Study of lifetime of bonds and microstrucure of attractive gels at intermediate volume fractions

Colloidal gels exhibit a variety of mechanical responses under different conditions. The consistent formation/rupture of interparticle bonds under flowing conditions determines the rheology of attractive colloidal system. Here, we study the origins of such mechanical and rheological features in short-range attractive colloids with respect to different characteristics of the particulate network. We decouple the role of different forces on particles, and also interrogate the evolution of the colloidal structure. Our results indicate that by increasing the Mason number (Mn), the micromechanics of interparticle interactions changes from attractive to hydrodyanmic dominated, with an intermediate transition regime where the competition between the two results in dynamical heterogeneities. By continuously tracking bonds, we present an analysis of their life and death mechanism. We show that at low Mn the old bonds are dominantly responsible for the mechanics of the gel, while at large Mn it is the young ones that determine the rheological response of the fluid. Finally, we present visual mapping of particle bond numbers, their lifetimes and the stress response under different conditions.