Experimental study of shear-bands of drying latex

Shear-bands are commonly seen during a latex drying even before close packing, suggesting the rate of water evaporation exceeds the rate of the local structural relaxation. The structural relaxation could be modified by the size of particles and the friction of the contact points. To verify the suggestion, we used particles with different sizes and different materials. We modified the interfacial friction by surfactant. In addition, we control the ambient vapor pressure to vary the water evaporation rate. We used optical coherence tomography (OCT) to image the detail structures of shear-bands. The results of this study help us understand how to control the dynamics of the structural relaxation the rate of water evaporation.