Research On The Properties Of Nano-SiC Modified Epoxy Adhesive

Epoxy adhesive is used widely in the industrial production because of its excellent comprehensive performances such as strong adhesion, excellent mechanical properties, good dielectric and chemical resistance properties. On the other hand, he epoxy adhesive has some shortcomings, for instance, poor toughness, easy to crack and lack of heat resistance. As the inorganic nano-particles have same special properties, hey have been used in epoxy adhesive modification more and more.In this paper, nano-SiC particles were used to modify epoxy adhesive. The preparation of silane coupling reagent of y-glycidoxy propyl trimethoxy silance(KH-560) modified nano-SiC and nano-SiC mdified epoxy adhesive have been studied. The mass fraction and whether modified of nano-SiC influencing on mechanical and heat resistance properties of SiC/EP composite adhesive were discussed. Through the SEM photographs of the impact fracture appearance of the snapped specimens, the toughening modification mechanism of nano-SiC/epoxy composite adhesive has been discussed.We used solution method, selected KH-560to carry out surface modification of nano-SiC. The best modification process condition is:coupling agent concentration2%, coupling reaction temperature70℃, reaction time3h. FIRT and TGA analysis show that the organic groups have been bound on the surface of SiC after the reaction between KH-560and SiC particle. The SEM and dispersity tests indicate that the agglomeration of the modified nano-SiC has decreased and it can disperse in acetone steady.The resin matrix choose epoxy E-51and AFG-90, when the mixture ratio is1:1, we can obtain the maximum bonding strength (13.1MPa) and higher Tg (196℃) On that basis, we research the mass fraction and whether modified of nano-SiC influencing on mechanical and heat resistance properties of SiC/EP composite adhesive. The results show that when the mass fraction of SiC is1%, all of the three mechanical properties reach maximum(tensile strength is67.5MPa, flexural strength is108.9MPa, impact strength is15.1kJ.m-2). The shear strength is larger with the adherends of fiber reinforced plastic(FRP) plates than with steel plates. The shear strength reached maximum when the SiC is1%, and they are20.5MPa and18.6MPa. Nano-SiC can significantly improve the Tg of epoxy resin, and with only1%SiC particles added, the Tg of the composites could rise to216℃. Nevertheless, with the increasing of SiC, the Tg changes little.The nano-SiC with surface modification performs better than the original SiC on epoxy adhesive modification. When the mass fraction of modified SiC is1%, The tensile strength is70.8MPa, flexural strength is111.4MPa, impact strength is17.2kJ.m-2. At the same time, modified SiC performs better than original SiC on enhancing the adhesive property. The steel-steel shear strength increased to19.7MPa, while the FRP-FRP shear strength increased to22.8MPa. The Tg is up to224℃, increased28℃and8℃respectively with the comparison to pure epoxy resin and original SiC modified epoxy resin.The toughening mechanism for the nano-SiC modified epoxy adhesive is studied through SEM of the fracture appearance analysis. A small number of evenly dispersed nano-SiC in the matrix resin can induce a mass of microcracks which may induce crazes and prevent the crazes evolved into big cracks when force acted on the materials. Thereby more energy will be absorbed, the toughness of the composite adhesive improved significantly. But when using surface modified nano-SiC, because of the high surface activity, it can fill into the crazes, and the alkoxy group on the SiC surface can react with hydroxyl-terminated groups of epoxy resin which will enhance the forces between the two phases. Finally improve the toughness of the composite adhesive.