Rheology and phase separation in a model upper critical solution temperature polymer blend

摘要: The viscoelasticproperties of a model binary polymer blend exhibiting an upper critical solution temperature phase diagram were investigated by utilizing small amplitude oscillatory and steady shear measurements. A mixture unentangled monodisperse polystyrene poly(phenyl methyl siloxane), Newtonian viscosity, was used, its established turbidity dynamic light scattering In the miscible region, concentration dependence viscosity adequately described mixing rule accounting for surface fractions instead volume fractions. Near separation far from glass transition, fluctuations dominated linear viscoelastic response responsible observed thermorheological complexity. An appropriate quantitative account these resulted in accurate rheological determination both binodal spinodal temperatures, extending thus applicability relevant procedure earlier applied to lower blends involving higher molecular weight entangled polymers. separated regime, normal stress dispersed undergoing decomposition followed recent scaling proposed mixtures with large difference.