Comparing Dynamics via Atomistic Simulations with Mechanics via Experiment: Utility of the Time-Temperature Superposition Principle

Large system size and computationally inaccessible timescales makes quantitative comparison of atomistic simulations and experiment non-trivial for polymer networks. Recently, we studied the temperature trend of the specific volume for an epoxy system using multiple cooling rates in conjunction with the time-temperature superposition principle (TTSP) and showed that this permits a direct quantitative comparison of simulation and experiment, bridging a ten order of magnitude mismatch in the respective rates. Here, we show that the time and temperature trend of the mean squared displacement can be used to create a master curve that incorporates the temporal effects at a convenient reference temperature. The features of this master curve relevant to the glass transition show quantitative agreement with published experimental data for creep compliance. Similar to our previous study, the use of the TTSP allows us to use simulations at elevated temperatures to bridge an eight order of magnitude mismatch in computational and experimental timescales. The integration of molecular resolution atomistic simulations with established experimental methods for the study of the thermo-mechanical properties of polymer networks holds tremendous promise for progress in materials research.