Surface modification of ferromagnetics for polymer composites

The adsorption properties of highly disperse powders of metallic nickel and γ-Fe2O3 used as a ferromagnetic filler in polymeric composites are investigated. It studied the adsorption of model compounds (octadecyl amine (ODA) and stearic acid (SA)) from an organic medium on ferromagnetic powders. It was established that there are approximately equal quantity of active acidic and basic sites at the γ-Fe2O3 surface available for the chemisorption of these surfactants. The adsorption of octadecylamine and octadecyl alcohol (ODCA) on nanodisperse nickel proceeds reversibly, whereas the adsorption of stearic acid is irreversible, thereby leading to the formation of dense modifying layers. The study of the physicochemical and magnetic properties of the magnetorheological suspensions in a VAGH solution (copolymer of vinyl chloride with vinyl acetate and maleic acid) allows us to establish that the use of nickel makes it possible to reduce the viscosity of γ-Fe2O3 organosuspensions and hence, to increase the degree of polymer filling with a solid disperse phase while conserving the desired performance properties of magnetic materials.