多壁碳纳米管的拉曼光谱研究

显微拉曼光谱技术在微尺度测量方面具备无损、无接触和空间分辨率高的优势。实验考察了拉曼激光参数对多壁碳纳米管拉曼特征光谱的影响;确定了使用785 nm拉曼激发光波长来表征多壁碳纳米管及其复合材料,能够有效避免荧光效应;选择<5%的激光功率,能够有效避免热效应。     

Thermal conductivities and Raman spectra of boron-doped carbon materials

Boron-doped carbons were prepared at temperatures from 1000 to 2800°C. The effect of boron doping on the thermal conductivity of carbons has been studied and discussed with the results from Raman scattering. Boron doping above 2200°C depressed the thermal conductivity of carbons and increased the intensity of the 1360-cm⁻¹ Raman band. It appeared that lowering the thermal conductivity is mainly caused by a distortion of the graphite lattice due to boron doping.     

Influence of diameter in the Raman spectra of aligned multi-walled carbon nanotubes

Aligned multi-walled carbon nanotubes (MWCNTs) were produced with different diameters, according to the thickness of Ni catalyst layer, by microwave plasmas enhanced chemical vapor deposition, in N₂/H₂/CH₄ environment. Raman spectroscopy, performed both on top and lateral surfaces, revealed that the relative intensity of the G′ band and the G and G′ bandwidths have high sensitivity to tube diameter distribution and also to structural variations along the tube axis. The D band present a distinct behavior: I_D/I_G is sensitive to structural organization, particularly along tube axis, while D bandwidth is sensitive to tube diameter distribution. This result may indicate D bandwidth as a parameter to correlate to the diameter of the aligned MWCNTs.     

Impedance spectra of carbon black filled high‐density polyethylene composites

Carbon black (CB) filled high‐density polyethylene (HDPE) composites are prepared by ordinary blending for use as an electrical conductive polymer composite. The composite changes from an electrical insulator to a conductor as the CB content is increased from 10 to 20 wt %, which is called the percolation region. For explanatory purposes, three models, namely, “conduction via nonohmic contacting chain,” “conduction via ohmic contacting chain,” and a mixture of them corresponding to the conductions in the percolation region, high CB loading region, and limiting high CB loading are proposed by the reasonable configurations of aggregate resistance, contact resistance, gap capacitance, and joining aggregates induction. The characters of the impedance spectra based on the three models are theoretically analyzed. In order to find some link between the electrical conductivity and the CB dispersion manner in the composites, the impedance spectra of three samples, HDPE/15 wt % CB (the center of the percolation region), HDPE/25 wt % CB (a typical point in the high CB loading region), and HDPE/19 wt % CB (the limiting high CB loading region), are measured by plotting the impedance modulus and phase angle against the frequency and by drawing the Cole–Cole circle of the imaginary part and real part of the impedance modulus of each sample. The modeled approached spectra and the spectra measured on the three samples are compared and the following results are found: the measured impedance spectrum of HDPE/15 wt % CB (percolation region) is quite close to the model of conduction via nonohmic contacting chain. The character of the measured spectrum of HDPE/25 wt % CB consists of the form of the model of conduction via ohmic contacting chain. The impedance behavior of HDPE/19 wt % CB exhibits a mixture of the two models. From the comparisons, it is concluded that the electrical conducting network in the percolation region of the CB filled HDPE composite is composed of aggregate resistance, nonohmic contact resistance, and gap capacitance, and that of the high CB loading region consists of continuously joined CB aggregate chains, which are possibly wound and assume helix‐like (not straight lines) conductive chains, acting as electrical inductions as the current passes through. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 1344–1350, 2005     

Raman spectra of ground natural graphite

Structural changes in Ceylon natural graphite with grinding were studied by Raman spectroscopy along with X-ray diffraction. The natural graphite shows a single Raman band at 1580 cm^?1, but the ground graphite samples exhibit two Raman bands at 1360 and 1620 cm^?1 in addition to the 1580 cm^?1 graphite band. The 1360 cm^?1 band increases in intensity with increasing grinding time, and becomes much stronger than the 1580 cm^?1 band after 200-hr grinding. Raman results are compared with structural parameters such as effective Debye parameter and C₀ spacing obtained from X-ray diffraction measurements, and discussed in terms of structural defects introduced into the crystal lattice of natural graphite. A linear relationship was obtained for the ground graphite when the relative intensity of the 1360 cm^?1 band is plotted as a function of effective Debye parameter. The slope of the linear plot is different for the ground graphite from that for the graphitized cokes, indicating a difference in the type of structural defects involved.     

