The origin of high adherence in PSA foam tapes

We investigate the exceptional adhesion performance of pressure-sensitive adhesive (PSA) foam tapes by linking microscale damage mechanisms to macroscopic peel behavior. Using instrumented peel tests, side-view imaging, and microscopy, we show that the key to high adherence lies in a transition from a stiff incompressible composite to a soft dissipative foam, triggered by debonding of the adhesive matrix from embedded hollow glass microspheres. This structural transformation enables large strain energy dissipation while maintaining structural integrity. We extend the equivalent fibril model (EFM) to accurately predict adherence energy in the high-performance regime and identify a master curve between the shape of the debonding region and adherence energy. This "time-temperature-interface equivalence" enables fast, image-based assessment of adhesive performance and provides a unified framework bridging fracture and cohesive zone models. Our findings offer fundamental insights and practical tools for the design and evaluation of advanced structural adhesives.