Adhesive failure analysis of pressure‐sensitive adhesives

Abstract

ABSTRACT:In this article we use a linear elastic fracture mechanics approach to characterize the adhesive performance of two commercially available pressure-sensitive adhesives (PSAs). An axisymmetric adhesion test involving the contact of a spherical indenter with a thin adhesive layer is used to generate "tack" curves for both adhesives. These curves describe the relationship between the normal loads and displacements during the test. Adhesive failure is understood in terms of crack propagation at the indenter/adhesive interface. We investigate the effects of adhesive layer thickness and crosshead velocity on the tack curves. Using fracture mechanics equations developed for thin layers, we show that the energy release rate is a unique function of the crack velocity for a given adhesive. Based on the tack curves and energy release rates, we discuss the coupling of the bulk and interfacial properties that produce the large adhesion energies typical of pressure-sensitive adhesives.

A Simple Microscopic Model for the Dynamics of Adhesive Failure

“…This result shows that the behavior of the force−displacement curve as τ → τ m is qualitatively similar to that observed in some experiments (e.g., in ref ), but not others (e.g., in ref ), which differ from each other mainly in the nature of the experimental geometry highlighting the role of confinement. In an unconfined adhesive, the failure is initiated by a fingering instability that occurs around the edge of the adhesive; a confined adhesive will fail via cavitation within the bulk of the adhesive . In the former case, the constitutive response of the elastomer that remains is unchanged, but in the latter case, the properties of the adhesive change because of its ability to accommodate the imposed deformation via bubble growth.…”

“…This result shows that the behaviour of the force-displacement curve as τ → τ m is qualitatively similar to that observed in some experiments (e.g. [4]), but not others (e.g. [3]), which differ from each other mainly in the nature of the experimental geometry highlighting the role of confinement.…”

“…In this paper, we have investigated the possibility that this might be produced by the effects of finite bond/chain length and shown that such finite length effects, in the absence of cavitation, produce tack curves in qualitative agreement with those obtained experimentally with unconfined adhesives (e.g. Crosby and Shull [4]). Our model allows us to also determine the region in phase space where this bi-modal behavior may be seen, and further explains the rapid failure of the adhesive following the second peak in the force.…”

Adhesion and detachment mechanisms of sugar surfaces from the solid (glassy) to liquid (viscous) states

“…5B shows a top view of the surface deformations at an early stage of separation, revealing micrometer-sized ripples or waves growing into the fluid, and much finer secondary structures at the external neck boundary. These ripples are similar to the viscous fingers observed at the peel front during the peeling of ''pressure-sensitive adhesive'' tape from a glass surfaces (27); and similar viscous fingers have also been reported in various dynamic studies of confined viscoelastic polymers (8,28,29). In the present experimental geometry, when the two coalesced fluid surfaces are pulled apart and the neck thins, fluid flows both axially and radially inward toward the center (Fig.…”

Influence of purified attapulgite clays on the adhesive properties of cement pastes as measured by the tack test

“…It suggests that the material is exhibiting residual resistance to the plates separating after the break in flow indicated by the initial peak. Similar strain hardening has been observed in polymer adhesives tested under spherical and flat punches [13,11], where higher initial maximum contact radiusto-height ratios made this effect more pronounced. This strain hardening was attributed to fibrillation and is akin to polymer materials.…”