Direct experimental evidence of time-temperature superposition at finite strain for an amorphous polymer network

- Time-temperature superposition property of an amorphous network is characterized.
- Comparison of the time-based shift factors in tension and in torsion is performed.
- Direct experimental evidence of time-temperature superposition at finite strain.
- Time-based shift factors measured at small strain and at large strain coincide.

The time-temperature superposition property of an amorphous polymer acrylate network is characterized at infinitesimal strain by standard dynamic mechanical analysis tests. Comparison of the shift factors determined in uniaxial tension and in torsion shows that both tests provide equivalent time-temperature superposition properties. More interestingly, finite strain uniaxial tension tests run until break at constant strain rate show that the acrylate network exhibits the same time-temperature superposition property at finite strain as at infinitesimal strain. Such original experimental evidence provides new insight for finite strain constitutive modelling of polymer amorphous networks.