The effects of surface and particle properties on adhesion in humid environments using the enhanced centrifuge method

Particle characteristics and environmental conditions, such as humidity, impact the adhesion behavior of powders. The adhesion between silica powders and glass surfaces was studied to document the effects of the topography of the particles and the surfaces on the adhesion. The study was performed utilizing an experimental and modeling framework called the enhanced centrifuge method (ECM), which measures the complete distribution of adhesion forces between a powder and surface as a function of the size of the particles in the powder. By systematically varying the relative humidity, the ECM can be used to capture how the adhesion forces between the surface and the powder change and can offer insight into the adhesion mechanisms. In this case, changes in relative humidity caused moisture adsorption onto the particles and in the interstitial space between the particles and surfaces. The balance between: 1) adsorbed moisture screening van der Waals forces, 2) adsorbed moisture inducing capillary interactions, and 3) adsorbed moisture increasing the removal force on particles by increasing their mass, caused changes in the particle adhesion as a function of particle size.