Theoretical and computational studies of carbon nanotube composites and suspensions: Electrical and thermal conductivity

Foygel, M.; Morris, Robin D.; Anez, D.; French, Samuel B.; Sobolev, V. L.

doi:10.1103/physrevb.71.104201

Cited by 569 publications

(411 citation statements)

References 21 publications

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“…The early Coniglio theory of percolation of long rigid rods, [ 49 ] predicts that the density of particles scales with the inverse square of the rod aspect ratio. Monte Carlo simulations on randomly oriented uniform rigid nanorods, performed by Foygel, [ 50 ] have demonstrated that the critical volume fraction on the verge of the percolation threshold, ϕ c , is inversely proportional to AR, being as low as 10 − 3 for AR values of about 10 3 ; polydispersity on nanorod length has the counter-intuitive effect of decreasing ϕ c , whereas nanorod fl exibility increases ϕ c . [ 51 ] …”

Section: Key Aspects In Polymer Nanocompositesmentioning

confidence: 99%

“…σ 0 is a pre-exponential factor that depends on the conductivity of the particles, the contacts between them and the topology of the percolation cluster; [ 50 ] ϕ c is the fractional volume at the percolation threshold, and t is a universal critical exponent. According Celzard, [ 67 ] t ≈ 2.0, but experimentally, values range between 2 and 6, depending on the polymeric media.…”

Section: Electrical Propertiesmentioning

confidence: 99%

“…According Celzard, [ 67 ] t ≈ 2.0, but experimentally, values range between 2 and 6, depending on the polymeric media. For nanotubes, Foygel, [ 50 ] has found that the exponent t is not universal since it depends on AR. In fact, t = 2 is the limiting value for spherical 3D objects and decreases to 1.2-1.6 for oblong objects with AR 10 2 -10 3 .…”

Section: Electrical Propertiesmentioning

confidence: 99%

“…At the percolation threshold, conduction paths are created all over the volume of the composite and a sudden increase in conduction occurs. Nevertheless, sheet-sheet junctions are highly resistive (for nanotubes, the contact resistance is in the order of 1 M Ω ), [ 50 ] and it has been proposed that the conduction mechanism is probably of the tunnel type. [ 68 ] Some authors, [ 50 ] prevent the use of experimental data at low loadings to estimate the conductivity of the individual particles.…”

Section: Electrical Propertiesmentioning

confidence: 99%

“…Nevertheless, sheet-sheet junctions are highly resistive (for nanotubes, the contact resistance is in the order of 1 M Ω ), [ 50 ] and it has been proposed that the conduction mechanism is probably of the tunnel type. [ 68 ] Some authors, [ 50 ] prevent the use of experimental data at low loadings to estimate the conductivity of the individual particles. But others, [ 73 ] used a modifi ed form of equation 1 ( Current research on graphene surface engineering able to prepare highly conductive materials focuses on the following challenges: a) generate the lowest number of defects within the graphene sheets, b) improve the graphene compatibility with polymer matrices (good dispersion and low percolation threshold), c) impart resistance to the chemical or electrochemical reduction, and c) reduce the sheet-sheet junction resistivity in order to allow electronic transport.…”

Section: Electrical Propertiesmentioning

confidence: 99%

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Interphases in Graphene Polymer‐based Nanocomposites: Achievements and Challenges

et al. 2011

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Graphene constitutes a two dimensional sp2 hybridized carbon material with outstanding electrical and mechanical properties. To date, novel methods for producing large quantities of graphene and its derivatives (doped or functionalized graphenes, nanoribbons and nanoplatelets) are emerging, and research dedicated to the fabrication of polymer nanocomposites using graphenes has started. In this Research News, we summarize the synthesis and properties of graphene and its derivatives, and provide an overview of the latest research dedicated to the fabrication of polymer composites for different applications, including mechanical, electrical, optical and thermal. Some of the recently fabricated composites exhibit outstanding properties, however, it is vital to understand the chemistry and physics of the interphases established between the polymer and the graphene surfaces. The challenges in the fabrication of super robust and highly conducting composites using graphenes are also discussed. It is believed that graphene‐based polymer composites will result in commercial products if their interphases and reactivity are carefully controlled.

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Section: Key Aspects In Polymer Nanocompositesmentioning

confidence: 99%

Section: Electrical Propertiesmentioning

confidence: 99%

Section: Electrical Propertiesmentioning

confidence: 99%

Section: Electrical Propertiesmentioning

confidence: 99%

Section: Electrical Propertiesmentioning

confidence: 99%

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Interphases in Graphene Polymer‐based Nanocomposites: Achievements and Challenges

et al. 2011

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Thermal conductivity in porous media: Percolation‐based effective‐medium approximation

Ghanbarian

Daigle

2016

Water Resources Research

115

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Knowledge of porosity and saturation-dependent thermal conductivities is necessary to investigate heat and water transfer in natural porous media such as rocks and soils. Thermal conductivity in a porous medium is affected by the complicated relationship between the topology and geometry of the pore space and the solid matrix. However, as water content increases from completely dry to fully saturated, the effect of the liquid phase on thermal conductivity may increase substantially. Although various methods have been proposed to model the porosity and saturation dependence of thermal conductivity, most are empirical or quasiphysical. In this study, we present a theoretical upscaling framework from percolation theory and the effective-medium approximation, which is called percolation-based effective-medium approximation (P-EMA). The proposed model predicts the thermal conductivity in porous media from endmember properties (e.g., air, solid matrix, and saturating fluid thermal conductivities), a scaling exponent, and a percolation threshold. In order to evaluate our porosity and saturation-dependent models, we compare our theory with 193 porositydependent thermal conductivity measurements and 25 saturation-dependent thermal conductivity data sets and find excellent match. We also find values for the scaling exponent different than the universal value of 2, in insulator-conductor systems, and also different from 0.76, the exponent in conductor-superconductor mixtures, in three dimensions. These results indicate that the thermal conductivity under fully and partially saturated conditions conforms to nonuniversal behavior. This means the value of the scaling exponent changes from medium to medium and depends not only on structural and geometrical properties of the medium but also characteristics (e.g., wetting or nonwetting) of the saturating fluid.

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Electrical Properties

Grady

2011

Carbon Nanotube–Polymer Composites

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Theoretical and computational studies of carbon nanotube composites and suspensions: Electrical and thermal conductivity

Cited by 569 publications

References 21 publications

Interphases in Graphene Polymer‐based Nanocomposites: Achievements and Challenges

Interphases in Graphene Polymer‐based Nanocomposites: Achievements and Challenges

Thermal conductivity in porous media: Percolation‐based effective‐medium approximation

Electrical Properties

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