Molecular modeling can be used to aid material developers and chemists in a variety of ways by specifically showing how different molecular structures may contribute to interfacial failure which influences the robustness of the composite being engineered. For example, environmental moisture is of concern for long term reliability of composites which can be shown to cause lowering of the modulus, and small-scale molecular models can be used to quickly evaluate the modulus trends when water is present. Interestingly, the simulated modulus appears to be quantitative when compared to experiment, which demonstrates that the underlying interactions for the linear part of the stress-strain (traction-separation) curve is very local. However, in order to impart higher levels of reality without resorting to bigger and bigger atomistic models (which require large computational resources), scaling methods are required and mesoscale models can be employed. The mesoscale model may be easily parameterized directly from small-scale molecular models, which allows the modeler an opportunity to model new molecular structures and materials without using generalized parameterizations found in most commercial software. This allows more specific targeting of mechanical issues. Such parameterized mesoscale models were used to generate a full stress-strain curve including the failure side of the curve past yield points. The modulus derived from these models demonstrates continuity of scale, and the property trends extracted were reasonably similar to what is observed. In addition, mesoscale models allow the molecular modeler to begin imparting morphology issues like surface roughness extending the usefulness of the molecular model. This paper will review work that follows the path from small molecular models to mesoscale models, including parameterization, for various applications.

Molecular and mesocale modeling for mechanical issues in composite interfaces

2019 Fall National Meeting

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