Experimental Investigation On Bonging And Property Of Epoxy Adhesive Modified By Nano-Materials

As the urgent saving need of energy,the urgent reduction demand of emission and the increasing protection demand of environmental,more and more research has been done on lightweight design.In the transportation field,especially air and new energy vehicles,some new materials have been adopted to achieve weight reduction goals.Carbon fiber reinforced composite materials are widely favored for their excellent performance such as high specific strength and high specific modulus.At present,integral molding of carbon fiber composite materials is difficult to realize,so connection between components is inevitable.How to minimize the loss of structural performance on the basis of structural integrity brings great challenges to lightweight design.The glue connection method solves the above problems well,but the performance optimization of the adhesive still needs further research.In this paper,Toho STS40 carbon fiber reinforced composite laminates were selected,and the mechanical property of three carbon fiber laminates of 0°,90° and ±45° were tested.Finally,a 0° layered carbon fiber reinforced composite layer was selected.Then,graphene and multi-wall carbon nanotubes(MWCNTs)were chosen,and added to the adhesive separately and in a mass ratio(1:1).Single-lap shear specimens of carbon fiber reinforced composite laminates were prepared for testing the shear strength and elongation at break of epoxy adhesive.The fracture mechanism of adhesive layer modified by graphene and MWCNTs was investigated using SEM.The effects of nano-materials on the thermal property of epoxy adhesive were studied using Thermo-gravimetric Analysis(TGA)and Differential Scanning Calorimeter(DSC).The results of shear experiments show that the modification of graphene and MWCNTs improves the interfacial adhesion of epoxy adhesive and improves the shear strength and elongation at break of single-lap joints at the same time.The results of individual modification and mixed modification indicate that the modification of graphene and MWCNTs has synergistic effect.When 0.5wt% graphene and MWCNTs were added for hybrid modification,the modification effect was the best,the shear strength increased by 34.52%,and the elongation at break increased by 43.16%.The results of TGA tests show that the modification of graphene and MWCNTs has the same synergistic effect on the thermal property of epoxy adhesive.When the mixed modification adding amount of graphene and MWCNTs is 0.75wt%,the decomposition temperature of the adhesive is the highest,so the thermal stability is the best.DSC experimental results show that the modification of nano-materials has little effect on the glass transition temperature of epoxy adhesive.The modification result is affected by agglomeration of nano materials,the mechanical property and thermal property of the adhesive are all affected when the content of nano materials is too high.