Electrical resistivity of polymeric matrix loaded with nickel and cobalt powders

Maaroufi, Abderrazak; Haboubi, Khadija; Amarti, Ahmed El; Carmona, F.

doi:10.1023/b:jmsc.0000007752.08385.e0

Cited by 60 publications

(61 citation statements)

References 20 publications

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“…The nature of the PTC effect is not definitively clear, but it is generally accepted that the sharp increase of resistance with increase of temperature is caused by the thermal expansion of the thermoplastic matrix near the melting temperature. The display of the PTC effect depends on many factors: the nature of filler, the size, the shape and the hardness of filler particles [9,14,15], the content of the filler in a composite [16,17], the chemical nature of the polymer matrix and its viscosity [15], polymer-filler interactions [18,19], etc. In Refs.…”

Section: Introductionmentioning

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: Introductionmentioning

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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“…There are a variety of particulate substances, such as metallic, ceramic, carbon, etc., that can be used as dopants in materials [1,2]. In particular, polymeric materials are of interest for doping with a variety of dopants and form composites with unique properties.…”

Section: Introductionmentioning

confidence: 99%

The Effects of Additive TiO<sub>2</sub> Nanoparticles on the Energy Gap of DCM Doped with PS Thin Films

Odah

2016

ILCPA

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Abstract. In this work thin films containing laser dye (DCM) doped with polystyrene (PS) were prepared using casting method. Titania (TiO 2 ) nanoparticles also were synthesized using sol gel technique. Characteristics of the tetania were done using XRD patter, and the characteristic peak of anatase is sharper and clear to observe, in particular at 25.40° degree. While scanning electron microscopy (SEM) was used to achieve the morphology of TiO 2 samples, and to determine the sizes of nanoparticles. Different titania nanoparticle densities (0.882×10 20 , 1.765×10 20 , 2.648×10 20 , 3.530×10 20 and 4.413×10 20 cm -3 ) were co-doping with dye doped polymer and study the effect of this addition on the optical properties and electronic transition energy gaps in cases of both direct and indirect transitions.

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“…It is known that conductive dopants can convert an insulating polymer to electrically conductive polymer mixtures [23][24][25][26]. The insulatingto-conducting transition [24] of the polymer composition occurs when the dopant concentration exceeds a critical value known as the percolation threshold (PT) [24,25,[27][28][29].…”

Section: Introductionmentioning

confidence: 99%

“…the nature of polymer host, the dopant nature and its size, shape, geometry, and surface energy, the composite porosity, dopant dispersion and alignment, potential chemical interactions, processing method, etc. Generally, it is desirable to have lower PT values, and these can be achieved more easily with elongated dopants [28][29][30] if compared with spherical ones [24,25,27]. The aspect ratio of dopants also affects the PT; the higher the dopant aspect ratio, the lower the PT [26,29].…”

Section: Introductionmentioning

confidence: 99%

“…There are different percolation models which interpret the behavior of the electrical conductivity of different mixtures: statistical, geometrical, thermodynamic and structure-oriented [24,25,28,35]. As a classical statistical model explanation of the conductivity of a composite (mixture),  m , is due to the existence of "infinite clusters" of connected conducting particles, i.e.…”

Section: Introductionmentioning

confidence: 99%

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The role of conductive dopants in polymer cholesteric liquid crystals

Petkoska¹

2014

Maced. J. Chem. Chem. Eng.

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A variety of conductive dopants were used to modify the electric properties of polymer cholesteric liquid crystals. Different types of carbon blacks and carbon nanotubes, as well as metallic particles were used as conductive dopants in this work. All affected the conductivity of the polymer matrix, but at different dopant concentrations. The percolation threshold behavior of used dopants in the polymer host showed pronounced dependence on the dopants" particle size and particle shape anisotropy. For instance, the higher the aspect ratio of carbon-based dopant particles (aspect ratio = length : diametar), the lower the percolation threshold. Additionally, increase in metallic dopants' diameter yielded higher percolation threshold of polymer composition.Keywords: polymer cholesteric liquid crystals; conductive dopants; carbon black; carbon nanotubes; percolation threshold УЛОГА НА СПРОВОДЛИВИ ДОПАНТИ ВО ПОЛИМЕРНИ ХОЛИСТЕРИЧНИ ТЕЧНИ КРИСТАЛИНајразлични спроводливи допанти се користени за модификација на својствата на полимерни холистерични течни кристали. Во овој труд како спроводливи допанти се користени различни видови јаглерод и јаглеродни наноцевки, како и метални честички. Сите тие имаат влијание врз полимерната матрица, но при различни концентрации на допантот. Прагот на перколација на користените допанти во полимерната матрица покажа зависност од големината на честиците на допантот и од анизотропијата на обликот на честиците. На пример, поголем сооднос на должината : диаметарот на допантот го намалува прагот на перколација. Понатаму, зголе-мувањето на дијаметарот на металните честички води кон повисок праг на перколација во полимерната композиција.Клучни зборови: полимерни холистерични течни кристали; спроводливи допанти; јаглерод; јаглеродни наноцевки; праг на перколација

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Electrical resistivity of polymeric matrix loaded with nickel and cobalt powders

Cited by 60 publications

References 20 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

The Effects of Additive TiO<sub>2</sub> Nanoparticles on the Energy Gap of DCM Doped with PS Thin Films

The role of conductive dopants in polymer cholesteric liquid crystals

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