Preparation And Properties Of Modified GO/EP Composite Adhesive

Epoxy resin（EP）is widely used as the matrix of high thermal conductivity adhesive,electronic packaging materials and other fields because of its strong adhesive ability and good insulation properties.However,it has some problems such as high brittleness and low thermal conductivity after complete curing,which limits the wider application of EP.Graphene oxide（GO）is a kind of high thermal conductivity filler.In this study,toluene diisocyanate（TDI）was used to optimize the interface between GO and EP to improve the properties of adhesive.The adhesive was prepared by combining with TDI-GO,GO grafted by TDI,and EP.The interface structure of GO/EP was improved by introducing TDI.The optimum dispersion solvent of GO was determined by analyzing the properties of GO_0.5/EP（0.5 means GO as a percentage of EP mass）composite adhesive when different inert solvents are used as GO dispersing medium.It was found that the dispersion stability of GO suspension was more than 12 h when solvent A was selected as the dispersion solvent of GO.Moreover,the properties of composite adhesives with different GO content were characterized.It was found that when the GO content was 0.5 wt.%of EP,the mechanical,electrical and thermal conductivity of GO/EP composite adhesive was the best.The chemical structure and microstructure of TDI-GO grafted were characterized.It was found that TDI-GO grafted was obtained by the reacting between TDI and-OH and-COOH,located on the surface of GO,and there were still unreacted-NCO groups in the TDI-GO grafted structure.It was found that the properties of composite adhesive has the best performance by analyzing the graft ratio of GO and TDI and the effect of the amount of GO in epoxy resin when the amount of GO added was 0.5 wt.%and that of TDI was 10 wt.%.The tensile strength of TDI₁₀-GO_0.5/EP composite adhesive was 5.34 MPa,and the T peeling strength was 9.62 N·mm^-1,while the flexural strength was 128.31 MPa and The impact strength is 20.49 kJ·m^-2.The breakdown field strength and the volume resistivity of TDI₁₀-GO_0.5/EP composite adhesive were increased due to forming a large number of tiny resistors and capacitors,produced by modified GO in the adhesive solidification.The interfacial thermal resistance between GO and EP was reduced to 1.19×10^-4 K·m²·W^-1 after modified by TDI,which increased the thermal conductivity of adhesive to 0.624 W·m^-1·K^-1.