EMI shielding and dynamic mechanical analysis of graphene oxide-carbon nanotube-acrylonitrile butadiene styrene hybrid composites

Carbon nanomaterials such as carbon nanotubes (CNTs), graphene and their hybrid have been studied extensively. Despite having excellent properties of CNTs and graphene have not yet been fully realized in the polymer composites. During fabrication agglomeration of CNTs and restacking of graphene is a serious concern that results in the degradation of properties of nanomaterials into the final composites. To improve the dispersion of CNTs and restacking graphene, in the present research work, we focused on the hybridization of graphene oxide and CNTs. Multiwalled carbon nanotubes (MWCNTs), functionalized carbon nanotubes (FCNTs), and graphene oxide-carbon nanotubes (GCNTs) reinforced acrylonitrile butadiene styrene (ABS) composites were prepared separately by vacuum filtration followed by hot compression molding. Further, dynamic mechanical analysis (DMA), and electromagnetic interference (EMI) shielding properties of ABS composites reinforced carbon nanofillers were investigated. The dynamic mechanical properties of polymers strongly depend on the adhesion of fillers and polymer, entanglement density of polymer chains in the presence of carbon fillers. The dynamic mechanical characteristics such as storage, loss modulus, and damping factor of prepared composites were significantly affected by the incorporation of MWCNTs, FCNTs, and GCNTs. Maximum EMI shielding effectiveness of −49.6 dB was achieved for GCNT-ABS composites which were highest compared to MWCNTs-ABS composites (−38.6 dB) and FCNTs-ABS composites (−36.7 dB) in the Ku band (12.4–18 GHz). These results depict the great potential of GCNTs-ABS composites to be used in various applications of efficient heat dissipative EMI shielding materials for electronic devices.     

Raman spectroscopy as a tool for the analysis of carbon-based materials (highly oriented pyrolitic graphite,multilayer graphene and multiwall carbon nanotubes) and of some of their elastomeric composites

Raman spectra of highly oriented pyrolitic graphite, multilayer graphene and multiwall carbon nanotubes are carried out at different laser powers and different excitation energies. The effects of the laser heating and the double resonance Raman scattering are investigated as a prerequisite for a correct interpretation of the Raman spectra of carbon materials-based composites. The Raman spectra of multilayer graphene and multiwall carbon nanotubes embedded in a silicone matrix are also analyzed in an attempt to get some insights into the polymer–filler interface.     

Preparation of antistatic high‐density polyethylene composites based on synergistic effect of graphene nanoplatelets and multi‐walled carbon nanotubes

Graphene nanoplatelets are promising candidates for enhancing the electrical conductivity of composites. However, because of their poor dispersion, graphene nanoplatelets must be added in large amounts to achieve the desired electrical properties, but such large amounts limit the industrial application of graphene nanoplatelets. Multi‐walled carbon nanotubes also possess high electrical conductivity accompanied by poor dispersion. Therefore, a synergistic effect was generated between graphene nanoplatelets and multi‐walled carbon nanotubes and used for the first time to prepare antistatic materials with high‐density polyethylene via 1‐step melt blending. The synergistic effect makes it possible to significantly improve the electrical properties by adding a small amount of untreated graphene nanoplatelets and multi‐walled carbon nanotubes and increases the possibility of using graphene nanoplatelets in industrial applications. When only 1 wt% graphene nanoplatelets and 0.5 wt% multi‐walled carbon nanotubes were added, the surface and volume resistivity values of the composites were much lower than those of the composites that were only added 3 wt% graphene nanoplatelets. Additionally, as a result of the synergistic effect of graphene nanoplatelets and multi‐walled carbon nanotubes, the composites met the requirements for antistatic materials.     

