Adhesion of latex films. Part III. Surfactant effects at various peel rates

In order to study the effect of surfactants on the adhesion of latex films, peel energy versus surfactant concentration curves were established at var ious peel rates. The main latex polymer was a methyl methacrylate (MMA)/eth yl acrylate (EA) copolymer synthesized in the presence of a hydrophilic pol yester. Another polymer, less extensively studied, a styrene/butyl acrylate /methacrylic acid tel polymer, was also used for comparison purposes. The s urfactants were either sodium dodecyl sulfate (SDS) or ethoxylated nonyl ph enol containing 30 segments of ethylene oxide (NP30). The substrates were g lass plates or poly(ethylene terephthalate) films. It was found that with S DS-containing films, whatever the substrate or the polymer, the curves went through a maximum, whereas with NP30 they went through a minimum, at mediu m or high peel rates. When the peel rats was decreased, the curves flattene d out and at zero peel rate (extrapolated values), they became horizontal. The peel energies at zero peel rate were three to four times higher than th e reversible works of adhesion. Qualitative interpretations are proposed fo r these results.