Synthesis of silica-coated graphite by enolization of polyvinylpyrrolidone and its thermal and electrical conductivity in polymer composites

Silica-coated graphite flakes, which have electrical insulating property and high thermal conductivity, were synthesized by a polyvinylpyrrolidone (PVP)-assisted sol–gel reaction. The critical role of keto-enol tautomerism of PVP in base-catalyzed silica sol–gel reaction was elucidated. The degree o...

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Bibliographic Details
Published in:Carbon (New York) 2013-08, Vol.60, p.254-265
Main Authors: Choi, Seongcheol, Kim, Kyunghee, Nam, Jeonghoon, Shim, Sang Eun
Format: Article
Language:English
Subjects:
Carbon
Cross-disciplinary physics: materials science
rheology
Exact sciences and technology
Fillers
Flakes
Fullerenes and related materials
diamonds, graphite
Graphite
Heat transfer
Materials science
Physics
Polyvinylpyrrolidone
Silicon dioxide
Sol gel process
Specific materials
Thermal conductivity
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Summary:Silica-coated graphite flakes, which have electrical insulating property and high thermal conductivity, were synthesized by a polyvinylpyrrolidone (PVP)-assisted sol–gel reaction. The critical role of keto-enol tautomerism of PVP in base-catalyzed silica sol–gel reaction was elucidated. The degree of silica coating on graphite was controlled by the amount of PVP and silica precursor, tetraethyl orthosilicate. The silica-coated graphite was used as a filler in thermoplastic polyester elastomer (TPEE). The in-plane (Λ) and through-plane (Λ⊥) thermal conductivity values of silica-coated graphite/TPEE composites are 67.5% and 86.6% of those of raw graphite/TPEE at 80phr loading. Even after a severe mixing process under high shear at elevated temperature, silica-coated graphite/TPEE composites retain the perfectly insulating surface resistivity of >1013Ω/sq up to high filler contents.
ISSN:0008-6223
1873-3891
DOI:10.1016/j.carbon.2013.04.034