基于碳纳米管的超级电容器研究进展

综述了基于碳纳米管及其复合材料作超级电容器的电极材料的研究现状,通过对碳纳米管的改性或与其它材料复合,能有效地提高电容器的电容特性。总结了近几年来在开发超级电容器电极材料领域中对碳纳米管的活化和提高碳纳米管的分散性技术、碳纳米管与过渡金属氧化物复合材料、碳纳米管与导电聚合物复合材料以及碳纳米管与石墨烯复合材料研究的进展。     

Analytical applications of nanomaterials in electrogenerated chemiluminescence

This critical review covers the use of carbon nanomaterials (single-wall carbon nanotubes, multi-wall carbon nanotubes, graphene, and carbon quantum dots), semiconductor quantum dots, and composite materials based on the combination of the aforementioned materials, for analytical applications using electrogenerated chemiluminescence. The recent discovery of graphene and related materials, with their optical and electrochemical properties, has made possible new uses of such materials in electrogenerated chemiluminescence for biomedical diagnostic applications. In electrogenerated chemiluminescence, also known as electrochemiluminescence (ECL), electrochemically generated intermediates undergo highly exergonic reactions, producing electronically excited states that emit light. These electron-transfer reactions are sufficiently exergonic to enable the excited states of luminophores, including metal complexes, quantum dots and carbon nanocrystals, to be generated without photoexcitation. In particular, this review focuses on some of the most advanced and recent developments (especially during the last five years, 2010–2014) related to the use of these novel materials and their composites, with particular emphasis on their use in medical diagnostics as ECL immunosensors.     

纳米碳材料在可穿戴柔性导电材料中的应用研究进展

可穿戴设备的兴起使得对柔性器件的需求日益提高,柔性导电材料作为可穿戴器件的重要组成部分而成为研究的热点。传统的电极材料主要是金属,因金属材料本身不具有柔性,一般通过降低金属层厚度以及设计波纹结构等策略实现其在柔性器件中的应用,其加工程序复杂,成本较高。以碳纳米管和石墨烯为代表的纳米碳材料兼具良好的柔性和优异的导电性,且具有化学稳定、热稳定、光学透明性等优点,在柔性导电材料领域展现了极大的应用潜力。本文简要综述了近年来纳米碳材料在柔性导电材料领域的研究进展,首先介绍了碳纳米管基柔性导电材料,分别包括基于碳纳米管水平阵列、碳纳米管垂直阵列、碳纳米管薄膜、碳纳米管纤维的柔性导电材料;继而介绍了石墨烯基柔性导电材料,包括基于剥离法制备的石墨烯和化学气相沉积法制备的石墨烯以及石墨烯纤维基柔性导电材料;并简述了碳纳米管/石墨烯复合柔性导电材料;最后论述了纳米碳材料基柔性导电材料所面临的挑战并展望了其未来发展方向。     

Segregated network polymer/carbon nanotubes composites

In this work we present the preparation of conductive polyethylene/carbon nanotube composites based on the segregated network concept. Attention has been focused on the effect of decreasing the amount of filler necessary to achieve low resistivity. Using high- and low-grade single-walled carbon nanotube materials we obtained conductive composites with a low percolation threshold of 0.5 wt.% for high-grade nanotubes, about 1 wt% for commercial nanotubes and 1.5 wt% for low-grade material. The higher percolation threshold for low-grade material is related to low effectiveness of other carbon fractions in the network formation. The electrical conductivity was measured as a function of the single-walled carbon nanotubes content in the polymer matrix and as a function of temperature. It was also found that processing parameters significantly influenced the electrical conductivity of the composites. Raman spectroscopy was applied to study single wall nanotubes in the conductive composites.     

Nanocarbon-Based Flame Retardant Polymer Nanocomposites

In recent years, nanocarbon materials have attracted the interest of researchers due to their excellent properties. Nanocarbon-based flame retardant polymer composites have enhanced thermal stability and mechanical properties compared with traditional flame retardant composites. In this article, the unique structural features of nanocarbon-based materials and their use in flame retardant polymeric materials are initially introduced. Afterwards, the flame retardant mechanism of nanocarbon materials is described. The main discussions include material components such as graphene, carbon nanotubes, fullerene (in preparing resins), elastomers, plastics, foams, fabrics, and film–matrix materials. Furthermore, the flame retardant properties of carbon nanomaterials and their modified products are summarized. Carbon nanomaterials not only play the role of a flame retardant in composites, but also play an important role in many aspects such as mechanical reinforcement. Finally, the opportunities and challenges for future development of carbon nanomaterials in flame-retardant polymeric materials are briefly discussed.     

