预氧化时间对中空多孔炭纤维介电常数的影响

摘要

Polyacrylonitrile-based hollow, porous carbon fibers (PAN-HPCFs) as lightweight radar wave absorbers were prepared by the oxidation of PAN hollow fibers in air followed by carbonization in nitrogen. The effects of oxidation time and carbonization temperature on the microstructure, composition, electrical conductivity and complex permittivity of the resulting PAN-HPCFs were investigated. Results indicated that heat-treatment parameters had no obvious effect on the microstructure of the PAN-HPCFs. The carbon content of the PAN-HPCF decreased, the nitrogen content increased and the electrical conductivity decreased with oxidation time. The real and imaginary parts of the complex permittivity (ε' and ε") decreased with oxidation time. The electrical conductivity and complex permittivity of the PAN-HPCFs can be adjusted by changing the heat-treatment parameters. The values of ε' and ε" of PAN-PHCFs were 17. 20 and 11. 90 respectively and the electrical conductivity was 564.50Ω-1m·-1 when oxidation time was 60 min and carbonization temperature was 800℃.%以中空多孔聚丙烯腈( polyacrylonitrile,PAN)原丝为原料,通过预氧化和炭化工艺制备了中空多孔炭纤维(Hollow-porous carbon fibres,HPCFs).研究了预氧化时间对其微观结构、元素组成、电导率和介电常数的影响.结果表明:预氧化时间对所获HPCFs微观结构的影响不大;HPCFs的碳含量随预氧化时间增加而减少,而氮含量则随预氧化时间增加而增加.随着预氧化时间增加,所得HPCFs电导率和介电常数依次降低.预氧化时间60 min、炭化温度800℃条件下所制HPCFs在2GHz处的介电常数实部和虚部分别为17.20和11.90,对应的电导率为564.50Ω1·m-1.可通过热处理工艺调节HPCFs的电导率和介电常数.