Preparation Of Carbon Fiber/GO Reinforcement And Its Effects On Interfacial Properties Of Epoxy Composites

In the past few decades,carbon fiber reinforced polymer composites have tremendous application potential in crucial fields such as improving fuel efficiency and reducing emissions due to their excellent properties such as lightweight,high specific stiffness and strength.However,due to the small surface energy and specific surface area of the carbon fiber surface,the interfacial bonding of the composite materials is poor,which is not conducive to the comprehensive performance of the composite materials.Therefore,how to effectively modify the surface of carbon fiber to improve the interface performance of composite materials has been a research focus in the field of composite materials.In this background,this paper starts from the perspective of the design of the interface structure of composite materials,uses the characteristics of graphene oxide(GO),such as large specific surface area,rich oxygen-containing functional groups on the surface and easy to modify,and exploits chemical grafting method and dipping method to construct GO and polyether amine(D400)alternating layered structure on the surface of carbon fiber to improve the interface performance of composites;On this basis,the effects of different interactions on the properties of composite interface were studied.The specific research contents and important conclusions are as follows:(1)Carbon fiber/D400/GO multi-scale reinforcement was prepared by chemical grafting on the surface of carbon fiber with different D400/GO alternate layered structures.The effects of different graft layers of D400/GO on the surface morphology and structure,surface wettability,surface chemical activity of carbon fiber reinforcements and interfacial microstructure and interfacial shear strength(IFSS)of epoxy matrix composites were compared and studied.The results show that after grafting the layered structure of one layer,two and four layers of D400/GO on the surface of carbon fiber respectively,the density and uniformity of GO on the surface of carbon fiber increase with the increase of D400/GO layer,and the D400/GO layer distributed on the surface of fiber increases the degree of defects on the surface of fiber and the wettability with resin matrix,which enabled the IFSS of carbon fiber composites compared to untreated carbon fiber composites increased by 7.7%,18.8%and 60%,respectively.Among the interface enhancement effects of composite materials,it can be found that the four layers D400/GO possess the most significant effect.The reason was that when the D400/GO was four layers on the fiber surface,the abundant polar functional groups attached to the D400/GO layer on the fiber surface contribute to the optimal wetting of the fiber and resin matrix.(2)Polyether amine and graphene oxide were dipping on the surface of carbon fiber layer by layer to prepare carbon fiber/D400/GO multi-scale reinforcement by dipping method.The effects of different D400/GO modified layers on the surface properties of carbon fiber reinforcement and the interface properties of fiber-reinforced epoxy composite materials were studied.The results show that the interfacial properties of the corresponding composite materials were improved by 38.3%and 8.3%respectively when the two and four layers D400/GO structures were constructed on the fiber surface.The reason was that the GO on the surface of the fiber increased the mechanical engagement between the fiber and the resin matrix,and the increase of the defect degree on the fiber surface also provided more active sites for the improvement of the interface performance.More importantly,the composite material exhibited excellent mechanical properties after the carbon fiber surface was dipping with two layers of D400/GO.The reason was that when there were two layers of D400/GO dipping on the fiber surface,GO was not only evenly spread on the surface of the carbon fiber in a prostrate manner,but also a small amount of GO was erect on the surface of the fiber,which was more conducive to improving the stress transfer and wettability between the fiber and the resin matrix.(3)By comparing the effects of different interactions on the interface performance of composite materials,taking two layers of polyether amine/GO as an example,it was found that the IFSS values of the ionic-ionic bond(CF-dG2)and covalent-covalent bond(CF-PGCl2)were 96.5 MPa and 97.25 MPa,which were 16.4%and 17.3%higher than that of ionic bond and covalent bond(CF-(D400-GO)2),respectively.Ionic-ionic bond and covalent-covalent bond have the best effect on the interface enhancement of composite materials,the reason for the increase in IFSS was that the surface of carbon fibers bonded in the form of ionic-ionic bond and covalent-covalent bond has a higher surface energy(32.70 mJ/m2 and 32.94 mJ/m2,respectively),and the increase of surface energy further improves the interfacial adhesion between fiber and resin matrix.