Synthesis of composites with alternating layers of poly(vinyl chloride) and single-wall carbon nanotubes homogeneously dispersed in carboxymethyl cellulose

For preparation of water-resistant and thermally stable nonlinear optical elements containing single-wall carbon nanotubes, an original method for the formation of layered structures based on alternating layers of poly(vinyl chloride) and a water-soluble polymer (carboxymethyl cellulose) with dispersed singlewall carbon nanotubes is proposed. An analysis of the optical properties of the resulting composites by means of optical-absorption spectroscopy and Raman scattering makes it possible to confirm that the nanocomposites contain individual (not united in bundles) single-wall carbon nanotubes.     

Vibrational Spectroscopic and Mechanical Investigation of Carbon Nanotube-Reinforced Styrene-Butadiene Rubbers

This paper reports investigations carried out on elastomeric matrices based on a styrene-butadiene copolymer filled with multiwall carbon nanotubes. Stress-strain measurements of the composites demonstrate that carbon nanotubes bring significantly improvements in the mechanical properties with regard to the pure polymer. Raman spectroscopy, which is one of the most extensively employed methods for the characterization of carbon materials, has been applied for the analysis of the dependence of the Raman spectra on the nanotube content and on application of an uniaxial deformation. The results reveal a negligible stress transfer suggesting a weak interface between the tubes and the polymer chains.     

二氧化碳膨胀乙醇体系中碳基金属复合物的合成及其催化和电化学性能(英文)

与块体材料相比,功能复合材料表现了更加优异的性能,而且比其中任何单一组分的性能都好,因此在催化、锂离子电池等领域得以广泛研究.通常情况下,在复合材料的制备中金属或金属氧化物粒子要求能够以足够小的粒径在基底上均匀分散,并实现活性组分负载量的可控.据报道,很多方法可以将金属(或氧化物)活性组分引入到载体之中,比如水热/溶剂热、水解、热分解、化学气相沉积等,但这些方法均存在如下缺点.第一,为了获得满意的负载量和可控包覆,碳基底需要预氧化处理使其表面含有丰富的含氧官能团.例如,由于碳纳米管自身的相容性和加工性较差,需要硝酸预氧化处理;石墨烯也需要预处理为石墨烯氧化物然后再进行第二组分的负载.但是,剧烈的氧化处理条件不可避免地造成对碳sp~2结构和电子特性的破坏,并且增加了繁杂的后续处理过程.第二,金属组分前驱体在基底上负载不完全,易形成自由粒子聚集在溶液中,从而降低活性组分的有效利用.第三,传统方法中由于使用水、乙醇等表面张力大的极性溶剂,导致粒子结晶再生长,形成的颗粒尺寸大,对催化剂会降低活性表面积及催化效率;对于电池材料会增加电极/电解液的接触面积,增加锂离子的扩散距离及电池充电过程的内部应力.而且,有机溶剂由于粘度大,不利于金属纳米粒子在基底上的均匀分散及合成过程的绿色化.因此,我们利用资源丰富,廉价的二氧化碳作为绿色溶剂,研究了二氧化碳膨胀的乙醇体系中金属(氧化物)纳米粒子在碳基底上均匀负载的方法.由于超临界二氧化碳具有独特的低粘度、"零"表面张力、高扩散能力、以及物性参数随温度和压力可调等特点,可以使金属(氧化物)前驱体不受液体毛细作用的限制在孔道中快速、均一地分散,保证孔结构稳定,对多孔复合材料的加工和制备表现了巨大的优势.同时,超临界二氧化碳的抗溶剂能力也能够有效降低乙醇和水引起的溶剂效应,从而降低纳米粒子之间的聚集.此外,通过改变前驱体的浓度可以精确调控表面组分的负载量.更重要的是,碳基底可以直接利用制备碳基复合材料,无需任何预处理及表面活性剂参与,避免了前处理对基底的形貌和电子特性的破坏.本综述首先介绍了超临界二氧化碳膨胀乙醇体系的属性,讨论了碳基复合材料在该体系中的形成机理.然后分别介绍了零维碳球、一维碳纳米管、二维石墨烯、三维多孔碳材料作为基底形成的一系列金属(氧化物)复合材料,及这些材料在催化和锂离子电池领域中的应用.最后,对超临界二氧化碳沉积方法的应用进行了总结和展望.     

