The Study on Functional Graphene Oxide Nanofluids and Their Epoxy-matrix Composites

Author:Li Pei Pei

Supervisor:zheng ya ping


Degree Year:2018





Epoxy resin is one of the most widely used thermosetting resin matrixes around the world.However,it still has many defects,such as large brittleness,high friction coefficient and easy inflammability,which limit its further application in some special engineering fields.Graphene oxide has extremely high specific surface area and mechanical strength.However,as functional nanofiller,there are some partical problems,such as the poor dispersibility in the epoxy resin matrix and easy accumulation of its sheets,which is a disaster for the whole performance of graphene oxide/epoxy composite.In order to solve those problems,several kinds of functional graphene oxide nanofluids were designed and successfully prepared,which is a kind of inorganic-organic composite system,exhibits liquid-like behavior at room temperature and shows good dispersion and excellent compatibility in organic solvent and epoxy resins.Then their effects on the mechanical,thermal,tribological and flame retardant properties of epoxy-matrix composites were carefully investigated.Finally,the dispersibility and the interface bonding between those nanofluids and epoxy-matrix composites were also carefully investigated to further explore their corresponding strengthening,toughening,antiwear and flame-retardant mechanism,respectively.The main research contents and conclusions are shown below.(1)Single-layer graphene oxide nanoribbons(GONRs)were prepared by the Hummers’method.And then the parent amphiphilic polyether amine(M2070)was introduced onto GONRs through the surface chemical engineer to prepared the graphene oxide nanoribbons colloid(GONRs-M2070).Then GONRs-M2070 was used as filler to prepared the matrix-epoxy composites(GONRs-M2070/EP),which exhibit enhanced properties,For example,compared with the pure epoxy resin,the flexural strength of0.6 wt.%GONRs-M2070/EP composites increased from 108 MPa to 126 Mpa,while its impact strength rised from 11.3 kJ/m2 to 20.6 kJ/m2.Most importantly,the coefficient of friction of 0.6 wt.%GONRs-M2070/EP composites decreased from 0.6 to 0.2,while its wear rate was also redued to 7×10-5 g/min,respectively.(2)Two-dimensional materials such as graphene-oxide is not easy to be liquefied because of its large dimensional effect.Fortuantaly,it had been found that the introduction of low-dimensional inorganic nanoparticle onto the surface of graphene oxide could effectively lower its dimension effect within the unit mass,thereby greatly improving its flowing activation energy.Accoring to this key finding,the funationalized graphene oxide nanofluids was successfully prepared.Its novel flowing mechanism was well proposed and revealed according to the experimental results and theory calculations.Most importantly,this is an effective and general method for the low cost and efficient preparation of functional graphene oxide nanofluids,which offers great theoretical guidance and cost protection for the liquefaction of other two-dimensional materials and future practical industrial application.(3)A kind of flame retardant solvent-free nanofluids(GO@ZHS-M2070)was successfully prepared by using GO@ZHS hybrid nanoparticles as the core,which was synthesized by loading Zinc nicotinate(ZHS)onto the surface of GO.The weight content of GO@ZHS hybrid nanoparticles was reached up to 17.25 wt.%in the GO@ZHS-M2070,which showed excellent solubility in various solvents,leading to the better compatibility with epoxy resins.Then GO@ZHS-M2070 was used as filler to prepared the matrix-epoxy composites(GO@ZHS-M2070/EP),which exhibit enhanced flame-retardant properties.For example,compared with the pure epoxy resin,the heat release rate of 12.0 wt.%GO@ZHS-M2070/EP composite was reduced from 718 kW?m-2 to 561.2 kW?m-2.The total heat release decreased from 102 M?m-22 to88.4 M?m-2,while the total smoke emission and the flame growth rate decreased to4378 m2?m2 and 3.118 kW?m-1?s-1,respectively.(4)A kind of graphene oxide nanofluids(GO@Fe3O4-PEGS)with magnetism-responsive capability at room temperature was prepared through the ionic bonding.Its specific saturation magnetization is 2.57 emu/g,and shows excellent dispersions in solvents such as DI water,ethanol,etc.And then,its epoxy-matrix composites(GO@Fe3O4-PEGS)were prepared by adding it into the epoxy resin as functional fillers.Benefiting from its good dispersion in epoxy-matrix composites and compareing with the pure epoxy,the impact strength and the glass transition temperature of 1.0 wt.%GO@Fe3O4-PEGS/EP composites was improved by 125% and 31.09℃,respectively.(5)We have demonstrated that the strong electrostatic interaction between hollow carbon spheres and polymerized ionic liquids can be utilized for the fabrication of a novel kind of stable and homogeneous porous carbon liquid(HCS-liquid)with typical liquid-like behaviour at room temperature.The porous structure of HCS-liquid was carefully investigated by the positron annihilation lifetime and the gas adsorption-desorption isotherms,demonstrateing a promising application in the gas storage.We believe that such a facile synthesis strategy could open up new and general scientific and technological opportunities for fabricating other types of porous liquids,such as those(e.g.,carbon nitride,boron nitride,metal organic frameworks,covalent organic frameworks etc.)also having the electrostatic interaction with polymerized ionic liquids,evidently advancing the development and understanding of porous liquids.