Viscoelasticity and the Persson-Brener Model*

Polymeric coatings are widely produced by industry and used to create barriers between structures and the elements. Recently, effort has focused on soft coatings that prevent ice and other unwanted foulants from adhering to surfaces. While low surface energies of soft materials, such as polydimethylsiloxanes (PDMS), promise easy removal of attached foulants and ice, the simple physical limit for adhesion strength based on surface energy has not been achieved in practice. It is largely believed that the discrepancy is due to viscoelastic losses in the soft coating materials. To better understand the viscoelastic losses in soft adherent PDMS materials, we perform JKR adhesion experiments on several elastomers, at different temperatures and over a set of speeds that spans several orders of magnitude. Each elastomer also undergoes DMA experiments to characterize the dynamic mechanical modulus from the glassy to rubbery regime. We demonstrate that the adhesion tests are qualitatively related to the dynamic moduli and use a more direct comparison (the Persson-Brener model of crack propagation [1]) to show a quantitative relationship between adhesion and dynamic moduli at low speeds.

 

[1] B. N. J. Persson and E. A. Brener, “Crack propagation in viscoelastic solids,” PHYSICAL REVIEW E 71, 036123 (2005).