Dielectric Constant of Selected Polymers

Table 5.22 gives resistivity and dielectric constants of selected polymers. Table 5.22. Resistivity and dielectric constants of some polymers...

A dataset containing the dielectric constants of 61 polymers measured at room temperature was prepared by careful comparison and combination of the data provided by many sources [3,14-20]. For polar polymers, special care was exercised to select values of e which represented, whenever possible, the "intrinsic" properties of the polymers, rather than the effects of the additives and fillers used. It will be seen in Section 9.D that the dielectric constants of typical commercial grades of many polar polymers, which contain significant amounts of additives, are considerably higher than the "intrinsic" values used in this section. 

Most polymer membrane ISEs are prepared by dissolving an ionophore in a polyvinylchloride (PVC) membrane. A large variety of plasticisers are used to increase the dielectric constant of the PVC and improve its hydrophilicity. Some membranes have complexes of the ions to be sensed to increase membrane conductivity, such as potassium tetraphenylborate in K -selective membranes. There is an extensive literature on the arcane arts of polymer membranes for electrodes with dissolved ionophores and a good review of this is given by Professor Ronald Armstrong in Section 3.7 of Gabor Harsanyi s book. Polymer films in sensor applications [14]. 

Chiu (116) used the apparatus previously described to study the thermal decomposition of selected polymers such as polyethylene terephthalate), po y(vinyl fluoride), po y(vinylidene fluoride), and others. The dielectric constant curves of a group of fluorocarbon polymers are shown in Figure 11.33. As illustrated, the more polar polymers such as poly(vinylidinefiuoride) (PVDF) and poly(vinyl fluoride) (PVF) show characteristic dielectric loss peaks that are distinguishable from the relatively featureless and low-loss curves of the other polymers. For PVF, the low-temperature process is due... 

Ta57e 457. Selecting Dielectric Constants of Polymers AT 60 Hz (Sheet 2 of 5)... 

Tawem Selecting Dielectric Constants OF Polymers at 1 MHz (shect i of 4)... 

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