Quantitative methods for correlating dispersion and electrical conductivity in conductor–polymer nanostrand composites

Hansen, Nathan; Adams, Daniel O.; Fullwood, David T.

doi:10.1016/j.compositesa.2012.05.008

Cited by 12 publications

(14 citation statements)

References 24 publications

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“…In some cases, tunneling could be the dominant mechanism. This conduction occur when the distances between the conductive particles are close enough, roughly less than 10 nm [40]. In addition, polymer type has a significant effect on the amount of particles required for percolation.…”

Section: Surface Resistivity Measurementsmentioning

confidence: 99%

“…The conductive particles form a continuous network inside the polymer matrix at percolation threshold. Increasing the number of particles generally has little effect on the electrical conductivity [40]. Nevertheless, a considerable decrease in the electrical resistivity of composite can be obtained by increasing the conductive particles above the percolation threshold.…”

Section: Surface Resistivity Measurementsmentioning

confidence: 99%

See 1 more Smart Citation

Conductive nylon fabric through in situ synthesis of nano-silver: Preparation and characterization

Montazer

Komeily‐Nia

2015

Materials Science and Engineering: C

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Section: Surface Resistivity Measurementsmentioning

confidence: 99%

Section: Surface Resistivity Measurementsmentioning

confidence: 99%

Conductive nylon fabric through in situ synthesis of nano-silver: Preparation and characterization

Montazer

Komeily‐Nia

2015

Materials Science and Engineering: C

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“…However, despite the existence of numerous publications in regard to CNT composites and their properties, reports aiming to explain the mechanisms that dominate the electrical conductivity at extremely low loading CNT values (% wt CNT below 0.1%) are scarce. It is generally agreed that the high conductivity observed even at low loadings of the conductive phase is related to (i) percolation, that is, to the formation of continuous strings of conductive material spanning in a non-conductive matrix material [5,6,7,8], (ii) a combined percolation-tunneling effect that allows electrons to hop from one conductive particle to another in close proximity [5,7,9], and/or (iii) the existence of excluded volumes in the matrix where no conductive material exists [10]. In standard percolation theory [11], based on conduction paths forming along strings of randomly placed conductive spheres in a non-conductive matrix, conductivity is only enhanced at relatively high loadings.…”

Section: Introductionmentioning

confidence: 99%

Electrically Conductive CNT Composites at Loadings below Theoretical Percolation Values

et al. 2019

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It is well established that dramatic increases in conductivity occur upon the addition of conductive filler materials to highly resistive polymeric matrices in experimental settings. However, the mechanisms responsible for the observed behavior at low filler loadings, below theoretical percolation limits, of even high aspect ratio fillers such as carbon nanotubes (CNT) are not completely understood. In this study, conductive composites were fabricated using CNT bundles dispersed in epoxy resins at diverse loadings, using different dispersion and curing protocols. Based on electron microscopy observation of the CNTs strands distribution in the polymeric matrices and the corresponding electrical conductivities of those specimens, we concluded that no single electron transfer model can accurately explain the conductive behavior for all the loading values. We propose the existence of two different conductive mechanisms; one that exists close to the percolation limit, from ‘low loadings’ to higher CNT contents (CNT % wt > 0.1) and a second for ‘extremely low loadings’, near the percolation threshold (CNT % wt < 0.1). The high conductivity observed for composites at low CNT loading values can be explained by the existence of a percolative CNT network that coexists with micron size regions of non-conductive material. In contrast, samples with extremely low CNT loading values, which present no connectivity or close proximity between CNT bundles, show an electrical conductivity characterized by a current/voltage dependence. Data suggests that at these loadings, conduction may occur via a material breakdown mechanism, similar to dielectric breakdown in a capacitor. The lessons learned from the data gathered in here could guide future experimental research aimed to control the conductivity of CNT composites.

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“…Likewise, the ability to model the phenomenon relies upon uniformity of the subsequent network. Dispersion trials for these materials were studied in and form the basis for the processing parameters and resultant consistent dispersion found in the materials studied in this article.…”

Section: Methodsmentioning

confidence: 99%

“…Using a simplified Hertz distribution for particle distribution, the probability of electron tunneling in the percolated composite, and the nodes‐link‐blobs (NLB) approach common in percolation theory , the TPM percolation model takes the form of:

σ \sim σ_{f} {true(\frac{φ}{1 - φ_{c}} - \frac{φ_{c}}{1 - φ_{c}} true)}^{t_{u n} + true(\frac{a}{d} - 1 true)}, φ > φ_{c}

where

t_{u n}

is the universal critical exponent,

a

is the separation distance between conductors, and

d

is the characteristic tunneling distance of the polymer system. Typically it is assumed that the separation distance between conductors is dependent on dispersion characteristics , the thickness of the polymer layer that is adsorbed on the conductor surface , and the volume fraction (and packing arrangement) of conductor.…”

Section: Models Used In This Studymentioning

confidence: 99%

Evaluation and development of electrical conductivity models for nickel nanostrand polymer composites

2014

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The electrical conductivity of composites and polymeric‐based systems is frequently improved by the addition of conductive additives to form a conductor–insulator binary system. This study considers nickel nanostrands as a conductive element in polymer systems. Materials characteristics are considered in order to form a basis for understanding and predicting the electrical percolation behaviors of nanostrand composites, specifically seeking models that can distinguish between different polymer systems. Empirical percolation data for nickel nanostrands in four different polymeric systems is presented and used to evaluate candidate electrical conductivity models. Classical percolation approaches are found to not show good fit, but more advanced models are able to provide good correlation to tested results. Specifically, Tunneling Percolation (TPM) models and the Two Exponent Phenomenological Percolation Equation (TEPPE) model based on the Generalized Effective Media (GEM) theory show good fit. A combined TEPPE‐TPM approach is developed that applies tunneling percolation to the GEM theory. This combined model includes tunneling considerations in equations that accurately represent behaviors in all regions of percolation behavior. POLYM. ENG. SCI., 55:549–557, 2015. © 2014 Society of Plastics Engineers

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Quantitative methods for correlating dispersion and electrical conductivity in conductor–polymer nanostrand composites

Cited by 12 publications

References 24 publications

Conductive nylon fabric through in situ synthesis of nano-silver: Preparation and characterization

Conductive nylon fabric through in situ synthesis of nano-silver: Preparation and characterization

Electrically Conductive CNT Composites at Loadings below Theoretical Percolation Values

Evaluation and development of electrical conductivity models for nickel nanostrand polymer composites

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