Viscoelastic properties of polystyrene/poly(vinyl methyl ether) blends with nearly critical compositions were measured under steady-shear flows near the phase separation temperatures. In the homogeneous region, shear rate dependences of shear viscosity η and shear compliance JS are practically the same as those of homopolymers. In the phase-separated region at quiescence, on the other hand, η and JS are enhanced at low shear rates, but they become almost the same as those in the homogeneous region when the shear rates are higher than their respective critical shear rates. The critical shear rate values from JS, γcJ, were found to be larger than those from η, γcV, and γcJ is considered to be almost equal to the critical shear rate for shear-induced homogenization γc. Moreover, it was pointed out that, when γcV is smaller than the critical shear rate for non-Newtonian behavior of η, there exists a plateau region in the shear rate dependence of η.
All Science Journal Classification (ASJC) codes
- Organic Chemistry
- Polymers and Plastics
- Inorganic Chemistry
- Materials Chemistry