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Petr Saha - One of the best experts on this subject based on the ideXlab platform.
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the electrical conductivity of ethylene butyl acrylate carbon black composites the effect of foaming on the percolation threshold
Synthetic Metals, 2014Co-Authors: Michaela Peliskova, P Piyamanocha, Jan Prokes, Martin Varga, Petr SahaAbstract:Abstract The main objective of this work is to study the influence of foaming on the percolation threshold of carbon black-Filled Polymer composites. The electrical conductivity, structure and tensile strength properties of solid and foamed ethylene butyl-acrylate/carbon black composites were investigated. The percolation threshold of solid composites was 10.9 vol.%, whereas for composite foams it decreased to 5.8 vol.% of carbon black. It was found that the charge transport mechanism of composites was not affected by the foaming. The reported decrease of the percolation threshold is attributed rather to the volume exclusion effect and carbon black redistribution. As a result, a conducting composite with a reduced specific volume and filler content can be prepared.
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correlation between the microstructure and the electromagnetic properties of carbonyl iron Filled Polymer composites
Composites Part A-applied Science and Manufacturing, 2007Co-Authors: M A Abshinova, A V Lopatin, Natalia E Kazantseva, Jarmila Vilcakova, Petr SahaAbstract:Abstract Electromagnetic properties of Polymer composites based on different types of carbonyl iron (CI) are investigated in the frequency range from 1 MHz to 10 GHz. A significant difference in the high frequency permeability of composites Filled with primary and processed CI powders is revealed, although the chemical composition and particle size distribution of these powders show small difference. Composites based on processed CI exhibit two regions of magnetic dispersion and higher absolute values of permeability and permittivity in the radio-frequency (RF) band. The observed differences are attributed to the microstructure of particles; namely, these differences depend on whether or not the particles are characterized by “onionlike” multilayered morphology. Electron microscopy and X-ray diffraction analyses show structural changes in the processed CI, which are responsible for the variety of electromagnetic properties of the composites.
Masao Sumita - One of the best experts on this subject based on the ideXlab platform.
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morphology and electrical properties of short carbon fiber Filled Polymer blends high density polyethylene poly methyl methacrylate
Journal of Applied Polymer Science, 1998Co-Authors: Cheng Zhang, Shigeo Asai, Hiroshi Yui, Masao SumitaAbstract:Morphology and electrical properties of short carbon fiber-Filled high-density polyethylene (HDPE)/poly(methyl methacrylate)(PMMA) Polymer blends have been studied. The percolation threshold of HDPE50/PMMA50 blends Filled with vapor-grown carbon fiber (VGCF), 1.25 phr VGCF content, is much lower than those of the individual Polymers. The SEM micrographs verified that the enhancement of conductivity could be attributed to the selective location of VGCF in the HDPE phase. A double percolation is the basic requirement for the conductivity of the composites, i.e., the percolation of carbon fibers in the HDPE phase and the continuity of this phase in the blends, which hereby are defined as the first percolation and the second percolation, respectively. The SEM micrographs also showed that the short carbon fibers could affect the morphology of the blends. With the increase of VGCF content, the HDPE domains are elongated from spherical into strip shape, finally develop to a continuous structure. As a result, the second percolation threshold of the blends Filled with 2.5 phr VGCF, 20 wt % HDPE, is lower than that of the blends Filled with 1.5 phr VGCF, 30 wt % HDPE. The influence of molding temperature and time on the second percolation threshold has also been investigated. For the composites molded at a lower temperature, the second percolation threshold is shifted to a higher VGCF content, but there is little influence of molding time on the second percolation threshold. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 1813–1819, 1998
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selective location and double percolation of short carbon fiber Filled Polymer blends high density polyethylene isotactic polypropylene
Materials Letters, 1998Co-Authors: Cheng Zhang, Shigeo Asai, Xiaosu Yi, Masao SumitaAbstract:The percolation threshold of high-density polyethylene (HDPE)/isotactic polypropylene (iPP) blends Filled with vapor-grown carbon fiber (VGCF), 1.25 parts per hundred parts resin (phr) VGCF content, is much lower than those of the individual Polymers. SEM micrographs verified that the improvement of electrical conductivity can be attributed to the selective location of VGCF in the HDPE phase. A double percolation is the basic requirement for the conductivity of the composites, i.e., the percolation of carbon fibers in the HDPE phase, and the continuity of this phase in the Polymer blends. Short carbon fibers may affect the morphology of the Polymer blends.
