ADHESION OF LATEX FILMS - INFLUENCE OF SURFACTANTS

The aim of the work presented in this article was to investigate the r ole of surfactants on adhesion properties of latex films. Several poly mer/surfactant/support systems were used. Polymers were poly(2-ethyl h exyl methacrylate) or a methyl methacrylate/ ethyl acrylate copolymer partially grafted onto a hydrophilic polyester. Surfactants were sodiu m dodecyl sulfate (SDS), hexadecyl pyridinium chloride (HPCl), or etho xylated nonyl phenol containing 10 or 30 segments of ethylene oxide (N P10 or NP30). Supports were glass plates or poly(ethylene terephthalat e) films. Adhesion was measured by a peel test at 180 degrees. Loci of failure were determined by multitechnique analysis of the surfaces re vealed after peeling. At medium and high peel rates, the peel energy v ersus surfactant concentration curves show either a maximum or a minim um, depending on the surfactant. When the peel rate is decreased, thes e maxima and minima flatten out and, at zero peel rate (extrapolated v alues), the peel energy becomes independent of the surfactant concentr ation. Surfaces analyses revealed that the surfactant is always presen t at the locus of failure. Rupture takes place in a thick (above 10 nm ) (SDS), in a thin (a few nanometers) (NP30), or at the top of a surfa ctant layer (HPCl). The locus of failure is independent of the peel ra te and of the surfactant concentration. The conclusion is that the sur factant strongly influences adhesion properties of latex films but sev eral points remain unexplained.