纳米多壁碳管结构变化对其复合材料微波性能影响

Influence of Structural Transformation of Multi-Wall Carbon Nanotubes on Microwave Properties of Multi-Wall Carbon Nanotubes Composites

采用不同温度热处理纳米多壁碳管,研究纳米多壁碳管结构变化对相应复合材料的微波特性的影响。采用拉曼光谱分析表征纳米多壁碳管热处理前后的结构变化;测试纳米多壁碳管/石蜡复合材料在0.5～6GH介电谱。结果显示,热处理温度≤1000℃,纳米多壁碳管的ID/IG值基本不变,相应复合材料的复介电常数大致相等且吸波性能基本相同;热处理温度>1000℃,ID/IG值明显减小,内部结构发生重排,纳米多壁碳管平均晶粒尺寸增大,相应的纳米多壁碳管复合材料的复介电常数无论实部还是虚部均明显下降,微波吸收峰向高频移动。通过热处理控制纳米多壁碳管的ID/IG值和平均晶粒尺寸,可以调整纳米多壁碳管复合材料的微波介电谱,达到调整纳米多壁碳管复合材料的微波吸收特性的目的。

The influence of the degree of graphitization of Multi-wall carbon nanotubes （MCNTs） on adjusting microwave properties of MCNTs composites was studied by means of treated （MCNTs） at 900℃ , 1000℃, 1100℃ and 1300℃ respectively. The structural trans- formation of the heat treated MCNTs was characterized by Raman spectroscopy. The dielectric spectra of the MCNT/paraffin composites was measured in the frequency range between 0.5 - 6GHz. Raman scattering measurement results show that the D-line peak intensity （1350 cm-1） to G-line peak intensity （1580cm-1） ratio （ID/IC ） of MCNTs samples are almost unchanged when treated below 1000℃ , so the complex permittivities and the absorbing properties of corresponding MCNTs composites also kept unchanged. With the increasing of the heat treatment temperature （ above 1000℃） , ID/IGratios decreases, the structures of MCNTs are re-arranged, the mean crystallite sizes of the MCNTs increase and the graphitization degree improve. The complex permittivities of MCNTs composites also decreased obviously and the absorbing peaks shifted to high frequence with ID/IGratio decreasing and the mean crystallite sizes of the MCNTs increasing. The spectra of dielectric and microwave absorbing properties of MCNTs composites can be adjusted through con- trolling ID/IGratio and the mean crystallite sizes of the MCNTs by heat treatment.