Mechanism of thermal and electrical conductivity in polymer‐nanocarbon composites

Abstract

The electrical and thermal conductivity of nanocarbon filled polymers were studied by adding nanocarbon fillers (thermoexfoliated graphite (TEG) and dispersed TEG (nanoTEG)) to epoxy resin (ED) or polyethylene oxide (PEO). The content of filler in composite materials (CM) was (0.5 -10) wt%. The temperature range of the investigations was (77 -300) K for electrical conductivity and (150 -423) K for thermal conductivity, respectively. It was found that electrical conductivity of CM obeys percolation dependence with low critical concentration C cr $ (1 -2) wt% (j cr $ (0.56 -1.1) vol%) and characterised by a positive temperature coefficient. The thermal conductivity is approximately linear on nanocarbon content. The model describing the mechanisms of electrical and thermal conductivity of CM had been proposed. The basic parameters of this model are following: content of nanocarbon anisotropic particles and their distribution in polymer matrix; the contact thermal (electrical) resistance both between the filler particles and on the interface of two phases -polymer-carbon filler.Keywords: Nanocarbon filler; aspect ratio, electrical properties; thermal properties; porosity Die elektrische und thermische Leitfähigkeit von Nanokohlenstoff-Polymer-Kompositen (CM) wurde untersucht. Die Materialien wurden unter Zugabe von Nanokohlenstoff-Füllmaterialien (thermoexfoliertem Graphit (TEG) und dispergiertem TEG (nano-TEG)) zu Epoxidharzen (ED) oder Polyethylenoxid (PEO) hergestellt.Der Gehalt an Füllstoffen in den Kompositmaterialien betrug 0,5 bis 10 wt%. Für die elektrischen Messungen wurden die Untersuchungen im Temperaturbereich von 77 bis 300 K und für die thermischen Leitfähigkeitsmessungen im Bereich 150 bis 423 K durchgeführt. Es konnte gezeigt werden, dass die elektrische Leitfähig-keit von CM der Perkolationsabhängigkeit mit einer niedrigen kritischen Konzentration von C cr $ (1 -2) wt% (j cr $ (0.56 -1.1) vol%) folgt und durch einen positiven Temperaturkoeffizienten charakterisiert ist. Die thermische Leitfähigkeit ändert sich linear mit dem Nanokohlenstoffgehalt. Auf dieser Basis wurde ein Modell für die elektrische und thermische Leitfähigkeit von CM vorgeschlagen.

Multifunctional high‐density polyethylene nanocomposites produced by incorporation of exfoliated graphene nanoplatelets 2: Crystallization, thermal and electrical properties

“…Furthermore, the dispersion status and the orientation of the filler in the polymer matrix are not considered in these models as well. However, the dispersion and orientation of fillers in the polymer matrix is believed to be the essential factor affecting the thermal conductivity for the fillers with high aspect ratio and anisotropic thermal properties [5].…”

“…Polymeric composites filled with metallic fillers have been traditionally used because of excellent thermal and electrical conductivity of metals. But the metal‐filled composites have the disadvantages such as higher density, greater susceptibility to oxidation/corrosion, and relatively high cost [5]. Currently, carbon black is commonly used as a conductive filler to increase the thermal and electrical conductivity of polymeric composites owing to its lower cost, low density, corrosion resistance, and ease of processing into host polymers compared with metallic fillers [6].…”

Thermal conductivity and electric properties of epoxy composites filled with TiO2-coated copper nanowire

“…Furthermore, the dispersion status and orientation of the filler in the polymer matrix are not considered in this model. However, the dispersion and orientation of fillers in the polymer matrix is believed to be the essential factor affecting the thermal conductivity of fillers with high aspect ratios and anisotropic thermal properties [25]. To better investigate the thermal conductivity of the CuNW composites as a function of CuNW loading, the thermal conductivity of the CuNWs was applied with the Agari model [26].…”

Extraordinary synergy in the thermal and electric properties of polymer matrix reinforced with hybrid fillers

“…The increase of the thermal conductivity in epoxy composite materials in case of combination of nanocarbon and boron nitride particles as fillers is not an additive effect but much higher, confirming a synergy effect in such composites. The dependence of the thermal conductivity from the temperature for the epoxy composite with single carbon filler as well as with the hybrid filler is complicated and determined by the changes with the temperature of the matrix thermal conductivity, individual filler particles and the contact thermal resistances both at interphase boundaries and between the filler particles (graphite nanoplatelet, multi-wall carbon nanotube, carbon fiber and boron nitride) [25].…”