Tack of a polymer melt: Adhesion measurements and fracture profile observations

We present an experimental study of the tack of a model polymer melt by the probe tack test coupled with an optical observation of the fracture profile. This set-up allowed us to study the different processes involved in tack and to estimate their importance. We distinguished three different regimes that can be correlated to the rheological properties of the adhesive. In particular, the regime where viscoelastic losses in the bulk of the polymer are important is discussed in detail, in the frame of a recent model by de Gennes. We found, in this case, an enhancement of the energy of adhesion and put into evidence peculiar fracture profiles similar to the "trumpet" profile predicted by the model. We also studied the influences of surface roughness and polymer adsorption on the formation of the bond.