单向取向碳基气凝胶的制备及电磁屏蔽性能研究

Preparation of unidirectional orientated carbon-based aerogel and its electromagnetic shielding performance

碳基气凝胶具有自支撑的三维导电网络,是开发新型高性能电磁屏蔽及吸波材料的研究热点。通过单向冷冻干燥法制备了具有单向取向结构的碳纳米管/壳聚糖(CNT/CS)气凝胶,考察了不同CNT/CS浓度及配比对气凝胶冷冻速率、线性收缩率、微观结构、电导率和电磁屏蔽效能的影响,研究了取向方向对气凝胶导电性能和电磁屏蔽效能的影响。结果表明:CNT/CS气凝胶具有显著的各向异性,取向方向上的电导率最高可达14.34S/m,是垂直于取向方向上的1.5~3.0倍。CNT/CS气凝胶具有优良的电磁屏蔽效能,在12GHz的频率下屏蔽效能最高可达20.3dB。气凝胶在垂直于取向方向上的电磁屏蔽效能高于取向方向。

Carbon-based aerogel has a self-supporting 3 D conductive network,which is a research hotspot in the development of new high-performance electromagnetic shielding and microwave absorbing materials.Carbon nanotube/chitosan(CNT/CS)aerogels with unidirectional orientation structure were prepared by a unidirectional freeze-drying method.The effects of different CNT/CS concentrations and ratios on the freezing rate,linear shrinkage,microstructure,electrical conductivity,and electromagnetic shielding effectiveness of the aerogels were investigated,and also studied the influence of orientation direction on the electrical conductivity and electromagnetic shielding effectiveness.The results showed that the CNT/CS aerogel had significant anisotropy,and the conductivity in the orientation direction reached up to 14.34 S/m,which was 1.5 to 3.0 times the direction perpendicular to the orientation.CNT/CS aerogel had excellent electromagnetic shielding effectiveness,the shielding effectiveness up to 20.3 dB at the frequency of 12 GHz.The electromagnetic shielding effectiveness of the aerogels perpendicular to the orientation direction was higher than that of the orientation direction.