On flocculation and gelation in concentrated particulate systems containing added polymer

Gelation in a concentrated dispersion of colloidal particles containing added polymer is modelled as a binary mixture of large and small spheres interacting with a combination of hard-sphere and sticky hard-sphere pair potentials. Numerical results are reported as a function of the stickiness parameter for the effects of particle and polymer volume fractions on the gel point in systems with a diameter ratio of 5:1. The theory predicts network formation either by bridging flocculation or by depletion flocculation depending on whether the strength of the particle-polymer attraction is finite or negligible. The model gives insight into the extreme sensitivity of the theology of concentrated particulate dispersions and emulsions to small additions of polymer.