Fluorination of carbon black

The kinetics of the fluorination of carbon black and the properties of the graphite fluoride prepared are discussed in comparison with those of graphite and petroleum coke. An appreciable weight increase is observed in the fluorination of carbon black even at room temperature because of the large surface area. The increment is approximately proportional to the surface area except for the heat-treated carbon black, and more than twice that of adsorption corresponding to the monolayer of fluorine. An iodide ion is oxidized to iodine by the adsorbed fluorine in the products. The reactivity of carbon black with fluorine decreases with increasing the crystallinity, and the product prepared from the lower crystalline carbon black is less thermostable. The reaction kinetics of carbon black with fluorine is similar to that of graphite, but the diffusion controlled regions are not present in the former. The fluorine content of the graphite fluoride prepared increases with decreasing heat-treatment temperature and with increasing reaction temperature. The crystallinity of the product increases with increasing heat-treatment temperature and with increasing reaction temperature. The heat of immersion of the product inn-butyl alcohol is equal to that of polytetrafluoroethylene.     

Reactions of carbon black. Part I. Nonthixotropic carbon black compositions

The solution polymerization of butyl acrylate in the presence of a furnace black was found to produce a stable dispersion of carbon black which showed Newtonian flow, while the mixture prepared by mixing the same carbon black into a solution of poly(butyl acrylate) homopolymer had a large degree of thixotropy. A marked change in the viscosity of the reaction mixture was also observed at an early stage of polymerization when the initial mixture which was a moist mass with no fluidity, turned to a fluid easily stirred. The change in viscosity and the transition in flow behavior were carefully followed with a rotary cylinder type viscometer. The non-Newtonian initial mixture was found to turn to a Newtonian fluid at low conversion of the monomer. Beside the adsorption of the homopolymer onto the surface of carbon black particles, which would occur also in mechanical mixing, the change in the flow behavior was estimated to be caused by the change in the shape and the size of the dispersed carbon black particles due to the change in the condition of the surface of the particles by which growing polymer radicals, as well as initiator radicals, were captured.     

废轮胎热解炭黑与工业炭黑的粒径及化学组成

用激光粒度分析仪测定了废轮胎热解炭黑的粒径分布,用扫描电子显微镜、X-射线衍射法及X-射线光电子能谱法分析了热解炭黑和工业炭黑的形态、表面化学组成以及表面碳元素的结合状况。结果表明,热解炭黑的粒径分布是添加在轮胎中各种型号工业炭黑粒径分布的叠加。热解炭黑表面形态和组成接近于工业炭黑N660;热解炭黑的表面附着更多的有机物以及ZnO、ZnS等无机物,且随着热解温度的升高,附着的有机物含量减小,无机物中ZnO含量减小,ZnS含量增多。     

紫色方钠石的拉曼光谱研究

通过对云南市场上一种光致变色宝石的拉曼鉴定,检测得出其为紫色方钠石.讲述了激光拉曼光谱的原理与优点,并分析了方钠石的变色原因.     

Effect of carbon black structure on the effectiveness of carbon black thermal interface pastes

Thermal pastes are needed for improving thermal contacts. The structure of carbon black, as described by the DBP value, governs the effectiveness of the black as a thermally conductive solid component in a thermal paste, as shown for pastes with a polyol ester vehicle. Carbon black with a lower DBP value (i.e., a lower structure) is more effective, as shown by a higher value of the thermal contact conductance measured across copper surfaces of roughness 15 μm. This is because a carbon black with a lower structure gives a smaller bond-line thickness, which is preferably less than 3 μm. In addition, this is because a lower structure gives a lower viscosity for the paste, thereby promoting conformability. The carbon black volume fraction has an optimum value for attaining maximum thermal conductance. A lower structure results in a higher value of the optimum carbon black volume fraction, due to the viscosity effect. For the same type of carbon black, this optimum is higher when the paste is tested between rougher surfaces. By using Tokaiblack #3800 carbon black (with DBP value 60 ml/g and optimum carbon black content 15 vol.%), a thermal paste that is more effective than the previously reported paste with Vulcan XC72 carbon black (with DBP value 188 ml/g and optimum carbon black content 2.4 vol.%) has been attained.     

