Effects of Colloidal Network Characteristics on Crack Dynamics

Cracking in drying films of colloidal dispersions is encountered in various applications such as in paints and coatings, ink, ceramic processing and even in drying of wet clay/mud. While a number of studies have focused on deriving the critical conditions for cracking, few have investigated the dynamics of cracking. In this work, we investigate the dynamics of cracking by developing an analytical theory for a propagating crack in a colloidal film saturated with liquid. The theory includes the effects of particle size and modulus, and packing characteristics to yield the asymptotic solution of stress, displacement, pressure fields and crack-tip velocity. The stress and the pressure field show 1/(√r) - singularity near the crack tip, same as observed for brittle solids. The speed of the crack tip reduces by an order of magnitude 10 compared to brittle solid.