Facile fabrication of magnetic nanocomposites of ordered mesoporous carbon decorated with nNickel nanoparticles

A magnetic nanocomposite of ordered mesoporous carbon (CMK-3) decorated with nickel nanoparticles was synthesized successfully by a simple chemistry method. Nickel nanoparticles were prepared and uniformly supported on ordered mesoporous carbon CMK-3 by reduction route with CMK-3 as a reducing agent at 673 K. The Ni/CMK-3 composite materials were characterized by powder X-ray diffraction, nitrogen sorption, and transmission electron microscopy. As-prepared nickel nanoparticles supported on CMK-3 were crystalline with a face-center-cubic phase and a size distribution ranging from 10 to 60 nm. The BET special surface area and pore volume of Ni/CMK-3 were as high as 797 m2 g(-1) and 0.72 cm3 g(-1), respectively. The formation mechanism of the nickel nanoparticles outside the surface of CMK-3 was preliminarily discussed. The hysteresis loops of the CMK-3 decorated with nickel nanoparticles were measured by vibrating sample magnetometer (VSM), and the results showed that the composite was ferromagnetism with the saturated magnetization of 15 emu/g, and the coercivity value of 214 Oe. Furthermore, the application of Ni/CMK-3 as magnetically separable adsorbent for vitamin B2 was primarily examined in this study.     

Preparation of hydrophilic mesoporous carbon and its application in dye adsorption

A hydrophilic mesoporous carbon (H-MS) has been prepared by a rapid redox reaction between mesoporous carbon (CMK-3) and an acidic potassium permanganate (KMnO₄) solution at room temperature. The obtained material has a hydrophilic surface by the modification of oxygen-containing groups, and meanwhile retains the ordered mesoporous structure. No obvious difference of pore size between H-MS and CMK-3, and the slight decrease of surface area and pore volume is due to the modification of oxygen-containing groups on the carbon surface. An improved property for adsorbing dyes in aqueous solution was observed in H-MC, and the adsorption amount at equilibrium is ~ 3 times higher than that of CMK-3.     

Facile fabrication of copper-supported ordered mesoporous carbon for antibacterial behavior

Copper-supported ordered mesoporous carbon (Cu/CMK-3) was prepared by impregnating ordered mesoporous carbon (CMK-3) with CuCl₂ aqueous solution. CMK-3 was served as a carrier for the continuous immobilization of Cu. The supported copper was observed to be the bivalence state, indicating that the Cu²⁺ ion was not reduced into cuprous species or metallic copper in the CMK-3. The BET surface area and pore volume of Cu/CMK-3 were 728 m²/g and 0.95 cm³/g, respectively. The antibacterial activities of Cu/CMK-3 were tested by means of minimal inhibitory concentration (MIC) and viable cell counting method. The results show that Cu/CMK-3 presents a good antibacterial performance against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), which indicates its potential applications as antibacterial material for microbiocides.     

Enhanced Dielectric Performance in Polymer Composite Films with Carbon Nanotube‐Reduced Graphene Oxide Hybrid Filler

The electrical conductivity and the specific surface area of conductive fillers in conductor‐insulator composite films can drastically improve the dielectric performance of those films through changing their polarization density by interfacial polarization. We have made a polymer composite film with a hybrid conductive filler material made of carbon nanotubes grown onto reduced graphene oxide platelets (rG‐O/CNT). We report the effect of the rG‐O/CNT hybrid filler on the dielectric performance of the composite film. The composite film had a dielectric constant of 32 with a dielectric loss of 0.051 at 0.062 wt% rG‐O/CNT filler and 100 Hz, while the neat polymer film gave a dielectric constant of 15 with a dielectric loss of 0.036. This is attributed to the increased electrical conductivity and specific surface area of the rG‐O/CNT hybrid filler, which results in an increase in interfacial polarization density between the hybrid filler and the polymer.     

