Molecular Dynamics Study of Cured ED-20 Epoxy Resin for Predicting the Glass Transition Temperature and Relationship with Structure Features.

A structural model of ED-20 epoxy resin cured by triethylenetetramine was constructed using a molecular dynamics (MD) simulation method. In order to model the epoxy resin hardening, we modified a typical stepwise protocol introducing cross-links between the amino groups and epoxide carbon atoms that allowed us to reproduce experimentally observed glass transition temperature at the value of 360-364 K. The set of MD trajectories of the final molecular-mechanical model can be useful for analysis of alterations in structural and physical properties of the epoxy resin depending on scaleable parameters. The relationships among qualitative alterations in macromolecular structure, the glass transition temperature, and the number of imposed cross-links were elucidated. Analysis of intermolecular interactions between the largest macromolecules and other molecules of a system made it possible to observe the features of the transition from glassy to the viscoelastic state of the studied polymer during the temperature rise.