Measurement of Forces Due to Liquid Bridge between Spherical Particles by Centrifugal Method

Abstract

Forces due to liquid bridge between spherical particles of equal size ranging from 80 to 700 μm were measured by a centrifugal method which has been used to measure adhesive forces between particles and plate. In the experiment, one spherical particle was adhered with nonvolatile liquid, DOP, to another particle which was fixed on a razor blade by glue. It simplifies the microscopic observation of the geometric shape of bridge. Then, the blade was inserted into the closed cell, which was set in a centrifugal disk. Experimental forces obtained from the speed of revolution at which the particle detached, were compared with Rumpf's liquid bridge theory for various half center angle of bridge and dimensionless separation distances between two equal spheres. It was concluded that this theory may also be applicable to fine particles which generally compose the practical wetted powder bed.
Adhesive forces in moist air were also measured in the same way. As a result, adhesion in high humidity seemed to be caused by liquid bridge.