The interaction of ions with nylon. Part I. Absorption of simple acids

The paper describes the titration relations for nylon 66 samples of different endgroup contents both for aqueous and alcohol solutions. The effect of temperature change is also considered. The results are consistent with a zwitterion structure of the nylon, carboxyl groups being protonated on acid titration. The acid groups are shown to be weaker than the corresponding monomeric acids in aqueous solution, owing to their environment inside the polymer. Individual ionic affinities are calculated from the experimental absorption isotherms and are in agreement with values obtained from a simple electrostatic theory. The low sulfate ion affinity can be explained by assuming interaction for this ion with single, fixed, isolated sites.