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The viscosity of aqueous and ethylene glycol (EG)/water solutions of sodium poly(styrenesulfonate) was measured in the presence and absence of a foreign salt in the shear rate range of 100-1350 s'1. The viscosity exhibited a substantial shear-thinning effect in both the water and binary solution at low-salt conditions: the effect was nearly independent of the EG content although the viscosity decreased markedly. With increasing salt concentration, the viscosity and the shear-thinning effect became smaller. Attention was drawn to the fact that the flexible ionic polymers and rigid ionic polymer latices displayed similar concentration and shear rate dependencies, which indicates that the conformation change effect invoked to explain the viscosity behavior of flexible ionic polymers does not play an important role.

The reduced viscosity of aqueous and ethylene glycol (EG)/water suspensions of ionic latex particles was measured in the presence and absence of a simple salt. The viscosity showed substantial shearthinning effects in both the water and binary systems. The reduced viscosity was generally much higher than the Einstein prediction and increased with increasing volume fraction of latex ( ). The viscosity decreased with increasing salt concentration. In the binary solvents the viscosity decreased with increasing EG content (up to 60%). The fraction of free counterions (H+) was found to decrease, though slightly, with increasing EG content. This was also confirmed by the mobility measurements. We critically examined existing interpretations of the concentration dependence of the reduced viscosity. It was demonstrated that there exists no direct correlation between the Debye length and the reduced viscosity. Furthermore, the possibility was recalled that, in low-salt macroionic and colloidal solutions, the Debye length loses its physical meanings as originally found for simple ionic systems. The intrinsic viscosity in water and binary solvents containing lChMO"6 M KC1 was in good agreement with that calculated by Booth's theory on the first-order electroviscous effect, while the agreement was not satisfactory at much lower KC1 concentrations.

Phase separation temperatures of the ternary system polystyrene (PS) (Mw = 1.67 × 104)/poly(α‐methyl styrene) (PαMS) (Mw = 9.0 × 104)/cyclopentane with a blend ratio PS/PαMS = 55/45 have been determined over the polymer concentration range 0.02 ≤ ψPS + PαMS ≤ 0.52, where ψ PS + PαMS is the segment fraction of polymer in ternary system. Phase separation temperatures for the upper critical separation in the ternary system decrease with increasing ψ PS + PαMS over the range 0.1 ≤ ψ PS + PαMS ≤ 0.52. The vapor—liquid equilibrium in this system with a blend ratio PS/PαMS=50/50 has been determined over the concentration range 0.925 ≤ ψPS + PαMS < 0.995 and the temperature range 60–100°C by the piezoelectric vapor sorption method. The polymer—polymer interaction parameters χ′12 determined are positive except at 100°C and increase with increasing ψ PS + PαMS. Values of χ′12 extrapolated to zero solvent concentration are positive (0.0–1.3) over the temperature range measured. Phase separation behavior is discussed in terms of phase separation temperature in a ternary system and the polymer–polymer interaction parameter.

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