载镍碳纳米管的载镍量分析

采用灼烧法预处理、丁二酮肟重量分析法来测定载镍碳纳米管的载镍量,获得稳定而准确的分析结果。结果表明,制备载镍碳纳米管催化剂时所加入的镍并不全部吸附在碳纳米管上;载镍效率随着碳纳米管载镍量的增加而降低。     

Ag/CNTs催化剂的载银量分析

在碳钠米管负载金属催化剂研究中，为了获得准确、可靠的载银数据，采用灼烧作预处理，佛尔哈德(Volhard)法测定了碳纳米管的载银量。结果表明，制备载银碳纳米管催化剂时所加入的银并不全部吸附在碳纳米管上，载银效率在75％左右。     

信箱

问:硫化镉或硫硒化镉颜色进行化学分析时,如何测定其中所含杂质碳酸镉或氧化镉?测定硫硒化镉中的硫含量时,如何排除硒的干扰? 答(一):未经煅烧的硫化镉、硫硒化镉颜料往往含有碳酸镉,而煅烧后则往往含有氧化镉。用氨性混合液溶解硫化镉和硫硒化镉中的碳酸镉或氧化镉,然后用EDTA标准溶液测定滤液中的镉氨络离子,方法简单、准确、快速。 氨性混合溶液的配制:27克NH_4Cl溶解于     

可控粒径纳米硫化镉的制备

采用溶剂热法,通过改变实验条件,得到影响粒径的主要因素和影响规律;在此基础上,制备了平均粒径范围是2.5～105 nm的六方球形纳米硫化镉。结果表明,硫源和镉源、S/Cd物质的量比和溶剂用量是影响粒径的主要因素。不同硫源、镉源适用于制备不同粒径范围的纳米硫化镉,采用TAA、乙酸镉并改变S/Cd配比和溶剂体积可制备出平均粒径在2.5～21.6 nm的纳米硫化镉;采用硫脲和硝酸镉并改变S/Cd配比可制备出平均粒径在38.5～105 nm的纳米硫化镉;纳米硫化镉的粒径随S/Cd物质的量比的增大而增大;随溶剂用量的增加而增大;反应温度对纳米硫化镉的粒径没有影响。纳米硫化镉的可控粒径的制备方法对纳米硫化镉的制备、研究与应用具有着重要的参考价值。     

金属元素在有色光学玻璃中的着色(续二)

八、硫化镉和硒的着色 (一) 硫化镉和硒着色的概况 用硫化镉和硒可使玻璃产生黄、橙、红等一系列颜色。这类玻璃的光谱透过曲线具有很大的斜率,也就是说有很纯的黄色、橙色和红色。这类有色光学玻璃在照相、电影、光学仪器和军事工业中有较广泛的应用。图31是硒硫化镉玻璃典型的光谱透过曲线。这类玻璃不是镉离子,硒离子或元素镉和硒着色,而是硫化镉(CdS)胶体和硒化镉(CdSe)胶体着色的。     

可控粒径纳米硫化镉的制备

采用溶剂热法,通过改变实验条件,得到影响粒径的主要因素和影响规律;在此基础上,制备了平均粒径范围是2.5～105 nm的六方球形纳米硫化镉。结果表明,硫源和镉源、S/Cd物质的量比和溶剂用量是影响粒径的主要因素。不同硫源、镉源适用于制备不同粒径范围的纳米硫化镉,采用TAA、乙酸镉并改变S/Cd配比和溶剂体积可制备出平均粒径在2.5～21.6 nm的纳米硫化镉;采用硫脲和硝酸镉并改变S/Cd配比可制备出平均粒径在38.5～105 nm的纳米硫化镉;纳米硫化镉的粒径随S/Cd物质的量比的增大而增大;随溶剂用量的增加而增大;反应温度对纳米硫化镉的粒径没有影响。纳米硫化镉的可控粒径的制备方法对纳米硫化镉的制备、研究与应用具有着重要的参考价值。     

分子筛负载硫化镉光催化降解罗丹明B的研究

采用湿化学法制备了分子筛多孔二氧化硅负载硫化镉光催化材料CdS-SiO2,用于可见光降解有机污染物罗丹明B。结果表明,相比单相的硫化镉,分子筛负载的硫化镉表现出更高的光催化效率,且光降解后催化剂沉淀回收后仍可表现出较高的光催化降解能力。     

模板法合成CdS及亚甲蓝光催化降解研究

利用聚丙烯酸钠胶体溶液为模板,通过离子交换反应,形成尺寸约为70 nm的聚丙烯酸镉纳米球;然后与硫化钠反应,制备了表面为硫化镉量子点的纳米球,TEM对聚丙烯酸镉与硫化镉形貌进行了表征。在模拟可见光的条件下,聚丙烯酸-硫化镉纳米球可在5 min内将亚甲蓝降解85.7%。     

