The present work concerns the study of the dielectric relaxation of dielectric oil based on Lagenaria siceraria (calabash) seeds. Dielectric spectroscopy was used to measure the loss angle, the dielectric constant and...The present work concerns the study of the dielectric relaxation of dielectric oil based on Lagenaria siceraria (calabash) seeds. Dielectric spectroscopy was used to measure the loss angle, the dielectric constant and the electrical modulus. Three relaxation processes in calabash oil were identified. It was also found that the relative permittivity decreases with increasing temperature and frequency. A study of the imaginary part of the electrical modulus was done and revealed a relaxation process at low frequencies. At higher frequencies, the dielectric relaxation is thermally activated. The increase in temperature leads to a decrease in the relaxation rate. The result obtained indicates that relaxation type is not of the Debye type in the high-frequency region. The Cole-Cole model of the imaginary part of the permittivity as a function of its real part in calabash oil for different temperatures was drawn and analyzed. It shows the existence of a negative temperature coefficient of resistance in the fluid and helps identifying a relaxation process in the conductivity of the sample studied. It highlights the presence of Debye relaxation which characterizes the presence of an abnormal dispersion of the dielectric constant over a frequency range. Calabash seed oil exhibits better dielectric constant (relative permittivity) compared to other oils.展开更多
The dielectric spectroscopy of polydimethylsiloxane is measured in temperature range of 190 to+120℃ The variation of frequency domain dielectric constant is very small, but time domain slow dielectric constants have ...The dielectric spectroscopy of polydimethylsiloxane is measured in temperature range of 190 to+120℃ The variation of frequency domain dielectric constant is very small, but time domain slow dielectric constants have high peaks at 120 and+80℃. According to H31 structure of molecule. the results can be explained. The time domain method can detect trace impurity of water to2×10-7 in polydimethylsiloxane.展开更多
文摘The present work concerns the study of the dielectric relaxation of dielectric oil based on Lagenaria siceraria (calabash) seeds. Dielectric spectroscopy was used to measure the loss angle, the dielectric constant and the electrical modulus. Three relaxation processes in calabash oil were identified. It was also found that the relative permittivity decreases with increasing temperature and frequency. A study of the imaginary part of the electrical modulus was done and revealed a relaxation process at low frequencies. At higher frequencies, the dielectric relaxation is thermally activated. The increase in temperature leads to a decrease in the relaxation rate. The result obtained indicates that relaxation type is not of the Debye type in the high-frequency region. The Cole-Cole model of the imaginary part of the permittivity as a function of its real part in calabash oil for different temperatures was drawn and analyzed. It shows the existence of a negative temperature coefficient of resistance in the fluid and helps identifying a relaxation process in the conductivity of the sample studied. It highlights the presence of Debye relaxation which characterizes the presence of an abnormal dispersion of the dielectric constant over a frequency range. Calabash seed oil exhibits better dielectric constant (relative permittivity) compared to other oils.
文摘The dielectric spectroscopy of polydimethylsiloxane is measured in temperature range of 190 to+120℃ The variation of frequency domain dielectric constant is very small, but time domain slow dielectric constants have high peaks at 120 and+80℃. According to H31 structure of molecule. the results can be explained. The time domain method can detect trace impurity of water to2×10-7 in polydimethylsiloxane.
