Mechanical Behavior of Pressure-Sensitive Adhesives (PSAs)

The mechanical performance (stress-strain behavior and creep curve) of joints bonded with pressure-sensitive adhesives (PSAs) are complex due to the multiple phases of morphological evolution of the adhesive layer under uniaxial tensile loading. PSAs are widely used in field applications because of their benign processing conditions, low price, and various available laminated configurations, most notably single-layered or double-layered adhesive (without or with a carrier layer). This study has two main focuses. The first focus is empirical observation of the effects of the configuration of PSA-bonded assemblies, including lamination configuration, substrate material, surface conditions and carrier layer (if any). The empirical results show the effects of the loading conditions for different PSA configurations. Results show complex behavior with multiple transitions in the mechanical response, depending on the absence or presence of carrier layers. The second focus is on developing a model which mechanistically predicts the mechanical behavior of PSA bond lines based on input loading parameters, material constants of the PSA/substrate combination (including substrate properties and roughness), and joint architecture. Model predictions are presented in this study for single-layered PSAs and are found to show reasonable agreement with experimental measurements. Future modeling work will focus on adding the effect of the extra interfaces and structural complexities introduced by flexible carrier layers in double-layered PSAs.