyl methacrylate) and polycarbonate/polystyrene. Blends were prepared at the compositions where phase inversion is expected to occur according to the predictions of the model of Avgeropoulos, equa ting the torque ratio with the volume-fraction ratio. The morphology o f the prepared blends was examined using scanning electron microscopy. The results obtained were then compared to the values of the point of phase inversion calculated with various semi-empirical models. The re sults show that the model of Avgeropoulos predicts satisfactorily the point of phase inversion for torque ratios close to unity, whereas usi ng the viscosity ratio the prediction is far away from the experimenta l values. The model of Metelkin and Blekht and that of Miles and Zurek were found to overestimate the composition at which phase inversion o ccurs, while the model of Utracki was found to agree with the experime ntal results for blends having a viscosity ratio far from unity. Moreo ver, no correlation was found between the torque ratio and the shear o r complex viscosity ratio for the different blends, suggesting that th e model of Avgeropoulos cannot be used by substituting the torque rati o by the viscosity ratio. Copyright (C) 1996 Elsevier Science Ltd.