MD Simulations On The Structure And Thermo-mechanical Properties Of Epoxy Resin And Its Nanocomposites

With the improvement of the voltage level of the power system,the temperature rise,self-weight and mechanical load of the power equipment increase,which put forward higher requirements on the thermo-mechanical properties of the insulating materials.Therefore,the thermo-mechanical properties of epoxy resin insulating materials have become a hot research topic in recent years.This work intends to study in depth the microstructure and thermo-mechanical properties of epoxy resin and its nanocomposite insulating materials based on MD simulations.Firstly,the bisphenol A epoxy resin?DGEBA?,dicyclopentadiene dioxide epoxy resin?DCPDE?,methyltetrahydrophthalic anhydride?MTHPA?and maleic anhydride?MA?curing agents were selected as monomers,which can form 4 kinds of crosslinked epoxy systems.The effect of crosslinking degree on the microstructure and thermodynamic properties of epoxy resin was investigated,and the relationships between the microstructure characteristics and thermo-mechanical properties of epoxy resin were preliminarily explored by MD simulations.Secondly,the nano-SiO2 filler models with different morphologies was constructed,and filled them into the DGEBA/MTHPA epoxy matrix was with different mass fractions.The effects of nano-SiO₂ fillers on the microstructure and thermo-mechanical properties of epoxy resin composites were analyzed.Finally,the effects of the type and graft ratio of coupling agents on the binding energy between SiO₂ fillers and matrix,and the diffusion characteristics of fillers in matrix were studied by using 3 kinds of silane coupling agents?KH550,KH560,KH570?to modify the surface of nano-SiO₂ fillers.And the microstructure and thermo-mechanical properties of EP/modified SiO₂ composites were calculated,and the mechanism of action of silane coupling agents on epoxy resin composites was analyzed as well.In this thesis,the structure and thermo-mechanical properties of epoxy resin and its nanocomposites were studied by employing MD simulations.The results in this research are expected to provide a theoretical guidance for the design of high performance epoxy resin insulating materials in terms of the loading content and morphology of fillers,and the type and dosage of coupling agents.