Surface Modification Of Carbon Fiber Based On Tannic Acid Coating And Properties Of Composites

The excellent properties of carbon fiber,such as high specific strength,high specific stiffness,high modulus and corrosion resistance,make carbon fiber reinforced polymers widely used in many fields.Compared with metal materials,carbon fiber-reinforced polymers can significantly reduce the weight of structural devices and have been used more and more widely.Generally,the interfacial properties of carbon fiber reinforced composites largely depend on whether the mechanical stress can be effectively transferred from the matrix to the fiber surface.However,due to the technological characteristics of carbon fiber,the inactive functional group of carbon fiber presents an inert smooth surface,which makes the bonding performance between the fiber itself and the resin weak,resulting in poor interface performance of the composite material.The development and application of carbon fiber reinforced composite materials in many fields.Therefore,it is necessary to perform interfacial modification on carbon fibers to enhance their interfacial properties.Some traditional methods to modify the surface of carbon fiber will introduce corrosive or toxic reagents during the experiment and the surface of the fiber monofilament,which will cause certain damage to the environment and the fiber monofilament.Corrosion of the monofilament fiber reduces its strength.In order to avoid To damage the fiber monofilament and use corrosive or toxic solvents,we focus on tannin,a substance extracted from natural plants.Its physical coating will not cause damage to the strength of the fiber itself,and the cost is low and green Mild and environmentally friendly trendsThe main research contents of this paper include the following two aspects:(1)Improving interfacial properties of carbon fiber epoxy resin composites by building strong interfacial properties through multi-mode interactionIn order to conform to the concept of environmental protection,green and sustainable development,the interface treatment of carbon fiber reinforced composite material should uphold the research concept of small damage to fiber single filament,low treatment process cost and green environmental protection.This paper under the premise of no carbon fiber filament damage,with chelation,Michael addition,hydrogen bond and interaction,with polypropylene imide and Ni~+as bridge agent introduced tannic acid(TA)and graphene oxide(GO)build multimodal interface layer,not only in CF surface of phenolic hydroxyl and amine group,improve the amount of GO grafting,but also improve the CF polarity,wetting and surface energy,in addition,the treatment process is mild and short time.SEM,Fourier infrared spectroscopy,X-ray electron energy spectrum,dynamic contact angle,and Raman analysis methods are used to study the characterization of different carbon fiber surface interface layers,which showed that we can improve the surface roughness and increase the number of surface active functional groups.The interface shear strength and layer shear strength were tested to reflect the characterization of the composite interface properties.The analysis results showed that the IFSS and ILSS increased by 57.3%and 56.4%,respectively,compared with the untreated carbon fiber composites.(2)Preparation of graphene oxide tannic acid-reduced silver nanoparticle carbon fibers and their interfacial properties of epoxy resin compositesUsing the function of the o-phenol group in tannic acid to complex with nickel ions and the good adhesion of the complex layer,the surface of carbon fiber and graphene oxide was modified,and the tannins were determined by scanning electron microscopy and energy spectroscopy.Acid coating and reaction conditions of o-phenol groups and nickel ions:when the p H of the reaction solution is 8,the coating effect of tannin is the best;when the concentration of Ni~+is 0.55g/L,the complexation effect is the best;The surface of the thin layer of reduced graphene oxide fiber is still slightly smooth.In order to increase its roughness,Ag~+is reduced to silver nanoparticles by using tannic acid,and the interface performance of the composite material prepared by it is tested.Using scanning electron microscopy,Fourier transform infrared spectroscopy,X-ray electron spectroscopy and Raman results to characterize the fibers with different treatments,the interfacial shear strength and interlaminar shear strength are used to reflect the interface properties of the composites.The results show that the prepared silver nanoparticles can effectively increase the surface roughness,thereby improving the interfacial properties of the composites,and the ILSS and IFSS are increased by 63.6%and 58.3%,respectively.