The viscosity anomaly of polymer mixture solution in extremely dilute concentration region

The measured reduced viscosity–concentration (ηsp/C–C) curves of compatible PPO/PS incompatible PMMA/PS mixtures with different composition in toluene all deviate linear and reveal downward turn in extremely dilute concentration region. Moreover, with the variation of composition, the ηsp/C–C curve of PS/PMMA/m-xylene solution bends downwards sometimes and bends upwards sometimes in the extremely dilute concentration region. It indicates that such viscosity anomaly should not be attributed simply to incompatibility, but be related to solvent, composition and so on. It is further suggested that, like the single polymer solution, the viscosity anomaly of polymer mixture solution be resulted mainly from the interference of wall effects on viscosity measurement, which could be eliminated quantitatively with a proposed theoretical formula.