Quantifying failure in geometrically confined adhesives by pressure-induced cavitation*

Many practical adhesives fail by the growth of interfacial cavities. Conventional contact adhesion measurements relate cavity growth to adhesive performance by recording force, displacement and contact images. Still, the influence of internal pressure within the cavities is an open question. Thus, in-situ cavity pressure measurements will enrich quantitative understanding of adhesive failure mechanisms. Here, we report a contact adhesion testing instrument that applies positive pressure at the contact interface to induce cavitation. We combine experiments with finite element analysis to develop models relating the pressure response in acrylic adhesives and silicone elastomers to their quanitative bulk and interfacial properties, including the elastic modulus and the critical strain energy release rate. Moreover, our experiments demonstrate that modifying interfacial pressure imparts control of failure modes during separation.