Adhesion of a Soft Material – Effect of Defects and Lengthscales.

Recently there has been renewed interest in the development of low-adhesion surfaces, motivated by the losses in efficiency incurred by ice or biofoulant accretion on ocean going vessels. One of the leading technologies is the use of silicone elastomers which have low surface energies and are typically soft materials. Predicting the adhesion strength in these materials, however, remains problematic due to uncertainties in how viscoelastic loss contributes to the separation problem. Several physics-based models have been proposed to describe the adhesive fracture process, but there is no consensus. In this work, we use a lap-shear adhesion test to measure the adhesive fracture process between glass and polydimethylsiloxane. We show how the process is affected by joint length and the existence of defects along the interface. Ultimately, we compare the propagation of the crack with several leading theories and comment on factors affecting the correlation between theory and experiment.