The Preparation Of Conductive Graphene Based Fiber Containing Silver

Graphene is a two-dimensional(2D)crystalline sheet with a monolayer of carbon atoms densely packed in a sp2-bonded honeycomb lattice with excellent electrical conductivity,thermal conductivity,thermal stability and mechanical properties.Therefore,graphene-based fibers have broad application prospect in the fields of sensors and capacitors because of its outstanding electrical and mechanical properties.However,graphene fibers still show limited mechanical strength and electrical conductivity,which greatly limits the development and application of graphene fibers.In this work,two aspects of graphene fiber were mainly studied.One is to study the synergistic effect of graphene and AgNWs by coating graphene on the surface of polyvinyl alcohol/silver nanowires(PVA-AgNWs)fiber,improving the electrical conductivity of the fiber.The second is to study the effect of silver ion doping on the compactness,mechanical properties and electrical conductivity of graphene fibers.The main research details and conclusions are as follows:(1)The prepared silver nanowire(AgNWs)and PVA were spun to obtain PVA-AgNWs fiber.The prepared GO and PVA were mixed into dispersion and coated onto the fiber,and then GO on the fiber surface was reduced with sodium bisulfite.The effects of GO content and coating times on the morphology and conductivity of the fibers were studied.The results showed that the amount and connectivity of GO sheets on the surface of the fiber increased with the increase of GO content in GO/PVA dispersion.When the weight ratio of GO/PVA in coating solution is 1:0.5,the coating effect of GO is the best.When coated for 3 times,the conductivity of the fiber can reach 2.05×10-3 S/m.(2)The GO water dispersion containing ammonia water was prepared,and then the dispersion was extruded into the acetone coagulating bath containing Ag+by wet spinning.The Ag+was diffused into the fiber while the fiber was solidified,and the silver-containing GO fiber was obtained.Finally,the reduced GO(rGO)fiber was obtained by soaking in aqueous solution containing vitamin C.The effect of Ag content and acetone concentration on the coagluting time,fiber morphology and silver ion content in the fiber were investigated.The replacement laws of Ag+and NH4+ in the spinning process were studied.The results showed that after Ag+diffused into the interior of the fiber,in addition to the combination of NH4+ and GO,free Ag+was also present.When the content of AgNO3 in coagulation bath reaches 1.5 wt%,the silver content of GO fiber did not change significantly.With the introduction of Ag+,the gap inside the fiber decreased obviously and the whole fiber became dense.(3)The effects of silver content on the morphology,mechanical properties and electrical properties of graphene fibers were studied by means of electron microscope,conductivity apparatus and fiber strength tester.The results showed that,compared with the pure GO fiber,the compactness of the fiber after the silver doping was significantly improved,resulting in a significant increase in the mechanical properties.When the silver content was up to 30 wt%,the tensile strength was increased from 89 MPa of pure GO fiber to 179 MPa and the electrical conductivity of the rGO fiber can be increased from 1.61×103 S/m of the pure fiber to 2.14×104 S/m.