Adhesion between a viscoelastic material and a solid surface

TL;DR

This paper analyzes the dissipative processes at the interface of viscoelastic polymers and solids, revising a classic model, and confirms theoretical predictions with experimental data on adhesion energy and crack profiles.

Contribution

It revises the 'viscoelastic trumpet' model to better predict interface toughness and adhesion energy scaling in viscoelastic materials.

Findings

Interface toughness G(V) increases from G_0 to G_0 (μ_∞/μ_0)

Adhesion energy for polymer melts scales as 1/V

Experimental data confirms the predicted G(V) dependence and crack profile changes

Abstract

In this paper, we present a qualitative analysis of the dissipative processes during the failure of the interface between a viscoelastic polymer and a solid surface. We reassess the "viscoelastic trumpet" model [P.-G. de Gennes, C. R. Acad. Sci. Paris, 307, 1949 (1988)], and show that, for a crosslinked polymer, the interface toughness G(V) starts from a relatively low value, G_0, due to local processes near the fracture tip, and rises up to a maximum of order $G_0 (\mu_{\infty}/\mu_0)$ (where $\mu_0$ and $\mu_{\infty}$ stand for the elastic modulus of the material, respectively at low and high strain frequencies). This enhancement of fracture energy is due to far-field viscous dissipation in the bulk material, and begins for peel-rates V much lower than previously thought. For a polymer melt, the adhesion energy is predicted to scale as 1/V. In the second part of this paper, we compare some of our theoretical predictions with experimental results about the viscoelastic adhesion between a polydimethylsiloxane polymer melt and a glass surface. In particular, the expected dependence of the fracture energy versus separation rate is confirmed by the experimental data, and the observed changes in the concavity of the crack profile are in good agreement with our simple model.