Studies On The Preparation And Conductivity Of Graphene And Its Phenolic Resin Composites

As the most ideal2-D nanomaterials，Graphene has many special properties, such as inthe fields of magnetic, light, electric, and so on; And graphene-polymer composites exhibitvarious properties in electrical conductivity, thermal conductivity, gas barrier and otherproperties. This paper deals with the electric conductivity of graphene and its composites withphenolic resin. The effect of in-situ reduction, iodine doping and nano Ag deposition werestudied and composite with conductivity of66.67S/m was prepared.Firstly, graphite oxide (GO) were prepared by Hummers’ method and improvedHummers’ method respectively. IR and Raman spectrums show that the two GO have similarstructures, as in carboxyl groups, epoxy groups, hydroxyl group and so on, while retaining thebenzene ring structure of graphite. XRD results show that the interlayer spacing of graphiteoxide prepared by improved Hummers’ method is greater than that of the ordinary Hummers’methods, UV-visible test results show that carbonyl-containing groups such as carboxy ofGO prepared by the improved are more than that of the ordinary Hummers’ methods,whichindicate that the degree of oxidation of the improved GO is higher than the GO prepared byordinary Hummers method.The conductivity difference of reduced graphene mats of GOprepared by both methods reduced by sodium borohydride is around0.25%, which is verysmall, indicate that the degree of oxidation does not affect the reduced conductivity ofreduced graphene oxide (RGO).Secondly，GO was reduced with hydrazine hydrate、sodium borohydride、hydroiodic, andRaman, XRD, SEM characterization show that, RGO reduced by hydroiodic acid with highestconductivity has a more compact structure and less defects. Through the comparingexperiment and the EDS, we kown that iodine has a doping effect on graphene，in addition tophysical adsorption，there may exist one interaction between the iodine and graphene toimprove the conductivity. Then the composites of RGO/PF were prepared by simple blendingand in-situ reduction method. The conductivity of composite from simple blending of RGOand PF resin is0.02S/m, which is lower than66.67S/m of RGO/PF made by situ method. Theprocessing temperature of the composites affects the conductivity too. The conductivity ofcomposite prepared by addition of GO into PF at60℃is higher than that at90℃after beingreduced in-situ, which are66.67S/m and37.95S/m respectively. The conductivitypercolation threshold of RGO/PF composites is around GO/phenol of1:10，at the ratio of1:5,composite of conductivity of66.67S/m is prepard. Finally, silver deposited graphene were prepared by in situ reduction methods. Sphericalsilver nanoparticles can be seen deposited on graphene plates in scanning electron microscopy.Conductivity results of the Ag-RGO mat show that when the ratio of silver carbonate andgraphite oxide was1:8，the composite gets the highest conductivity which is1.04×104S/m,further increasing the contents of Ag, the conductivity changes little. Followed the compostesof Ag-RGO/PF were prepared through in-situ reduction methods. Under the condition of thatsilver carbonate and phenol in a ratio of1:4, the percolation threshold of the composite is atGO/phenol of1:20. The conductivity of the compostes shows that silver and graphene havesynergistic effect which can reduce the percolation threshold of the composite near50%.