Molecular Structure, Mechanical Behavior and Adhesion Performance of PSAs
Tack is a dominant property of pressure sensitive adhesives that is defined as the ability of an adhesive to form a bond of measurable strength to another material under conditions of low contact pressure and short contact time. Tack is, thus, not a fundamental material property but depends on the test methods and the conditions of measurement.
The procedure for measuring tack is a two-stage process of bond formation and bond separation. During bond formation, contact in molecular dimensions between the adhesive and the adherend is established by deformation and flow as well as by wetting. The second step, the bond separation with a certain rate, is connected with deformation and crack propagation within the adhesive joint. Adhesion and tack are accordingly related to surface properties and to the mechanical behavior. The latter correlation is the topic of this article.