多壁碳纳米管的分散性研究

为提高多壁碳纳米管在水中的分散性,采用混酸超声法对其进行处理。通过傅里叶变换红外光谱仪、X-射线衍射仪等对处理前后碳纳米管的结构和分散性进行了研究。结果表明,经混酸超声处理,多壁碳纳米管表面被接枝上羟基和羧基官能团且其石墨结构保留完好;多壁碳纳米管在水中的分散性能得到提高,经100h静置,碳纳米管的浓度仅降低9.2%。     

嵌段共聚物F127高效分散单壁碳纳米管

利用浓硫酸和浓硝酸对单壁碳纳米管(SWNTs)进行氧化酸处理,制备羧基化单壁碳纳米管(SWNTsCOOH),以两亲性三嵌段聚醚Pluronic F127{(PEO)_(99)(PPO)_(65)(PEO)_(99)}为分散剂,制备SWNTs-COOH/F127分散液。采用激光粒度分析仪、傅里叶红外光谱、紫外-可见光吸收光谱、拉曼光谱对所制备分散液进行表征,并比较了SWNTs、F127修饰SWNTs、羧基化SWNTs、F127修饰羧基化SWNTs 4种水分散液的分散情况。结果表明,经混酸处理后,单壁碳纳米管表面成功修饰上羧基,相对于原始碳纳米管,其在水中的分散性及稳定性大大地提高。制备的SWNTs-COOH/F127分散液在4 000 r/min离心30 min未见沉淀,室温静置30 d以上不发生絮凝。     

多壁碳纳米管的羧基化及其对硝基苯的电催化性能

采用浓硝酸氧化法对多壁碳纳米管(MWNT)进行硝化处理制备了羧基化多壁碳纳米管(C-MWNT),通过红外光谱法研究了硝化温度和硝化时间对MWNT羧基化的影响。以C-MWNT为电催化剂制备了羧基化多壁碳纳米管粉末微电极,采用循环伏安法研究了酸性溶液中C-MWNT对硝基苯的电催化性能。结果表明,碳纳米管经羧基化处理后对硝基苯的电催化活性得到了显著地提高。     

壁碳纳米管的表面改性与分散工艺研究

通过浓硝酸对多壁碳纳米管(MWCNTs)进行纯化,以钛酸四丁酯为原料,采用溶胶-凝胶法对纯化后的MWCNTs进行表面改性,采用XRD、TEM分析手段对表面改性的多壁碳纳米管的物相组成和形貌进行表征,并研究了MWCNTs在乙醇中的分散性,结果表明:采用浓硝酸浸泡可以有效地纯化MWCNTs;采用溶胶-凝胶法在MWCNTs表面负载了纳米TiO2;纯化、负载纳米TiO2和超声波震荡提高了MWCNTs在乙醇中的分散性.     

原位合成制备碳纳米管/羟基磷灰石复合粉体

对多壁碳纳米管进行了浓酸氧化处理,然后采用原位合成法制备了碳纳米管/羟基磷灰石复合粉体,并对氧化处理前后的碳纳米管及所得复合粉体进行了红外光谱、X射线衍射、透射电镜检测.实验表明:经过浓硝酸氧化处理之后,多壁碳纳米管的端口被打开并在缺陷处引入大量的羟基与羧基,这是原位合成复合材料的基础;所得复合粉体中仅有碳管和羟基磷灰石两种物相,其中纳米级的短棒状羟基磷灰石均匀吸附在碳纳米管表面,形成了较强的界面结合.     

膦酸酯修饰的多壁碳纳米管的制备与表征

为提高多壁碳纳米管(MWCNTs)的表面活性,故对其表面进行有机修饰。以苯酚为原料,分别通过磷酸化和phospha-Fries重排反应,合成了2-羟基-苯膦酸二乙酯。膦酸酯上的羟基与酰氯化的多壁碳纳米管发生反应,得到了膦酸酯修饰的多壁碳纳米管。核磁共振波谱和红外光谱表征分析了膦酸酯及膦酸酯修饰的碳纳米管的组成结构,并且对比了修饰与未修饰的碳纳米管的分散性。结果表明,膦酸酯对碳纳米管的表面修饰有助于提高其在四氢呋喃中的分散性。     

多壁碳纳米管表面羧基化及其阻燃ABS的性能

采用硝酸氧化/低温等离子处理两步法,将多壁碳纳米管(MWCNTs)羧基化(MWCNTs-COOH),以改善其在ABS基体中的分散性。通过熔融共混的方法制备不同组分ABS/MWCNTs-COOH复合材料。利用红外、拉曼分析、扫描电镜对改性修饰后MWCNTs结构进行研究;利用扫描电镜、热重分析、极限氧指数、残炭分析、力学性能测试对ABS/MWCNTs-COOH复合材料分散性、热性能、阻燃性能、力学性能进行研究。实验结果表明,MWCNTs羧基化改性后提高了在ABS基体材料中的分散性;当MWCNTs-COOH含量为1%时,复合材料初始分解温度和最大分解温度分别提高了22.69℃和27.90℃,热稳定性提高,同时复合材料力学性能也得到改善,拉伸强度提高了18.3%;极限氧指数和残炭测试表明,MWCNTs-COOH加入提高了复合材料的极限氧指数,MWCNTs-COOH在复合材料燃烧过程中,会在材料表面形成网络状炭层,提高复合材料的阻燃性能。     

