Transition from viscoelastic to fracture-like peeling of pressure-sensitive adhesives

TL;DR

This study explores the slow peeling dynamics of pressure-sensitive adhesives like Scotch tape, revealing a transition from viscoelastic to fracture-like behavior influenced by humidity, with detailed velocity measurements at nanometer scales.

Contribution

It provides a quantitative analysis of the transition from viscoelastic to fracture-like peeling in adhesives, highlighting humidity's role in this process.

Findings

Peeling velocity remains non-zero at very low speeds.

Humidity affects adhesive strength and peeling behavior.

Two distinct peeling regimes identified: viscoelastic and fracture-like.

Abstract

We investigate the process of the slow unrolling of a roll of typical pressure-sensitive adhesive, Scotch tape, under its own weight. Probing the peeling velocities down to nm/s resolution, which is three orders of magnitudes lower than earlier measurements, we find that the speed is still non-zero. Moreover, the velocity is correlated to the relative humidity. A humidity increase leads to water uptake, making the adhesive weaker and easier to peel. At very low humidity, the adhesive becomes so stiff that it mainly responds elastically, leading to a peeling process akin to interfacial fracture. We provide a quantitative understanding of the peeling velocity in the two regimes.