Electric properties of polymers

Antioxidants are used to retard the reaction of organic materials with atmospheric oxygen. Such reaction can cause degradation of the mechanical, aesthetic, and electrical properties of polymers loss of flavor and development of rancidity ia foods and an iacrease ia the viscosity, acidity, and formation of iasolubles ia lubricants. The need for antioxidants depends upon the chemical composition of the substrate and the conditions of exposure. Relatively high concentrations of antioxidants are used to stabilize polymers such as natural mbber and polyunsaturated oils. Saturated polymers have greater oxidative stabiUty and require relatively low concentrations of stabilizers. Specialized antioxidants which have been commercialized meet the needs of the iadustry by extending the useflil Hves of the many substrates produced under anticipated conditions of exposure. The sales of antioxidants ia the United States were approximately 730 million ia 1990 (1,2). 

By the time the next overview of electrical properties of polymers was published (Blythe 1979), besides a detailed treatment of dielectric properties it included a chapter on conduction, both ionic and electronic. To take ionic conduction first, ion-exchange membranes as separation tools for electrolytes go back a long way historically, to the beginning of the twentieth century a polymeric membrane semipermeable to ions was first used in 1950 for the desalination of water (Jusa and McRae 1950). This kind of membrane is surveyed in detail by Strathmann (1994). Much more recently, highly developed polymeric membranes began to be used as electrolytes for experimental rechargeable batteries and, with particular success, for fuel cells. This important use is further discussed in Chapter 11. 

Blythe, A.R. (1979) Electrical Properties of Polymers (Cambridge University Press, Cambridge). 

Sazhin BI (ed) (1970) Electrical properties of polymers, Leningrad Chemistry (in Russian)... 

We can define the principal electrical properties of polymers in terms of four characteristics electrical resistance, capacitive properties, dielectric strength, and arc resistance. We can change the surface characteristics of a polymer by subjecting it to a corona discharge generated by a strong electrical field. Lastly, we must also consider the influence of other physical properties on the application of polymers in electrical applications. 

Alignment of CNTs markedly affects the electrical properties of polymer/CNT composites. For example, the nanocomposites of epoxy/MWCNTs with MWCNTs aligned under a 25 T magnetic field leads to a 35% increase in electric conductivity compared to those similar composites without magnetic aligned CNTs (Kilbride et al., 2002). Improvements on the dispersion and alignment of CNTs in a polymer matrix could markedly decrease the percolation threshold value. 

The electric properties of polymers are also related to their mechanical behavior. The dielectric constant and dielectric loss factor are analogous to the elastic compliance and mechanical loss factor. Electric resistivity is analogous to viscosity. Polar polymers, such as ionomers, possess permanent dipole moments. These polar materials are capable of storing... 

Following are some relationships that are generally pertinent to describing the electrical properties of polymers. 

Barford, W. 2005. Electronic Properties of Conjugated Polymers. Oxford University Press, Oxford. Blythe, T. and Bloor, D. 2005. Electrical Properties of Polymers. Cambridge University Press, Cambridge. Chiellini, E., Gil, H., Braunegg, G., Buchert, J., Gatenholm, P., and vander Aee, M. 2001. Biorelated Polymers. Kluwer, New York. 

K. C. Frisch and A. V. Patsis, Electrical Properties of Polymers, Technomic, Westport, Conn. (1972). 

As described in Chapter 6, Electric Properties of Polymers, there is a general relationship between the delocalization of electrons throughout a polymer chain or network and color so that the incidence of and darkness of color increases as electron delocalization increases. Thus polyethylene is colorless while polyacetylene is black. 

J. Mort and G. Pfister, Electrical Properties of Polymers, Wiley, New York (1982). 

C. C. Ku and R. Liepins, Electrical Properties of Polymers Chemical Principles, Hanser, Munich (1987). 

Murayama.N. Piezoelectric and pyroelectric effects of polymer electrets. Microsymposium on Electrical Properties of Polymers, Tokyo (Jan. 1972). 

Seanor DA (ed) (1983) Electrical properties of polymers Academic, New York, Chap 5... 

While the study of the conventional semiconducting materials has progressed rapidly, the study of organic materials has received much less attention until the past few years. In particular the electrical properties of polymers have been much neglected and little authoritative work exists in the literature. In view of current developments in theories of the electrical properties of organic molecular crystals, it seems profitable to take stock of the situation as far as charge transfer in polymers is concerned. 

Despite the volume of work which has appeared concerning the electrical properties of polymers and pyropolymers, the mechanism of charge transfer is much less well understood than that of organic mole-... 

Emerson JA, Torkelson JM (eds) (1991) Optical and electrical properties of polymers, vol 214. Materials Research Society, Pittsburgh... 

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