Polarization, polymer electricity, alternating

The dielectric constant of a polymer (K) (which we also refer to as relative electric permittivity or electric inductive capacity) is a measure of its interaction with an electrical field in which it is placed. It is inversely related to volume resistivity. The dielectric constant depends strongly on the polarizability of molecules tvithin the polymer. In polymers with negligible dipole moments, the dielectric constant is low and it is essentially independent of temperature and the frequency of an alternating electric field. Polymers with polar constituents have higher dielectric constants. When we place such polymers in an electrical field, their dipoles attempt... 

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. 

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. 

Polyvinylidene fluoride (PVDF) is a homopolymer of 1,1-difluoroethene with alternating CH2 and CF2 groups along the polymer chain. These groups impart a unique polarity that influences its solubility and electrical properties. The polymer has the characteristic stability of fluoropolymers when exposed to aggressive thermal, chemical, and ultraviolet conditions. 

P-IOMBT in dichloroacetic acid was investigated in an alternating electric field. Experimental data show that the molecules of this polymer, just as those of other mesomorphic polymers, are characterized by a relatively high Kerr constant and the corresponding high dipole moment and orientational polar order. 

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