Elastic analysis of the loop tack test for pressure sensitive adhesives

The behavior of pressure sensitive adhesive (PSA) tapes is sometimes examin ed via the loop tack test, in which a loop of the tape is brought into cont act with a flat surface and then pulled away. A numerical analysis of the t est is presented here. The loop is treated as an elastica, but with a nonli near moment-curvature relation, so that the material is assumed to be elast ic and inextensible. Debonding at the edge of the contact region is assumed to occur when the adhesive reaches a critical elongation. This elongation is assumed to depend on the maximum contact pressure and, in part of the re sults, on the length of time of contact. Shapes of the loop and values of t he corresponding forces are obtained using a shooting method, and the effec ts of the stiffness and thickness of the adhesive and backing are examined.