Nanomechanical properties of silica-coated multiwall carbon nanotubes-poly(methyl methacrylate) composites

The mechanical properties of polymer composites, reinforced with silica-coated multiwall carbon nanotubes (MWNTs), have been studied using the nanoindentation technique. The hardness and the Young's modulus have been found to increase strongly with the increasing content of these nanotubes in the polymer matrix. Similar experiments conducted on thin films containing MWNTs, but without a silica shell, revealed that the presence of these nanotubes does not affect the nanomechanical properties of the composites. While carbon nanotubes (CNTs) have a very high tensile strength due to the nanotube stiffness, composites fabricated with CNTs may exhibit inferior toughness. The silica shell on the surface of a nanotube enhances its stiffness and rigidity. Our composites, at 4 wt % of the silica-coated MWNTs, display a maximum hardness of 120 +/- 20 MPa, and a Young's modulus of 9 +/- 1 GPa. These are respectively 2 and 3 times higher than those for the polymeric matrix. Here, we describe a method for the silica coating of MWNTs. This is a simple and efficient technique, adaptable to large-scale production, and might lead to new advanced polymer based materials, with very high axial and bending strength.     

Effect of carbon nanotube modification on poly(butylene terephthalate)-based composites

The influence of the chemical modification of carbon nanotubes on the mechanical, thermal and electrical properties of poly(butylene terephthalate)-based composites was investigated. Polymer composites based on poly(butylene terephthalate) were obtained via in situ polymerisation or extrusion. Commercially available multi-walled carbon nanotubes (Nanocyl NC7000) at different loadings (mass %: 0.05, 0.25, 1, 2) were used as fillers. The functionalisation process took place under a chlorine atmosphere followed by a reaction with sodium hydroxide. The effect of carbon nanotube modification was analysed according to the changes in the polymer thermal and mechanical properties. An addition of modified carbon nanotubes in the amount of 0.05 mass % improved the mechanical properties of the composites in terms of both Young’s modulus and tensile strength by 5–10 % and 17–30 % compared with composites with unmodified carbon nanotubes and neat poly(butylene terephthalate), respectively. The in situ method of composite preparation was a more effective technique for enhancing the matrix-filler interactions, although a significantly lower amount of fillers were used than in the extrusion method.     

Aligned Nanotubes

Since the discovery of carbon nanotubes by Iijima in 1991, various carbon nanotubes with either a single‐ or multilayered graphene cylinder(s) have been produced, along with their noncarbon counterparts (for example, inorganic and polymer nanotubes). These nanostructured materials often possess size‐dependent properties and show new phenomena related to the nanosize confinement of the charge carriers inside, which leads to the possibility of developing new materials with useful properties and advanced devices with desirable features for a wide range of applications. In particular, carbon nanotubes have been shown to exhibit superior properties attractive for various potential applications, ranging from their use as novel electron emitters in flat‐panel displays to electrodes in electrochemical sensors. For many of the applications, it is highly desirable to have aligned/patterned forms of carbon nanotubes so that their structure/property can be easily assessed and so that they can be effectively incorporated into devices. In this Review, we present an overview on the development of aligned and micropatterned nanotubes, with an emphasis on carbon nanotubes.     

The effect of crystallization behavior on high conductivity,enhanced mechanism and thermal stability of poly(ε-caprolactone)/multi-walled carbon nanotube composites

Poly(ε-caprolactone) (PCL) composites filled by multi-walled carbon nanotubes (MWCNTs) which was non-covalently modified by the combined surfactants of poly(sodium 4-styrenesulfonate) and cetyltrimethyl-ammonium bromide (PSS-CTAB) were fabricated via simple solution precipitation method. PCL/MWCNTs composites provided with the low procolation threshold (0.4?wt%) and high electrical conductivity due to good dispersion of MWCNTs. And the excellent mechanical properties and enhanced thermal stability were also obtained with the addition of modified MWCNTs. In addition, all PCL composites showed significantly enhanced crystallization with increasing the MWCNTs contents, which demonstrated that the MWCNT-induced crystallization of PCL could effectively regulate the properties of composites. In a word, introducing non-covalent functionalized MWCNTs in the polymer system was a promising way for developing excellent conductive composites.     

