TY  - THES
T1  - Debonding of viscoelastic materials : from a viscous liquid to a soft elastic solid
A1  - Nase,Julia
Y1  - 2010/01/06
N2  - In the present experimental study, we investigate the transition in the debonding mechanism when going from a viscous liquid to a soft elastic solid using a probe tack geometry. We have developed a model system consisting of PDMS with different degrees of crosslinking, ensuring a continuous transition between the material classes. During debonding, a fingering instability with characteristic wavelength evolves. We explain the subsequent coarsening of the pattern for a Newtonian oil by linear stability analysis and identify the influence on the adhesion energy. Over a wide range of properties from liquid to solid, we present a quantitative description of the initially destabilizing wavelength for the observed interfacial and bulk mechanisms. We predict the transition between these mechanisms from linear viscoelastic and surface properties. Furthermore, we investigate the debonding quantitatively in terms of adhesion energy and maximum deformation. For interfacial debonding, we are able to explain the speed dependence in the adhesion energy by bulk properties only and confirm thus over two decades in the elastic modulus an existing empiric law. Adapting a recent 3D technique, we visualize for the first time in situ the contact line between viscoelastic material and rigid probe in three dimensions and provide thus direct access to the boundary conditions.
KW  - Adhäsion
KW  - Viskoelastizität
KW  - Strukturbildung
KW  - Weiche Materie
CY  - Saarbrücken
PB  - Universitäts- und Landesbibliothek
AD  - Postfach 151141, 66041 Saarbrücken
UR  - http://scidok.sulb.uni-saarland.de/volltexte/2010/2539
ER  -