Intrinsically conductive plastic

ICP intrinsically conductive plastic IMM injection-molding machine... 

There has been a trend in recent years to move towards the electrostatic deposition of paints for exterior automotive applications. Reasons for this include improved paint transfer efficiency. Normally, plastic parts need to be painted with a conductive primer prior to the electrostatic painting of base and clear coats. One of the most recent developments in the area of external automotive applications is that of intrinsically conductive resins for electrostatic painting. Currently there are commercial applications for body panels that utilize PPE/PA that contains carbon black as the conductive component. In the USA, a mirror shell application uses PPE/PA where the conductivity is achieved through the incorporation of graphite nano-tubes. 

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... 

Clearly, blending is an important technique to obtain conducting materials based on intrinsically conductive polymers and conventional as well as rubbery plastics. In a recent study, Martins et al. (2006) prepared an electrically conductive thermoplastic elastomer by blending butadiene-styrene copolymer (SBR) and... 

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

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. 

Eeonomers are a new class of conductive additives for thermoplastics made via in-situ deposition of intrinsically conductive polyaniline or polypyrrole on carbon black. Eeonomers are highly thermally stable, pH neutral conductive materials that are compatible with the chemistry and melt processing conditions of acid sensitive polymers. Compounding studies with thermoplastics indicate better electrical, mechanical, and melt flow properties of Eeonomer blends as compared to blends with traditional carbon blacks. In co-continuous plastic blends it was possible to fine tune the polarity of Eeonomer by varying the conductive polymer to CB ratio. The same variation affords very low percolation thresholds due to preferred Eeonomer localization at the 2D phase boundary. 

In order to dissipate the electrical charge on the surface of the plastic, we must render the surface electrically conducting in some way. This enables the electrons to be dissipated. There is no problem if a plastics material is already conducting, because of the additives it contains, or because the base polymer is intrinsically conducting - the latter situation is uncommon. 

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. 

Today, however, there are signs of new ways and means of achieving electrical conductivity in plastics. New kinds of polymers, known as intrinsically conductive polymers (ICPs), have been developed whose electrical conductivity is no longer due to additives but to their chemical and crystalline structure, or morphology. 

To overcome the cost issue especially for high-volume production, low-cost coatings are required which avoid the use of expensive ingredients, without jeopardizing the performance and durability of the bipolar plate. Various materials are known from the literature that implement conductive polymers or polymer-based coatings. Already used in the emerging industry of plastic electronics, stable and intrinsically conductive polymers have been used by various groups to apply a... 

When one thinks of polymers, one perhaps envisions common plastics, such as polythene, that one may encounter in everyday life. If one then conjures up a conducting polymer, one may perhaps envision these plastics filled up with conductors such as metal or carbon particles. The Conducting Polymers (CPs, also sometimes called Conductive Polymers or Conjugated Conductive Polymers or Organic Polymeric Conductors), which are the subject of this book, are quite a different beast, in the sense that they are intrinsically conducting, and do not have any conductive fillers as such. 

Epstein, A.J. Joo, J. Wu, C.-Y. Benatar, A. Faisst, C.F., Jr. Zegarski, J. MacDiarmid, A.G., "Polyanilines Recent Advances in Processing and Applications to Welding of Plastics", p. 165 in Aldissi, M. (Ed.), Intrinsically Conducting Polymers An Emerging Technology, Kluwer Academic Publishers, Boston, Massachusetts, USA (1993), and references therein. 

Thickness. The traditional definition of thermal conductivity as an intrinsic property of a material where conduction is the only mode of heat transmission is not appHcable to low density materials. Although radiation between parallel surfaces is independent of distance, the measurement of X where radiation is significant requires the introduction of an additional variable, thickness. The thickness effect is observed in materials of low density at ambient temperatures and in materials of higher density at elevated temperatures. It depends on the radiation permeance of the materials, which in turn is influenced by the absorption coefficient and the density. For a cellular plastic material having a density on the order of 10 kg/m, the difference between a 25 and 100 mm thick specimen ranges from 12—15%. This reduces to less than 4% for a density of 48 kg/m. References 23—27 discuss the issue of thickness in more detail. 

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