Study On The Grafting Of Dual Macromolecules On Graphene Oxide Surface And Its Interfacial Effect In Different Composite Material

Due to their excellent performance,composites are widely used in aerospace,automotive,construction,medical,sports,and many other fields.However,the increasing strength requirements of materials indicate the continuously modification and reinforcement.Graphite oxide(GO)is a new carbon material with high specific strength and stiffness,which is widely used in the reinforcement of composite materials.The mechanical properties and thermal stability of the composites with GO will be greatly improved.However,GO will agglomerate due to its own structure,and the stacking of layers will not make full use of its performance.To solve this problem,GO needs to be further modified.According to previous studies,there are many defects while enhancing by small molecules,nanoparticles and single macromolecules.Therefore,the use of double macromolecules to modify GO has become a research hotspot.In this work,a variety of macromolecules were used to modify GO,and applied to block and film composite materials.The interface effects were also analyzed in depth.The specific research contents of this paper are as follows:1.Graphene oxide functionalized with chitosan(CS)and polyethylene glycol diglycidyl ether(EGDE)was prepared by two simple reactions.The rigid-flexible transition interface of GO-CS-EGDE-EP was constructed,and its influence on the dispersion,interface and mechanical properties of the composite was studied.FT-IR,Raman,XPS and TEM tests showed the successful covalent grafting of the two macromolecules onto GO and they could balance the modulus of GO and the resin,effectively improve the dispersion in the epoxy resin,and form stronger interfacial combination.The mechanical tests showed that the tensile strength,flexural strength and impact strength of GO-CS-EGDE(only 0.1wt%)/epoxy resin composite were increased by 36.2%,42.9% and 54.3% respectively,and the elongation at break was increased by 102.7% compared with pure epoxy resin.2.As a reinforcing material,the GO-CS-EGDE prepared in the previous work was applied to the sizing agent for carbon fibers.By changing the concentration of GO-CSEGDE in the sizing agent,a multiscale interface with different modulus changes was constructed,and the effect of different modulus from CF to resin on the interfacial properties of the composite was studied.The experimental results showed that properly increasing the modulus of the composite interface could smooth the modulus from fiber to resin,and the reinforced resin modulus could narrow the modulus gap,synergistically balancing the modulus between CF and resin.The results showed that when the concentration of GO-CS-EDGE in the resin was 0.1 wt% and the content of GO-CS-EDGE in the sizing agent was 1 wt%,the interlaminar shear strength(ILSS)of CF composite increased by 51% compared with the original CF composite.The mechanism of improving the interfacial properties of composites by double modulus control was analyzed.3.Inspired by the natural pearl layer,the "brick-mortar" reinforced structural composite film with GO as "brick" and CS and carbon-oxygen cross-linking chain as "mortar" was prepared.It was expected to use the toughness of CS to improve the toughness of the composite film,and use the cross-linking network formed by the carbon-oxygen crosslinking chain to connect the GO layer,leading to high strength.Among them,1,4-butanediol diglycidyl ether(BDE),1,6-hexanediol diglycidyl ether(HDE)and polyethylene glycol diglycidyl ether with different molecular weights were selected for the carbon-oxygen cross-linking to further explore the effect of different length of the chain on the mechanical properties of the film.The results showed that the length of carbon-oxygen chain was directly proportional to the mechanical properties of the composite,and the tensile strength of GO-CS-EGDE was up to 31.54 MPa,which was 39.2% higher than that of GO-CS and 5.6 times higher than that of the original GO.4.A simple and low-cost method is used to introduce chitosan and polypyrrole(PPy)into GO in turn to prepare composite film with both high mechanical and electrochemical properties which was reduced by hydroiodic acid.Its structure was characterized by FT-IR,Raman,XPS and other tests,which verified the existence of covalent bonds,π-πinteractions and hydrogen bonds,and effectively improved the poor interface bonding between GO sheets.The mechanical test showed that the tensile strength of the composite film was increased by 182% and the microhardness was increased by 30 times compared with r GO.Electrochemical tests showed that the addition of CS and PPy could significantly improve the electrochemical activity of r GO,and the capacitance value of the composite film could reach 170 F/g.In addition,the mechanism of strengthening and compatibilization of the composite film by double macromolecules was also discussed.