Adhesion: role of bulk viscoelasticity and surface roughness

Abstract

We study the adhesion between smooth polydimethylsiloxane (PDMS) rubber balls and smooth and rough poly(methyl methacrylate) (PMMA) surfaces, and between smooth silicon nitride balls and smooth PDMS surfaces. From the measured viscoelastic modulus of the PDMS rubber we calculate the viscoelastic contribution to the crack-opening propagation energy γeff(v,T) for a wide range of crack tip velocities v and for several temperatures T. The Johnson-Kendall-Roberts (JKR) contact mechanics theory is used to analyze the ball pull-off force data, and γeff(v,T) is obtained for smooth and rough surfaces. We conclude that γeff(v,T) has contributions of similar magnitude from both the bulk viscoelastic energy dissipation close to the crack tip, and from the bond-breaking process at the crack tip. The pull-off force on the rough surfaces is strongly reduced compared to that of the flat surface, which we attribute mainly to the decrease in the area of contact on the rough surfaces.

Evaluation of energy dissipation involving adhesion hysteresis in spherical contact between a glass lens and a PDMS block

“…After the loading process completed, the unloading process was performed until the lens detached. A dependence of the maximum loading displacement on the adhesion hysteresis has been reported [16,20]. Hence, three different maximum loading displacement were chosen: −Z max = 10, 20, 30 μm, which is sufficiently smaller than the thickness of the PDMS block 10 mm.…”

“…The energy dissipation in the adhesive contact is mainly investigated and discussed using the strain energy release rate G (i.e., the energy required to separate unit contact area J/m 2 ) [9][10][11][12][13][14][15][16][17][18]. Maugis and Barquins [10] first introduced a concept of linear elastic fracture mechanics into the Johnson-Kendall-Roberts (JKR) contact [6].…”

The speed of an inclined ruck

“…[26]). However, it is also observed that contamination of the surfaces by dust particles (or roughening) can significantly reduce w 0 [18]. As a parallel to these semi-empirical models, we take…”

“…From simple tests based on the gravitational deflection of a section of the rubber clamped horizontally at one end, we estimated that L b = (B/ρgd) 1 For many surfaces, the work of adhesion w 0 (or w ± ) is quoted to be of the order of 0.1 J m −2 . Estimates of the parameters (n, U F ) in the fit (4.3) are more varied: data for a PDMS surface in contact with glass or acrylic suggest a range from (0.4, 10 −6 m s −1 ) to (0.12, 10 −9 m s −1 ) [18,22]. Data from Gent [35], Maugis & Barquins [21] and Shull [13] indicate that (n, U F ) ∼ (0.25, 10 −12 m s −1 ) for a styrene butadiene rubber, (0.6, 10 −6 m s −1 ) for polyurethane, and (0.6, 10 −8 m s −1 ) for PNBA, respectively.…”

“…All three of these models are motivated by work on elastomer adhesion where viscoelastic losses, interfacial bonds and liquid coatings are all inferred to contribute (e.g. [16][17][18]). Our main goal is to determine whether such peeling models can describe the parametric dependence of ruck rolling speeds and the threshold for motion.…”