多壁碳纳米管接枝超支化聚(胺-酯)

采用混酸氧化,使碳纳米管表面产生羧基,再分别以接出法(grafting from)的方式在碳纳米管表面"长出"超支化大分子;以接入法(grafting to)的方式将由"一步法"合成的超支化聚(胺-酯)通过酯化反应接枝到碳纳米管表面。通过SEM、FTIR、TGA-DSC以及XRD等表征手段并结合酸碱滴定法测定修饰后碳纳米管表面的羟基密度,对功能化修饰的碳纳米管进行分析。结果表明,分别以"grafting from"和"grafting to"方式接枝超支化聚(胺-酯)后,碳纳米管的羟基密度分别为24.74 mmol/g和20.04 mmol/g,修饰后的碳纳米管分散性能明显提高,同时末端丰富的官能团为碳纳米管的进一步功能化修饰创造了条件。     

长链醚胺修饰碳纳米管衍生物及其制备方法

通过氧化后多壁碳纳米管上所引入的羧基和十八叔胺聚氧乙烯醚之间的酸碱反应,制备了长链醚胺修饰的碳纳米管衍生物,并利用红外光谱表征了醚胺功能化前后的碳纳米管上的功能基团,验证了酸碱反应形成的羧基盐的存在。通过热失重分析得出该衍生物中醚胺的质量分数高达76.8%,为改善碳纳米管在极性聚合物中的分散性及与聚合物基质间界面相互作用提供了途径。     

用红外光谱研究硝酸处理对多壁碳纳米管表面羧基的影响

用红外光谱研究了硝酸处理多壁碳纳米管时,不同处理时间对其表面羧基的影响。结果表明,煮沸的硝酸可使碳纳米管表面产生羧基,羧基量随处理时间的增加而增加,但处理时间不宜超过２ ｈ。     

硝酸处理对活性炭性质的影响

采用硝酸改性活性炭,通过正交实验确定了适宜的氧化条件,对改性后的活性炭进行了表征.结果表明,适宜的氧化条件为:硝酸浓度0.15 g·mL-1、回流温度20℃、回流时间3 h;适度氧化后,活性炭中孔孔容扩大,硝酸改性在活性炭表面引入的官能团大部分为羧基,各因素对羧基含量影响大小依次为:回流温度>硝酸浓度>回流时间.硝酸改...     

Chemical modification of multiwalled carbon nanotube with the liquid phase method

In this study, multiwalled carbon nanotubes (MWNTs) were purified by using chemical method with different proportion of nitric acid and sulfuric acid liquid phase mixture. Carboxyl groups and other functional groups could be modified on the MWNTs surface. However, oxidation can damage the structure of carbon atoms on the surface of the carbon nanotube. Furthermore, the characteristic properties of MWNTs specimens were demonstrated by Raman spectrograph and Fourier transform infrared spectrum. The thermal properties and morphology of MWNTs were checked by Thermogravimetric analysis and Scanning electron microscope. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Modification of multi-walled carbon nanotubes with fatty acid and their tribological properties as lubricant additive

Multi-walled carbon nanotubes (MWNTs) were treated with mixture of sulfuric acid and nitric acid. The surface modification of the oxidized MWNTs was achieved by refluxing the MWNTs with stearic acid (SA). The modified MWNTs were examined by the transmission electron microscope, scanning electron microscope, Raman spectroscopy and Infrared spectroscopy. Furthermore, the modified MWNTs were added to base lubricant and the tribological properties of resultant MWNTs lubricant were investigated by using a pin-on-plate wear tester. The results indicated that an esterification was formed in the oxidized MWNTs and SA, and the modification led to an improvement in the dispersion of MWNTs and the tribological properties of MWNTs as lubricant additive.     

High electrical conductivity of nylon 6 composites obtained with hybrid multiwalled carbon nanotube/carbon fiber fillers

The synergetic effect of multiwalled carbon nanotubes (MWNTs) and carbon fibers (CFs) in enhancing the electrical conductivity of nylon 6 (PA6) composites was investigated. To improve the compatibility between the fillers and the PA6 resin, we grafted γ‐aminopropyltriethoxy silane (KH‐550) onto the MWNTs and CFs after carboxyl groups were generated on their surface by chemical oxidation with nitric acid. Fourier transform infrared spectroscopy and thermogravimetric analysis proved that the KH‐550 molecules were successfully grafted onto the surface of the MWNTs and CFs. Scanning electron microscopy and optical microscopy showed that the obtained modified fillers reduced the aggregation of fillers and resulted in better dispersion and interfacial compatibility. We found that the electrical percolation threshold of the MWNT/PA6 and CF/PA6 composites occurred when the volume fraction of the fillers were 4 and 5%, respectively. The MWNT/CF hybrid‐filler system exhibited a remarkable synergetic effect on the electrically conductive networks. The MWNT/7% CF hybrid‐filler system appeared to show a second percolation when the MWNT volume fraction was above 4% and a volume resistivity reduction of two orders of magnitude compared with the MWNT/PA6 system. The mechanical properties of different types of PA6 composites with variation in the filler volume content were also studied. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40923.     

