Molecular dynamics simulations are used to study highly cross-linked epoxy networks comprised of furanyl epoxy monomer, 2,5-bis[(2-oxiranylmethoxy)methyl]-furan (BOF), that is cross-linked by two furanyl amine hardeners, 5,5'-methylenedifurfurylamine (DFDA) and 5,5'-ethylidenedifurfirylamine (CH3-DFDA). Important properties of these fully furan-based systems, including room temperature density, glass transition temperature, and Young's modulus are found to agree with previous experimental results. We also compare the simulated and experimental values of four fully furan-based thermosetting materials to those using the conventional resin diglycidyl ether of bisphenol A (DGEBA) cured with the two furanyl hardeners. Our simulation results predict a slight decrease in density and Young's modulus, but no impact on the glass transition temperature, upon adding the methyl group in DFDA. Detailed analyses of the MD trajectories reveal the underlying mechanisms responsible for the observed structure/property relations, which center on the lack of collinear covalent bonds in the BOF molecular structure. (c) 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2017, 55, 285-292