6533b7d7fe1ef96bd1267822

RESEARCH PRODUCT

Shear Effects on the Phase Diagrams of Solutions of Highly Incompatible Polymers in a Common Solvent. 2. Experiment and Theory

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Cloud point temperatures (Tcp) were measured at different constant shear rates for three representatives of the ternary system cyclohexanone/polystyrene/poly(n-butyl methacrylate) (CHO/PS/PBMA) by means of a newly constructed rheo-optical apparatus that can be operated in the temperature range from 0 to 100 °C up to maximum shear rates of 1440 s-1 and maximum stresses of 384 Pa. In all cases one observes an extension of the homogeneous region as the shear rate γ is raised. With the system CHO/PS 196w/PBMA 2050 (the figures denote the molar masses of the polymers in kilograms/mole) the effects become maximum for high concentrations of PBMA, where the demixing temperatures increase by more than 25 °C per 100 s-1. For a pronounced predominance of one polymer in the mixture, Tcp is a linear function of γ in the entire range of shear rates. At blend compositions in between, the slope of Tcp versus γ is largest at the lowest shear rates and diminishes as γ is increased until the dependence becomes linear ag...