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Non-linear viscoelasticity in debonding of soft adhesives

Tetsuo Yamaguchi The University of Tokyo

When a soft adhesive (PSA) film is debonded or peeled off
from a substrate, it is known that complex deformations
such as cavitations or fibrillations occur inside the film,
and pointed that large, non-linear viscoelastic deformation
of the adhesive affects the fracture behavior. However,
the relationship between non-linear viscoelasticity and
macroscopic stress-strain behavior remains still unclear.

In this presentation, we introduce our studies on
the debonding process of soft adhesives. First, we explain
a simple technique to visualize the stereoscopic shape
of cavities. The results show that the shape of the cavities
is strongly dependent on the cross-linking density
of the adhesives, and the stress-strain behavior is
explained by their growth kinetics. Then we talk about
the debonding process of a double-sided adhesive tape
sandwiched between two glass plates. When the glass
plates are separated from each other at a constant rate,
highly asymmetric extension of top and bottom adhesive
layers and bending of the inner film are seen first. As the
separation is continued, elongation of both layers becomes
symmetric, and the inner film becomes flat again. When this
happens, there appear local maxima in the stress-strain curve.
We explain this asymmetry-symmetry transition and discuss
the role of non-linear elasticity in the debonding behavior.

References :

[1] T. Yamaguchi, K. Koike, M. Doi, EuroPhys. Lett 77 (2007) 64002.

[2] T. Yamaguchi, H. Morita, M. Doi, Eur. Phys. J. E 20 (2006) 17.

[3] T. Yamaguchi, M. Doi, Eur. Phys. J. E 21 (2006) 331.

[4] H. Muroo, T. Yamaguchi, Y. Sumino, M. Doi, submitted.