Preparation And Properties Of Graphene Oxide/Bromobutyl Rubber Composites

Hydrogen energy,as a green energy and energy carrier,is coming out in the dual requirements of energy crisis and environmental protection.However,hydrogen and its isotopes are extremely permeable and potentially harmful to the environment.Therefore,it is important to research on gas barrier material.As an excellent two-dimensional flake filler,graphene has attracted more and more attention on gas barrier composite due to the good physical and chemical properties.However,graphene is very difficult to disperse in a polymer matrix as a functional filler caused by its amphiphobic property and easily reunited,which will influence the performance of the nanocomposite.Graphene oxide(GO)is a derivative of graphene,the well dispersibility and easy functionality make it can be applied widely on barrier nanocomposites.In this paper,brominated butyl rubber(BIIR)is used as the polymer matrix and GO is used as the sheet filler.The GO/BIIR nanocomposites with randomly homogeneous structure by electrostatic repulsion and GTA-GO/BIIR nanocomposites with segregated network structure by electrostatic attraction are prepared respectively.GO sheets are obtained from graphite powder according to Hummer method in this article.GO was modified by different quaternary ammonium salts.The fabricated laminal fillers were analyzed by scanning electron microscope(SEM),infrared spectrum(IR),X-ray photoelectron spectroscopy(XPS),raman spectra(Raman),X-ray diffraction(XRD),scanning probe microscope(AFM)and Zeta potential.The results show that the main layered structure of graphene is retained of GO and2,3-epoxy propyl three methacrylate ammonium modified graphene oxide(GTA-GO),the thickness of GO and GTA-GO within1-2 nm,and some oxygen-containing groups or modified groups are added on the sheet surface,respectively.GO sheet is negatively charged in water but GTA-GO is with the opposite charge.Then,GO and GTA-GO nona-sheets were dispersed in anionic brominated butyl rubber latex(BIIRL)matrix by latex mixed route.The uniform dispersive structure of GO/BIIR nanocomposites by electeostatic repulsion and the segregated network structure of GTA-GO/BIIR nanocomposites by electrostatic interaction between GTA-GO and BIIRL were obtained respectively.The micromorphology of the composites were characterized by SEM and TEM.The results show that GO sheets are evenly distributed in the BIIR matrix.However,the GTA-GO sheets are in favour of the formation of a segregated network structure in the matrix.The helium permeability is detected of homogeneous GO/BIIR and segregated GTA-GO/BIIR nanocomposites consisting different mass of fillers.The results show that the helium permeability coefficient for segregated network structure of the GTA-GO/BIIR nanocomposite is lower than that of the GO/BIIR nanocomposites which with randomly distributed structure.In addition,the composites show prominent decreases in helium permeability coefficient with the increasing of the nano-sheets till a minimum value.As the content of sheets continue increase,the helium permeability coefficient of the composite starts to rise and eventually tends to steady.The minimum helium permeability coefficient of the composite with random uniform dispersion is about 50%of pure BIIR,and the minimum helium permeability coefficient of composite with segregated network structure is around 63%of BIIR.It shows that the segregated structure of composite can allow much longer diffusion path for gas molecules in matrix,and the gas barrier property of polymer can be further improved without sacrificing the flexibility.At the same time,the T_g of the composite can be enhanced.