TY - GEN
T1 - Comparative study of dielectric relaxation spectra of electrically and thermally aged low density polyethylene
AU - Lança, Maria do Carmo Henriques
AU - Dias, Carlos Jorge Mariano Miranda
AU - Das-Gupta, Dilip K.
AU - Marat-mendes, José Narciso
PY - 2003
Y1 - 2003
N2 - Low-density polyethylene (LDPE) films were thermally aged in a sodium chloride aqueous solution at constant temperature (thermal aging). Some of the samples were simultaneously immersed in solution and subjected to an electric AC field (electrical aging). The dielectric relaxation spectra at 30 °C in the range of 10-5 Hz to 105 Hz were obtained for unaged and aged samples. For the low frequency (LF) region (10-5 Hz to 10-1 Hz) the time domain technique was used. A lock-in amplifier was used for the 10-1 Hz to 101 Hz medium frequency (MF) region. While for the high frequency (HF), 10-1 Hz to 105 Hz, RLC bridge measurements were performed. The main differences can be seen between electrically, thermally aged and unaged LDPE in the HF and LF regions. The LF peak is a broad peak related to localized space charge injection driven by the electric field. For electrically aged samples this peak increases in an earlier stage of electrical aging, decreasing afterwards. While in thermally aged samples the peak amplitude always increases with aging time. Finally the HF shows the beginning of a peak due to the γ and β transitions. This peak decreases with aging disappearing for the most aged samples.
AB - Low-density polyethylene (LDPE) films were thermally aged in a sodium chloride aqueous solution at constant temperature (thermal aging). Some of the samples were simultaneously immersed in solution and subjected to an electric AC field (electrical aging). The dielectric relaxation spectra at 30 °C in the range of 10-5 Hz to 105 Hz were obtained for unaged and aged samples. For the low frequency (LF) region (10-5 Hz to 10-1 Hz) the time domain technique was used. A lock-in amplifier was used for the 10-1 Hz to 101 Hz medium frequency (MF) region. While for the high frequency (HF), 10-1 Hz to 105 Hz, RLC bridge measurements were performed. The main differences can be seen between electrically, thermally aged and unaged LDPE in the HF and LF regions. The LF peak is a broad peak related to localized space charge injection driven by the electric field. For electrically aged samples this peak increases in an earlier stage of electrical aging, decreasing afterwards. While in thermally aged samples the peak amplitude always increases with aging time. Finally the HF shows the beginning of a peak due to the γ and β transitions. This peak decreases with aging disappearing for the most aged samples.
UR - http://www.scopus.com/inward/record.url?scp=0242664833&partnerID=8YFLogxK
U2 - 10.1109/CEIDP.2003.1254819
DO - 10.1109/CEIDP.2003.1254819
M3 - Conference contribution
SN - 0-7803-7910-1
T3 - Conference on Electrical Insulation and Dielectric Phenomena (CEIDP), Annual Report
SP - 161
EP - 164
BT - 2003 Annual Report Conference on Electrical Insulation and Dielectric Phenomena
PB - IEEE Dielectrics and Electrical Insulation Society
CY - Piscataway
T2 - 2003 Annual Report: Conference on Electrical Insulation and Dieletric Phenomena
Y2 - 19 October 2003 through 22 October 2003
ER -