Carbon nanotubes conductive filler

Winey, K.I. Kasiwagi, T. Mu, M. (2007). Improving electrical conductivity and thermal properties of polymers by addition of carbon nanotubes as fillers. MRS Bulletin, 32, 348-353. 

Suitable electrically conductive fillers include carbon black, carbon fibers, vapor grown carbon fibers, carbon nanotubes, metal fillers, conductive non-metal fillers, metal coated fillers, etc (7). 

Carbon nanotubes can be employed either as electrode materials or conductive fillers for the active materials in various electrochemical energy-storage systems [20]. For energy generation and storage, nanotubes hold promise as supercapacitors. 

Lin Q, Harb JN. Implementation of a thick-film composite Li-ion microcathode using carbon nanotubes as the conductive filler. J Electro chem Soc 2004 151 A1115-A1119. 

Nanocarbon material (NCM), containing both the ordered carbon structures (carbon nanotubes (CNT), the particles of nanographite) and the particles of the disordered carbon phase, is known to be promising for using as elements of the nanodimensional devices and as fillers, for example, of lithium batteries. Structure and phase composition of NCM depend essentially on the methods of their obtaining and the regimes of the subsequent temperature and chemical treatment. Therefore, finding the correlation between the structural and phase composition and transport properties of NCM as well the description of the mechanisms of their conductivity are the important problems. 

This paper represents an overview of investigations carried out in carbon nanotube / elastomeric composites with an emphasis on the factors that control their properties. Carbon nanotubes have clearly demonstrated their capability as electrical conductive fillers in nanocomposites and this property has already been commercially exploited in the fabrication of electronic devices. The filler network provides electrical conduction pathways above the percolation threshold. The percolation threshold is reduced when a good dispersion is achieved. Significant increases in stiffness are observed. The enhancement of mechanical properties is much more significant than that imparted by spherical carbon black or silica particles present in the same matrix at a same filler loading, thus highlighting the effect of the high aspect ratio of the nanotubes. 

The recognition of the unique properties of carbon nanotubes (CNTs) has stimulated a huge interest in their use as advanced filler in composite materials. In particular, their superior mechanical, thermal and electrical properties are expected to provide much higher property improvement than other nanofillers (18-22). For example, as conductive inclusions in polymeric matrices, CNTs shift the percolation threshold to much lower loading values than traditional carbon black particles. 

Graphene-polymer nanocomposites share with other nanocomposites the characteristic of remarkable improvements in properties and percolation thresholds at very low filler contents. Although the majority of research has focused on polymer nanocomposites based on layered materials of natural origin, such as an MMT type of layered silicate compounds or synthetic clay (layered double hydroxide), the electrical and thermal conductivity of clay minerals are quite poor [177]. To overcome these shortcomings, carbon-based nanofillers, such as CB, carbon nanotubes, carbon nanofibers, and graphite have been introduced to the preparation of polymer nanocomposites. Among these, carbon nanotubes have proven to be very effective as conductive fillers. An important drawback of them as nanofillers is their high production costs, which... 

In order to render a plastic conductive although it is, by nature, an electrical and thermal insulator (with the exception of intrinsically conducting polymers, ICPs), we need to dope it with electrically conductive fillers such as steel microfibers (pFSs) [FEL 06], CNPs [FEL 01] or indeed carbon nanotubes [FEL 11]. By gradually varying the proportion of fillers in the polymer matrix, we see that its resistance goes... 

Figure 3.16 shows that electrical conductivity can be dramatically improved by addition of carbon nanotubes.The electrical conductivity of composites abruptly increases by many orders of magnitude when the filler content exceeds the threshold concentration. ... 

Other, nanometer-scale forms of carbon, such as nanotubes and graphenes, have been proposed as ESD fillers, though their early use may be greater with engineering polymers. Carbon nanotubes (CNTs), in diameters of lO-lOOnm, can induce the conductivity needed for electrostatically paintable plastic automotive body panels, for example. They are also said to be replacing carbon black and fiber in small, detailed electronics applications [6-5]. 

The effects of nano-structured carbon fillers [fuUerene C60, single wall carbon nanotube (SWCNT), carbon nanohom (CNH), carbon nanoballoon (CNB), and ketjenblack (KB) and conventional carbon fillers [conductive grade and graphi-tized carbon black (CB)]] on conductivity (resistance), thermal properties, crystallization, and proteinase K-catalyzed enzymatic degradation of PLA films were investigated by Tsuji et al. [70]. The researchers found that the addition of 1 wt% SWCNT effectively decreased the resistivity of PLA film compared with that of conventional CB. The crystallization of PLA further decreased the resistivity of films. The addition of carbon fillers, except for C60 and CNB at 5 wt%, lowered the glass transition temperature, whereas the addition of carbon fillers, excluding... 

Due to the exceptional properties of carbon nanotubes (CNTs), such as high electrical and thermal conductivity and excellent mechanical properties, they are expected to have great potential as fillers for polymeric matrices. CNTs are incorporated in electrically insulating polymer materials to achieve electrostatic dissipative behavior or electrical conductivity and improved mechanical properties. Current applications for such nanocomposites include electrostatically dissipative plastic housing or fuel lines, as well as lightweight and electrostatically paintable plastic components replacing metals in car panel applications. Incorporation of CNTs in polymers on an industrial scale is... 

Other very promising nanosized fillers have been developed, of which carbon nanotubes are amongst the most promising ones due to their high stiffness and strength as well as their outstanding electrical conductivity. 

Recently, nanostructured carbon-based fillers such as Ceo [313,314], single-wall carbon nanotubes, carbon nanohorns (CNHs), carbon nanoballoons (CNBs), ketjenblack (KB), conductive grade and graphitized carbon black (CB) [184], graphene [348], and nanodiamonds [349] have been used to prepare PLA-based composites. These fillers enhance the crystalUza-tion ofPLLA [184,313,314].Nanocomposites incorporating fibrous MWCNTsandSWCNTs are discussed in the section on fibre-reinforced plastics (section 8.12.3). 

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