Time-temperature superposition principle for the shear fracture behaviour of soft adhesive layers: From bulk to interface

Soft adhesive layers have attracted great attention as a commonly used adhesive technique, particularly because of their shear fracture behaviour at extreme loading rates and temperatures. Therefore, the present study examined the shear fracture properties of a soft adhesive layer through systematic rheological experiments, loading-unloading shear tests and shear fracture tests. Due to a similar viscoelastic characteristic in rheological properties and fracture properties, the time-temperature superposition principle (TTSP) was extended from the bulk to the interface to investigate its shear cohesive failure. A shear fracture toughness master curve was defined using the time-temperature equivalence shift factors derived from the rheological properties. The shear fracture behaviour of the soft adhesive layer could be predicted using data from a narrow range of loading rates/temperatures. The results demonstrated the potential of extending the TTSP approach from the bulk to a soft adhesive layer having viscoelastic character, which might be utilised to predict the shear fracture toughness of soft adhesive materials under extreme conditions.