Inhibition of Acid Corrosion by Soluble Monomer and Polymer Amines Containing Identical Functional Groups

Samples of 3 kinds of very low polymer amines were examined in aqueous HC1 solutions to determine their inhibitor effectiveness. The results show that soluble molecules containing multiple repeating units which are identical in functionality are more efficient corrosion inhibitors than the corresponding monomers, presumably because of multiple adsorption bonding. The compounds used in these experiments are poly (4-vinylpyridine), poly (4-vinylpiperidine), and polyethyleneamines. Chains 4 units in length and longer produce inhibition equivalent to monomer at concentrations which are nearly 4 orders of magnitude lower than those required for the monomer. This effect is due to the increased stability of the adsorption bonding, and also to some overlapping of ennobled micro areas. In the high ranges, the inhibition is not linearly related to coverage. The differences in inhibitor effectiveness among the 3 monomers are retained in parallel by the polymers. (10 refs.)