Dynamics of concentration fluctuations for polydimethylsiloxane-diethyl carbonate

Abstract

The scaled decay rate ${\Gamma }^{*}[=\frac{{\Gamma }^c}{\overline{R}{k}_B}\frac{T{k}^3}{\eta }\mathrm{}(T\left)\right]$ of the system polydimethylsiloxane-diethyl carbonate, where $\eta \mathrm{}\left(T\right)\mathrm{}$ is the shear viscosity, $k$ the transfer wave vector, and $\overline{R}$ a universal constant, is in agreement with the mode-coupling theory in the range of $0.2\lesssim k\xi \lesssim 3$, and in disagreement with the renormalization-group calculation of critical dynamics with $\overline{R}=1.2\mathrm{}{\left(6\mathrm{}\pi \right)}^{-1\mathrm{}}$. The nonlinear shear viscosity due to shear gradients is in agreement with the theoretical prediction by Oxtoby.