I have a viscoelastic pressure sensitive adhesive that crosses unity (tan delta = 1) at a moderately low frequency (~3 Hz). However, due to instrument limitations, I am only able to sweep up to 100 Hz. Around this frequency of 100 Hz, I notice a change in concavity as tan delta starts to creep back up, and assume it would cross back over at ~1000Hz.

From a fundamental polymer science perspective, why am I (likely) seeing two crossover points for tan delta? Does it have to do with bond formation at low frequency, and bond deformation at high frequency? Could there be a third cross over point past ~1000 Hz? If so, which is the most important/relevant for studying wetting behavior / substrate adherence?