RETRACTED ARTICLE: A Study on the percolation threshold of polyethylene matrix composites filled carbon powder

Shin, Soon-Gi

doi:10.3365/eml.2010.06.065

Cited by 13 publications

(7 citation statements)

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“…[3] In this about carbon black-filled polyethylene matrix composites, P t differs depending on the species of the filled carbon black. [13] However, the changes in conductivity and relative dielectric constant caused by Vc are explained by the exponent law. [3,4] To explain the results of Fig.…”

Section: Resultsmentioning

confidence: 98%

RETRACTED ARTICLE: Effect of temperature on the dielectric properties of carbon black-filled polyethylene matrix composites below the percolation threshold

Shin

Kwon

2011

Electron. Mater. Lett.

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The temperature dependence of dielectric properties of carbon black-filled polyethylene matrix composites below the percolation threshold was studied based on the effect medium approximation theory (EMA theory). Although the literature on calculation based on the EMA theory by changing the parameters is vast, an overall discussion taking into account the EMA theory is required to explain the dielectric properties of the composites and their temperature dependence. Changes of the dielectric properties of carbon black-filled PMC and their temperature dependence below the percolation threshold for the volume fraction of carbon black have been discussed based on the EMA theory. The composites satisfy the universal law of conductivity above the percolation threshold, whereas it gives the critical exponent of s = 1 for dielectric constant below percolation threshold. The rates of the decrement of both % changes of dielectric constant and dielectric loss factor for temperature become larger with an increase in the volume fraction below percolation threshold. By incorporating the effect of thermal expansion into the EMA theory, the temperature dependence of dielectric properties is successfully explained.

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Section: Resultsmentioning

confidence: 98%

RETRACTED ARTICLE: Effect of temperature on the dielectric properties of carbon black-filled polyethylene matrix composites below the percolation threshold

Shin

Kwon

2011

Electron. Mater. Lett.

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“…The transition-like change in the conductivity of these composites has attracted many researchers to propose models for the phenomenon. [3][4][5]7,[9][10][11] For example, Reboul [3] and Flory [12] applied Flory's theory of gelation taking place during the polymerization of poly-functional monomers to predict the sharp increase in electrical conductivity at particular carbon black contents, and Shin [7] used an averaged number of contacts of conduction powders to discuss the possibility of network formation. These approaches are all very interesting.…”

Section: Introductionmentioning

confidence: 99%

“…[1][2][3][4][5][6][7] This break point in the relationship between the content of conducting material and the conductivity of PMC implies a sudden change in the dispersing state of the conducting powders, i.e. the coagulation of the powders to form networks which facilitate electrical conduction through the PMC.…”

Section: Introductionmentioning

confidence: 99%

RETRACTED ARTICLE: Effect of carbon content on the electrical conductivity of carbon black-filled pmc with various matrices

Shin

2011

Electron. Mater. Lett.

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The electrical conductivity of carbon black-filled polymer matrix composites (PMC) with various matrices was studied as a function of carbon content to find the break point of the relationship between carbon content and conductivity. Conductivity jumps by as much as ten orders of magnitude at the break point. The critical carbon content corresponding to the break point varies depending on the matrix species and tends to increase with increase in the surface tension of the matrix. To explain the dependency of the critical carbon content on the matrix species, a simple equation was derived under some assumptions, the most important of which is that when the interfacial excess energy introduced by particles of carbon black into the matrix reaches a universal value ( ), the particles of carbon black begin to coagulate so as to avoid any further increase of the energy and to form networks which facilitate electrical conduction. The equation well explains the dependency through surface tension, as long as the difference of the surface tensions between the particles of carbon black and the matrix is not very small.

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“…[4][5][6] 여기서 괄호 속의 V는 첨가된 도전성 입자의 체적분율이다. 이러한 PMC에 있어서 도전성 입자의 체적분율 증가 에 따른 저항율(ρ) 변화 형태는 이전의 연구 [7][8][9] 13,14) 이와 같 이 Fig. 1에 Fig.…”

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“…본블랙 cluster는 전극 사이를 단락하는 소위 침투현상을 발생시키지 않는다. 따라서 Pt 이하의 V CB 를 갖는 PMC 에 흐르는 전류는 확대부분에 나타낸 것과 같이 카본블 랙 cluster사이에 존재하는 얇은 층에 의하여 율속된다 8). 여기서 얇은 층을 저항(R G )과 커페시턴스(C G )의 병열회 로로, 카본블랙 cluster의 저항을 R CB 라고 하면 확대부분 은…”

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Percolation Threshold and Critical Exponent of Dielectric Breakdown Strength of Polyethylene Matrix Composites added Carbon Black

Shin¹

2011

Korean. J. Mater. Res.

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Abstracts Composites of insulating polyethylene and carbon black are widely used in switching elements, conductive paint, and other applications due to the large gap of resistance value. This research addresses the critical exponent of dielectric breakdown strength of polymer matrix composites (PMC) made with carbon black and polyethylene below the percolation threshold (Pt) for the first time. Here, Pt means the volume fraction of carbon black of which the resistance of the PMC is transferred from its sharp decrease to gradual decrease in accordance with the increase of carbon-black-filled content. First, the Pt is determined based on the critical exponents of resistivity and relative permittivity. Although huge cohesive bodies of carbon black are formed in case of being less than the Pt, a percolation path connecting the conducting phases is not formed. The dielectric breakdown strength (Dbs) of the PMC below Pt is measured by using an impulse voltage in the range from 10 kV to 40 kV to avoid the effect of joule heating. Although the observed Dbs data seems to be well fitted to a straight line with a slope of 0.9 on a double logarithm of (Pt-V CB ) and Dbs, the least squares method gives a slope of 0.97 for the PMC. It has been found that finite carbon-black clusters play an important role in dielectric breakdown.

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RETRACTED ARTICLE: A Study on the percolation threshold of polyethylene matrix composites filled carbon powder

Cited by 13 publications

References 13 publications

RETRACTED ARTICLE: Effect of temperature on the dielectric properties of carbon black-filled polyethylene matrix composites below the percolation threshold

RETRACTED ARTICLE: Effect of temperature on the dielectric properties of carbon black-filled polyethylene matrix composites below the percolation threshold

RETRACTED ARTICLE: Effect of carbon content on the electrical conductivity of carbon black-filled pmc with various matrices

Percolation Threshold and Critical Exponent of Dielectric Breakdown Strength of Polyethylene Matrix Composites added Carbon Black

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