Pattern Formation during Deformation of a Confined Viscoelastic Layer: From a Viscous Liquid to a Soft Elastic Solid

Abstract

We study pattern formation during tensile deformation of confined viscoelastic layers. The use of a model system (PDMS with different degrees of crosslinking) allows us to go continuously from a viscous liquid to an elastic solid. We observe two distinct regimes of fingering instabilities: a regime called "elastic" with interfacial crack propagation where the fingering wavelength only scales with the film thickness, and a bulk regime called "viscoelastic" where the fingering instability shows a Saffman-Taylor-like behavior. We find good quantitative agreement with theory in both cases and present a reduced parameter describing the transition between the two regimes and allowing to predict the observed patterns over the whole range of viscoelastic properties.

Debonding of confined elastomeric layer using cohesive zone model

“…(16). The predicted debonding nucleates periodically 6 along the xdirection implying long debonding channels along the y-direction The size of the rigid adherend is taken to be 25 mm  10 mm. 4 We assume mode-independent values of the initial slope, the peak traction, and the fracture energy; see [36] for details of a mixed mode bilinear TS relation.…”

“…, and Gc ¼ 0.166 N / m. 6 The inhomogeneity in the distribution of interfacial tractions, singular at the corners [37][38][39][40] triggered by the free-edges of the elastomer layer and the adjoining traction-free portion of the adherend likely acts as the perturbation to the homogeneous solution over the central region. If horizontal displacements at the free edges of the interlayer are constrained, then the undulatory debonding is not predicted.…”

“…A frequently observed phenomenon is the occurrence of contact undulations when a stiff layer is separated from the soft layer under tensile tractions. Classical examples include the formation of ripples when a contactor approaches an elastic film bonded to a fixed base [2][3][4], and wavy debonds in peel [5] and probe tack tests [6][7][8].…”

Large-Area Patterning of the Tackiness of a Nanocomposite Adhesive by Sintering of Nanoparticles under IR Radiation

“…However, the equations of Nase et al 28 and the criteria of Deplace et al 22 apply for the failure of an elastic material. As the nanocomposites are visco-plastic, as is apparent in their yielding (Figure 3a), we propose to substitute the yield stress,  y , for E' in the criteria for fibrillation.…”

Chemical modification of PDMS surface without impacting the viscoelasticity: Model systems for a better understanding of elastomer/elastomer adhesion and friction

“…Crosslinked PDMS Sylgard 184 has a tendency to slip under the plates of the rheometer. To the best of our knowledge, the only extensive study of the viscoelastic properties of this material [39] has been performed by having the samples crosslink directly between the plates to ensure good adhesion between the sample and the rheometer. In our case, this method was not possible, since chemical modification was made after the crosslinking.…”