Investigation of physical properties of epoxy-functionalized graphene nanoplatelets composite coatings on DC-GIL insulators by molecular dynamics simulation

Surface charge accumulation has become a major limiting factor for long-term operation of DC Gas Insulated Metal-enclosed Transmission Line (DC-GIL). It is an effective measure to restrain the surface charge accumulation by coating the insulator surface with nano-scale modified material. In this paper, epoxy based nano composites were designed using molecular dynamics (MD) simulation. Epoxy resin and four kinds of graphene nanoplatelets (unmodified, hydroxyl functionalized, carboxyl functionalized and amino functionalized) composite models were established. Vital physical properties, including dielectric constant, thermal conductivity, mechanical properties, and glass transmission temperature were investigated under LAMMPS. The results show that the physical properties of the polymer can be improved at different levels by doping graphene nanoplatelets. Epoxy doped with hydroxyl functionalized graphene nanoplatelets (EP-GNOH) reduces dielectric constant by 25.9% which is the most important parameter to suppress surface charge accumulation with other physical properties improved. Epoxy doped with amino functionalized graphene nanoplatelets (EP-GNNH(2)) only has the maximum rise of thermal conductivity by 44.86% while other physical properties improves insignificantly. It is concluded that the selection of EP-GNOH as the dopant of epoxy resin is more suitable for the suppression of surface charge accumulation in practical engineering.