Preparation Of Graphene Using Expansible Graphite And Its Application In Improving Electrical Properties Of PVC

At present, there are many ways to preparation of graphene/polymer nano-composites,but the industrial scale dispersion of graphene in a polymer matrix is particularly difficult forpolymer nanocomposites because of reaggregatting. At the same time, the existingpreparation method has difficult steps, high cost and low yield. Focusing on this question, wesuccess to prepare PVC/graphene compounding powders and PVC/CPE/graphenecompounding powders which are prepared to nanocomposites as master batch by Solid StateShear Milling (S~3M) using Pan-Mill equipment. S~3M provides a simple, useful and easy foroperation method and as a possible way for graphene scale production.The experimentalresults are as follows:1. Expanded graphite was prepared through the heating method and microwave method.Compared with the method of heating, the expanded graphite prepared by microwave methodhas large amount of nano-scale pores,whose pore diameter is smaller, and higher expandedvolume.2. The PVC/graphite compounding powder is prepared by S~3M, and the correspondinglynanocomposite material is made. The results of XRD、TEM、AFM、Raman show that,pan-mill equipment can exert fairly strong squeezing force in normal direction and shear forcein both radial and tangential directions on milled materials, functioning like pairs ofthree-di-mensional scissors, and has excellent friction, tensile, dislocation, extrusion chimeric,stretch slipping, shear exfoliating, grinding, mixing，dispersion on between expanded graphiteand PVC. Expanded graphite is exfoliated in compounding powder and realized the complexon a nanometer of yardstick of PVC and expanded graphite in composite.3.The PVC/CPE/graphene compounding powder is prepared by S~3M, and thecorrespondingly nanocomposite material is made. The results of XRD、TEM、AFM、Ramanshow that CPE, PVC and graphite will be pulverized, well mixed, and embeded into each other when they are co-milled with pan-mill. Because of the viscoelastic property of CPE,which conduce that it will easily adhere to the surface of graphite,Adding the10wt%of CPEis more favorable to exfoliate and disperse graphene. TEM shows that the thickness ofgraphene layers reach0.8nm.4. The electrical conductivity of PVC/graphite and PVC/CPE/graphene composites havebeen studied.The result shows that the electrically conductive properties of two kinds ofcomposites significantly improve at low content of graphene.4wt%，3wt%should be thepercolation threshold of two kinds of composites to form a continuous graphene network,andelectrical conductivity increase to10-7S/m (improving7orders). It should be noted thatPVC/CPE/graphene composites appear dual percolation threshold value phenomenon andelectrical conductivity increase to0.01S/m at the content of5wt%.5. The mechanical properties of PVC/graphite and PVC/CPE/graphene composites havebeen studied.Mechanical test results showed that both of the impact strength and the tensilestrength were increased at ppropriate content of graphite.