碳纳米管-聚偏氟乙烯共混超滤膜的制备及性能研究

采用硫酸、硝酸混酸改性多壁碳纳米管(MWNTs),将改性的MWNTs分散于1-甲基-2-吡咯烷酮(NMP)中,再与聚偏氟乙烯(PVDF)的NMP溶液混合,采用浸没相转化法制备MWNTs-PVDF复合超滤膜,考察了制膜条件对膜结构和性能的影响。结果表明,当铸膜液中MWNTs的质量分数到达0.09%、凝胶浴温度达到30℃时,纯水通量最大;随着预蒸发时间的延长,纯水通量下降;铸膜液溶解温度在40～80℃时,所制膜的纯水通量也随溶解温度的升高而增加。     

羧基化碳纳米管的酯化与酰氯化修饰研究

采用稀硝酸和浓硝酸、浓硝酸和浓硫酸两种方法在碳纳米管上引入羧酸基团，利用羧酸基团修饰的碳纳米管分别与溴代正丁烷和氯化亚砜反应，在碳纳米管上引入了酯基和酰氯基团，采用红外光谱对所引入的基团进行了表征验证，为碳纳米管的进一步功能化和应用提供了实验方法。     

Enhancing performance of ZnO dye-sensitized solar cells by incorporation of multiwalled carbon nanotubes

ABSTRACT: A low-temperature, direct blending procedure was used to prepare composite films consisting of zinc oxide [ZnO] nanoparticles and multiwalled carbon nanotubes [MWNTs]. The mesoporous ZnO/MWNT films were fabricated into the working electrodes of dye-sensitized solar cells [DSSCs]. The pristine MWNTs were modified by an air oxidation or a mixed acid oxidation treatment before use. The mixed acid treatment resulted in the disentanglement of MWNTs and facilitated the dispersion of MWNTs in the ZnO matrix. The effects of surface property and loading of MWNTs on DSSC performance were investigated. The performance of DSSCs was found to depend greatly on the type and the amount of MWNTs incorporated. At a loading of 0.01 wt%, the acid-treated MWNTs were able to increase the power conversion efficiency of fabricated cells from 2.11% (without MWNTs) to 2.70%.     

Facile fabrication of polystyrene/carbon nanotube composite nanospheres with core-shell structure via self-assembly

In this paper, a novel method for fabrication of core-shell nanospheres with polystyrene (PS) as the core and multi-walled carbon nanotubes (MWNTs) as the shell via hydrogen-bonding self-assembly is introduced. The PS nanospheres with carboxyl acid groups on the surface (PS-COOH nanospheres) were prepared by typical soap-free emulsion copolymerization with acrylic acid as comonomer. The MWNTs were grafted with poly(vinyl pyrrolidone) (PVP), in which the carbonyl oxygen can act as proton acceptors to form hydrogen bonds with the carboxyl acid groups. The results show that the functionalized MWNTs can self-assemble onto the surface of PS-COOH nanospheres rapidly via hydrogen bonding interaction, and the process is reversible and can be well controlled by adjusting pH value of the system. These core-shell nanospheres have the potential to be used as conductive and synergistic reinforcement fillers in fabricating high-performance and functional nanocomposites.     

静电纺丝制备MWNTs/PVA/PEO复合超细纤维

采用硝酸对多壁碳纳米管(MWNTs)进行纯化处理,利用表面活性剂十二烷基磺酸钠(SDS)或聚乙烯醇(PVA)对纯化后的MWNTs进行了表面修饰,将修饰后的MWNTs添加到PVA和聚氧化乙烯(PEO)共混水溶液中,通过静电纺丝制备了MWNTs/PVA/PEO复合超细纤维。结果表明:PVA修饰的MWNTs比SDS修饰的MWNTs在PVA/PEO纺丝液中有更好的分散稳定性。随MWNTs添加量的增加,纤维的平均直径减小;当添加PVA修饰的MWNTs质量分数为0.53%时,纤维平均直径达368 nm,且纤维表面光滑、分布均匀。     

Studies in chemically modified celluloses. IV. Lactones in chemically modified celluloses

Cellulose has been modified by hydrolysis followed by oxidation with chlorous acid to produce gluconic carboxyl groups, which can form only δ-lactones. A method has been described for reducing these gluconic acid groups by sodium borohydride into alcoholic groups. Iodometric and alkalimetric methods were used for estimating the carboxyl value of various chemically modified samples.