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Double percolation effect on the electrical conductivity of conductive particles Filled Polymer blends
Colloid and Polymer Science, 1992Co-Authors: Masao Sumita, Kazuya Sakata, Shigeo Asai, Keizo Miyasaka, Y. Hayakawa, M. TanemuraAbstract:Electrical conductivity of carbon black (CB) Filled Polymer blends which are incompatible with each other was studied as a function of the Polymer's blend ratio. Transmission electron microscope (TEM) analysis shows that CB distributes unevenly in each component of a Polymer blend. TEM photographs of phase structure of solvent extracted HDPE/PMMA blend and solvent extraction experiments of PMMA/PP blend detect the blend ratio at which the structural continuity of filler rich phase is formed. The electrical conductivity of Polymer blends is found to be determined by two factors. One is the concentration of CB in the filler rich phase and the other is the structural continuity of this phase. This double percolation affects the conductivity of conductive particle Filled Polymer blends.
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dispersion of fillers and the electrical conductivity of Polymer blends Filled with carbon black
Polymer Bulletin, 1991Co-Authors: Masao Sumita, Kazuya Sakata, Shigeo Asai, Keizo Miyasaka, Hideaki NakagawaAbstract:Dispersion state of carbon black(CB) was studied in Polymer blends which are incompatible with each other. It was found that CB distributes unevenly in each component of the Polymer blend. There are two types of distribution. (1) One is almost predominantly distributed in one phase of the blend matrix, and in this phase fillers are relatively homogeneously distributed in the same manner as a single Polymer composite. (2) In the second, the filler distribution concentrates at interface of two Polymers. As long as the viscosities of two Polymers are comparable, interfacial energy is the main factor determining uneven distribution of fillers in Polymer blend matrices. This heterogeneous dispersion of conductive fillers has much effect on the electrical conductivity of CB Filled Polymer blends. The electrical conductivity of CB Filled Polymer blends is determined by two factors. One is concentration of CB in the filler rich phase and the other is phase continuity of this phase. These double percolations affect conductivity of conductive particle Filled Polymer blends.
Cheng Zhang - One of the best experts on this subject based on the ideXlab platform.
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morphology and electrical properties of short carbon fiber Filled Polymer blends high density polyethylene poly methyl methacrylate
Journal of Applied Polymer Science, 1998Co-Authors: Cheng Zhang, Shigeo Asai, Hiroshi Yui, Masao SumitaAbstract:Morphology and electrical properties of short carbon fiber-Filled high-density polyethylene (HDPE)/poly(methyl methacrylate)(PMMA) Polymer blends have been studied. The percolation threshold of HDPE50/PMMA50 blends Filled with vapor-grown carbon fiber (VGCF), 1.25 phr VGCF content, is much lower than those of the individual Polymers. The SEM micrographs verified that the enhancement of conductivity could be attributed to the selective location of VGCF in the HDPE phase. A double percolation is the basic requirement for the conductivity of the composites, i.e., the percolation of carbon fibers in the HDPE phase and the continuity of this phase in the blends, which hereby are defined as the first percolation and the second percolation, respectively. The SEM micrographs also showed that the short carbon fibers could affect the morphology of the blends. With the increase of VGCF content, the HDPE domains are elongated from spherical into strip shape, finally develop to a continuous structure. As a result, the second percolation threshold of the blends Filled with 2.5 phr VGCF, 20 wt % HDPE, is lower than that of the blends Filled with 1.5 phr VGCF, 30 wt % HDPE. The influence of molding temperature and time on the second percolation threshold has also been investigated. For the composites molded at a lower temperature, the second percolation threshold is shifted to a higher VGCF content, but there is little influence of molding time on the second percolation threshold. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 1813–1819, 1998
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selective location and double percolation of short carbon fiber Filled Polymer blends high density polyethylene isotactic polypropylene
Materials Letters, 1998Co-Authors: Cheng Zhang, Shigeo Asai, Xiaosu Yi, Masao SumitaAbstract:The percolation threshold of high-density polyethylene (HDPE)/isotactic polypropylene (iPP) blends Filled with vapor-grown carbon fiber (VGCF), 1.25 parts per hundred parts resin (phr) VGCF content, is much lower than those of the individual Polymers. SEM micrographs verified that the improvement of electrical conductivity can be attributed to the selective location of VGCF in the HDPE phase. A double percolation is the basic requirement for the conductivity of the composites, i.e., the percolation of carbon fibers in the HDPE phase, and the continuity of this phase in the Polymer blends. Short carbon fibers may affect the morphology of the Polymer blends.
Shigeo Asai - One of the best experts on this subject based on the ideXlab platform.