SiC填料对光伏封装用EVA导热复合胶膜的影响

目的探讨乙烯-醋酸乙烯酯共聚物(EVA)胶膜中加入晶须碳化硅(SiC)无机填料后,对EVA胶膜交联度、力学性能及导热性能的影响。方法通过将晶须SiC无机填料导入EVA,使得在整个体系内呈连续相的有机大分子与呈分散相的无机填料共混成一体,再通过挤出流延成形得到厚度均一的胶膜。结果随着晶须SiC含量的增加,EVA复合胶膜的抗拉强度和断裂伸长率均有所下降。交联度随着SiC含量的增加而略微增大,最终达到平衡,剥离强度先增大后减小。使用不同的偶联剂对SiC表面进行处理,EVA导热复合胶膜导热性能存在差异。使用同一种偶联剂对SiC表面进行处理,SiC粒径尺寸的差异同样对EVA导热复合胶膜导热性能存在差异。结论添加晶须SiC的尺寸规格、添加量、表面处理情况对EVA导热复合胶膜的力学性能、交联度影响较大。     

Numerical Study of Thermal Conductivities of Carbon-Based Mesoporous Composites

The thermal conductivities of ordered mesoporous carbon CMK-3 filled with Al nanoclusters were studied in this article. CMK-3 is a typical example of carbon rods which are arranged in a relatively regular two-dimensional hexagonal array. The initial structure of CMK-3 was generated from the amorphous carbon and validated by XRD simulation which is coincident with experimental data. The thermal conductivities of carbon rods in CMK-3 and Al nanoclusters with 133 atoms were simulated by an equilibrium molecular dynamics method. Then, the effective thermal conductivity (ETC) of a mesoporous composite, CMK-3 filled with \(\text {Al}_{133}\) , was obtained via one-dimensional heat conduction analysis. The influences of the substrate porosity, nanocluster filling ratio, and temperature were discussed. As an anisotropic material, ETCs along the \(X\) and \(Y\) directions are extremely poor, due to the overwhelming effect of the air thermal resistance. However, in the \(Z\) direction, the ETC improves almost linearly as the porosity decreases, and the value is much higher than those of \(X\) and \(Y\) directions. In the case of a 70 % filling ratio, when the porosity is below 59.7 %, the ETC in the \(Z\) direction exceeds the thermal conductivity of Al nanoclusters and approaches a peak value around the melting temperature of \(\text {Al}_{133}\) nanoclusters. The results indicate that the carbon-based mesoporous CMK-3 filled with Al nanoclusters might become a promising phase change material.     

Ordered mesoporous carbon-supported CoFe<Subscript>2</Subscript>O<Subscript>4</Subscript> composite with enhanced lithium storage properties

A high and stable reversible specific capacity (1277.7 mAh g^?1) was successfully achieved by the CoFe₂O₄/ordered mesoporous carbon nanohybrids (CFO/CMK-3) composite anode at the current density of 0.1 A g^?1 after 100 cycles. CFO/CMK-3 electrode also exhibited a stable capacity up to 733.2 and 482.6 mAh g^?1 at the current densities of 0.5 and 1 A g^?1 after 500 cycles, respectively. The CFO particles were found to be uniformly distributed inside the pore channels of CMK-3. Structure characterization before and after 100 tests revealed that the specific CMK-3 mesoporous structure and CFO crystallites remained unchanged. The stability of the anode composite stability and the rapid redox capability of CFO gave rise to superior lithium storage capacity and excellent cycling stability. CFO/CMK-3 showed a great promise to serve as anode for high-performance lithium-ion battery.     

