Study On Mechanical Properties Of Graphene And GO/Epoxy Composites

As an em erging carbon nanomaterial,graphene features outstanding mechanical,electric,optical and thermal properties.It has attracted great attention when it was exfoliated successfully in 2004.By now,graphene has been successfully applied in the sectors of basic research,sensor,transistor,flexible display screen,new-energy battery,sea water desalinization,hydrogen storage material,aerospace,photosensitive element and composites material.The strength and nanometer-deformation failure mechanism of graphene exert great influences on its application prospect.Therefore,the research on the mechanical property of graphene is significant.In the process of preparing,manufacturing and transferring the graphene,various defects occur in the surface of the graphene would be inevitable.The influences generated by the defects on the graphene and graphene reinforced composites shall not be ignored.Defect’s influence on mechanical property of graphene also serves as the hot spot for both domestic and overseas study.Being the functional derivative of graphene,oxidized graphene is regarded as the optimal filler of nanocomposite with its excellent mechanical property,simplicity of preparation and production,water-soluble property as well as features of organic solvent.This paper adopted the method of numerical simulation to study the elastic property of graphene and graphene reinforced epoxy resin and analyzed the performance of oxidized graphene reinforced epoxy resin with the approach of experimental measurement.In terms of the numerical simulation:the molecular structural mechanics method was applied to establish the equivalent model of graphene—space frame structure model;then,it discussed the chirality and dimension associativity and studied the elastic performance of multilayer graphene under two premises of considering surface relaxation and not considering surface relaxation;furthermore,the influences on the elastic performance of single-layer graphene by defect type(monatomic vacancy defect,diatomic vacancy defect and category I STW),defect location,defect quantity and defect density were analyzed.At last,the multiscale model for graphene reinforced epoxy resin composite was established and the influence of defect on the elastic property of composite material was researched.The simulation results show that the elastic properties of perfect single-layer graphene nanoribbons and the graphene nanoribbons with defect have chirality and size dependence Defects reduce the elastic properties of graphene and graphene/epoxy composites.The elastic modulus of the composites with graphene increment increases approximately linearly with the increase of the volume fraction of graphene.In terms of experimental measurement:it firstly manufactured oxidized graphene with advanced Hummers method.Then,oxidized graphene reinforced epoxy resin composite material with different mass fraction was produced;after that,approaches of SEM,TEM,Raman spectrum,XRD and XPS were utilized to make microstructure characterization;in the end,it discussed the influences of the mass fraction of oxidized graphene on different properties of composite materials.The addition of graphene oxide enhances the tensile,flexural and impact properties of epoxy resin.When the content of graphene oxide is 0.8 wt%,the tensile,flexural and impact properties of the composites are the strongest.The maximum fracture stress,flexural strength,flexural modulus and impact strength of the composites are 34.9%,60.93%,14.71%and 21.60%higher than those of pure epoxy resin,respectively.