THERMODYNAMIC PROPERTIES OF THE S L INTERFACIAL LAYER - STABILIZATIONOF THE COLLOIDAL SYSTEM IN BINARY LIQUIDS/

In the knowledge of the adsorption and wetting properties of solid par ticles the influence of particle-liquid and interparticle interaction has been examined on the stability and structure formation of suspensi ons obtained for hydrophobic SiO2 colloids in the mixtures benzene+n-h eptane and methanol+benzene. The Hamaker constants of the adsorption l ayer of composition range. The Hamaker constant have been determined b y optical dispersion measurements in the entire mixture composition ra nge. The Hamaker constant of the adsorption layer of composition diffe rent from that in the bulk have been calculated at several mixture com positions on the basis of the adsorption results. Having the excess is otherms available enabled us to determine the adsorption layer thickne ss as a function of the bulk composition. For interparticle attractive potentials, model calculations have been effected on the basis of the Vincent model. In the case of hydrophobic particles dispersed in benz ene+n-heptane and methanol+benzene mixtures it was established that th e change of the attractive potential was in accordance with the intera ctions obtained from rheological measurements.