Dielectric Responses of Polyurethane/Zinc Oxide Blends for Dry-Type Cast Cold-Curing Resin Transformers

Abstract

The influence of different concentrations (0.5, 1.0, and 2.0 wt.%) of Zinc Oxide (ZnO) filler on the dielectric properties of the cold-curing polyurethane (PU) resin is presented in this study. For this purpose, the direct DC conductivity and the broadband dielectric spectroscopy measurements were used to describe the changes in dielectric responses of PU/ZnO nanocomposites over the frequency and temperature range, respectively. It can be stated that, the 1.0 wt.% nanoparticles and lower caused a decrease in the real relative permittivity compared to the pure PU resin, while the higher concentration of nanoparticles for frequencies above 1 Hz had the opposite effect. The presence of nanoparticles in the polyurethane resin affected the segmental dynamics of the polymer chain and changed a charge distribution in the given system. These changes caused a shift of local relaxation peaks in the spectra of imaginary permittivity and dissipation factor of nanocomposites. It is suggested that the temperature-dependent transition of the electric properties in the nano-composite is closely associated with the α-relaxation and intermediate dipolar effects (IDE).

Effect of ZnO nanoparticles on the dielectric properties of polyurethane and epoxy resins

“…The r was almost frequency independent at temperatures 20 and 40 °C, and it increased for low frequencies at higher temperatures. This increase is the effect of the -relaxation process, which was also observed in various works, [12][13][14]. -relaxation is the result of the micro-scaled Brownian motion of the whole chain of polymers.…”

“…Within the given frequency range, we observe a various significant change in r of nanocomposites by ZnO. Firstly, ZnO filler caused a significant 040004-2 decrease in r relative to pure VUKOL 022 for the frequencies higher than 2 Hz [12]. In the case of EPOXYLITE 3750 LV, the ZnO filler caused an increase in the real permittivity in the whole frequency range.…”

“…The final nanocomposites consist of base matrices of PU, which are doped with 1 wt.% ZnO nanoparticles. A very detailed description of preparing NCs based on the VUKOL 022 was described in [12]. In the case of NCs based on the EPOXYLITE 3750 LV, the process of preparing samples is almost the same in the case of VUKOL 022.…”

Life Prediction of Dry Reactor Sensor Based on Deep Neural Network

“…Combined with the typical waveform of on-off overvoltage, the influence law of random parameters such as cut-off value and action time difference on overvoltage is analyzed. The theoretical analysis model of the threephase circuit breaker breaking the shunt reactor is built [8][9][10].…”

Dielectric properties and dielectric relaxation process of polymethylphenylsiloxane/silicon dioxide nanocomposites

“…With more silica content in PMPS composites, the relaxation time decreases, and this indicates that the effect of MWS polarization is more pronounced. This results in faster orientation of the dipoles of PMPS chains that are bound to nanosilica particles 52 . With an increase in temperature, the width of MWS relaxation of the composites did not change, but the symmetry of the relaxation peaks was significantly improved.…”