Interaction between polymers and magnetic particles: effect on the properties of particulate magnetic recording media

Abstract

The interaction between vinyl chloride–vinyl acetate-vinyl alcohol copolymers and cobalt-modified γ-Fe₂O₃(Co–γ-Fe₂O₃) magnetic particles has been studied. Adsorption isotherms and heats of adsorption were measured for polymers with various kinds and concentrations of functional groups. The interaction of the polymer with Co–γ-Fe₂O₃, and the amount of polymer adsorbed, increased in proportion to the hydroxy-group concentration of the polymer. Introducing a few carboxy groups into the polymer also produced stronger interaction. This interaction affected the properties of particulate magnetic recording media considerably. The interaction strength of the polymer with Co–γ-Fe₂O₃ has been shown to determine the Young's modulus of a magnetic coating layer. Stronger interaction led to higher dispersibility of Co–γ-Fe₂O₃ in the magnetic coating layer.