Linxiang He

Low percolation threshold of graphene/polymer composites prepared by solvothermal reduction of graphene oxide in the polymer solution

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.

Facile synthesis of silver-decorated reduced graphene oxide as a hybrid filler material for electrically conductive polymer composites

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.

Alternating current electrical conductivity of high-density polyethylene-carbon nanofiber composites

Abstract.High-density polyethylene (HDPE)-carbon nanofiber (CNF) composites with good dispersion of fillers in the polymer matrix were melt-compounded in a Haake mixer. The dependences of the alternating current conductivity of such nanocomposites on the filler content, temperature, and DC bias were investigated. The results showed that the electrical conducting behavior of HDPE-CNF nanocomposites can be well characterized by the direct current conductivity (

A graphene oxide–polyvinylidene fluoride mixture as a precursor for fabricating thermally reduced graphene oxide–polyvinylidene fluoride composites

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Nano silver-anchored reduced graphene oxide sheets for enhanced dielectric performance of polymer nanocomposites

, characteristic frequency (fc) and critical exponent (s . It was found that

Aqueous graphene oxide-dispersed carbon nanotubes as inks for the scalable production of all-carbon transparent conductive films

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Silver-decorated reduced graphene oxides as novel building blocks for transparent conductive films

of percolating HDPE-CNF nanocomposites increases with increasing filler concentration and follows the scaling law of percolation theory. Increasing temperature caused a reduction of

High dielectric permittivity and low loss tangent of polystyrene incorporated with hydrophobic core–shell copper nanowires

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Scalable Fabrication of High-Performance Transparent Conductors Using Graphene Oxide-Stabilized Single-Walled Carbon Nanotube Inks

, leading to the occurrence of positive-temperature-coefficient effect near the melting temperature of HDPE matrix. Application of DC bias led to an increase of

Zener Tunneling in Polymer Nanocomposites with Carbonaceous Fillers

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