Studies in the nature of adhesive tack

By measuring tack energy using a modified probe tack testing procedure, the interrelation of bulk energy and surface energy effects in pressure-sensitive adhesives was studied. Tack energy was strongly influenced by the solvent used in the preparation of the adhesive film. A procedure was empirically derived which reduced the number of variables to a single variable, yielding a single master curve in which the independent variable was the speed of probe withdrawal expressed on a logarithmic scale. The form of the curve was a simple exponential function, y = A exp (mx), where A and m are constants and y and x are the dependent and independent variables, respectively. The constant m was found to be a unique function of the type of adhesive used. A theoretical interpretation of the devised procedure was based on bulk viscoelastic effects and a combined activation energy–free volume concept of adhesive bonding. The wider implications of this are briefly discussed.