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Polymer Carbon Nanotube Composites: The Polymer Latex Concept
Pan Stanford Publishing Pte. Ltd, Dec 2011, Pages: 350
Conductive polymer nanocomposites are receiving more and more attention, both from academic research groups as well as from industry. Because of their intrinsic conductivity, and because of their high aspect (length/diameter) ratio, carbon nanotubes (CNTs) are very interesting nanofillers for easily processable conductive polymer materials, since a conductive percolating network can already be obtained for very low nanofiller loadings, provided that the CNTs are (almost) individually dispersed in the polymer matrix. Not only in view of the current high price of commercially produced carbon nanotubes, but also in view of the strong requirement to retain the good processability of the original polymer matrix material, the nanofillers, exhibiting a huge interfacial area, need to be dispersed in the polymer matrix in the most efficient way. Only then the aspect ratio of the filler particles is very high, and conductivity can be realized for minimum CNT loadings, and the processability of the polymer nanocomposite will be similar to that of the original polymer matrix material. So, an optimal dispersion of CNTs is crucial, both for cost saving and processability reasons.
Conductive polymer/nanocomposites are showing great promise in various applications, mainly in the field of functional polymer systems, such as ant-static coatings, EMI shielding materials, and even in electrical and electronics applications such as Field Effect Transistors.
This book provides the reader with a comprehensive toolbox for dispersing single-walled and multi-walled carbon nanotubes in thermoplastic polymer matrices, a crucial step for obtaining conductive and easily processable materials with high potential in the application area of functional materials. After a short introduction, the book starts with an overview of all known techniques for dispersing CNTs in thermoplastic polymers, and in subsequent chapters concentrates on one of the most versatile techniques known nowadays, viz. the so-called latex technology. This technique consists of four steps: 1) ultrasonically dispersing CNTs in aqueous solutions of surfactants, stabilizing the (predominantly) individualized CNTs, 2) mixing the CNT dispersion with a polymer latex, 3) removing the water by freeze drying, and 4) melt-processing the resulting powder into thin conductive films. Discussed are the basic principles of this latex technology, the role of the matrix viscosity on percolation threshold, the importance of the intrinsic CNT quality, the use of ‘smart’ surfactants facilitating electron transport in the final composite, the preparation of highly loaded master-batches which can be diluted with virgin polymer by melt-extrusion, and some promising potential applications.
Readership
Academic and industrial researchers in the field of polymer/nanocomposites, physics, chemistry and materials science. Managers of start-up companies in the field of functional polymer systems.
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