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1.
活性炭材料是一种性能优良的吸附剂,在环境治理方面具有重要的意义。活性炭材料的孔隙结构及表面性质决定了活性炭的性能,通过孔隙结构的调控和表面修饰可以提高其吸附性能。概述了活性炭的各种孔结构调控和表面修饰处理的方法,展望了其发展趋势。 相似文献
2.
Specific interfacial interactions in multi-component systems such as composites improve the chemical compatibility between the filler and the matrix, prevent the filler from aggregating and strengthen the interface. Carbon nanotube (CNT) based polyacrylonitrile (PAN) composites were prepared either by extrusion or electrospinning to yield fibers with diameters on two different scales - micro- and nanometric. Introduction of a third component, ethylene carbonate, a plasticizer which is capable of forming strong dipolar interactions with the nitrile group of the polymer, had a four-fold effect. It enabled melt-processing of the polymer, caused a structural transition in the crystalline matrix, improved the uniformity and decreased the diameter of the electrospun fibers. It also indirectly revealed a preferred interaction between the π-electrons of the CNT and the nitrile groups of PAN, as was identified based on synchrotron microbeam WAXD, DSC, 13C NMR and FTIR of CNT-filled and unfilled PAN fibers. The nature of CNT and PAN interaction was modeled by charge-transfer of CNT π-electrons from the highest occupied molecular orbital to the empty nitrile π ∗ orbital of PAN. 相似文献
4.
The properties of the fiber/matrix interface in carbon fiber-reinforced composites play a dominant role in governing the overall performance of the composite materials. Understanding the surface characteristics of carbon fibers is a requirement for optimizing the fiber-matrix interfacial bond and for modifying fiber surfaces properly. Therefore, a variety of techniques for the surface treatment of carbon fibers have been developed to improve fiber-matrix adhesion as well as to enhance the processability and handling of these fibers. Many research groups have studied the effects of plasma treatments, correlating changes in surface chemistry with the interfacial shear strength. This article reviews the recent developments relative to the plasma surface modification of carbon fibers. 相似文献
5.
Nanofibers produced by electrospinning method are widely used for drug delivery, as tissue scaffolding materials and filtration
purposes where specific pore characteristics are required. For continued growth in these areas, it is critical that the nanofibers
be properly designed for these applications to prevent failure. Most of the current methods only provide an indirect way of
determining pore structure parameters and contain inherent disadvantages. In this study, we developed a novel image analysis
method for measuring pore characteristics of electrospun nanofiber webs. Five electrospun webs with different pore characteristics
were analyzed by this method. The method is direct, very fast, and presents valuable and comprehensive information regarding
pore structure parameters of the webs. Two sets of simulated images were generated to study the effects of web density, fiber
diameter and its variations on pore characteristics. The results indicated that web density and fiber diameter significantly
influence the pore characteristics, whereas the effect of fiber diameter variations was insignificant. 相似文献
6.
以电煅无烟煤(5~3、3~1、≤1及≤0.088 mm,w(固定碳)=95.17%,w(挥发分)=0.37%,w(灰分)=4.14%)、鳞片石墨(≤0.147和≤0.074 mm,w(固定碳)=96.5%)、棕刚玉粉(≤0.074 mm,w(Al2O3>)=93.5%,w(TiO2)=2.3%)和硅粉(≤0.043 mm,w(Si)=96.37%)为原料,固定骨料与细粉的质量比为60∶40,细粉中硅粉和电煅无烟煤细粉总量固定为14%(质量分数),改变硅粉加入量(质量分数)分别为3%、5%、8%、10%、14%,以液态热塑性酚醛树脂为结合剂,乌洛托品作固化剂制成炭砖,于1 400℃3 h埋炭焙烧,借助于X射线衍射仪、压汞仪、激光导热仪、扫描电子显微镜和能谱分析仪等测试手段,研究了不同硅粉加入量的焙烧炭砖的孔结构及热导率.结果表明:因炭砖焙烧过程单质硅原位反应形成β-SiC、Si2N2O和石英等陶瓷相,填充、阻隔或封闭了气孔,故硅粉加入量控制着试样内部的气孔分布、平均孔径和孔径<1 μm气孔的孔容积率;受材料组成和孔结构变化影响,炭砖的热导率也发生相应变化;随硅粉加入量增加,试样中孔径分布范围由宽变窄,平均孔径逐渐减小,<1 μm孔的容积率增加,气孔呈微孔化趋势;当试样中硅粉加入量超过8%时,气孔的平均孔径<0.3 μm,<1 μm孔容积率超过70%,试样的热导率急剧下降. 相似文献
7.
