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CPP: Chemische Physik und Polymerphysik

CPP 29: POSTER: Polymer physics

CPP 29.24: Poster

Dienstag, 8. März 2005, 16:30–18:30, Poster TU D

Cavity growth in soft adhesives — •Arnaud Chiche, Josef Dollhofer, and Costantino Creton — ESPCI, Paris (France)

We have studied the growth of cavities in a SIS based soft adhesive layer submitted to a hydrostatic stress, in a flat-probe geometry (tack). We have shown that cavity growth occurs from lack of interfacial contact during the bonding process, due to the elastic properties of the adhesive material. These initial flaw sizes have been varied through the change of both probe and adhesive surface roughness. This size appears to be a critical parameter for the cavitation process. The growth of large enough flaws is not affected by their size and appears to be controlled by a local stress criterion that depends on the elastic properties of the material. On the other hand the growth of small flaws becomes extremely size sensitive: the smaller is the initial defect, the higher is the stress it eventually grow, always above the previous criterion. The expansion then appears to be controlled by the amount of available elastic energy, consistent with the observed sensitivity to the adhesive layer thickness. These new experimental results are consistent with a model we developed based on the assumption that potential flaw size effect results on its surface energy.