Construction Of Carbon Fiber Multi-scale Reinforcement And Study On The Properties Of Epoxy Resin Composites

Carbon fibers composites are well known for their desirable properties,for example,high strength、light weight、corrosion resistance,and as such have been used in chemical industry、rail transit and other fields.As with any composites,the interphase between the constituent materials is of vital importance to facilitate efficient stress transfer from the relatively weak resin matrix material to the strong CF reinforcement material.However,the chemical inertness、smooth and non-polar surface of carbon fiber（CF）surface resulted in a weak interfacial bonding between CF and resin,which were difficult to eliminate the interfacial stress concentration.Therefore,the interfacial adhesion between fiber and resin greatly affected the mechanical properties of composites.This paper started from the construction of multi-scale reinforcement on the fiber surface,and aimed at improving the interfacial adhesion of composites,the different reinforcement structures were fabricated by combining MXene with nano particles and polymers to modified the fiber.（1）The positive charged SiO₂-NH₂ and negative charged MXene were deposited on the fiber surface via a simple、high-effective and green self-assembly method on that PEI was used as the“bridge”based on electrostatic interaction.The effects of modified-CF on surface morphologies、microstructure and chemical composition of interfacial properties of CF composites were investigated systematically.The introduction of MXene/SiO₂ three-dimensional structure greatly increased the number of surface functional groups、fiber roughness and surface energy.Compared to Unsized-CF composites,the interfacial shear strength、interlaminar shear strength and flexural strength of CF/MXene/SiO₂ composites were increased by 73.2%、61.2%and 39.2%,respectively.Moreover,the fracture morphologies and dynamic mechanical properties of composites also indicate an excellent interfacial adhesion of CF composites.（2）MXene/PEA multi-scale reinforcement was prepared by self-assembly method with simple process and mild experimental conditions.The"regid-flexible"structure interphase was constructed between fiber and resin to improve the interface strength of composites.FTIR and SEM were utilized to tested the surface morphology and chemical microstructure of the CF,which demonstrated that MXene/PEA were modified on the CF surface successfully constructed a compact"regid-flexible"interface layer.The test results showed that the interlaminar shear strength and flexural strength of the CF/MXene/PEA composites were increased by 66.9%and 36.5%,compared to unsized CF,respectively.Finally,the mechanism of the"regid-flexible"enhancement structure was analyzed.