Characterization of water absorbed epoxy insulating coating material used in ZnO varistors by dielectric measurements

Electrical impedance spectroscopy study of biological tissues

“…These results correlate well with the results reported for human skin [3]. Tan δ variation with frequency-Dielectric physics [24] indicates that the loss tangent in the low frequency range is caused by electrical conduction current, and, can be expressed as (3) where f is the applied frequency, σ is the electrical conductivity, ε o is the dielectric permittivity of free space, ε r is the relative permittivity. Thus, it is an expression of the frequency dependence of the relative dielectric constant, ε r or the capacitance C and the conductivity σ.…”

Dielectric analysis of water uptake in polymer coating using spatially defined Fick's law and mixing rule

“…Using previous parameters from gravimetric analysis (diffusion coefficient D and relative maximal mass uptake ratio X M | ∞ - Table 1) as well as additional values listed in Table 2 3 leads to results depicted in Figure 8, where the experimental equivalent permittivities have been obtained by multiplying the measured capacitance by the mean sample thickness and inverse electrode surface, yielding polymer coating equivalent permittivity in the same range than reported values in the literature ( [44,45] Cole-Cole coefficient α sec 0.87 Table 2: Additional parameters for dielectric analysis ( 0 denotes the vacuum permittivity). due to the limited decreasing slope with frequency (consistent with the literature - [23,20]), but it should be kept in mind that the use of such a permittivity model does not have any impact on the exposed principles and can be advantageously replaced by another one (note that the same observation also applies for the mixing rule or for the evolution of the water mass uptake; the latter being possibly non-Fickian).…”

“…Nevertheless, coupon extraction for gravimetric measurements without damaging the operating structure (such as pipe for instance) is barely feasible. Hence, in order to be able to assess the integrity of the coating by in-situ techniques, dielectric analysis through direct capacitance measurements ( [18,19,20]) or by means of Electrochemical Impedance Spectroscopy (EIS - [21,22]) for instance and its correlation with water mass uptake ( [23,24]) has been proposed.…”

Study on the moisture absorption of zwitterionic copolymers for moisture‐sensitive shape memory applications

“…The moisture absorption was determined by weighing method described in previous publications . Before testing, the specimens were completely dried.…”