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Cruz-Estrada, Ricardo Herbé; Folkes, M. J.

doi:10.1023/a:1019970901254

Cited by 12 publications

(12 citation statements)

References 14 publications

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“…Depending on the amount of converted copper, sudden contact between the nanofibers is formed. As soon as the percolation threshold is reached, an abrupt increase of the conductivity is found, similar as in [17]. Furthermore, [25,26] found such an accumulative percolation behavior for conductometric NO x sensors when rare earth metals are transformed from carbonates into nitrates.…”

Section: Basic Resultssupporting

confidence: 68%

“…To obtain a more quantitative model, the increasing conductivity shall be described by a General Effective Media Theory (GEMT), which is an extension of the percolation theory [16]. It reproduces even better the entire range including the smaller conductivity increase when many percolation paths exist [17]. For the GEMT, the conductivity must be plotted over the volume content of the conductive phase, Φ .…”

Section: Basic Resultsmentioning

confidence: 99%

“…Both measurements are calculated for the same time interval and the conductivity was plotted against the NiS volume content, Φ , derived from the shrinking core model. With these parameters, the GEMT model according to Equation (1) can be applied [17]. Equation (1) has to be solved numerically.…”

Section: Basic Resultsmentioning

confidence: 99%

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Why does the Conductivity of a Nickel Catalyst Increase during Sulfidation? An Exemplary Study Using an In Operando Sensor Device

Fremerey

Jess

Moos

2015

Sensors

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In order to study the sulfidation of a catalyst fixed bed, an in operando single pellet sensor was designed. A catalyst pellet from the fixed bed was electrically contacted and its electrical response was correlated with the catalyst behavior. For the sulfidation tests, a nickel catalyst was used and was sulfidized with H2S. This catalyst had a very low conductivity in the reduced state. During sulfidation, the conductivity of the catalyst increased by decades. A reaction from nickel to nickel sulfide occurred. This conductivity increase by decades during sulfidation had not been expected since both nickel and nickel sulfides behave metallic. Only by assuming a percolation phenomenon that originates from a volume increase of the nickel contacts when reacting to nickel sulfides, this effect can be explained. This assumption was supported by sulfidation tests with differently nickel loaded catalysts and it was quantitatively estimated by a general effective media theory. The single pellet sensor device for in operando investigation of sulfidation can be considered as a valuable tool to get further insights into catalysts under reaction conditions.

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Section: Basic Resultssupporting

confidence: 68%

Section: Basic Resultsmentioning

confidence: 99%

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Why does the Conductivity of a Nickel Catalyst Increase during Sulfidation? An Exemplary Study Using an In Operando Sensor Device

Fremerey

Jess

Moos

2015

Sensors

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“…[6], GEMT has been successfully applied to description of the composition dependent specific electrical conductivity of PEDOT:PSS. The GEMT relates specific electrical conductivities of a conductive inclusion material (σ c ) and more resistive matrix material (σ r ) with the conductivity of a composite media (σ m ) by the following equation [2,10]: …”

Section: Methods and Approachmentioning

confidence: 99%

“…This enabled us to account for contributions from the PSS part within the Tauc-Lorentz optical model and from the PE-DOT part within the Drude-Lorentz model. Moreover, we relate the optical conductivity of the PEDOT part to the electrical specific conductivity of PEDOT:PSS in the frame of the generalized effective medium theory (GEMT) [2,10].…”

Section: Introductionmentioning

confidence: 99%

The Influence of PEDOT to PSS Ratio on the Optical Properties of PEDOT:PSS Thin Solid Films - Insight from Spectroscopic Ellipsometry

et al. 2016

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In this work, we study the influence of the PEDOT to PSS ratio on the optical properties of PEDOT:PSS thin solid films using spectroscopic ellipsometry and UV-vis spectrometry. In the data analysis, we develop a consisted composition dependent optical model of PEDOT:PSS. This enabled us to account for contributions from PSS part within the Tauc-Lorentz optical model and from PEDOT part within the Drude-Lorentz optical model. Moreover, we relate the optical properties of PEDOT:PSS thin solid films to their electrical specific conductivities in the frame of the generalized effective medium theory. Determined in this manner electrical conductivities of five commercially available water dispersions of PEDOT:PSS are compared with their nominal values.

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Evaluation of the rheological and electrical percolation of high‐density polyethylene/carbon black composites using mathematical models

SiIva

Cavalcanti

Alves

et al. 2021

Polymer Engineering & Sci

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In this work, conductive polymer composites (CPCs) of bio‐based polyethylene (BioPe) containing different concentrations of carbon black (CB) were developed. By using oscillatory rheology analysis, a Newtonian plateau was observed in BioPe, and all BioPe/CB composites had a behavior of a pseudo‐solid and that composites with volume fractions ranging from 0.24 to 0.56 presented higher viscosity, storage, and loss modulus. This suggests the formation of a percolated network and by using the power‐law models, it was observed that the electrical percolation threshold was higher than the rheological percolation threshold. The electrical conductivity was measured using the four‐point probe method and a sigmoid model was used to predict the CPCs' electrical conductivity percolation threshold. The results indicated that the four‐point probe method presented satisfactory results according to the calculated standard deviations and voltage–current characteristics for each round of measurements considering the same ranging as used in rheology analysis. The analytical model used showed a coefficient of determination (R2) higher than 95%, allowing the prediction of the electrical conductivity of the CPC and the percolation threshold as a function of the volumetric fraction of the CB.

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Untitled

Cited by 12 publications

References 14 publications

Why does the Conductivity of a Nickel Catalyst Increase during Sulfidation? An Exemplary Study Using an In Operando Sensor Device

Why does the Conductivity of a Nickel Catalyst Increase during Sulfidation? An Exemplary Study Using an In Operando Sensor Device

The Influence of PEDOT to PSS Ratio on the Optical Properties of PEDOT:PSS Thin Solid Films - Insight from Spectroscopic Ellipsometry

Evaluation of the rheological and electrical percolation of high‐density polyethylene/carbon black composites using mathematical models

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