On flocculation and gelation in concentrated particulate systems containing added polymer

Abstract

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 rheology of concentrated particulate dispersions and emulsions to small additions of polymer.