Double percolation effect on the electrical conductivity of conductive particles filled polymer blends

Sumita, Masao; Sakata, Kazuya; Hayakawa, Yu; Asai, Shigeo; Miyasaka, Keizo; Tanemura, Masaharu

doi:10.1007/bf00652179

Cited by 328 publications

(231 citation statements)

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“…The low value of percolation threshold for the PE/POM-Fe composite is caused by the presence of the branched conductive POM-Fe network. In this case, conductivity is controlled by the conditions of double percolation [26], i.e., first the continuity of the conductive-filled polymer phase is necessary and second the conductive filler inside the polymer component should create the conductive network. In the structure model, it is assumed that the value of the filler content in the POM-Fe phase is kept constant (namely 32 vol%) during dilution of the masterbatch by pure PE.…”

Section: Electrical Conductivity Of the Compositesmentioning

confidence: 99%

PTC effect and structure of polymer composites based on polyethylene/polyoxymethylene blend filled with dispersed iron

Mamunya

Muzychenko

Lebedev

et al. 2006

Polymer Engineering & Sci

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The temperature dependence of resistivity, structure, and thermal expansion of composites based on polyethylene/polyoxymethylene (PE/POM) blends filled with dispersed iron (Fe) have been studied. The dependence of conductivity on filler content shows percolation behavior, with the values of the percolation thresholds equal to 21 vol% for PE‐Fe, 24 vol% for POM‐Fe, and 9 vol% for the filled blend PE/POM‐Fe, with two‐step character of the conductivity curve. The evolution of structure of the composite PE/POM‐Fe demonstrates transition from polymer matrix POM‐Fe, with inclusions of PE through cocontinuous phases of both POM‐Fe and PE, to PE matrix, with inclusions of POM‐Fe. Such a structure occurs due to localization of the filler only in one of the polymer phases, namely in POM. Measurements of the coefficient of thermal expansion α show the presence of two values of α: higher value (equal to α of PE) and lower value (equal to α of POM‐Fe), the transition between them corresponding to the structure with cocontinuous phases. The PE/POM‐Fe composites demonstrate double‐positive temperature coefficient (PTC) effect, with the presence of two transitions and a plateau between them. In such a system, two contributions to the PTC effect coexist: the first contribution originates from the thermal expansion of the nonconductive PE phase with higher value of the coefficient α, which leads to the break of the continuity of the conductive POM‐Fe phase; the second contribution originates from the break of the conductive structure of the filler inside the POM‐Fe phase because of the morphological changes in the vicinity of the melting temperature of POM. The double PTC effect is explained in terms of these two processes (thermal expansion and melting). POLYM. ENG. SCI., 47:34–42, 2007. © 2006 Society of Plastics Engineers

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Section: Electrical Conductivity Of the Compositesmentioning

confidence: 99%

PTC effect and structure of polymer composites based on polyethylene/polyoxymethylene blend filled with dispersed iron

Mamunya

Muzychenko

Lebedev

et al. 2006

Polymer Engineering & Sci

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“…Both the conductive pathway of CB particles in the phase and the continuity of the phase in the composites are basic requirements for maintaining a conductive network through the composite. [13][14][15] When a given CB-filled polymer composite is injected into a molding chamber, the difference in conductivity levels may be observed by the segregation of CB particles during flow-induced orientation into axial channels. 8 It is known that injection-molded materials always possess a characteristic skin-core microstructure that exhibits a stronger orientation at the sub-skin zone and a relatively uniform microstructure at the core zone.…”

Section: Introductionmentioning

confidence: 99%

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confidence: 99%

Effect of the processing of injection-molded, carbon black-filled polymer composites on resistivity