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morphology and electrical properties of short carbon fiber Filled Polymer blends high density polyethylene poly methyl methacrylate
Journal of Applied Polymer Science, 1998Co-Authors: Cheng Zhang, Shigeo Asai, Hiroshi Yui, Masao SumitaAbstract:Morphology and electrical properties of short carbon fiber-Filled high-density polyethylene (HDPE)/poly(methyl methacrylate)(PMMA) Polymer blends have been studied. The percolation threshold of HDPE50/PMMA50 blends Filled with vapor-grown carbon fiber (VGCF), 1.25 phr VGCF content, is much lower than those of the individual Polymers. The SEM micrographs verified that the enhancement of conductivity could be attributed to the selective location of VGCF in the HDPE phase. A double percolation is the basic requirement for the conductivity of the composites, i.e., the percolation of carbon fibers in the HDPE phase and the continuity of this phase in the blends, which hereby are defined as the first percolation and the second percolation, respectively. The SEM micrographs also showed that the short carbon fibers could affect the morphology of the blends. With the increase of VGCF content, the HDPE domains are elongated from spherical into strip shape, finally develop to a continuous structure. As a result, the second percolation threshold of the blends Filled with 2.5 phr VGCF, 20 wt % HDPE, is lower than that of the blends Filled with 1.5 phr VGCF, 30 wt % HDPE. The influence of molding temperature and time on the second percolation threshold has also been investigated. For the composites molded at a lower temperature, the second percolation threshold is shifted to a higher VGCF content, but there is little influence of molding time on the second percolation threshold. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 1813–1819, 1998
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selective location and double percolation of short carbon fiber Filled Polymer blends high density polyethylene isotactic polypropylene
Materials Letters, 1998Co-Authors: Cheng Zhang, Shigeo Asai, Xiaosu Yi, Masao SumitaAbstract:The percolation threshold of high-density polyethylene (HDPE)/isotactic polypropylene (iPP) blends Filled with vapor-grown carbon fiber (VGCF), 1.25 parts per hundred parts resin (phr) VGCF content, is much lower than those of the individual Polymers. SEM micrographs verified that the improvement of electrical conductivity can be attributed to the selective location of VGCF in the HDPE phase. A double percolation is the basic requirement for the conductivity of the composites, i.e., the percolation of carbon fibers in the HDPE phase, and the continuity of this phase in the Polymer blends. Short carbon fibers may affect the morphology of the Polymer blends.
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Double percolation effect on the electrical conductivity of conductive particles Filled Polymer blends
Colloid and Polymer Science, 1992Co-Authors: Masao Sumita, Kazuya Sakata, Shigeo Asai, Keizo Miyasaka, Y. Hayakawa, M. TanemuraAbstract:Electrical conductivity of carbon black (CB) Filled Polymer blends which are incompatible with each other was studied as a function of the Polymer's blend ratio. Transmission electron microscope (TEM) analysis shows that CB distributes unevenly in each component of a Polymer blend. TEM photographs of phase structure of solvent extracted HDPE/PMMA blend and solvent extraction experiments of PMMA/PP blend detect the blend ratio at which the structural continuity of filler rich phase is formed. The electrical conductivity of Polymer blends is found to be determined by two factors. One is the concentration of CB in the filler rich phase and the other is the structural continuity of this phase. This double percolation affects the conductivity of conductive particle Filled Polymer blends.
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dispersion of fillers and the electrical conductivity of Polymer blends Filled with carbon black
Polymer Bulletin, 1991Co-Authors: Masao Sumita, Kazuya Sakata, Shigeo Asai, Keizo Miyasaka, Hideaki NakagawaAbstract:Dispersion state of carbon black(CB) was studied in Polymer blends which are incompatible with each other. It was found that CB distributes unevenly in each component of the Polymer blend. There are two types of distribution. (1) One is almost predominantly distributed in one phase of the blend matrix, and in this phase fillers are relatively homogeneously distributed in the same manner as a single Polymer composite. (2) In the second, the filler distribution concentrates at interface of two Polymers. As long as the viscosities of two Polymers are comparable, interfacial energy is the main factor determining uneven distribution of fillers in Polymer blend matrices. This heterogeneous dispersion of conductive fillers has much effect on the electrical conductivity of CB Filled Polymer blends. The electrical conductivity of CB Filled Polymer blends is determined by two factors. One is concentration of CB in the filler rich phase and the other is phase continuity of this phase. These double percolations affect conductivity of conductive particle Filled Polymer blends.
Xiufeng Song - One of the best experts on this subject based on the ideXlab platform.
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thermal conductivity of ceramic particle Filled Polymer composites and theoretical predictions
Journal of Materials Science, 2007Co-Authors: Yanchun Han, Yuan Shen, Xiufeng SongAbstract:Models and theories for predicting the thermal conductivity of Polymer composites were discussed. Effective Medium Theory (EMT), Agari model and Nielsen model respectively are introduced and are applied as predictions for the thermal conductivity of ceramic particle Filled Polymer composites. Thermal conductivity of experimentally prepared Si3N4/epoxy composite and some data cited from the literature are discussed using the above theories. Feasibility of the three methods as a prediction in the whole volume fraction region of the filler from 0 to 1 was evaluated for a comparison. As a conclusion: both EMT and Nielsen model can give a well prediction for the thermal conductivity at a low volume fraction of the filler; Agari model give a better prediction in the whole range, but with larger error percentage.