Research On Preparations Of SiO₂@MWCNTs And Properties Of Epoxy Resin Nanocomposites

The rapid development of national economy was inseparable from highperformance materials.Epoxy resin?EP?,because of its excellent properties of electrical insulation,strong adhesion and good chemical stability,was widely used in the field of electronic/electrical,aviation/aerospace,machinery manufacturing and other building materials,which has also aroused widely concern of researchers.Along with the improvement of material performance requirements in various fields,the modification of epoxy resin also changed.Rubber elastomer modified epoxy resin from the early to the modification of inorganic nanoparticles recently,which accumulated valuable experience for future exploration,especially the emergence of inorganic carbon materials,such as carbon nanotubes?CNTs?,because of its excellent comprehensive performance,was favored by many scholars.Relevant research showed that the addition of a small amount of carbon nanotubes in the epoxy resin had a significant effect on the strength and thermal properties of composites;However,with the increase of the amount of carbon nanotubes,whether it will affect the electrical insulation properties of epoxy resin,which is a hot spot in the study of the modification of epoxy resin for electrical engineering.This project was based on bisphenol A epoxy resin/anhydride curing system and the CNTs was introduced to the system.Taken advantage of toughening effect of CNTs,surface insulation treatment of CNTs,and the suppress effect of CNTs conductive network,the epoxy nanocomposites can be toughened and used for insulated material at the same time.In this experiment,the multi walled carbon nanotubes?MWCNTs?was modified by mixed acid?MWCNTs-OH?,silicon dioxide coating?SiO₂@MWCNTs?and Silane coupling agent KH560?KH560-SiO₂@MWCNTs?,and then used it to modify the bisphenol A epoxy resin.MWCNTs-OH/EP,SiO₂@MWCNTs/EP,KH560-SiO₂@MWCNTs/EP and KH560-SiO₂@MWCNTs/O-MMT/EP were prepared by solution blending method,and the methyl-hexahydro phthalicanhydride was used curing agent.The coating effect of carbon nanotubes was characterized by Fourier Transform Infrared Spectroscopy?FT-IR?,scanning electron microscope?SEM?and transmission electron microscope?TEM?,We also tested the impact strength,bending strength,thermal decomposition temperature,Martin heat resistance temperature,dielectric loss,volume resistivity and breakdown strength of the composite.The results showed that the surface insulation treatment effect by using silica coated MWCNTs was obvious.SiO₂@MWCNTs was processed for two times by KH560,which can improve the mechanical and thermal properties of the composites,when the KH560-SiO₂@MWCNTs content was 0.5 wt%,the impact strength and bending strength of KH560-SiO₂@MWCNTs/EP reached the maximum,its numerical value were 36.2 k J·m-2 and 134.5 MPa,which compared with the pure EP was increased by 144.6 % and 49.4 % respectively.O-MMT was added to the system,the mechanical strength of KH560-SiO₂@MWCNTs/OMMT/EP decreased.Among all kinds of composite materials,the thermal decomposition temperature of KH560-SiO₂@MWCNTs/EP was the highest,which compared with the pure EP was improved by 21.55 ?.The dielectric constant and dielectric loss of the composites were affected by the functional mode and the content of the MWCNTs.SiO₂@MWCNTs was treated by KH560 can reduce the dielectric constant and dielectric loss of the material;After the MWCNTs were coated with silica,the volume resistivity of KH560-SiO₂@MWCNTs/EP and SiO₂@MWCNTs/EP compared with pure EP decreased only by one order of magnitude.Method of SiO₂@MWCNTs processed for two times by KH560 had obvious effect on improving the breakdown strength of the composite,and added O-MMT to the system promoted the improvement of the breakdown strength of the composites.