ADHESION AND FRICTION BETWEEN POWDERS AND POLYMER OR ALUMINUM SURFACES DETERMINED BY A CENTRIFUGE TECHNIQUE

Adhesion and friction phenomena between single particles of calcium carbonate and pre-gelatinized starch and solid surfaces made from polyoxymethylene polymer or aluminium were investigated using a centrifuge technique. In the case of pure adhesion between the contiguous bodies, the experiments indicate that surface roughness, hydrophilic/energetic surface properties and plastic/elastic properties are involved, but the dominant factor varies from system to system. The results indicate that frictional force depends primarily on the particle properties rather than on the substrate surface properties. The softer pregelatinized starch appears to have greater surface contact showing higher friction properties than the harder calcium carbonate. A direct determination of the frictional force for both powdered materials was not possible, but the force necessary to push the particles along the substrate surface could be estimated.