Nonlinear Viscoelastic Modeling of Adhesive Failure for Polyacrylate Pressure-Sensitive Adhesives

TL;DR

This study develops a nonlinear viscoelastic model for polyacrylate pressure-sensitive adhesives, revealing how extensional rheology influences adhesion energy and explaining deviations from linear predictions for more viscoelastic adhesives.

Contribution

The paper introduces a nonlinear model capturing the rate-dependent adhesion energy of PSAs, highlighting the importance of extensional rheology and complex debonding criteria.

Findings

Nonlinear model explains adhesion energy dependence on peeling rate.

Linear viscoelastic approaches suffice for elastic PSAs.

Viscoelastic PSAs exhibit complex, rate-dependent debonding behavior.

Abstract

We investigate experimentally the adherence energy $\Gamma$ of model polyacrylate Pressure Sensitive Adhesives (PSAs) with combined large strain rheological measurements in uniaxial extension and an instrumented peel test. We develop a nonlinear model for such peel test which captures the dependence of $\Gamma(V)$ with peeling rate $V$ revealing the key role played by the extensional rheology. Our model explains in particular why traditional linear viscoelastic approaches correctly predict the slope of $\Gamma(V)$ curves for sufficiently elastic PSAs characterized by a simple rate-independent debonding criterion. However, for more viscoelastic adhesives, we identified a more complex rate-dependent debonding criterion yielding a significant modification of the $\Gamma(V)$ curves, an effect that has been largely overlooked so far. This investigation opens the way towards the understanding of fibrils debonding, which is the main missing block to predict the adherence of PSAs.