导热高分子材料在包装印刷领域的研究进展

目的综述导热高分子材料在包装印刷领域的应用及研究现状,拓展导热高分子材料的应用领域。方法首先介绍2类导热高分子材料的制备方法,即本征型和填充型导热高分子材料;其次全面综述用于包装印刷领域的导热膜/纸、导热胶黏剂和导热油墨;最后总结常用的各类导热机理模型。结果与本征型导热高分子相比,填充型导热高分子具有加工简单、成本低廉、应用面广等优点,是目前研究最多的导热高分子材料。导热膜/纸、导热胶黏剂和导热油墨具有广泛的研究基础,市场需求旺盛。导热预测模型虽能够有效预测复合材料的热导率,但会受到填料含量和粒子形貌的影响。结论导热高分子材料在包装印刷领域拥有巨大的应用需求,开展导热高分子的研究具有重要的现实和理论意义。     

Improved mechanical and thermal properties of spent coffee bean particulate reinforced poly(propylene carbonate) composites

Using biodegradable polypropylene carbonate (PPC) as the polymer matrix and 5 to 25?wt% content of spent coffee bean powder (SCBP) as filler, completely biodegradable composite films of PPC/SCBP were prepared. These composite films were characterized by polarized optical microscopy (POM), Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), thermogravimetric analysis, differential scanning calorimetry (DSC), and tensile tests. The POM images indicated the uniform distribution of the SCBP in the composites. The FTIR spectra indicated that the PPC structure was retained by the composite films. The XRD analysis found that the composite films had lower crystallinity than the PPC due to the presence of amorphous hemicellulose containing SCBP. A significant enhancement in thermal stability of the filler reinforced composite was noticed which was more than 30% of the PPC matrix due to the presence of polyphenols in SCBP. A maximum increase of 35% of tensile strength was observed with the addition of 20?wt% SCBP filled composite films. These biodegradable composite films with higher thermal stability and tensile strength can be considered for packaging applications.     

纳米导电胶粘剂的研究

采用化学镀法在碳纳米管表面包覆金属银,从而获得了导电性极好的纳米银-碳复合管,并以该复合管为导电功能体制备导电胶。研究表明,所得的纳米导电胶导电性和理化性能均较好,且比传统的银粉导电胶节省银30%～55%。     

Synthesis, characterization, and evaluation of lubrication properties of composites of ordered mesoporous carbons and luminescent CePO4:Tb nanocrystals

Having new potential applications in forging processes in mind, composites of an ordered mesoporous carbon and luminescent metal phosphate nanocrystals were synthesized for the first time. Three kinds of CMK-3/CePO₄:Tb nanocomposites were prepared by treating a mesoporous CMK-3 host with different lanthanide phosphate precursor solutions. Characterization of the obtained nanocomposites by small-angle X-ray scattering, wide-angle X-ray diffraction, transmission electron microscopy, thermogravimetry, and nitrogen physisorption analysis showed that in two cases, the nanocrystals (ca. 2–3 nm in size) were located inside the mesopores, whereas in the third case the nanocystals (ca. 6 nm in size) merely adhered to the outer surfaces of the carbon particles. The CMK-3 and the two nanocomposites had ordered hexagonal structures (space group p6mm); all the materials possessed amorphous carbon walls. After combustion of the nanocomposites, the residues upon excitation with UV light exhibited the typical green luminescence of Tb³⁺. A preliminary evaluation of the lubrication properties of the CMK-3 and one nanocomposite material was performed. The friction factors determined by means of ring upsetting tests revealed that the carbon materials were able to lower frictional forces although they were 3–4 times less efficient than a commercial graphite-based reference lubricant.     

石墨烯硅橡胶复合材料的性能研究

本文采用复配的石墨烯、碳纳米管和氧化铝为导热填料制备了具有导热功能的有机硅复合材料。研究了石墨烯、碳纳米管和氧化铝的复配比例对复合材料体积电阻率、导热系数、拉伸强度等性能的影响;同时,以Gr-C-4#样品为基础配方,采用硅烷偶联剂Si-G-1分别对石墨烯、碳纳米管及氧化铝进行改性,并用改性后的填料配制石墨烯硅橡胶复合材料Gr-C-Si-1#,对比样品Gr-C-4^#与Gr-C-Si-1^#的性能差异,分析了改性复配填料对复合材料性能的影响。采用石墨烯硅橡胶复合材料对电缆终端进行了封装,对封装好的电缆终端开展了100、150、200A电流下的温升实验,未出现局部过热,并测定水浸泡前后的电缆终端电阻,封装后的电缆终端电阻未出现明显上升,实验结果表明本材料可以在电缆终端或中间连接处进行灌封,可对封铅连接处的良好的保护作用,工程应用意义重大。     

