Kumar S, Rath T, Khatua B B, Dhibar A K, Das C K
Materials Science Centre, Indian Institute of Technology, Kharagpur 721302, India.
J Nanosci Nanotechnol. 2009 Aug;9(8):4644-55. doi: 10.1166/jnn.2009.220.
This paper focuses on the preparation and characterization of Poly(methyl methacrylate)/multi-walled carbon nanotube composites through ex-situ and in-situ processes. The extent of dispersion and fracture morphology was studied by TEM, AFM, SEM and FESEM. The increase in conductivity at percolated loading of 2.91 wt% was more for in-situ prepared PMMA/MWNTs nanocomposite as compared to ex-situ prepared nanocomposites. The dielectric constant of pure PMMA was increased from 5 to 72 in the ex-situ prepared PMMA/MWNTs nanocomposites with 4.76 wt% of MWNTs loading. Moreover, for the ex-situ nanocomposites containing 2.91 wt% of MWNTs, the dielectric constant was 15, but in-situ prepared PMMA/MWNTs nanocomposite showed two times increase at same loading of 2.91 wt% of MWNTs. Dielectric constant of PMMA/MWNTs nanocomposites loaded with (< 4.76 wt%) of MWNTs remained almost constant with frequency. Dynamic mechanical analysis showed remarkable increase in storage modulus, especially at higher temperatures with 4.76 wt% loading of carbon nanotubes as compared to pure PMMA. The presence of additional peak before T(g) indicated that CNTs could be used to wake up secondary relaxations, which were inactive in pure PMMA. Thermogravimetric analysis (TGA) showed that thermal stability of PMMA/MWNTs nanocomposites increased by 45 degrees C (in N2) and 27 degrees C (in air) at 4.76 wt% of MWNTs as compared to the pure PMMA.
本文重点研究了通过非原位和原位工艺制备聚甲基丙烯酸甲酯/多壁碳纳米管复合材料及其表征。通过透射电子显微镜（TEM）、原子力显微镜（AFM）、扫描电子显微镜（SEM）和场发射扫描电子显微镜（FESEM）研究了分散程度和断裂形态。与非原位制备的纳米复合材料相比，原位制备的聚甲基丙烯酸甲酯/多壁碳纳米管（PMMA/MWNTs）纳米复合材料在渗滤负载量为2.91 wt%时电导率的增加更为显著。在非原位制备的负载量为4.76 wt%的MWNTs的PMMA/MWNTs纳米复合材料中，纯PMMA的介电常数从5增加到72。此外，对于含有2.91 wt% MWNTs的非原位纳米复合材料，介电常数为15，但原位制备的PMMA/MWNTs纳米复合材料在相同负载量2.91 wt%的MWNTs下介电常数增加了两倍。负载量小于4.76 wt%的MWNTs的PMMA/MWNTs纳米复合材料的介电常数随频率几乎保持不变。动态力学分析表明，储能模量显著增加，特别是在碳纳米管负载量为4.76 wt%时，与纯PMMA相比，在较高温度下更为明显。在玻璃化转变温度（T(g)）之前出现的额外峰表明，碳纳米管可用于激发纯PMMA中不活跃的次级弛豫。热重分析（TGA）表明，与纯PMMA相比，在MWNTs负载量为4.76 wt%时，PMMA/MWNTs纳米复合材料在氮气中热稳定性提高了45℃，在空气中提高了27℃。
