Abstract
The effect of two polyacrylate based polyelectrolytes, one cationic, the other anionic, on the corrosion of mild steel in aqueous solutions has been examined. It is shown that under conditions where they accelerate corrosion the effect arises from different properties of the compounds in each case. The cationic polymer is a mild oxidising agent and, in alkaline solution, is aggressive to passive films producing localised attack. The anionic compound acts as an anodic stimulator in neutral and alkaline solutions possibly by virtue of its ability to form a complex ion with the emerging cation. Both compounds therefore accelerate corrosion in neutral and alkaline solutions. By contrast, the anionic polyelectrolyte is a mild mixed inhibitor in acid solutions. It is suggested that not all soluble polymers will adversely affect the corrosion of mild steel and that by redesign of the molecule it might be possible for polyectrolytes generally to act as both water treatment chemicals and corrosion inhibitors.
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