DISPERSION OF AGGREGATE PARTICLES IN LIQU ID BY A FREEZING METHOD

A simple method to disperse aggregate particles suspended in liquid is proposed. The method consists of successive freezing and melting of s uspensions. Aggregates consisting of submicron particles were found to be almost completely dispersed into primary particles after about 5 f reezing-and-melting cycles, provided that the particle surface could b e well wetted with the freezing liquid (dispersion medium). As the dis persion mechanism, it is thought that when the liquid phase is frozen, the expansion or shrinkage of the volume of liquid existing between p rimary particles causes relative displacement between the particles. T his displacement increases the interstice between them resulting in th e decrease in adhesion force.