Carbon nanotubes additive fillers

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. 

The viscoelastic properties of natural rubber (NR) nanocomposites filled with silica/multiwall carbon nanotube hybrid fillers have been studied by H. Ismail et al. [46]. The addition of hybrid fillers (MWCNTs-i-silica) to the NR matrix... 

There is currently considerable interest in processing polymeric composite materials filled with nanosized rigid particles. This class of material called "nanocomposites" describes two-phase materials where one of the phases has at least one dimension lower than 100 nm [13]. Because the building blocks of nanocomposites are of nanoscale, they have an enormous interface area. Due to this there are a lot of interfaces between two intermixed phases compared to usual microcomposites. In addition to this, the mean distance between the particles is also smaller due to their small size which favors filler-filler interactions [14]. Nanomaterials not only include metallic, bimetallic and metal oxide but also polymeric nanoparticles as well as advanced materials like carbon nanotubes and dendrimers. However considering environmetal hazards, research has been focused on various means which form the basis of green nanotechnology. 

As already reported by several authors, the addition of carbon nanotubes did not affect the storage modulus in the glassy region, nevertheless a strong increase with the filler content is observed in the rubbery region. In conventional composites, this increase is mainly attributed to interfacial interactions leading to introduction of additional cross-links into the network by the filler. These interfacial interactions contribute to the formation of an adsorption layer whose thickness has been estimated around 2 or 3 nm and where... 

One of common approaches for strengthening the durability against radiation, is the addition of fillers to the matrix materials. Carbon nanotubes (CNT)s have inspired scientists and engineers to examine a wide range of potential applications [2,3] as exotic filler materials, since the discovery of their extraordinary mechanical, electrical, magnetic and thermal properties [4]. 

In addition, there is also the possibility of tailoring the properties of plain composites further by adding particles (such as metallic fillers [29,30], carbon nanotubes [31] or urea formaldehyde [32]) to the composite layers to create multifunctional and self-healing materials, von Klemperer and Maharaj [29] added copper and aluminium powder fillers to carbon fibre epoxy laminates to improve the electromagnetic shielding capacity of the composite panels. Blast tests on the laminates [30] showed that the laminates with filler particles outperformed their plain composite counterparts, although the margin was small. 

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. ... 

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... 

During the past decades, nanotechnology has attracted great attention due to its marvellous potential applications in numerous areas [90]. Polymer nanocomposite is a unique addition in the nanotechnology family. In polymer nanocomposite, one phase is dispersed in another phase in nanometer level [19]. Different types of reinforcing fillers such as sodium montmo-rillonite, sodium bentonite, layered double hydroxide, exfohated graphite, fullerene, carbon nanofiber, and carbon nanotube have been successfully used in the preparation of polymer nanocomposites [19]. Recently,... 

Hybrid carbon filled PPS composites have been prepared by compression molding with graphite as main filler [94]. In addition, different shaped supplementary filler materials such as carbon black, carbon fiber, and multi-walled carbon nanotubes have been added. 

A speciality of such nanocomposites is the very high surface of well dispersed nanofillers, which results in a very high interfacial area. Here, the behavior of the polymer chains near the interface is influenced by the interaction with the filler, leading to an interphase with new properties which aheady at low amounts of nanofillers can determine the nanocomposite s properties. In addition, quite big effects are observed aheady at quite low filler loadings, especially if the filler has an anistropic shape. As an example, in thermoplastic polymers electrical conductivity can be reached with carbon nanotubes even below 1 wt% addition. 

We have also shown that electrospun fibres can be functionalised by the use of additives, and fillers of many kinds can be used to form composite fibres. The properties of electrospun fibres can be modified using nanosized fillers. Carbon nanotubes (CNT) are widely used as fillers in electrospun fibres. Typically, their function is to serve as a reinforcement component in electrospun polymeric fibres. 

Meanwhile, salts and other conductive additives have been found on some occasions to reduce the fibre diameter, but on other occasions to increase it. Researchers obtained finer fibres with CNT-containing solution compared to a CNT-free one. It was also observed that beads formed, especially when the CNT concentration was high or the dispersion of CNT in the solution was poor. On the other hand, it was found that carbon nanotubes led to a broader fibre diameter distribution and, especially, to the occurrence of fibres having larger diameters. According to the reports, this can be explained by the increase in solution viscosity or by the creation of new interfaces between the polymer and CNT. The effect of fillers and additives on fibre diameter varies from system to system, depending on tbe polymer and the solvent as well as the additive. 

Polymer composites consist of a polymer matrix with the addition of fillers to enhance strength and other properties. This book reviews current research on the manufactirre and properties of the main types of polymer nanocomposite. It discusses types of polymer nanocomposite as defined by filler such as carbon nanotube-based nanocomposites, as well as types of nanocomposite as defined by base such as nylon-based and PET-based nanocomposites. The book also considers apphcations in such areas as aerospace engineering and optical materials. 

Improved dispersion of nanoscaled fillers in polymers is expected to lead to better mechanical properties. The question is if by using a nano-modified matrix instead of a laminate with neat polymer as the matrix, in a fiber-reinforced composite can lead to improve delamination resistance. In the case of semicrystalline polymer matrices, the scenario is even more complicated as the microstructure is not only influenced by the processing but also by the presence of nanofillers. The addition of different types of nanoscaled reinforcements such as carbon nanotubes, nanofibers or... 

More recently nanoscale fillers such as clay platelets, silica, nano-calcium carbonate, titanium dioxide, and carbon nanotube nanoparticles have been used extensively to achieve reinforcement, improve barrier properties, flame retardancy and thermal stability, as well as synthesize electrically conductive composites. In contrast to micron-size fillers, the desired effects can be usually achieved through addihon of very small amounts (a few weight percent) of nanofillers [4]. For example, it has been reported that the addition of 5 wt% of nanoclays to a thermoplastic matrix provides the same degree of reinforcement as 20 wt% of talc [5]. The dispersion and/or exfoliahon of nanofillers have been identified as a critical factor in order to reach optimum performance. Techniques such as filler modification and matrix functionalization have been employed to facilitate the breakup of filler agglomerates and to improve their interactions with the polymeric matrix. 

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