化学处理对多壁碳纳米管电化学储锂性能的影响

为了提高多壁碳纳米管(MWNTs)的电化学储锂性能,对MWNTs采用如下方法处理:混酸浸泡(H2SO4/HNO3)→高温处理→Li2CO3溶液浸泡,将所得样品和原始样品进行结构及电化学性能测试。结果表明,经处理的MWNTs样品的准石墨层间距增大,表面产生羰基等官能团,电化学储锂容量比原始样品提高约45%～85%。通过微分容量曲线对原始和处理后的样品进行机理分析,可以看出处理过的样品其电化学嵌脱锂的电压峰值之间的差值较未处理的样品小,说明锂离子在该样品中脱出所受到的阻力减小。     

多壁碳纳米管的球磨处理对其吸附储氢性能的影响

研究了球磨改性对多壁碳纳米管储氢性能的影响,球磨处理前后的碳纳米管微观结构采用TEM和XRD进行表征. 结果发现,球磨处理能使碳纳米管长度变短,管端口打开,缺陷增多,表面积增大,球磨处理12 h的碳纳米管的吸附量从未球磨的1.60%(w)提高到2.55%(w),表明球磨改性能明显提高碳纳米管的吸附量.     

Synthesis of hyperbranched aromatic polyamide–imide and its grafting onto multiwalled carbon nanotubes

A flexible hyperbranched aromatic polyamide–imide (PAI) having an amine group in the center and carboxyl groups in the ends was synthesized from a AB₂ type of monomer of 2‐(6‐aminohexylcarbomoyl) terephthalic acid that was prepared from trimellitic anhydride and 1,6‐diaminohexane. Fourier transformed infrared spectra (FTIR), NMR, and ES‐MS were used to characterize the structure of the monomer and the synthesized hyperbranched polymer. Then the hyperbranched PAI was grafted onto the multiwalled carbon nanotubes (MWNTs) that was first treated by acid and changed into MWNT‐COCl by SOCl₂ in a tetrahydrofuran solution. By observation with transmission electron microscopy and characterization with FTIR and thermal gravity of analysis, the functionalized MWNTs were terminally enclosed with polymer; it was believed that the MWNTs were linked with a big carboxylic claw at the end and the adsorption ability of the MWNTs to NH₂‐substrate was enhanced. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

4,4'-二氨基二苯甲烷-多壁碳纳米管共价衍生物的制备

采用4,4'-二氨基二苯甲烷(DDM)对短切的多壁碳纳米管(MWNTs)进行化学修饰,合成了结构新颖的衍生物MWNT-DDM.FTIR、1HNMR和13CNMR研究表明,DDM通过酰胺键与MWNTs共价连接.TGA测试表明,该衍生物中MWNTs的含量为65.7%.该衍生物可溶解于N,N'-二甲基甲酰胺、N,N'-二甲基乙酰胺和二甲亚砜,有利于进一步合成多种功能化碳纳米管衍生物.此外,该衍生物在高分子交联剂等方面具有潜在的应用前景.     

MWNTs-OH/PET纳米复合材料的燃烧性能与阻燃机理研究

用原位聚合方法制备了纯PET和MWNTs-OH/PET纳米复合材料,用锥形量热仪测试了4种样品的燃烧性能,用场发射扫描电镜表征了纳米复合材料的微观机构。对比分析了4种样品的燃烧性能、烟及毒气释放量。结果表明复合材料的热释放速率(HRR)峰值及平均值,总放热量(THR)和有效燃烧热(EHC)平均值都有所降低,纳米复合材料的CO生成速率峰值较平缓且低于纯PET的CO生成速率,没有增加PET材料的毒性。从扫描电镜图和锥形量热仪测试结果可以初步断定,MWNTs-OH/PET纳米复合材料属于气相阻燃和凝固相阻燃机理。     

Synthesis,characterisation and performance of piezo-resistive cementitious nanocomposites

