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Effect of Heating Rate on the Complex Permittivity of Hollow―porous Carbon Fibers

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Author(s): XIE Wei, CHENG Hai-Feng, KUANG Jia-Cai, CHEN Zhao-Hui, CHU Zeng-Yong, LONG Chun-Guang

Journal: Journal of Inorganic Materials
ISSN 1000-324X

Volume: 26;
Issue: 9;
Start page: 939;
Date: 2011;
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Keywords: hollow-porous carbon fibers; preoxidation; carbonization; complex permittivity

ABSTRACT
A series of polyacrylonitrile―based hollow―porous carbon fibres (PAN―HPCFs) were prepared by oxidating PAN hollow―porous fibers in air and carbonizing their cured fibers in nitrogen. The effects of preoxidation and carbonization heating rate on the microstructure, composition, electrical volume conductivity and complex permittivity were investigated. The microstructure of the obtained PAN―HPCFs is changed greatly by the heating rate. The electrical volume conductivity and complex permittivity decrease with the increase of heating rate. The electrical volume conductivity is in the range 1997.14 S/m to 153.39 S/m with the preoxidation heating rate increasing from 0.5¡æ/min to 4¡æ/min. At 2 GHz, the value of ε″ of composites of paraffin and PAN―PHCFs decreases from 70.35 to 6.99 when preoxidation heating rate increases form 0.5¡æ/min to 4¡æ/min. Results indicate that the electrical conductivity and complex permittivity of PAN―HPCFs can be adjusted by the heating rate.
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