Viscoelasticity near the gel-point: a molecular dynamics study

Original · EN

We report on extensive molecular dynamics simulations on systems of soft spheres of functionality f, i.e. particles that are capable of bonding irreversibly with a maximum of f other particles. These bonds are randomly distributed throughout the system and imposed with probability p. At a critical concentration of bonds, pc approximately equal to 0.2488 for f=6, a gel is formed and the shear viscosity ηdiverges according to η (pc-p)⁻ˢ. We find s is approximately 0.7 in agreement with some experiments and with a recent theoretical prediction based on Rouse dynamics of phantom chains. The diffusion constant decreases as the gel point is approached but does not display a well-defined power law.