采用负载铁的介孔分子筛催化模板剂合成多壁碳纳米管

用水热法合成纯硅介孔分子筛(mesoporous molecular sieves,MCM-41)。用浸渍法将MCM-41负载不同量铁制得负载铁的介孔分子筛(Fe-loading mesoporous molecular sieve,Fe/MCM-41)。以Fe/MCM-41作为催化剂催化热解乙醇制备碳纳米管。用N2物理吸附、Raman光谱、透射电镜和高分辨透射电镜等手段对样品进行了表征。结果表明:制备出了多壁碳纳米管,并且随着催化剂中Fe负载量的增加,所生成碳纳米管的管径增加。     

碳材料吸附去除水体中镉离子研究进展

活性炭、碳纳米管和石墨烯是最主要的三种碳材料,由于其良好的环境稳定性、较大的比表面积以及易修饰性,被作为吸附材料广泛用于去除水中污染物研究,本文重点介绍了三种碳材料改性方法及其吸附水中镉离子研究现状。改性方法主要有两种,一是强酸氧化处理引入含氧官能团,增大比表面积;二是嫁接一些能与镉离子发生离子交换反应的化学官能团。三种材料经过改性后对镉的吸附能力有不同程度提高,吸附量大小顺序为石墨烯碳纳米管活性炭,对镉吸附都是自发吸热反应,遵循拟二级动力学规律。机理分析表明,表面含氧官能团是最主要活性吸附位,通常与镉离子发生离子交换吸附。与活性炭、碳纳米管复合材料相比,石墨烯复合材料吸附能力强,镉最大吸附量可达到250 mg/g左右,而且制备成本低于碳纳米管,易于再生,是一类非常有实用化发展前景的吸附剂。     

Decoration of multiwall nanotubes with cadmium sulfide nanoparticles

This study focuses on in situ synthesis of CdS nanoparticles on the surfaces of multiwalled carbon nanotubes. By chemical reaction of cadmium chloride and thioacetamide in the solution with carbon nanotubes, which were pretreated by air oxidization and acid modification, cadmium sulfide nanoparticles densely supported on carbon nanotubes with 10 nm size and homogeneous distribution were prepared. The composite material with the composite structure of CdS decorating the nanotube surfaces was characterized using scanning electron microscopy, high-resolution transmission electron microscopy, X-ray diffraction and electron diffraction pattern. The CdS nanoparticles are of cubic crystal structure, show good adhesion to the nanotubes. This method can be extended to prepare other inorganic nanoparticle-carbon nanotube composites.     

Mechanical,Rheological, and Electrical Properties of Multiwalled Carbon Nanotube Reinforced Nanocomposites of 50/50 Acrylonitrile–Styrene–Acrylate/Zn+2 poly(ethylene-co-methacrylic acid) Ionomer Blend

The effect of variable amount of multiwalled carbon nanotubes on mechanical, rheological, and electrical properties of acrylonitrile–styrene–acrylate/Zn⁺²-poly(ethylene-co-methacrylic acid) ionomer blend system has been evaluated. Optical micrographs as well as alternating current conductivity data shows the formation of nanotube percolation network at 1 wt% nanotube content. The polymer/nanotube interaction increased the rate of tensile modulus to 55 GPa at low nanotube content. The polymer chain relaxation time was increased upto 1 wt% of nanotube content, but higher nanotube loading reduced the time. The zero-shear viscosity was function of nanotube content whereas the infinite-shear viscosity was independent of nanotube content.     

The effect of nanotube alignment on stress graphitization of carbon/carbon nanotube composites

Carbon nanotubes, when used as filler in a glass-like carbon matrix, has been reported to induce stress graphitization in the matrix. The effects on stress graphitization of the amount of carbon nanotube loading and nanotube orientation in the composite were investigated through microscopy and X-ray diffraction analyses. Results showed that an increase in nanotube content and nanotube alignment could increase the extent of formation of anisotropic regions, thereby hastening stress graphitization. It was shown that the distance between nanotubes could affect the formation of the anisotropic structures, such that they could develop in a circumferential manner around the nanotubes when the nanotubes are situated far from each other or develop continuous regions between nanotubes when they are closer together. The development of these microstructures and its relationship to the residual stresses that accumulate in the material during heat treatment is discussed here.     

