Graphene/polyvinylidene fluoride (PVDF) composites were prepared using in-situ solvothermal reduction of graphene oxide in the PVDF solution. The electrical conductivity of the composites was greatly improved by doping with graphene sheets. The percolation threshold of such composite was determined to be 0.31 vol.%, being much smaller than that of the composites prepared via blending reduced graphene sheets with polymer matrix. This is attributed to the large aspect ratio of the SRG sheets and their uniform dispersion in the polymer matrix. The dielectric constant of PVDF showed a marked increase from 7 to about 105 with only 0.5 vol.% loading of SRG content. Like the other conductor-insulator systems, the AC conductivity of the system also obeyed the universal dynamic response. In addition, the SRG/PVDF composite shows a much stronger nonlinear conduction behavior than carbon nanotube/nanofiber based polymer composite, owing to intense Zener tunneling between the SRG sheets. The strong electrical nonlinearity provides further support for a homogeneous dispersion of SRG sheets in the polymer matrix.
Aqueous graphene oxide-dispersed multi-walled carbon nanotubes were used as inks for the simple, fast, and industrially scalable fabrication of hybrid transparent conductive films by rod coating.
Facile synthesis of silver-decorated reduced graphene oxide as a hybrid filler material for electrically conductive polymer composites Linxiang He and Sie Chin Tjong * Nano silver-decorated reduced graphene oxide (Ag-RGO) sheets were synthesized by simply dissolving graphite oxide and silver nitrate in N,N-dimethylformamide and keeping the suspension at 90 C for 12 h. These highly stable hybrid sheets were then incorporated into a polar polymer, polyvinylidene fluoride (PVDF), to prepare the Ag-RGO/PVDF nanocomposites via solution mixing. The Ag-RGO hybrid sheets were dispersed homogeneously in the polymer matrix, resulting in a low percolation threshold of 0.17 vol%. Above the percolation threshold, electrical conductivity of the Ag-RGO/PVDF composite system was about one order of magnitude higher than that of thermally reduced graphene/PVDF composites. This was attributed to the high intrinsic electrical conductivity of silver. The improved electrical properties render this novel composite system an attractive material for antistatic, electrostatic dissipative and electromagnetic/radio frequency interference shielding applications.Furthermore, the resistivity of the composite system increased with increasing temperature, generating a pronounced positive temperature coefficient effect of resistivity. Fig. 8 Effect of temperature on resistivity of Ag-RGO/PVDF composites with 0.17 vol% and 0.24 vol% filler loadings.Fig. 9 (a) Stress-strain curves of Ag-RGO/PVDF nanocomposite sheets with different Ag-RGO contents. (b) Tensile strength (left) and tensile strain (right) versus Ag-RGO loading content.This journal is
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