Sonochemical synthesis of ordered SnO₂/CMK-3 nanocomposites and their lithium storage properties

In this study, we successfully prepare SnO(2) nanoparticles inside the pore channels of CMK-3 ordered mesoporous carbon via sonochemical method. The content of SnO(2) is 17 wt % calculated according to the energy-dispersive X-ray spectroscopy (EDS) result. CMK-3 with 17 wt % loading of SnO(2) nanoparticles has a large specific surface area and pore volume. Electrochemical performance demonstrates that the ordered SnO(2)/CMK-3 nanocomposites electrode possesses higher reversible capacity and cycling stability than that of original CMK-3 electrode. Moreover, the ordered SnO(2)/CMK-3 nanocomposites electrode also exhibits high capacity at higher charge/discharge rate. The improved electrochemical performance is attributed to the nanometer-sized SnO(2) formed inside CMK-3 and the large surface area of the mesopores (3.4 nm) in which the SnO(2) nanoparticles are formed.     

膨胀石墨-碳纤维/尼龙三元导热复合材料制备

以尼龙6（PA6）为基体,膨胀石墨（EG）和碳纤维（CF）作为导热填料,采用熔融共混法制备了EG/PA6、CF/PA6和CF-EG/PA6导热复合材料。重点研究当固定导热填料（CF和EG）填充量为40wt%时,CF与EG不同的填充比例对CF与EG的接触方式及CF-EG/PA6复合材料的导热性和力学性能的影响。结果表明,相比单一CF填充,EG的加入有利于CF-EG/PA6复合材料热导率的增加;CF:EG质量比是25:15时的EG-CF/PA6三元复合材料,热导率可以达到2.554 W/（m·K）,是PA6的8倍,拉伸强度提高了125.34%,弯曲强度提高了119.8%,同时具有优异的耐热性。SEM结果表明,纤维状CF与蠕虫状EG片层在适当的填充比例下可以形成"面接触"的三维网络结构,这种三维网络结构不仅显著增大EG-CF/PA6复合材料的热导率,而且明显提高了其力学性能和耐热性能。为研制填充型导热高分子材料提供了一条新思路。      

Synergetic effects of carbon nanotubes and carbon fibers on electrical and self-heating properties of high-density polyethylene composites

High-density polyethylene (HDPE) composite films filled with carbon fibers (CF), carbon nanotubes (CNT) as well as hybrid filler of CF and CNT were prepared by melt mixing. The electrical and self-heating properties of the composite films were investigated. Results showed that: when the total content of filler was the same, (i) the electrical resistivity of composite films filled with hybrid fillers was lower than those with single filler; (ii) the composite films filled with hybrid fillers displayed more excellent self-heating performance such as a higher surface temperature (T _s), a more rapid temperature response, and a better thermal stability. This indicates the synergetic effect of combination of CNT and CF on improvement of the electrical and self-heating properties of HDPE-based composite films. The synergy can be considered to be the result of the fibrous filler CF acting as long distance charge transporters and the CNT serving as an interconnection between the fibers by forming local conductive paths.     

Electromagnetic shielding effectiveness of thin film with composite carbon nanotubes and stainless steel fibers

Using the polymer blending method, conductive materials and waterborne polyurethane (WPU) were mixed to fabricate conductive composite films for application in electromagnetic shielding. First, nitric acid was used to purify the multi-walled carbon nanotubes (MWCNT). Second, sodium dodecyl sulfate (SDS) was utilized to disperse the carbon nanotubes, and then they were mixed with 8 microm diameter and 2 mm long stainless steel fibers (SSF) in the WPU by the polymer blending method. Finally, the thickness of 0.25 mm of conductive composite film was fabricated by means of coating. According to the ASTM D4935-99 standard, a coaxial transmission line was used to measure the electromagnetic shielding effectiveness (EMSE) of conductive composite film within the range of 50 MHz approximately 3.0 GHz. Moreover, the influence of the prior and posterior dispersion of carbon nanotubes dispersed on electromagnetic shielding was dealt with in the paper. Results demonstrated that the conductive composite film, within 50 MHz approximately 3.0 GHz, fabricated by the 15 wt% of the multi-walled carbon nanotubes and 30 wt% of the stainless steel fibers can achieve the maximum of the electromagnetic shielding effectiveness, 34.86 dB, and its shielding effect, 99.9%.     

