Influence of conversion on dielectric constant of Dicyandiamide cured epoxy resin:a molecular dynamic simulation and experiment study.

In this study, molecular dynamic simulation and experiment study are combined to explore the main control factors of dielectric constant of Dicyandiamide cured epoxy resin. The density and glass transition temperature obtained by experiment and simulation were compared to verify the rationality of simulation models. Then dielectric constant was calculated by dipole fluctuation formula, here motion mobility, polarity, and free volume were employed to interpret the influence mechanism of conversion on dielectric constant. Results indicate that before gelation the dielectric constant is controlled by the content of unreacted monomers especially dicyandiamide, and after gelation it is dominated by the segmental mobility, hydroxyl group density and free volume, where the influence of segmental mobility is more significant than that of free volume and hydroxyl group density. [Display omitted] • Molecular dynamics simulation and experiment have good consistency in the changing trend. • The control factors of the dielectric properties change significantly before and after gel. • At high crosslinking degree, the influence of segment motion ability on dielectric constant is most significant. [ABSTRACT FROM AUTHOR]