Smart material reinforced non-destructive structural health monitoring technique has been evolving as the most predominated route for assessing the performance of the civil structures. In the present study, multiwalled nanotubes (MWNT) were suitably incorporated into the cement matrix, which act as actively embedded sensor for monitoring real-time flaws in structures. Initially, the stable homogenous MWNT dispersion was prepared by using ionic surfactant technique with high-intensity ultrasonic agitation process. Since, a suitable and adequate synthesis procedure to incorporate MWNT in cement matrix is essential, but complicated, the role of amplitude and frequency of sonication on dispersion of nanotubes was categorically evaluated. Further, this paper focuses to find out the effect of surfactant on MWNT dispersion by using the UV Visible spectroscopy and by evaluating the effective hydro-dynamic diameter. Based on micromechanics based analytical model, the influence of the interface layer thickness and geometrical configuration of nanotubes on the electrical conductivity of cement nano-composite are also analyzed. Further, the electrical conductivity of MWNT incorporated cement system, as developed in the present study, is measured using four probe method. Piezo-resistivity of the oven dried samples is measured to evaluate the change in potential drop under cyclic loading regime. It is found that the efficiency of the piezo-resistive strain sensors greatly depends on synthesis process and the circuit system. Appropriately proportioned and properly synthesized MWNTs incorporated in cement matrix were capable of providing consistent and steady response under the variable external stress. Thus, the material can be used as embedded sensor for health monitoring and identifying initiation of any damage in reinforced concrete structure.     

Preparation of multi-walled carbon nanotubes grafted with synthetic poly(l-lysine) through surface-initiated ring-opening polymerization

A surface-initiated ring-opening polymerization approach was used to functionalize multi-walled carbon nanotubes (MWNTs) with linear poly(l-lysine) (PLL). The oxidized MWNTs, which resulted from the treatment of MWNTs with mixed concentrated sulfuric acid and nitric acid, were converted into amino-functionalized MWNTs (MWNT-NH₂) by the amidation of carboxylic group on MWNT surface with excess 1,6-diaminohexane. Surface-initiated ring-opening polymerization of ?-(benzyloxycarbonyl)-l-lysine N-carboxyanhydride with MWNT-NH₂ as the initiator resulted in MWNTs grafted with poly(?-(benzyloxycarbonyl)-l-lysine) (MWNT-g-PLys(Z)). After the acidolysis of benzylcarbamate group of the grafting poly(?-(benzyloxycarbonyl)-l-lysine) chain, water-soluble MWNTs grafted with PLL (MWNT-g-PLL) were obtained. The successful grafting was confirmed by Fourier transform infrared spectroscopy, thermal gravimetric analysis, X-ray photoelectron spectroscopy, elemental analyses, high-resolution transmission electron microscopy (HRTEM) and field-emission scanning electron microscopy. HRTEM indicates that MWNTs were enveloped by PLL layer. The as-prepared MWNT-g-PLys(Z) and MWNT-g-PLL exhibited excellent ability to disperse homogeneously in THF and water, respectively.     

多壁碳纳米管／环氧树脂复合材料性能研究

采用物理机械方法与化学方法相结合的手段,制备了多壁碳纳米管（MWNTS）／环氧树脂（Epoxy）复合材料。通过力学拉伸试验测试了MWNTs/Epoxy复合材料拉伸强度和拉伸模量与MWNTS添加量的关系,利用扫描电镜（SEM）分析了MWNTS／Epoxy复合材料的拉伸断面,并用表面电阻测试仪对所制备的碳纳米管复合材料进行了电学性能测试。结果表明：经过化学酸化的方法处理后的MWNTS在复合材料中的分散得到了改善,力学性能也得到了明显的提高,但酸处理后的复合材料的电学性能明显低于未处理的复合材料。     

热酸氧化及镀镍对碳纳米管吸波性能的影响

利用浓硝酸沸腾状态下氧化性强的特点,采用冷凝回流的方法对碳纳米管进行纯化处理,并采用化学镀的方法在碳纳米管表面镀上了一层均匀的金属镍.测量了镀镍及原始碳纳米管的介电常数、磁导率以及R～f曲线.研究了浓硝酸氧化及镀镍对碳纳米管复合材料吸波性能的影响.结果表明,与原始碳纳米管相比,镀镍后碳纳米管复合材料的吸波峰向低频移动,出现在6.92GHz,峰值为-10.46dB,吸波频带宽度为2.46GHz(R＜-10dB)和5.41GHz(R＜-6dB).碳纳米管表面镀镍后吸收峰值虽然变小,但吸收峰有宽化的趋势,这种趋势有利于制造宽频吸波材料.