Adhesion of latex films. Part II. Loci of failure

In order to continue our work on surfactant effects on the adhesion propert ies of latex films, we investigated a new system based on an acrylic copoly mer, synthesized in the presence of a hydrophilic polyester. The surfactant s were either sodium dodecyl sulfate (SDS) or an ethoxylated nonyl phenol c ontaining 30 ethoxy groups (NP30). As substrates, either glass plates or po ly(ethylene terephthalate) (PET) films were used. This article describes th e analysis of the loci of failure after peeling of the films. The analytica l techniques used were X-ray photoelectron spectroscopy (XPS) (Or ESCA), St atic secondary ion mass spectrometry (SSIMS), and contact angle measurement s. It was shown that the loci of failure were independent of the peel rate and of the nature of the substrate. The failure occurs in a thick surfactan t layer for SDS, and in a thin one for NP30. The thickness of the layer inc reases with the concentration of surfactant in the latex film. The surfacta nt is located near the surface of the substrate, on top of a layer of hydro philic polyester. The consequences of the structure of the film-substrate i nterface on the adhesion properties is presented in Part III in this series .