Electromagnetic Interference Shielding Study Of Nanocomposites And Film Fabricated From Graphene Sponge

Graphene has shown enormous potential application in the field of electromagnetic interference(EMI)shielding,due to its excellent electrical property.In the practice application,graphene nanosheets usually can not exhibit its unique electrical property.Many efforts have been put to assemble graphene nanosheets into three dimensional graphene foam.Because the graphene foam more easier manipulate than the graphene nanosheets when put graphene excellent property into practice.In this dissertation,we utilized graphene foam to prepare macroscopic graphene materials.Moreover,we focused on the research of electromagnetic interference shielding property of these macroscopic graphene materials.The main results summarized as follows:Graphene oxide foam was fabricated by directly freeze-drying.To prepared graphene foam,as-prepared graphene oxide foam was chemically reduced by hydrazine.Graphene foam/PDMS composites have been fabricated by incorporated the PDMS with graphene foam.Before incorporated with PDMS,the graphene foam was annealed to improve electrical property.The average EMI shielding value of the composites can reach 54.26 d B,with the graphene content of 3.07wt%,at the thickness of 2mm and in the range of 8~12GHz,and the electrical conductivity can reach 103S/m.After analyze the EMI shielding mechanism of t he graphene foam/PDMS composites,the absorption EMI shielding value was much higher than reflection EMI shielding value,confirming that that the graphene foam /PDMS nanocomposites is the absorption-dominant shielding materials.Graphene oxide foam was fabricated by directly freeze-drying.To prepared graphene foam,as-prepared graphene oxide foam was chemically reduced by hydrazine.With the graphene foam served as raw material,flexible graphene film was fabricated by In-situ hot pressing sintering method.We studied the the EMI shielding property,electrical property,heat conduction property and the x-ray transmissivity of the flexible graphene film.In the range of 1.7GHz~40GHz,at the thickness of 50?m,the EMI shielding value above 50 dB.Besides,the electrical conductivity and thermal conductivity can reach 1.14×105S/m S/m and 1073.83 W/(m·K)respectively.With the energy of the x-ray increase,the transmissivity increase.