COAGULATION RATE MEASUREMENTS OF COLLOIDAL PARTICLES BY SIMULTANEOUS STATIC AND DYNAMIC LIGHT-SCATTERING

In this work we study the kinetics of coagulation of monodisperse sphe rical colloids in aqueous suspension at the early stage of coagulation . We have performed the measurements on a multiangle static and dynami c light scattering instrument using a fiber-optics-based detection sys tem which permits simultaneous time-resolved measurements at different angles. The absolute coagulation rate constants are determined from t he change of the scattering light intensity as well as from the increa se of the hydrodynamic radius at different angles. The combined evalua tion of static and dynamic light scattering results permits the determ ination of coagulation rate constants without the explicit use of ligh t scattering form factors for the aggregates. For different electrolyt es fast coagulation rate constants were estimated. Stability curves we re measured as a function of ionic strength using different particle c oncentrations.