How does the surface free energy influence the tack of acrylic pressure-sensitive adhesives (PSAs)?

This article describes a comparative study of the tack properties of a model acrylic pressure-sensitive adhesive (PSA) crosslinked using aluminum acetylacetonate on several substrates, including stainless steel, glass, polyethylene, polypropylene, polytetrafluoroethylene, polycarbonate, and poly(methyl methacrylate). The tack measurements were conducted using a technique commonly used to measure the tack of an adhesive tape in the PSA industries. The surface free energy (SFE) values of the materials were evaluated using the Owens-Wendt and van Oss-Chaudhury-Good methods. The experiments showed a clear relationship between the SFE of the substrate and the tack of the model acrylic PSA. In general, larger differences between the SFE values of the substrate and adhesive (Delta(SFE)) were correlated with greater tack values. The tack of the model acrylic PSA was found to be optimal over the Delta(SFE) range of 7.0-13.1 mJ/m(2). The trend in the tack as a function of the SFE difference was attributed to the quantity of energy dissipated at the jointed points during the separation stage in the loop tack test.