Evaporation-controlled nanocasting approach to a precision replication at nanometer scale

An evaporation-controlled nanocasting approach, a templating method in which a precision replication can be realized for the first time, was demonstrated for preparing highly ordered mesoporous materials. To ensure a complete filling of the pores of mesoporous carbon (CMK-3), an excessive amount of tetraethyl orthosilicate (TEOS) was used for infiltration. After the infiltration step, the TEOS molecules on the particle external surface were removed by evaporation. The obtained silica replica, ECN-S, can not only retain the macroscopic morphology, but also have the same lattice parameter as the carbon mold. Interestingly, it is observed that the wall thickness of ECN-S is exactly the same as the pore size of CMK-3, and the pore size of ECN-S is also the same as the wall thickness of CMK-3.     

Effect of the addition of milled carbon fiber as a secondary filler on the electrical conductivity of graphite/epoxy composites for electrical conductive material

In this work, carbon composite bipolar plates consisting of synthetic graphite and milled carbon fibers as a conductive filler and epoxy as a polymer matrix developed using compression molding is described. The highest electrical conductivity obtained from the described material is 69.8 S/cm for the in-plane conductivity and 50.34 S/cm for the through-plane conductivity for the composite containing 2 wt.% carbon fiber (CF) with 80 wt.% filler loading. This value is 30% greater than the electrical conductivity of a typical graphite/epoxy composite with 80 wt.% filler loading, which is 53 S/cm for the in-plane conductivity and 40 S/cm for the through-plane conductivity. The flexural strength is increased to 36.28 MPa compared to a single filler system, which is approximately 25.22 MPa. This study also found that the General Effective Media (GEM) model was able to predict the in-plane and through-plane electrical conductivities for single filler and multiple filler composites.     

聚偏氟乙烯基复合材料的制备及介电性能

为有效改善聚合物基复合材料的介电性能,兼顾高介电常数和低填料量同时并存,采用以聚偏氟乙烯(PVDF)为基体树脂,钛酸钡(BT)和石墨烯(GNP)分别为介电填料和导电填料,在BT-GNP/PVDF复合体系内部构建微电容器结构.采用溶液法和热压法制备GNP/PVDF薄膜和BT-GNP/PVDF复合薄膜.结果表明,BT和GN...     

石墨/酚醛树脂复合材料双极板的制备与性能

双极板是质子交换膜燃料电池的重要组成部分,石墨与聚合物的复合材料双极板是目前研究的重要方向。采用模压热固化二步法,以酚醛树脂为粘结剂、天然鳞片石墨为导电骨料、炭黑为添加剂制备了质子交换膜燃料电池用复合材料双极板。系统研究了不同种类石墨对石墨/酚醛树脂复合材料电性能和抗弯强度的影响。结果表明:以天然鳞片石墨为导电原料时,所制备的石墨/酚醛树脂双极板的性能最好;添加导电炭黑能有效提高石墨/酚醛树脂复合材料的电导率;在复合材料制备中加入4wt%的碳纤维,碳纤维-石墨/酚醛树脂复合材料的抗弯强度提高了29%;碳纤维表面液相氧化处理能有效提高纤维与基体间的结合强度,随着处理时间的延长与处理温度的升高,碳纤维-石墨/酚醛树脂复合材料的电导率和抗弯强度都有很大程度的提高;最终固化温度主要影响酚醛树脂的交联程度,随着最终固化温度的升高,酚醛树脂的交联程度增加,电导率增大,但抗弯强度有一定程度减小。