Nonequilibrium molecular dynamics of complex fluids near the gel point

Abstract

We have carried out nonequilibrium molecular dynamics simulations of a system of crosslinked particles under shear flow conditions. As the fraction of crosslinks $p$ is increased the system approaches a gel point at which the shear viscosity $\eta$ and the first and second normal stress coefficients ${\Psi }_1$ and ${\Psi }_2$ diverge. All three quantities seem to diverge with a power law form: $\eta \sim {\epsilon }^{-s}$, ${\Psi }_{1,2}\sim {\epsilon }^{-\lambda }$ where $\epsilon =p_c-p$ and $s\approx 0.7$ and $\lambda \approx 3.15$ in three dimensions and $s\approx 2.0$ and $\lambda \approx 6.0$ in two dimensions.

5 pages, 9 figures