TACK OF A POLYMER MELT - ADHESION MEASUREMENTS AND FRACTURE PROFILE OBSERVATIONS

We present an experimental study of the tack of a model polymer melt b y the probe tack test coupled with an optical observation of the fract ure profile. This set-up allowed us to study the different processes i nvolved in tack and to estimate their importance. We distinguished thr ee different regimes that can be correlated to the rheological propert ies of the adhesive. In particular, the regime where viscoelastic loss es 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 f racture profiles similar to the ''trumpet'' profile predicted by the m odel. We also studied the influences of surface roughness and polymer adsorption on the formation of the bond.