Viscoelastic Contributions to Adhesion: Measurement and Modeling

Modeling the velocity dependent adhesion between a solid probe and soft elastomeric material is an important step in streamlining the production of anti-fouling/anti-icing coatings. We compare three models with experimental adhesion measurements. In particular, we assess a polyurethane elastomer, several polydimethylsiloxane elastomers, and several styrene-isoprene-styrene triblock elastomers. The models considered are based on energy conservation arguments and take the zero-speed energy release rate, frequency of deformation (relaxation time), and dynamic modulus (creep compliance) as inputs. Johnson-Kendall-Roberts (JKR) style experiments were performed at twelve different speeds over several orders of magnitude to measure the velocity dependent energy release rate between an optically smooth glass lens and elastomeric material. Dynamic mechanical analysis (DMA) experiments were performed on each elastomer to measure the dynamic modulus from the rubbery to glassy domain, which were used as inputs to the models. We find varying degrees of agreement and conclude that there remain too many 'free' parameters to clearly identify success in matching experiment and theory.