Carbon microfibers suspended across carbon walls were fabricated by Electro-Mechanical Spinning and subsequent pyrolysis of a SU-8 based carbon precursor. The shrinkage and elongation of these polymer fibers during the pyrolysis process was observed to depend on the height of the supporting walls. We demonstrate that this shrinkage and elongation during pyrolysis strongly influences the resulting carbon electrical properties. Compared to fibers that retained their length during pyrolysis, conductivity was enhanced by a factor of seven after fibers were elongated four times their initial pre-pyrolysis length with a concurrent shrinkage of their diameter by half. 相似文献
8.
在工程线上进行了四元共聚及四元氨化改性聚丙烯腈(PAN)原丝及其碳纤维研制。采用浊点测试法表征了含磺酸基第四单体纺丝液的亲水性,并确定了其共聚含量;通过动态机械分析(DMA)和差示扫描量热分析(DSC)分别测试了氨化前后原丝的玻璃化转变温度(Tg)和预氧化特性。采用质量膨润度、原丝碘吸附量、结晶取向度、原丝体密度等表征了氨化前后四元共聚原丝的结构致密性。结果表明,氨化改性较磺酸基第四单体可显著提高四元共聚纺丝液的亲水性;红外光谱证明第四单体共聚于PAN分子链中;氨化后PAN原丝Tg升高约2.6℃,达到111.28℃;氨化未改变预氧化的峰顶温度。质量膨润度及原丝体密度表明氨化提高了原丝的致密性,但结晶取向度和原丝拉伸模量下降。工程线上碳纤维生产结果表明,四元氨化改性碳纤维强度〉3 500 MPa的合格率较四元共聚的提高12%,达到90%,同时钩接强力也由四元的76 N提高到87 N。 相似文献
10.
A simple method for the synthesis of multi-walled carbon nanotubes (MWCNTs) containing Si, P–N and N is reported, and their gas sensing properties were investigated. The MWCNTs were synthesised by the thermal decomposition of aerosols containing mixtures of ferrocene/triphenylsilane, ferrocene/triphenylphosphine/benzylamine, and ferrocene/benzylamine/toluene. Electron microscopy studies revealed that the addition of Si, P, and N alters the structure of CNTs dramatically. Gas sensing experiments were carried out using Si, P–N, N-containing MWCNTs, and were compared with pure MWCNTs synthesised at similar experimental conditions. These experiments showed that the gas sensitivity and selectivity of CNT-based sensors can be indeed tailored without any post-processing of the raw nanotubes. The efficient in situ tailoring of nanotube properties and functionality are important for nanotubes to become viable materials at the industrial scale where low cost processes are required. 相似文献
11.
Piezoresistive behavior of individual electrospun carbon nanofibers (CNF) was studied for the first time via a microelectromechanical systems platform. The gage factor of CNFs was found to vary from 1.96 to 2.55, not correlating with nanofiber diameter. The measured strain sensitivity of electrical resistance of individual CNFs could not be solely explained based on strain induced dimensional changes of CNFs, pointing to piezoresistivity in nanofibers. The microstructure of CNFs was studied via TEM imaging and Raman spectroscopy, suggesting the presence of sp 2 and sp 3 hybridized carbon atoms in CNFs. The piezoresistivity of CNFs was explained in light of their hybrid structure. A one-dimensional model was adopted to relate CNFs piezoresistivity to their microstructure and electron tunneling between sp 2 hybridized regions through sp 3 hybridized regions. The calibrated model revealed tunneling distances of 0.15–0.3 nm between sp 2 hybridized atoms. Moreover, our study pointed to the degree of graphitization and elastic mismatch between differently hybridized carbon atom regions in CNFs as critical parameters controlling CNFs’ piezoresistivity. This study sets the stage for the utilization of CNFs, not just as load bearing elements, but also as multifunctional nanoscale components with strain sensing capabilities, for instance in Nanoelectro-mechanical systems applications. 相似文献
12.
简介了碳纤维的界面特征及相关的界面理论,综述了冷等离子体接枝法、γ射线辐射处理技术、表面电聚合涂层技术、超声连续改性处理技术等碳纤维表面改性技术的现状与发展趋势,并对每一种不同表面改性技术的优劣进行了比较。 相似文献
13.