Liao

Jiang

et al. 2011

Polym J

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To improve the application of carbon black (CB)-filled polymer composites, we investigated the relationship between the processing parameters, microstructure and electrical properties of injection moldings made from the material. Standard tensile specimens were fabricated under different injection pressures and packing pressures. Up to five layers were removed from the surfaces of the molded specimens to observe the microstructure at different positions within the moldings. Microstructures were observed with a scanning electron microscope, and electrical properties were measured at room temperature with a standard two-terminal direct current (DC) resistor. The results showed that CB particles form the best conductive path at high packing pressures combined with high injection pressures. If the packing pressure is low, the resistivity in the skin zone when loaded by high injection pressures is less than when loaded by low injection pressures, but resistivity increases in the sub-skin zone. We found that the sub-skin zone is a high-resistivity area that can be expanded under the action of higher injection pressures along with lower packing pressures. In contrast to an injection-molded single polymer, an injection-molded, CB-filled polymer composite develops a highly oriented microstructure in the core zone rather than in the skin or sub-skin zones because of the migration of CB particles. Polymer Journal (2011) 43, 930-936; doi:10.1038/pj.2011.95; published online 21 September 2011Keywords: CB particle/polymer composite; injection; resistivity INTRODUCTIONPolymers are often endowed with some outstanding properties when mixed with different fillers. Nanotechnology-stimulated research attempts to create multifunctional composites by integrating nanoparticles into polymer matrices. Nanoscale carbon black (CB) particles, a type of filler, have practical applications in manufacturing nanoparticle reinforced polymer composites because of their low cost and good moldability. In past decades, many researchers have focused on the electrical properties of CB-filled polymer composites. 1-3 For a given composite, its electrical conductivity is determined not only by the CB structure and concentration but also by the specific polymer matrix used and the morphology generated during processing. [4][5][6][7] There is extensive research on the conductive characteristics of polymer-containing CB particles with different morphologies [8][9][10] and the effect of the dispersion state of CB particles in the matrices on the electrical conductivity. 11,12 When CB particles fill a polymer matrix, it is beneficial to conductivity when the CB particles are located in the amorphous phase or in the interface between two phases. Both the conductive pathway of CB particles in the phase and the continuity of the phase in the composites are basic requirements for maintaining a conductive network through the composite. [13][14][15] When a given CB-filled polymer composite is injected into a molding chamber, the difference in conductivity levels m...

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“…With lower filler content as the aim, CPCs based on polymer blends have been observed to achieve percolation at lower filler loadings than those based on a single polymer [12,[25][26][27]. This can be attributed to a mechanism called double-percolation [28][29][30][31][32][33][34][35] i.e., the filler is selectively localized in one of the blend components forming a conductive network. However, in most of these cases the two polymers have weak interfacial adhesion, resulting in poor mechanical properties of the blend.…”

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confidence: 99%

Conductivity of microfibrillar polymer-polymer composites with CNT-loaded microfibrils or compatibilizer: A comparative study

Panamoottil¹,

Pötschke²,

Lin³

et al. 2013

Express Polym. Lett.

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Conductive polymer composites have wide ranging applications, but when they are produced by conventional melt blending, high conductive filler loadings are normally required, hindering their processability and reducing mechanical properties. In this study, two types of polymer-polymer composites were studied: i) microfibrillar composites (MFC) of polypropylene (PP) and 5 wt% carbon nanotube (CNT) loaded poly(butylene terephthalate) (PBT) as reinforcement, and ii) maleic anhydride-grafted polypropylene (PP-g-MA) compatibilizer, loaded with 5 wt% CNTs introduced into an MFC of PP and poly(ethylene terephthalate) (PET) in concentrations of 5 and 10 wt%. For the compatibilized composite type, PP and PET were melt-blended, cold-drawn and pelletized, followed by dry-mixing with PP-g-MA/CNT, re-extrusion at 200°C, and cold-drawing. The drawn blends produced were compression moulded to produce sheets with MFC structure. Using scanning electron microscopy, CNTs coated with PP-g-MA could be observed at the interface between PP matrix and PET microfibrils in the compatibilized blends. The volume resistivities tested by four-point test method were: 2.87•108 and 9.93•107 Ω•cm for the 66.5/28.5/5 and 63/27/10 (by wt%) PP/PET/(PP-g-MA/CNT) blends, corresponding to total CNT loadings (in the composites) of 0.07 vol% (0.24 wt%) and 0.14 vol% (0.46 wt%), respectively. For the non-compatibilized MFC types based on PP/(PBT/CNT) with higher and lower melt flow grades of PP, the resistivities of 70/(95/5) blends were 1.9•106 and 1.5•107 Ω•cm, respectively, corresponding to a total filler loading (in the composite) of 0.44 vol% (1.5 wt%) in both MFCs

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Double percolation effect on the electrical conductivity of conductive particles filled polymer blends

Cited by 328 publications

References 3 publications

PTC effect and structure of polymer composites based on polyethylene/polyoxymethylene blend filled with dispersed iron

PTC effect and structure of polymer composites based on polyethylene/polyoxymethylene blend filled with dispersed iron

Effect of the processing of injection-molded, carbon black-filled polymer composites on resistivity

Conductivity of microfibrillar polymer-polymer composites with CNT-loaded microfibrils or compatibilizer: A comparative study

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