Intrinsically conductive polymer-carbon

Thermally Stable Intrinsically Conductive Polymer-Carbon Black Composites as New Additives for Plastics... 

When the first intrinsically conductive polymer (ICP) was discovered by Hideki Shirakawa, Alan G. Mac-Diarmid and Alan J. Heeger at the University of Pennsylvania in Philadelphia in the late seventies, it was thought in the initial euphoria that it would not be long before such materials could be put to practical use. The idea was that it ought to be possible to process them more easily and in larger quantities than classical metallic conductors and compared with carbon-blackfilled plastics they were expected to possess better and more uniform conductivity and better mechanical properties. 

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... 

The first conducting polymers (named ICPs for intrinsically conducting polymers, or ECPs for electroactive conducting polymers) were discovered in the seventies by McDiarmid, Heeger, and Shirakawa [1] who showed that unsaturated conjugated polymers (polyacetylene, polyphenylene) became conductive when doped, corresponding to the chemical oxidation of the ethylene or polyphenyl carbon chain. 

Besides the intrinsic conductive polymers, some deformable polymers, such as shape-memory polymers, are usually activated by heating. After incorporating with conductive fillers, such as carbon nanomaterials, they can be simulated by the electricity through Joule heating (Liu et al., 2009 Hu and Chen, 2010 Koerner et al., 2004). This kind of electro thermally active polymer composites can produce expansion/contraction and bending behaviors upon with the electricity. Moreover, these actuators can work durably... 

R Saini, M. Arora, Microwave Absorption and EMI Shielding Behavior of Nanocomposites Based on Intrinsically Conducting Polymers, Graphene and Carbon Nanotubes. In New Polymers for Special Applications De Souza A. Gomes, Ed. InTech Croatia, 2012 pp. 71-112. 

Keywords Thermoelectric power, Seebeck coefficient, thermal conductivity electrical conductivity power factor, figure of merit, intrinsically conducting polymers, polyaniline, polypyrrole, polythiophene, nanoparticles, graphene, carbon nanotubes (CNTs), hybrids, nanocomposites... 

Keywords Electromagnetic interference (EMI) shielding, microwave absorption, electrical conductivity, nanocomposites, intrinsically conducting polymers (ICPs), polyaniline, carbon nanotubes, graphene, shielding effectiveness, reflection loss, absorption loss, complex permittivity and permeabdity... 

Materials/characteristics Liquids quaternary ammonium, polymeric anti-statics. Solids carbon black, coated metal particles, glass spheres. Intrinsically conductive polymers polyanilines. 

The advantages for the use of intrinsically conducting polymers in electrochemical capacitors rather than carbon-based or mixed metal oxide electrodes may be summarised as follows ... 

Furthermore, intrinsically conducting polymers (ICPs) such as polyanilines (PANI), polypyrroles, and polyphenylenes have been used as part of conductive composites on account of their much higher conductivity than other polymers. They are often mixed with other polymers as investigated by Taipalus (2001) and Totsra and Friedrich (2004). On the other hand Dweiri (2007) have found the addition of PANI to a composite of PP/carbon black/graphite for bipolar plates to be unsuitable for processing due to the poor thermal stability of PANI. The company Bac2 is currently the only manufacturer to use a patented electrically conductive polymer called ElectroPhen in their composite bipolar plates. 

One of the main limitations of intrinsically conductive polymers (ICP s) towards their wide application as conductive additives for thermoplastics is their poor thermal-oxidative stability at typical melt processing temperatures (i.e., above 200 °C). On the other hand, the use of high surface area carbon blacks (CB) as conductive additives is limited due to the increased melt viscosity of their blends with thermoplastics. Eeonomers are a new class of thermally stable, chemically neutral, and electrically conductive composites made via in-situ deposition of conductive polyaniline (PANI) or polypyrrole (PPY) on CB substrates. Eeonomer composites are more stable (up to 300 °C) than pure ICP s and more easily processible with thermoplastics than CB. Use of Eeonomers as conductive additives for plastics lead to compounds with improved electrical, mechanical, and processing properties. By varying Ae conductive polymer to CB ratio, it is possible to fine tune the polarity of Eeonomer composites and achieve very low percolation thresholds. This control is possible because of preferred Monomer localization at the 2D phase boundary of the immiscible polymer blends. 

Conductive polymer composites can be defined as insulating polymer matrices which have been blended with filler particles such as carbon black, metal flakes or powders, or other conductive materials to render them conductive. Although the majority of applications of polymers in the electrical and electronic areas are based on their ability to act as electrical insulators, many cases have arisen more recently when electrical conductivity is required. These applications include the dissipation of electrical charge from rubber and plastic parts and the shielding of plastic boxes from the effects of electromagnetic waves. Consequently, materials scientists have sought to combine the versatility of polymers with the electrical properties of metals. The method currently used to increase the electrical conductivity of plastics is to fill them with conductive additives such as metallic powders, metallic fibres, carbon black and intrinsically conducting polymers such as polypyrrole. 

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