A thin film of viscous liquid between two solids acts as an adhesive due to
the large force resisting separation of the solids. This effect is exploit
ed in pressure-sensitive adhesive bonds. One method of investigating such b
onds is to use a probe tack test in which a rigid probe is indented into a
thin adhesive layer coating a rigid flat base. These experiments are charac
terized by two quantities: the total work of separation, that is, the work
done in extracting the rigid punch from the adhesive film, and the peak adh
esive force, otherwise known as the adhesive strength. Little effort, howev
er, has been spent on understanding the connection between these quantities
and the apparatus used to measure them. In this article we shall study the
simplest case of fluid adhesion where a spherical probe and flat are bound
by a high viscosity Newtonian polymer melt (polydimethylsiloxane or polybu
tene) and examine the role of apparatus-specific parameters in determining
the measured adhesive strength and work of separation. We shall show how a
dimensionless master-curve can be derived to capture the dependence of the
adhesive strength on the testing regime. Specific attention is paid to the
effect of system compliance on the adhesion, as introduced by the presence
of a compliant load cell used to measure the adhesive force. A relationship
linking the adhesive strength of a Newtonian film and the work of separati
on is also presented. (C) 2001 American Institute of Physics.