Transport properties of incipient gels

Original · EN

We investigate the behavior of the shear viscosity η(p) and the mass-dependent diffusion coefficient D(m,p) in the context of a simple model that, as the crosslink density p is increased, undergoes a continuous transition from a fluid to a gel. The shear viscosity diverges at the gel point according to η(p) (pc-p)⁻ˢ with s≈ 0.65. The diffusion constant shows a remarkable dependence on the mass of the clusters: D(m,p) m⁻⁰.⁶⁹, not only at pc but well into the liquid phase. We also find that the Stokes-Einstein relation Dη∝ kBT breaks down already quite far from the gel point.