title: Fluctuations in dispersion rheology
abstract: On the basis of the mesoscopic fluctuations of excess density, an experimentally verified model is developed to describe the effective shear viscosity and modulus of complex dispersions as a function of concentration, frequency, and temperature. A stochastic differential equation is used in the derivation of the zero-shear viscosity that shows large viscosity enhancement over a broad range of concentrations. The scaling behavior of shear thinning is determined from an anomalous diffusion equation. We obtain the shear-thinning exponent 1>beta>1 / 2, which depends on the tenuous fractal structure of the complex systems. The divergence of the shear viscosity in the vicinity of a critical temperature is derived as a dynamic critical phenomenon due to thermal fluctuations, and the critical exponent relates directly to the shear-thinning exponent.
authors.affiliation: Xerox Research and Technology, 800 Phillips Road, 0114-39D, Webster, New York 14580, USA.
authors.initials: TS
authors.lastname: Chow