Polarization, polymer electricity, alternating currents

Alternating currents of variable frequency are commonly used to measure the total electrical resistance i t of polymer coatings. On increasing the frequency to 2-25 kHz the ohmic constituent Rq of the total resistance can be estimated accurately enough. At low frequencies (400-1000 Hz) the recorded resistance value characterizes the polarizing resistance Rp of the coating. 

Displacement of mobile charges is often spatially limited due to heterogeneous stmcture of the polymer matericds or blocking electrodes therefore, the dc conductance may be not observable, but alternative current (ac) conductivity (cfac) can be found at sufficiently high frequencies. If the limitation of carrier mobility occurs at the phase boundary, the interfacial polarization occurs. The polarization may also be induced by the reorientation of the dipoles present in the stmcture of maciomolecules in the direction of electrical field. The polarization effects are related to dielectric properties characterized by complex dielectric permittivity which is frequency... 

Material response is typically studied using either direct (constant) applied voltage (DC) or alternating applied voltage (AC). The AC response as a function of frequency is characteristic of a material. In the future, such electric spectra may be used as a product identification tool, much like IR spectroscopy. Factors such as current strength, duration of measurement, specimen shape, temperature, and applied pressure affect the electric responses of materials. The response may be delayed because of a number of factors including the interaction between polymer chains, the presence within the chain of specific molecular groupings, and effects related to interactions in the specific atoms themselves. A number of properties, such as relaxation time, power loss, dissipation factor, and power factor are measures of this lag. The movement of dipoles (related to the dipole polarization (P) within a polymer can be divided into two types an orientation polarization (P ) and a dislocation or induced polarization. 

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