白炭黑/炭黑配比对天然橡胶基复合材料性能的影响

以硅烷偶联剂作为白炭黑(SiO_2)的表面改性剂,以改性SiO_2/炭黑作为天然橡胶(NR)的混合填料,采用半有效硫化体系制备了NR基复合材料。研究结果表明:当m(SiO_2)∶m(炭黑)=20∶40时,硫化胶中混合填料分散均匀,并且硫化胶的撕裂强度(62 k N/m)相对最高、交联密度相对最大且佩恩效应相对较弱。     

Surface modification of carbon black to facilitate suspension polymerization of styrene and carbon black

To carry out suspension polymerization of styrene in the presence of carbon black, an effective method was introduced to modify carbon black using nitric acid for oxygen treatment. The surface modification of carbon black with oxidation was confirmed by Fourier transform infrared spectroscopy, thermogravimetric analysis, and scanning electron microscopy (SEM), which demonstrated that the chemical structure of carbon black has clearly changed. Compared with pristine carbon black (CB), SEM illustrates that the aggregation phenomenon of modified carbon black (MCB) was clearly weakened. After modification, the aggregation and inhibition effects of MCB on the polymerization of polystyrene/modified CB (PS/MCB) composite particles are obviously weakened. The lipophilicity of CB after modification was also increased during the synthesis of PS/MCB. The oxidized CB was successfully dispersed by polystyrene using in situ suspension polymerization. The dispersion and dosage of MCB in PS/MCB composite particles was greatly improved over that of CB in PS/CB composite particles. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46387.     

Electrochemical characterization of carbon black

Electrochemical characterization of carbon black suspensions enabled us to distinguish the presence of phenolic, quinone, carboxylic and lactone groups. In addition, we were able to determine the position of the Fermi level for several carbon blacks, which was found to depend on their acidity.The intensity of each characteristic electrochemical wave gives the concentration of these functional group at the surface of the carbon, while the potential at which the redox process occurs, reflect the energy state of these functional groups.The results of polarographic and voltammetric determination of the functional properties of the surface of eight samples of carbon blacks are given. Chemical modification of the samples changes electrochemical properties of their surface.     

Raman spectroscopy of carbon nanohoops

We present the Raman spectra for [n]Cycloparaphenylenes ([n]CPPs) of different sizes. A plethora of Raman modes are observed in these spectra, including modes that are analogous to those of the carbon nanotubes (CNTs) such as G-band, as well as Raman peaks that are unique for carbon nanohoops. In addition, we have calculated the theoretical Raman spectra of [n]CPPs for n = 4–20 using density functional theory (DFT), which are then compared to the experimental results for the assignment of different modes. The Raman peak positions are seen to be dependent on the size of the nanohoop from both the experimental and the calculated results.     

橡胶用炭黑及特种炭黑主要性能对比

宁波德泰化学有限公司是一家专业生产炭黑的中外合资企业。公司依托中石化华东分公司的乙烯焦油和宁钢的煤焦油等资源优势,在消化吸收国内外先进炭黑生产技术的基础上,开发国内最先进的大型五段反应器生产技术,进口了许多关键生产设备和检测设施,并在原料油预处理、DCS微机控制技术、高温空气预热器、显热回收、高效脉冲袋滤、湿法造粒、炭黑精制处理、尾气综合利用、     

Interpretation of the Raman spectra of ultrananocrystalline diamond

It has long been known that by slightly altering the deposition conditions for diamond in plasma-enhanced chemical vapor deposition (PECVD), a transition from a microcrystalline to a nanocrystalline diamond morphology can be affected. The method of this transition, however, is not clear. This work investigates that transition by using transmission electron microscopy (TEM), scanning electron microscopy (SEM), and Raman spectroscopy. These experiments show that far from being a continuous transition, there is competitive growth between microcrystalline and nanocrystalline diamonds. Additionally, this work confirms the interpretation that certain peaks in the Raman spectrum previously attributed to “nanocrystalline diamond” are indeed due to the presence of hydrogen at the grain boundaries. For ultrananocrystalline diamond (UNCD) films, we verify that none of the spectral features observed using visible Raman spectroscopy can be attributed to sp³-bonded carbon, although the sample is composed of ∼95% sp³-bonded carbon. Thus, the Raman signal in UNCD can be considered to be solely due to the disordered sp²-bonded carbon at the grain boundaries.