预氧化温度对中空多孔炭纤维介电常数的影响

摘要

A series of polyacrylonitrile-based hollow-porous carbon fibres(PAN-HPCFs) were prepared by oxidating in air and carbonizing in nitrogen to get lightweight radar wave absorbers. The effects of preoxidation temperature on the microstructure, composition and complex permittivity of the resultant PAN-HPCFs were investigated. Results indicate that the microstructure of the obtained PAN-HPCFs has not been effected by changing the preoxidation temperature. The C content of PAN-HPCF decreases with the increase of preoxidation temperature. The real and imaginary part of the complex permittivity(ε＇ and ε") decrease with the increase of preoxidation temperature. The values of ε＇ and ε" of composites of paraffin and PAN-PHCFs are 23. 12 and 73. 51 when preoxidation temperature is 250℃, 19. 32 and 9. 87 when preoxidation temperature is 310℃, and carbonization temperature is 800℃. The complex permittivity of PAN-HPCFs can be adjusted by heat-treatment process.%以中空多孔聚丙烯腈(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.研究了预氧化温度对其微观结构、元素组成和介电常数的影响.结果表明,预氧化温度对中空多孔炭纤维微观结构的影响不大;碳含量随预氧化温度的升高而减少,而氮、氧含量则相反.随预氧化温度的升高,所得中空多孔炭纤维的介电常数依次降低.在2GHz处,预氧化温度为250℃时ε′和ε″分别为23.12和73.51,而预氧化温度为310℃时ε′和ε″分别为19.32和9.87.因此,可通过预氧化温度来调节中空多孔炭纤维的介电常数.