The effect of simple shear flow on the phase behavior and morphology was investigated for both polystyrene/poly(vinyl methyl ether) (PS/PVME) and poly(methyl methacrylate)/poly(styrene-co-acrylonitrile) (PMMA/SAN-29.5) blends, which have LCST (lower critical solution temperature)-type phase diagram. The measurements were carried out using a special shear apparatus of two parallel glass plates type. The PS/PVME blends showed shear-induced demixing and shear-induced mixing at low and high shear rate values, respectively. In addition, the rotation speed and the sample thickness were found to have a pronounced effect on the phase behavior under shear now. On the other hand, PMMA/SAN blend showed only shear-induced mixing and the magnitudes of the elevation of the cloud points were found to be composition and molecular weight dependent. The morphology of the PMMA/SAN=75/25 blend indicated that shear-induced mixing occurred at a critical shear rate value, below which the two phases were highly oriented and elongated in the flow direction. [References: 8]
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