폴리에틸렌옥사이드 수용액의 유변학적 특성 평가(II)-정상류점도와 동적점도, 복소점도의 상관관계-

Rheological Characterization of Aqueous Poly(Ethylene Oxide) Solutions(II)-Comparison of Steady Flow Viscosity with Dynamic and Complex Viscosities-

Using a Rheometrics Fluids Spectrometer (RFS II), the steady shear flow viscosity and dynamic viscoelastic properties of aqueous poly(ethylene oxide) (PEO) solutions have been measured over a wide range of shear rate and angular frequency. In this paper, the relationship between the steady flow viscosity and dynamic viscosity was investigated, and the property of a conversion factor was determined from the data. Further, the validity of the Cox-Merz rule was examined by comparing the steady flow viscosity and the magnitude of the complex viscosity. The influence of a coil overlap parameter on the applicability of the Cox-Merz rule was discussed finally. Main results obtained from this study can be summarized as follows : (1) At higher range of shear rate and angular frequency, tile dynamic viscosity decreases more rapidly than does the steady flow viscosity. A conversion factor between the steady flow viscosity and dynamic viscosity increases with increasing shear rate and angular frequency (2) At relatively lower polymer concentration, the steady flow viscosity is higher than the complex viscosity, which is reversed at highly concentrated solutions. (3) A coil overlap parameter has an effect on the validity of the Cox-Merz rule. Especially, the use of a coil overlap parameter including the molecular weight distribution can be regarded as an effective method to evaluate the Cox-Merz rule for all kinds of linear polymer solutions.