改性碳纳米管/环氧树脂复合材料的介电性能

实验采用混酸法对碳纳米管(CNTs)表面进行改性，制得羧基化碳纳米管(C-CNTs)。采用溶胶-凝胶法制得SiO₂包覆的C-CNTs (C-CNTs@SiO₂)、TiO₂包覆的C-CNTs (C-CNTs@TiO₂)，采用原位聚合法制得聚苯胺包覆的C-CNTs (C-CNTs@ PANI)。以环氧树脂(EP)为基体材料，通过溶液共混法制备出C-CNTs/EP、C-CNTs@SiO₂/EP、C-CNTs@TiO₂/EP和C-CNTs@PANI/EP四种复合材料。研究结果表明:当掺杂相的质量分数均为1 wt%时，四种EP基复合材料的冲击强度相对于未改性的环氧树脂均有不同程度的提高。当掺杂相质量分数为7 wt%时，C-CNTs/EP、C-CNTs@SiO₂/EP、C-CNTs@TiO₂/EP和C-CNTs@PANI/EP四种复合材料的介电常数分别是EP的14.1、7.2、2.5、18.8倍。在实验掺杂量下，C-CNTs@SiO₂/EP和C-CNTs@TiO₂/EP的介电损耗几乎没有变化，C-CNTs@PANI/EP的介电损耗略有增加。当掺杂相质量分数为1 wt%时，C-CNTs@SiO₂/EP和C-CNTs@TiO₂/EP的击穿强度相对于EP明显提高。 

Dielectric properties of modified carbon nanotube/epoxy composites

The surface of carbon nanotubes (CNTs) was modified by mixed acid method to obtain carboxylated carbon nanotubes (C-CNTs). SiO₂-coated C-CNTs (C-CNTs@SiO₂) and TiO₂-coated C-CNTs (C-CNTs@TiO₂) were prepared by sol-gel method. Polyaniline-coated C-CNTs (C-CNTs@PANI) were prepared by in-situ polymerization. Four kinds of composites of C-CNTs/EP, C-CNTs@SiO₂/EP, C-CNTs@TiO₂/EP and C-CNTs@PANI/EP were prepared by solution blending with epoxy resin (EP) as the matrix. The results of the study indicate that when the mass fraction of the doped phase is 1 wt%, the impact strengths of the four EP matrix composites are improved to different degrees with respect to the unmodified epoxy resin. When the doping phase content is 7 wt%, the dielectric constants of C-CNTs/EP, C-CNTs@SiO₂/EP, C-CNTs@TiO₂/EP and C-CNTs@PANI/EP composites are 14.1, 7.2, 2.5 and 18.8 times that of the unmodified EP, respectively. At the experimental doping amount, the dielectric losses of C-CNTs@SiO₂/EP and C-CNTs@TiO₂/EP are almost unchanged, and the dielectric loss of C-CNTs@PANI/EP is slightly increased. When the doping phase mass fraction is 1 wt%, the breakdown strengths of C-CNTs@SiO₂/EP and C-CNTs@TiO₂/EP are significantly improved.