Coefficient of friction reduction of ethylene-co-acrylic acid film: Effects of grafted 12-aminododecanamide and solvent exposure

The effect of covalently bound 12-aminododecanamide on the surface coefficient of friction (COF) of ethylene-acrylic acid copolymer (EAA) films was investigated. The reaction involved grafting 12-aminododecanoic acid to the inherent carboxylic acid groups on the film, followed by amidation of the grafted amino acid. Conversion of film carboxylic acid groups to primary amide groups was also conducted to compare the impact of direct surface amidation. Subsequent measurements showed that both surface amidation schemes reduced the kinetic COF from 0.30 to 0.15 ~ 0.18. Repetitive COF testing revealed that amide-modified EAA films maintained low COF values that were independent of the number of COF test runs. However, control experiments showed that COF values also depended greatly on simply exposing film to the various reaction solvents, which increased surface roughness.