The variation in the dielectric constant with the frequency indicates the occurrence of an interfacial polarization
in the PVDF composites.
At elevated temperature, impurities such as H+, Na+, and Fe3+ ions diffuse toward the interface between PEDOT:PSS cathode and tantalum pentoxide dielectrics to form an accumulation of charges; thus interfacial polarization
occurs as depicted in Figure 5.
Second, differences in the dielectric constant and conductivity of PANI and the surrounding epoxy matrix may lead to the Maxwell-Wagner-Sillars (MWS) interfacial polarization
effect because of the accumulation of mobile charges at the interfaces between the two matrices [34, 35].
The internal factors of influencing dielectric constant were the condition of dielectric polarization and polarization divided into electronic polarization, atomic polarization, orientation polarization, and interfacial polarization
according to different molecular polarization mechanisms.
However, the model accounts only for the Stern layer (the inner portion of the electrical double layer coating the surface of mineral grains) polarization  and neglects an important polarization mechanism in the intermediate frequency range (0.1 MHz-100 MHz), often referred to as Maxwell-Wagner polarization or interfacial polarization
, due to the build-up of charge on the interfaces of the heterogeneous systems (e.g., ).
The two mechanisms are likely to be involved when blood is subject to field and temperature; aggregation and interfacial polarization
. Generally, blood cells are liable to aggregate when certain plasma proteins are present.
In the frequency range from dozens of megahertz to several gigahertz, three main polarization phenomena contribute to the dielectric dispersive behavior of oil bearing reservoirs: the electronic polarization (rock's inherent permittivity), the molecular polarization (brine water molecules) and the interfacial polarization
which is also called Maxwell-Wagner polarization.
This interfacial polarization
is relatively slow compared with other types of polarization (atomic, electronic, or dipolar) and is related to the dielectric properties of the sample at low frequencies .
This causes the localized accumulation of charges under the influence of electric field, which results in interfacial polarization
. At higher frequencies the electron exchange between ferrous and ferric ions cannot follow the alternating field, which causes a decrease in the contribution of interfacial polarization
in dielectric constant, and as a result, we see a decrease in the dielectric constant and dielectric loss factor.
This kind of polarization is called the Maxwell-Wagner or interfacial polarization
Moreover, the contribution of Maxwell-Wagner interfacial polarization
due to heterogerfiety present in the system progressively increases as the measurement frequency is decreased (ref.
The characteristic dependence of the [epsilon]' of PPTMP on frequency can be explained with interfacial polarization
and dipolar polarization in the lower and higher frequency regions, respectively.