ZnO纳米线基MWNTs/PVDF复合热电材料的制备及特性研究

将不同比例的多壁碳管(MWNTs)与聚偏二氟乙烯(PVDF)聚合物混合后,喷涂于n型ZnO半导体纳米线阵列上,制备了一种新型ZnO纳米线基MWNTs/PVDF热电复合材料.与以往采用价格昂贵的p型与n型单壁碳纳米管(SWNTs)与聚合物混合制备的复合热电材料特性相比,这种新型热电复合材料在降低制造成本的同时,利用分散于聚合物中MWNTs的一维电子传输特性及形成的大量界面势垒,加上ZnO半导体纳米线具有的较高载流子密度与迁移率,提高了复合热电材料中电子的输运特性,增加了材料对声子的散射强度.测试发现,在一定的温度梯度下,随着MWNTs添加质量百分比的增加,热电材料的温差电动势和电导率也随之增加,但其Seebeck系数变化量不大.研究表明,这种热电材料有望替代采用p型与n型SWNTs构建的SWNTs/PVDF复合热电材料.研究结果对开发超轻、无毒、廉价、可应用于各种微纳电子领域的新型电源具有重要的参考价值.     

电化学法制备石墨烯及其复合材料

石墨烯是一种具有优异物理和化学性质的新型二维碳纳米材料,大规模低成本制备高品质石墨烯的方法是其能够得到广泛实际应用的重要前提. 电化学方法可以快捷、绿色无污染、批量制备高质量的石墨烯及其复合材料. 本综述在对石墨烯各种制备方法进行简要比较之后,对近年来石墨烯、石墨烯/无机纳米复合材料、石墨烯/聚合物复合材料以及类石墨烯材料的电化学法制备进展进行介绍并作了展望.     

Nanoarchitectured Graphene‐Based Supercapacitors for Next‐Generation Energy‐Storage Applications

Tremendous development in the field of portable electronics and hybrid electric vehicles has led to urgent and increasing demand in the field of high‐energy storage devices. In recent years, many research efforts have been made for the development of more efficient energy‐storage devices such as supercapacitors, batteries, and fuel cells. In particular, supercapacitors have great potential to meet the demands of both high energy density and power density in many advanced technologies. For the last half decade, graphene has attracted intense research interest for electrical double‐layer capacitor (EDLC) applications. The unique electronic, thermal, mechanical, and chemical characteristics of graphene, along with the intrinsic benefits of a carbon material, make it a promising candidate for supercapacitor applications. This Review focuses on recent research developments in graphene‐based supercapacitors, including doped graphene, activated graphene, graphene/metal oxide composites, graphene/polymer composites, and graphene‐based asymmetric supercapacitors. The challenges and prospects of graphene‐based supercapacitors are also discussed.     

A review on the mechanical,electrical and EMI shielding properties of carbon nanotubes and graphene reinforced polycarbonate nanocomposites

Recently, it has been found that carbon nanotubes (CNTs) and graphene could prove to be the most promising carbonaceous fillers in polymers nanocomposites field because of their better structural and functional properties. Their uniform dispersion in polymer matrix leads to significant improvements in their several properties. This paper reviews the effect of nanofillers, ie, CNTs, derivatized CNTs, and graphene on the polycarbonate nanocomposite and its application in aerospace, automobile, sports, electronic sectors, and various industries. The comparative analysis of carbon‐based fillers on the different properties of polycarbonate nanocomposites is also included.     

两种碳材料混合填充聚合物复合材料的导电特性及渗流阈值的计算模型

介绍了用碳纳米管与炭黑（或石墨）混合填充的聚合物复合材料的导电特性;阐述了混合填充聚合物体系的导电机理;介绍了基于线性混合规则和已占体积理论的渗流阈值的计算模型;分析了模型计算值与实验值的差异。利用已占体积理论,重新推导了混合填充体系渗流阈值的计算公式,并与文献公式做了比较。新公式表明：混合填充聚合物复合材料的渗流阈值...