碳纳米管填充聚合物基电磁屏蔽复合材料的研究进展

对碳纳米管填充聚合物基电磁屏蔽复合材料的研究进展进行了综述。在阐述研究电磁屏蔽材料必要性的基础上,介绍了复合材料的电磁屏蔽机理,重点论述了碳纳米管填充量、长径比及管径、屏蔽体的厚度、复合材料的加工方式等对复合材料电磁屏蔽性能的影响。最后对碳纳米管填充聚合物基复合电磁屏蔽材料的研究进行了展望,指出低成本填料与碳纳米管协同作用、可提高碳纳米管分散性的制备工艺的研究以及复合材料电磁屏蔽机理的研究等为未来的研究方向。     

Properties of microinjection molding of polymer multiwalled carbon nanotube conducting composites

The effects of processing conditions on the microstructure and properties of polypropylene/multiwalled carbon nanotube (PP/MWCNT) and polycarbonate/multiwalled carbon nanotube (PC/MWCNT) composites were studied. Samples of various MWCNT loadings were prepared by diluting commercial masterbatches. Different processing conditions were then used to systematically change the degree of nanotube alignment, from random to highly aligned. The crystallinity of the PP/MWCNT nanocomposites was found to go through a maximum as a function of nanotube content while the overall rate of crystallization increased. For the highly sheared microinjected PP/MWCNT samples well oriented crystals were formed. Electrical conductivity of the nanocomposites was improved by the presence of the crystalline structure; however, the high degree of nanotube alignment in the microparts resulted in a significant increase in the electrical percolation threshold. The PP nanocomposites exhibited mechanical properties significantly enhanced by nanotube loading; this effect was small in the case of the PC nanocomposites. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers     

Grafting of Amine-Functionalized Multiwall Carbon Nanotubes with Free Acid Anhydride in Carboxylic Acid Modified Epoxy

The novel approach was developed for grafting of amine-functionalized multiwall carbon nanotubes with carboxylic acid, modified epoxy resin containing free acid anhydride group, which gives enhanced grafting. The amine-functionalized multiwall carbon nanotubes was dispersed in benzyl alcohol by sonication at 60°C and incorporated with modified epoxy. The amine functioned Multiwall carbon nanotubes were controlled loading of carboxylic acid, modified epoxy resin-grafted with amine-functionalized multiwalll carbon nanotube polymer composites. These were characterized by FTIR, SEM. TEM and NMR analysis. The improved mechanical properties observed for low amounts of MWCNT loading due to uniform dispersion.     

Ejection of DNA molecules from carbon nanotubes

Ejection of DNA molecule from carbon nanotubes subjected to torsion is investigated with molecular dynamics simulations. The wall of a carbon nanotube undergoes a collapse and a corresponding propagation of the collapse when a torsion loading applied to the tube is beyond a critical value. The van der Waals force between the encapsulated DNA molecule and the collapsed wall of the nanotube on one hand is a driving force to push the molecule out of the tube, while may also prevent the ejection when the onset of the collapsed wall is in front of the molecule. To ensure a complete DNA ejection, a design of a stopper, a small fixed portion on the carbon nanotube to prevent the collapsed wall from propagating in front of the DNA molecule, is developed. The effects of the environmental temperature, the torsion loading, and the size of the nanotube on the delivering process of the DNA molecule are also examined. Simulation results demonstrate the feasibility of ejection of DNA molecules from carbon nanotubes subjected to torsion and provide guidance on designs of the DNA delivery in biology and medical applications.     

Electrical and rheological properties of MWCNT/polycarbonate nanocomposites

The electrical and rheological percolation behaviors of polycarbonate/multiwall carbon nanotube nanocomposites were investigated. To determine the effects of surface functionalization on a carbon nanotube surface, poly(styrene-co-acrylonitrile) (SAN)-grafted multiwall carbon nanotubes were prepared using surface-initiated atom transfer radical polymerization. The amount of grafted SAN was controlled by changing the polymerization time and was characterized using TGA. FT-IR and TEM were used to characterize the surface of the functionalized carbon nanotubes. The rheological and electrical percolation behaviors of the SAN-grafted multiwall carbon nanotube/polycarbonate nanocomposites were compared to those of pristine multiwall carbon nanotubes, where the effects were shown to increase with increasing SAN content. The results are attributed to the compatibility of SAN with polycarbonates, which induced uniform dispersion of the functionalized carbon nanotubes. Uniform dispersion was also confirmed by evaluating a tensile-fractured nanocomposite specimen.     

Trends in Conducting Polymer and Hybrids of Conducting Polymer/Carbon Nanotube: A Review

Several conducting polymers, including polyaniline, polypyrrole, polythiophene, polyvinylpyrrolidone, poly(3,4-ethylenedioxythiophene), poly(m-phenylenediamine), polynaphthylamine, poly(p-phenylene sulfide), and their carbon nanotube reinforced nanocomposites are discussed in this review. The physical, electrical, structural and thermal properties of polymers along with synthesis methods are discussed. A concise note on carbon nanotubes regarding their purification, functionalization, properties and production are reported. Moreover, the article focuses upon synthesis methods, properties and applications of conducting polymer/carbon nanotube nanocomposites are focused. Nanotube dispersion, loading concentration and alignment within conducting polymer/carbon nanotube nanocomposite affect their performance and morphology. The conducting polymer/carbon nanotube nanocomposites are substantially used in sensors, energy storage devices, supercapacitors, solar cells, EMI materials, diodes, and coatings.