Ternary copolymers composed of acrylic acid, acrylamide and sodium stylene sulfonate [P (AA/AAm/NaSS)] were synthesized and these inhibition effects on corrosion of mild steel in cooling water system were investigated by physicochemical methods. P (AA/AAm/NaSS) acted as an adsorption-type inhibitor in solutions with low concentrations of ionic species and suppressed mainly the anodic reaction during corrosion of mild steel. In solutions with high concentrations of ionic species, the corrosion of mild steel was inhibited by the formation of the film mixed with scale and P (AA/AAm/NaSS) on the steel when 25mg/l or less of the copolymer was containded. By contrast, the adsorption of P(AA/AAm/NaSS) on the steel surface inhibited the corrosion when 75mg/l or more of the copolymer was contained.
