COLLOIDAL INTERACTIONS STUDIED BY SEDIMENTATION FIELD-FLOW FRACTIONATION

Sedimentation Field-Flow Fractionation (SdFFF) is a relatively new tec hnique for the separation and characterization of monodisperse or poly disperse colloidal materials and macromolecules. In the present work, with the aid of SdFFF, the interactions between the polydisperse, irre gular Hydroxyapatite (HAP) particles were studied. The stability of HA P, which is of paramount importance in its applications, is dependent upon the total potential energy of interaction between the Hydroxyapat ite particles. The latter, which is the sum of the attraction potentia l energy and that of repulsion, depends on particle size, the Hamaker constant, the surface potential, and the Debye-Huckel reciprocal dista nce, which is immediately related to the ionic strength of carrier sol ution.