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RESEARCH PRODUCT

Phase diagrams calculated for sheared ternary polymer blends

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Abstract On the basis of the generalized Gibbs energy of mixing G γ (which is the sum of the Gibbs energy for zero shear and the energy the system stores in steady flow) phase diagrams were calculated as a function of shear rate γ for ternary model blends. This modelling uses simple equations for the description of the stagnant systems (Flory-Huggins) and for the contributions resulting from flow. Surface and alignment effects are neglected. A new procedure, which does not require the derivatives of G γ with respect to composition, was used to that end. Choosing typical values for the binary interaction parameters and molar masses, four classes of ternary systems were studied in greater detail. Under equilibrium conditions, with two of them there only exist one-phase and two-phase regions in the temperature range of interest. At least one three-phase domain occurs with the other two types of ternary mixtures. In addition to all effects observed for binary systems, the following new phenomena were calculated: (i) twofold disappearance of closed loops of immiscibility and twofold reappearance; (ii) creation and annihilation of three phase areas; and (iii) creation and annihilation of islands of homogeneity in the centre of the ternary phase diagram. © 1997 Elsevier Science Ltd.