Mechanics of Soft PSAs (Pressure Sensitive Adhesives)

The adhesive performances of a PSA (Pressure Sensitive Adhesive) are attributed to their viscoelastic properties. In this paper we analyze the viscoelastic behavior of different PSAs having substantially similar adhesive performance. Linear and non linear analyses were performed using small amplitude oscillatory shear tests and tensile stress-strain tests, respectively. It is shown that linear viscoelastic tests are useful to qualitatively characterize the adhesive performances. However, deeper knowledge can be achieved by non linear viscoelastic tests. The true stress - true strain curves are modeled by using a theory accounting for the interpenetration of micro-network and the linear polymer. It is shown that the same substantial in-service properties can be achieved with adhesives showing different fingerprints in terms of viscoelastic spectra.