多孔碳纤维吸波复合材料的性能及其影响因素

Microwave Absorbing Performance of Composites Filled with Porous Carbon Fibers Having Different Features

为了获得吸收频带更宽、质量更轻、吸收更强的吸波剂,采用聚丙烯腈(PAN)为碳前驱体,聚甲基丙烯酸甲酯(PMMA)为致孔剂,通过湿法纺丝制备出PAN/PMMA共混纤维原丝,将原丝进行预氧化和碳化制备出了多孔碳纤维。其中PAN/PMMA共混纤维中PMMA的比例影响多孔碳纤维的孔体积进而影响吸波性能,当PAN/PMMA质量比例为70/30时多孔碳纤维的电磁波吸收性能最佳,其反射率小于-10 dB的有效频带为2.0 GHz,最低反射率达-38 dB。多孔碳纤维不但利用实体碳的介电损耗,同时也利用其中孔对电磁波多次反射产生的干涉来耗散电磁波,故多孔碳纤维是一种高效电磁波吸收剂。另外过高碳化温度下制得的多孔碳纤维因电导率高不利于阻抗匹配,使电磁波吸收性能降低,以1200℃碳化温度为宜。

In order to obtain a microwave absorber with wider absorption band,lighter weight and stronger absorption,PAN/PMMA blend fiber precursor was prepared by wet spinning with polyacrylonitrile(PAN)as carbon precursor and polymethylmethacrylate(PMMA)as porogen.Porous carbon fiber was prepared by pre-oxidation and carbonization.The proportion of PMMA in PAN/PMMA blend fiber affects the pore volume of porous carbon fiber,and then affects the microwave absorption performance.When PAN/PMMA is 70/30,the electromagnetic wave absorption performance of porous carbon fiber is the best,the effective frequency band with reflectivity less than-10 dB is 2.0 GHz,and the minimum reflectivity is-38 dB.Porous carbon fiber not only uses the dielectric loss of solid carbon,but also uses the interference generated by the multiple reflection of electromagnetic wave by the hole to dissipate electromagnetic wave.Therefore,porous carbon fiber is an efficient electromagnetic wave absorber.In addition,the porous carbon fiber prepared at too high carbonization temperature is not conducive to impedance matching due to its high conductivity,which reduces the electromagnetic wave absorption performance.The carbonization temperature of 1200℃is appropriate.