Electric conductivity in polymers

Table 2 shows the present state-of-the-art for the electrical conductivity of doped conjugated polymers. The magnitude of the electrical conductivity in polymers is a complex property determined by many stmctural aspects of the system. These include main-chain stmcture and TT-ovedap, molecular... 

An irradiation-induced expansion could conceivably be caused by the ions, formed as precursors of the radicals, or by thermalized electrons trapped within the polymer. Irradiation induces electrical conductivity in polymers, and this conductivity decays after irradiation is ceased (4, 5). The decay process is accelerated by increased temperature or plasticity of the specimen, presumably by facilitating leakage of the trapped electrons or ions to ground. One might speculate that the sample expands upon irradiation because of the local mutual electrical repulsions of like charges which are trapped in the polymer matrix, and that both increased temperature and plasticizer content diminish this expansion because of charge leakage out of the specimen. It is difficult to prove or disprove this hypothesis. 

Jana, S.C. (2003) Loss of surface and volume electrical conductivities in polymer compoimds due to shear induced migration of conductive particles. Polym. Eng. Sci., 43, 570. 

Thermal conductivity (k) n. The basic measure of steady heat-transfer rate within solid materials (and still fluids) by atomic or molecular contact and vibration. It derives from Fourier s law of heat conduction and may be thought of as the rate of heat flow between two opposite faces of a unit cube whose other faces are perfectly insulated when the temperature at the warmer face is 1 K above that of the cooler face. The SI dimensions corresponding to this concept are (J/S)/(m K/m), which reduces to W/m K. Some conversions from other units to SI are given in the Appendix. For plastics and other materials, k increases with rising temperature. Tide DR (ed) (2004) CRC Handbook of chemistry and physics. CRC Press, Boca Raton, EL. Ready RG (1996) Thermodynamics. Pleum Publishing Company, New York. Seanor DA (1982) Electrical conduction in polymers. Academic Press, New York. 

Tree formation n. The generation of a treelike void structure in a transparent plastic by electron bombardment at a point on the surface. The effect in acrylic blocks is dramatically decorative. Similar breakdown structures form in dielectrics subjected to strong electric fields, eventually penetrating the dielectric and causing a short circuit. Ku CC, Liepins R (1987) Electrical properties of polymers. Hanser Publishers, New York. Seanor DA (1982) Electrical conduction in polymers. Academic Press, New York. 

The chapter describes some fundamental aspects concerning electrical conduction in polymers (in undoped and doped stales) and their composites. The current characterization methodologies for electrical conductivity are presented. The performance of polymers containing single or multiple conductive phases is reviewed in accordance with the applications of these multiphase materials in electronics, optoelectronics, and in other fields. 

The Theory of Bloch-Type Electric Conduction in Polymers and Its Applications... 

Seanor DA (1982) Electrical conduction in polymers. Academic Press, New, Academic Press, New York). 

Saleh BEA, Teich MC (1991) Fundamentals of photonics. Wiley, New York Schoeser M (2003) World textiles a concise history. Thames Hudson Seanor DA (1982) Electrical conduction in polymers. Academic, New York... 

Several factors can affect electrical conductivity in polymers. These factors include the extent of conjugation and regioregularity of the polymer, its molecular weight, and the interchain distance (29). Processing variables, such as temperature and pH, are also important (33). These factors will be discussed below using polypyrrole and 3-undecylbithiophene as examples. 

Metal-coated nonconductive or low-conduction fillers can also be used to induce electrical conductivity in polymer composites. DUsiz et al. (1997) coated spindle-type hematite and magnetite particles and nickel filaments with silver by using chemical reduction. The concentration of the reactants, the reaction time, and the type of reducing agent greatly influenced the morphology of the silver coating and the conductivity of the coated particles. 

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