<br/>Many defense applications rely on the thermomechanical response of network polymers to ballistic strain rates. At such conditions, the design of controlled experiments can be challenging. Atomistic simulations, on the other hand, are well-suited to study thermomechanical behavior at such exceptionally high rates while preserving specific chemical interactions within the network that can provide structure-property insight. The associated computational cost, however, limits the accessible time scale and hence makes the quantitative comparison and the integration of computation and experiment nebulous. Here, we perform atomistic simulations of a cross-linked epoxy network to study the dynamics within the network. We find that the time-temperature superposition principle can be successfully invoked for the simulation trends to create a master curve that extends to experimentally relevant time scales. Thus, the dynamics studied via simulations can be directly compared with experimental data on mechanics for the same network that is available in the literature. By bridging these time and length scales, we are able to consider the molecular origin of dynamic heterogeneity in the system, which is of great relevance for applications ranging from metrology to mechanical toughening. We believe that our approach should be generally applicable to other glass-forming systems, where rate effects on thermomechanical behavior are an important consideration.

Bridging the vast mismatch in the time scale of atomistic simulations and experiment for cross-linked epoxy using time-temperature superposition

256th National Meeting (2018)

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