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80. "Cavity Nucleation and Delamination During Adhesive Transfer of a Thin Viscoelastic Film," McSwain, R.L.; Shull, K.R., J. Appl. Phys., 99, 053533 (2006).
A model acrylic copolymer system was used to study the processes involved in
the transfer of a thin viscoelastic film from a weakly adhesive elastomeric
substrate to a more strongly adhesive surface. The film consisted of a layer
of acrylic diblock copolymer micelles that was spun-cast onto a silicone elastomer
from a suspension in butanol. A circular portion of the layer was transferred
to a hemispherical glass indenter with which it was brought into contact. Transfer
of the film during tensile loading of the indenter began with nucleation of
a cavity at the film/elastomer interface, and was followed by delamination of
the film at this interface. Statistical variations in cavity nucleation for
identical loading conditions were quantified by defining a Weibull modulus similar
to that used to describe the failure of brittle materials. The average energy
release rate required for cavity nucleation at a fixed induction time increased
with film thickness in a way that is consistent with the existence of a critical
value of the hydrostatic tension at the film/substrate interface. This critical
hydrostatic tension was comparable in magnitude to the elastic modulus of the
substrate, and was about ten times the elastic modulus of the thin film.
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