For elastomers and polymers, measuring the time-dependence of the stiffness can be done in a number of ways, stress relaxation testing, creep testing, rate-testing (family of monotonic pull tests at various strain-rates), cyclic testing at various harmonic excitations,  or DMA testing.  Researchers discovered that for a certain class of materials, called thermo-rheologically simple (TRS), there is a relationship between the time-dependence and the temperature -dependence.  This leads to the idea of a time–temperature superposition principle (TTS).  

https://en.wikipedia.org/wiki/Time%E2%80%93temperature_superposition

There are a variety of other posts here in the SIMULIA Community that describe aspects of this, with this particular post showing how to create a master curve from DMA test data (using Excel):

https://r1132100503382-eu1-3dswym.3dexperience.3ds.com/#community:39/post:4071

And a similar post where the same workflow is done entirely within the calibration app (R2023x FD01):

Generate Master Curve from DMA test data

This post is here to store a variety of master curves and speak to a few of the challenges in calibration of material models (Prony series, PRF).  One common attribute of a typical master curve is that it spans many decades in time/frequency, 10 to 20 decades of time/frequency are fairly common.  Along with a broad span of time/frequency (x-axis), master curves typically span many decades of stress/stiffness (y-axis).  

Error Norm: RSE  When calibrating master curves, you should select the RSE error norm. I will create a dedicated post to the why behind this.

Optimizer: Differential Evolution and Particle Swarm   We have found both the Differential Evolution and Particle Swarm optimizer to be particularly effective when calibrating master curves

One of my "go-to" references for viscoelasticity is John Ferry's classic book Viscoelastic Properties of Polymers.  Appendix D of his book gives some tabular data for master curves. 

Ferry's Appendix D, Table 3, Shear Moduli Master Curve for Polyisobutylene

Ferry's Appendix D, Table 6, Relaxation Modulus Master Curve for Polyisobutylene

Acrylate Polymer (data posted under "polymers")

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