Effectively improving the quick-repair characteristics of epoxy coatings for the SF6-inflate metal tubes through molecular modifications

Abstract Four crosslinked epoxies, agented by ODA, SDA, DDS, and SSDDS, were constructed, followed by DFT calculations and MD simulations to assist the selection of coatings for the quick repairment of GIL. The DFT-based ground-state charge density results indicate that the core group and molecular length impact the reactivity of diamine curing agents. Based on the MD simulations, the key physical properties were predicted. The glass transition temperatures, in the narrow range from 374 to 396 K, of epoxies crosslinked by various agents, are close, owing to the similar polymer network-determine crystallinity. SDA cured epoxy model with the lowest Young’s module, which is only 1.877 GPa, shows the best elastic behaviors under the action of axial mechanical stresses. The fractional free volume of the crosslinked epoxies, no more than 10−5 Pa cm2/s, is small enough to forbid the motion of SF6 inside, leading to low permeability. Furthermore, the results indicated that the SDA crosslinked epoxy model had the most prominent effects. Therefore, the SDA may be an effective curing agent for the epoxy coating in the GIL quick repairing application.