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71.
72.
Functionalized benzenesulfonic groups were grafted onto the surface of multi-walled carbon nanotubes (MWCNTs) supported Pd catalysts in direct methanol fuel cells by a new and simple in situ radical polymerization of 4-styrenesulfonate and isoamyl nitrite. The resultant sulfonated MWCNTs-supported Pd catalysts (S-MWCNTs/Pd) were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and Fourier transform infrared (FTIR) spectrometry measurements. Electrochemical characterizations of S-MWCNTs/Pd catalysts for methanol electro-oxidation in alkaline solution were investigated by cyclic voltammetry techniques. These results showed that S-MWCNTs/Pd exhibited higher electrocatalytic activity, enhanced CO tolerance and better stable life than did that with the unsulfonated counterparts, mainly due to the easier access with methanol and well dispersed distribution of the S-MWCNTs/Pd catalysts in water. In addition, compared with traditional sulfonation of MWCNTs, this new approach is more advantageous to make small and uniform dispersion of Pd particles loaded onto the surfaces of sulfonated MWCNTs, indicating it is a simple, rapid, and efficient method to functionalize MWCNTs. 相似文献
73.
Chromium-multiwalled carbon nanotubes (Cr-MWNT) composite coatings are electrodeposited from “environmentally acceptable” trivalent Cr electrolytes containing MWNTs under ultrasonic agitation. The structures, hardness and tribological behaviors are investigated using the transmission electron microscope (TEM), field-emission scanning electron microscope (FE-SEM), Vickers hardness indenter, tribology tester and three-dimensional profile tester, respectively. Results show that MWNTs are dispersed evenly in Cr matrix. The introduction of MWNTs obviously improved the hardness, toughness and tribological performance of Cr coatings. 相似文献
74.
以MWNTs为核,采用3-硅羟基-1-丙基氯化铵和磺酸盐PEGS,通过离子键,制备离子型无溶剂MWNTs纳米流体。通过TEM、DSC、TGA、流变仪对无溶剂MWNTs纳米流体的结构和性能进行表征。采用溶液法和机械法制备无溶剂MWNTs纳米流体/聚丙烯纳米复合材料,研究无溶剂MWNTs对聚丙烯结晶性的影响。研究表明,无溶剂纳米流体中MWNTs的含量为23.67wt%,具有固-液转变现象。无溶剂MWNTs纳米流体加入聚丙烯中,均促进了聚丙烯树脂形成晶核的过程,使形成的晶核数目增加,结晶度提高。 相似文献
75.
T. V. Reshetenko L. B. Avdeeva V. A. Ushakov E. M. Moroz A. N. Shmakov V. V. Kriventsov D. I. Kochubey Yu. T. Pavlyukhin A. L. Chuvilin Z. R. Ismagilov 《Applied Catalysis A: General》2004,270(1-2):87-99
Coprecipitated Fe-Al2O3, Fe-Co-Al2O3 and Fe-Ni-Al2O3 catalysts is shown to be very efficient in carbon deposition during methane decomposition at moderate temperatures (600–650 °C). The carbon capacity of the most efficient bimetallic catalysts containing 50–65 wt.% Fe, 5–10 wt.% Co (or Ni) and 25–40 wt.% Al2O3 is found to reach 145 g/gcat. Most likely, their high efficiency is due to specific crystal structures of the metal particles and formation of optimum particle size distribution. According to the TEM data, catalytic filamentous carbon (CFC) is formed on them as multiwall carbon nanotubes (MWNTs). The phase composition of the catalysts during methane decomposition is studied using a complex of physicochemical methods (XRD, REDD, Mössbauer spectroscopy and EXAFS). Possible mechanisms of the catalyst deactivation are discussed. 相似文献
76.
通过原位分散方法将不同含量的多壁碳纳米管(MWNTs)引入聚对苯撑苯并二噁唑(PBO)聚合体系,共混产物采用液晶纺丝法纺制成高性能MWNTs/PBO纤维。用偏光显微镜观察了MWNTs的分散状况,发现将MWNTs先预分散在多聚磷酸(PPA)中再添加可以有效地改善其分散性,热失重分析仪、强力仪研究了纤维的热稳定性能和力学性能。结果表明,MWNTs质量分数为2%的共混纤维的拉伸强度和模量分别达到4.69 GPa和128.8 GPa,比相同卷绕速度下PBO纤维提高了24.2%和23.5%,起始热分解温度也从668.9℃提高到700.8℃。MWNTs的质量分数达到5%时由于团聚严重,降低了PBO的可纺性,影响了纤维的性能。 相似文献
77.
碳纳米管聚合物复合材料的力学性质 总被引:1,自引:0,他引:1
用二甲基甲酰胺表面活性剂来超声分散多壁碳纳米管,制备成碳纳米管增强的环氧树脂基聚合物。常温下力学性能测试表明,随着碳纳米管含量的增加,其弹性模量先增后降。在50℃时,对于碳纳米管含量≤1%(质量分数)的复合材料,经历了可逆的粘弹性阶段后进入塑性变形,且温度对复合材料的弹性模量和拉伸强度影响较大;而对于碳纳米管含量>1%的复合材料,其力学性能反而发生退化。 相似文献
78.
Zeinab TalaeiAli Reza Mahjoub Ali morad RashidiAzadeh Amrollahi Majid Emami Meibodi 《International Communications in Heat and Mass Transfer》2011,38(4):513-517
In this research, the pristine CNTs sample synthesized by the CCVD method contains catalytic particles and the carbonaceous impurities, and then the special purification procedure was done. By different methods CNT functionalized with various concentration of COOH was prepared. The carboxylated CNTs were analyzed by back titration method for determining the COOH concentrations on the surface of the oxidized CNTs. Thermal conductivity of difference carbon nanotube fluid has been measured under the stable condition by KD2 prob. For the first time, we have compared the effect of difference COOH concentration as important parameter in stability and heat transfer behavior of nanofluid. The results show that increasing the functionalized group causes better stability and higher thermal conductivity if the surface of MWNT does not damage in functionalize process. 相似文献
79.
本文采用溶液混合、超声波分散的方法,制备了多壁碳纳米管(MWNTs)/高密度聚乙烯(HDPE)、MWNTs/超高分子量聚乙烯(UHMWPE)两种复合材料,并对其进行50、150、300 kGy的60Co γ射线辐照,研究了MWNTs/PE复合材料的辐射交联对电性能的影响.结果表明MWNTs/PE复合材料经过辐射交联后,... 相似文献
80.