Evaluation of Particle Adhesiveness Using the Shear Stress Induced by Pulling a Rod across a Compressed Particle Bed

Abstract

A new apparatus was developed for the evaluation of particle adhesiveness. This apparatus uses shear stress that is induced by pulling a rod across a compressed particle bed. The tested samples were spherical silica particles with number based median diameters of 0.4 and 2.8μm.
When the height of the particle bed ≥ 17.0mm and the length of the rod in the bed ≥ 11.5mm, the shear stresses obtained by this apparatus were independent of either values of the bed height or the length of the rod. Using the values of stress, the inter-particle shear forces were calculated. The calculated forces increased with packing fraction and reached asymptotic values. The order of the asymptotic values agreed with that of the theoretical values of van der Waals force. This would be because frictional forces are based on adhesive forces in the real contact area （not the apparent contact area） of the 2 bodies. Thus, the new apparatus could be used to evaluate particle adhesiveness reflecting van der Waals force.