| Carbon fiber reinforced epoxy(CF/EP)composites have excellent mechanical properties and excellent design structural design performance.Therefore,it is not only beneficial to the development of aviation industry,transportation and other fields,but also widely used in sports building materials,building reinforcement and other industries.Since the CF/EP composites can exhibit excellent performance in its plane,but it is only bonded by the resin matrix in the radial direction out of the plane.Therefore,when the composites is under load,the load can be easily transmitted in the composites.When the load is transferred across the plane,because the CF fabric layer is only bonded by the resin matrix,the lack of effective connection between the reinforcements cannot resist the lateral load,so it is easy to produce lateral defects and reduce the interlayer shear of the composites.Performance,which seriously limits the application of composite materials.Improving the interlaminar shear strength(ILSS)of CF/EP composites,consequently,has very important practical significance.In this work,we modified the epoxy body by introducing functionalized short carbon fiber(SCF)into the matrix,and finally hoped to achieve the enhancement of the ILSS of CF/EP composites.The main content and results of the study are as follows:1.Oxidized SCF was prepared by oxidation treatment and used as a filler to prepare CF/EP composites.The study found that the oxidation degree and content of SCF have a significant effect on the ILSS of the composite.Under the appropriate oxidation degree,only 0.07 wt% of SCF can increase ILSS from 51.8 MPa to 58.8 MPa 13.5%.SCF mainly reinforces the composite by strengthening the epoxy group.The excessive oxidation degree and content of SCF will affect the ILSS of the composite.2.The modified Hummers method is used to prepare graphene oxide(GO),and GO is loaded onto the surface of SCF by a simple aqueous solution treatment to prepare surface functionalized GO@SCF and use it as a reinforcing filler to strengthen CF/EP composites.Through the study of the microstructure and reinforcement mechanism of the composites,it is found that GO and SCF have a similar π=π graphite structure,which allows GO to be firmly loaded on the surface of SCF.The interface adhesion between SCF and EP can be effectively improved by GO,which promoted the dissipation and conduction of stress,and finally achieving a great enhancement on the ILSS of composites.3.The surface of SCF is modified with diphenylmethane diisocyanate(MDI)by chemical coating to improve the surface characteristics of SCF.Studies have shown that MDI can effectively improve the interfacial adhesion between SCF and EP,and further enhance the enhancement effect of SCF on composites.Oxidative etching,GO treatment and MDI coating on the surface of SCF can produce rich oxygen-containing functional groups on the surface of SCF.Enhancement of composites.Finally,the ILSS of CF/EP composite was increased effectively by the introduction of functionalized SCF,which increased by 13.5%,14.7% and 28.1%,respectively.This indicates that adding functionalized SCF is an effective method for optimizing the ILSS of CF/EP composites. |
