Thermally Stimulated Discharge Current Studies  on Storage Time of Liquid–Crystalline Random  Copolyester, Vectra A

Sapna Kalia; Vandana Sharma

Volume : II, Issue : X, October - 2013

Thermally Stimulated Discharge Current Studies on Storage Time of Liquid–Crystalline Random Copolyester, Vectra A

Sapna Kalia, Vandana Sharma

Abstract :

We have investigated the thermally stimulated discharge current (TSDC) spectra in temperature range 15250 oC for different storage time (ts) [2 hrs – 96 hrs] of Vectra A. The TSDC spectra of Vectra A consist of peaks namely β and α peaks located at temperature 25 oC and 110 oC respectively. The β and α are the dipolar peaks, β–peak arises due to the orientation of HNA group and α–peak is attributed due to the orientation of main chain and associated with the glass transition temperature of Vectra A. The peak value of depolarization current decreases with increase in storage time that agrees with the concept of free volume theory. Also, the location of peak temperature shifts towards higher temperature with increase in storage time confirming the existence of distributed polarization. The important dielectric relaxation parameters; activation energy, charge released and relaxation time are also determined.