Effective crack-prevention strategy with composite of two clays of different sized particles

Crack formation and its possible prevention or remedy is an important branch of material science, closely related to study of granular materials and soft matter physics. This work reports a study on cracking behaviour in composites of bentonite and Laponite((R)) in varying proportions. Both components are clays of the montmorillonite group. Our experiments demonstrate that for the particular composition - Laponite((R)) : bentonite similar to 1:1, cracks are totally absent. If either component exceeds the other, cracks develop. This is demonstrated over a range of film thickness. Scanning Electron Microscope (SEM) images of the films at different compositions indicate that at this particular ratio, the much smaller particles of Laponite((R)), pack into the spaces between the bentonite platelets perfectly, to form a defect-free smooth film.