Resistance, polymer electrical properties measurement techniques

It is through the solid state characteristics of polymers that we - as users - primarily interact with them. For convenience, we can divide the principal properties of polymers into five categories mechanical, optical, surface contact, barrier, and electrical. Weather resistance is a sixth category that can influence each of the other five categories. In order to understand these properties we must be able to quantify them. In this chapter we shall concentrate on measurement techniques, since it is through these methods that we learn how a polymer will behave during use. 

Nelson et al. [16] have shown that the etching solution attacks only the surface regions of the fluorocarbon polymer. They examined a cut section of etched PTFE and, from optically microscopy, determined that the depth of the coloured surface region was about 1 /xm. However, they reported that the bulk electrical properties of the treated and untreated polymer were virtually identical and that their electron diffraction patterns were indistinguishable, indicating that no changes had been induced in the bulk polymer s crystallinity. These observations may be attributed to the thinness of the treated surface layer and thus the properties of the layer are not measured when analytical techniques are employed which monitor the bulk properties of the material. Indeed, Benderley [17] has since reported that the treated layer does have a substantially lower surface resistivity than the untreated material. 

This analysis technology was applied to screening of chemosensitive properties of polyanilines and copolymers of anilines and aniline derivatives. Combinatorial libraries were prepared by electrically addressed polymerization.42 43 Gaseous hydrogen chloride was selected as an analyte. The measured signal was electrical resistance detected simultaneously by 2 and 4-point techniques (s24 technique44,52), and the ratio of these values provides information on the contribution of the polymer/contact resistance into the total resistance measured by 2-point configuration. 

Although the electronic conductivity of an interphase that is present on an electrode can be related to various optoelectronic properties that are also measurable with spectroscopic techniques, the direct measurement of surface conductivities is not a spectroelectrochemical method. It is nevertheless a surface sensitive method that provides results closely related to those of other methods discussed in this book. Data on the electrosorption of alcohols on gold electrodes [45] or the electrode potential dependent conductivity of intrinsically conducting polymers [46] have been obtained with in situ surface conductivity measurements. Figure 4.4 shows the electrical resistance of a poly(2-propylaniline) film measured in situ under experimental conditions suppressing any influence of solution phase conduction. The influence of... 

For metal or resin impregnated carbon.graphite materials, the extent of polymerization, cure cycles, and degradation can be assessed by measuring electrical resistance of the resin [lOlj. For example, the internal viscosity of a polymer can be determined by monitoring the electrical resistivity as a function of temperature. Electrical and electromagnetic properties of composites as well as NDT techniques are described next. 

This study demonstrates, for the first time, the ability to manipulate the resistance of a conductive polymer without doping. Techniques were developed to allow blending conductive PANIS with commercially available polymers, and methods were devised to measure the resistance of the resulting blends. Polymer preparation, solvent selection and solvent removal have been shown to be critical in producing the desired physical, electrical and optical properties. 

Other techniques that can be used to measiue the degree of crystallinity include the measurement of properties such as specific heat, electrical resistivity, and the heat of fusion. If we can say that a property p of the polymer can be written as... 

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