Molecular dynamics studies of the mechanical behaviors and thermal conductivity of the DGEBA/MTHPA/CNB composites

Abstract

Epoxy resin systems based on Diglycidyl ethers bisphenol A (DGEBA) and methyl tetrahydrophthalic anhydride (MTHPA) often experience problems related to brittleness, large internal stress, undesirable shock resistance, low fatigue durability and heat resistance. It is thus of vital importance to improve the thermal and mechanical properties of the DGEBA/MTHPA epoxy resins. In this study, the effects of the addition of carbon nanobud (CNB) to the mechanical properties and thermal conductivities of cross-linked epoxy resins based on the DGEBA and MTHPA are investigated using molecular dynamics (MD) simulations. Different molecular models are constructed, and comparisons are made for the pure DGEBA/MTHPA and their nanocomposites containing carbon nanotube (CNT), single CNB, functionalized nanobuds with one and four fullerenes attached to the CNT, respectively. It has been shown that all these reinforced epoxy systems have an increased glass transition temperature (Tg), Young's modulus and shear modulus, whereas the DGEBA/MTHPA/FCNBs performs the best. Compared with pure DGEBA/MTHPA, the Tg value of the DGEBA/MTHPA/FCNBs increases by 34.3% (140 K). The improvement of the Young's modulus and shear modulus is also significant, with an increase of 44.5% and 51.8%, respectively. The enhancement in the thermal conductivity, however, is limited due to the small length of SWCNTs/CNBs introduced.