Effects of the furan ring in epoxy resin on the thermomechanical properties of highly cross-linked epoxy networks: a molecular simulation study

Two highly cross-linked epoxy networks based on two epoxy resin model compounds with similar structures, 2,5-bis[(2-oxiranylmethoxy)-methyl]-furan (BOF) and 2,5-bis[(2-oxiranylmethoxy) methyl]-benzene (BOB), and the same curing agent PACM were constructed by using molecular dynamic simulations. Several thermomechanical properties of these two systems including glass transition temperatures, coefficients of thermal expansion, Young's moduli, and Poisson's ratios were calculated. The simulated values were compared with the available experimental results, and good agreements were obtained. This consistency proved the validity of the atomistic models. The changes of aromatic structures in the epoxy monomers from phenyl to furyl lead to a higher glassy Young's modulus of the cross-linked epoxy network. This phenomenon can be illustrated by the reduced mobility of the polymer chains arising from the increased packing efficiency. These changes are considered to be induced by the higher van der Waals energy within the furan-based epoxy.