Evaluation of Compression-Permeability Characteristics of Soft and Hard Colloids Using Analytical Centrifuge

摘要

The compression-permeability characteristics of O/W emulsion were clarified on the basis of the centrifugal flotation experiments with the aid of an analytical centrifuge, and then the data of the soft particles such as oil droplets were compared with those of the rigid particles. From the measurements of the flotation velocity, it was shown that the effective specific surface of the oil droplets decreased with decreasing porosity of emulsion because of the mutual contact of the oil droplets. In contrast, it is significant to note that the effective specific surface remained almost constant in the case of sedimentation of suspension of silicon dioxide articles. From the measurements of the flotation equilibrium, it was estimated that the creaming layer tends to have a much more compact structure at the interface of the creaming layer and the air layer in comparison to a relatively loose condition at the interface of the creaming layer and the clear liquid because the oil droplets are highly compressible. Interestingly, a part of the creaming layer had the porosity which was less than hexagonal close packing of spheres. These results provide important new insight into the mechanisms involved in the solid-liquid separation of the deformable particles.