Abstract:
The transient extensional viscosity of a polyisobutylene (PIB)-based pressure-sensitive adhesive (PSA) is measured in a filament stretching instrument at three stretch rates, and compared with theoretical predictions based on the linear viscoelastic (LVE) properties of the PSA and the use of linear and non-linear constitutive equations. Based on previously reported adhesive stretch rate profiles across the peel front, a model predicting peel force from peel rate is proposed and evaluated for each constitutive equation. A new expression for the relative contributions of the individual relaxation modes of the polymeric material to the total measured peel force is derived and the result is discussed with regard to correlation of LVE data to peel performance. Comparison of predicted and measured peel force values reveals that peeling of this PSA is only qualitatively described by linear viscoelasticity; quantitative agreement is obtained when the strain-hardening behaviour of the adhesive is properly modelled. 

Published: Int. J. Adhesion & Adhesives, 18(5), 1998,  p. 333-343