Activated carbon fibers (ACFs) prepared from petroleum isotropic pitch and the same containing silver and cobalt nitrate, cobalt and palladium acetylacetonates, as well as mixtures of two salts with a total metal or metal mixture content of 1 wt% have been studied. The processing parameters are summarized for activated carbon fibers containing individual metals and metal mixtures. The results suggest that the generation of metal-containing particles and the formation of pore structure depend on many different factors including the composition of the metal and pitch precursors, the interaction of the metal and pitch precursors during the fiber production process, and the interaction between the two metal precursors when more than one metal salt is used. The addition of silver and cobalt in the form of nitrate salts enlarges the micropores and generates small mesopores with a narrow range of sizes. The addition of palladium as an acetylacetonate salt leads to the formation of both small micropores and larger mesopores. The cobalt additive as an acetylacetonate salt catalyzes the activation process, creating large mesopores and macropores. Mixing of two different metal precursors affects the particle composition and size. This, in turn, controls the pore structure of the final activated fibers. During activation, the two metal precursors can act independently (Ag/Co mixture). However, in other cases their effect can be additive (Co/Pd mixture), or even synergistic (Ag/Pd mixture). 相似文献
17.
In the present work, carbon black (CB) works as a pore-forming agent in the preparation of alumina porous ceramics. The pore structures ( i.e. mean pore size, pore size distribution and various pores size proportions) were characterized by means of Micro-image Analysis and Process System (MIAPS) software and mercury intrusion porosimetry. Then their correlation and thermal conductivity as well as strength were determined using grey relation theory. The results showed that the porosity and mean pore size increased against the amount of CB, whereas the thermal conductivity, cold crushing strength and cold modulus of rupture reduced. The <2 μm pores were helpful for enhancing the strength and decreasing the thermal conductivity whereas the >14 μm pores had the opposite effects. 相似文献
18.
In our study, mesoporous carbon fibers were prepared by using electrospinning and physical activation. In order to develop mesoporous structure, silica was used as a physical activation agent due to meso-size of particle. The diameter of activated carbon fibers increased and surface became rougher after physical activation. Textural properties of carbon fibers were evaluated by using surface pore structure analysis apparatus. The specific surface area increased 12 times and total pore volume increased about 57 times through physical activation using silica. The development of mesoporous structure was confirmed by pore size distribution and fraction of micropore volume. From the DFT pore size distribution, it is sure that broad meso-sized porous carbon fibers were obtained from physical activation in our experiment. The fact that fractions of micropore volume are too low showing less than 2% by the results of total pore volume and HK pore volume concedes that silica activated CFs are pretty mesoporous. Eventually activated carbon fibers having broad meso-sized pores were obtained successfully. 相似文献
19.
Composites of diamond-reinforced particles offer extraordinary thermal- and mechanical characteristics attributable to their manageable outer surface and huge available uppermost layer. Uniform distribution of diamond powder in polymeric matrix, and enhanced interactions between them are the two significant problems to attain robust polymer composites. In this work, the crystalline diamond particles as received and chemically modified ones were integrated in polyacrylonitrile (PAN) matrix uniformly by electrospinning method. This procedure avoided agglomeration of the reinforced diamonds through uniform distribution in the polymer matrix. The shapes of diamond-integrated PAN fibers were attuned by adapting diamond loading, polymer concentration, flow rate, and applied voltage to achieve beads free fibrous structures. PAN was chosen as a carrier polymeric-matrix to enhance the electrostatic forces between functionalized diamond-particles and PAN molecular chains. Tensile tests showed that the loading of 2 wt% modified diamond-particles improved Young’s modulus of fibers by 74.94% and tensile strength by 125%. Therefore, modification of the outer surface of the diamond particles improved the chemical interactions between the diamond surface and matrix, and stress was transferred to the diamond particles in composite fibers. Additionally, thermal stabilities of the diamond-based polymer composites were enhanced by the integration of diamond powder in composite fibers. 相似文献
20.
在自制的实验装置上,研究了粘胶基活性炭纤维(ACF)对甲苯气体的吸附及其吸附饱和后采用高温水蒸气解吸、再生。正交实验表明,甲苯气体流量、浓度和粘胶基ACF的填充高度对吸附过程都有显著的影响。最佳操作参数为:温度13.0℃、粘胶基ACF用量1.50 g、填充高度15 cm、甲苯气体流量0.8 m3/h、甲苯进口平均浓度89.7 mg/m3,脱附平均温度136.0℃时,粘胶基ACF对甲苯气体吸附再生效果较好。验证了粘胶基ACF的吸附量与气体进口浓度成正比,与气体流量成反比关系。 相似文献
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