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Type: Artigo
Title: Thermal-Diffusivity Measurements of Conductive Composites Based on EVA Copolymer Filled With Expanded and Unexpanded Graphite
Author(s)/Inventor(s): Tavman, Ismail Hakki
Turgut, Alpaslan
Fonseca, Henrique Massard da
Orlande, Helcio Rangel Barreto
Cotta, Renato Machado
Magalhães, Maycon Cesar Figueira
Abstract: Indisponível.
Abstract: In this research, the thermal diffusivity of composites based on ethylene- vinyl acetate (EVA) copolymer filled with two kinds of reinforcement graphite materials was investigated. The reinforcement graphite fillers were untreated natural graphite (UG) and expanded graphite (EG). Composite samples up to 29.3 % graphite particle volumetric concentrations (50 % mass concentration) were prepared by the melt- mixing process in a Brabender Plasticorder. Upon mixing, the EG exfoliates in these films having nanosized thicknesses as evidenced by TEM micrographs. Thus, the thermal diffusivity and electrical conductivity of composites based on the ethylene-vinyl acetate matrix filled with nanostructuralized expanded graphite and standard, micro-sized graphite were investigated. From the experimental results it was deduced that the electrical conductivity was not only a function of filler concentration, but also strongly dependent on the graphite structure. The percolation concentration of the filler was found to be (15 to 17) vol% for micro-sized natural graphite, whereas the percolation concentration of the filler in nanocomposites filled with expanded graphite was much lower, about (5 to 6) vol%. The electrical conductivity of nanocomposites was also much higher than the electrical conductivity of composites filled with micro-sized filler at similar concentrations. Similarly, the values of the thermal diffusivity for the nanocomposites, EG-filled EVA, were significantly higher than the thermal diffusivity of the composites filled with micro-sized filler, UG-filled EVA, at similar concentrations. For 29.3 % graphite particle volumetric concentrations, the thermal diffusivity was 8.23 × 10−7 m2 · s−1 for EG-filled EVA and 6.14 × 10−7 m2 · s−1 for UG-filled EVA. The thermal diffusivity was measured by the flash method.
Keywords: Conductive nanocomposites
Electrical conductivity
Expanded graphite
Unexpanded graphite
Flash method
Thermal diffusivity
Production unit: Núcleo Interdisciplinar de Dinâmica dos Fluidos
Publisher: Springer Verlag
In: International Journal of Thermophysics
Volume: 34
Issue: 12
Issue Date: 24-Jun-2012
DOI: 10.1007/s10765-012-1231-z
Publisher country: Brasil
Language: eng
Right access: Acesso Aberto
ISSN: 0195-928X
Appears in Collections:Engenharias

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