Dielectric Relaxation Investigations in Copolyesteramide (Vectra B950) Polymer Liquid Crystal: Thermally Stimulated Polarization Current Technique

Thermally stimulated polarization currents (TSPC) in copolyesteramide (Vectra B950) polymer liquid crystal have been investigated in the temperature region 20°–250°C under different polarizing fields ranging from 0.7 to 7 kV/cm and with different heating rates. The low temperature region of the TSP current spectra shows a pronounced peak (P1) around 30°C. This peak has been attributed to the dipolar relaxation process associated with ester group. The peak (P2) observed around 140°C has been attributed to a combination of two relaxation processes, the dipolar and space charge relaxation processes. A steady rise in the TSP currents by several orders of magnitude is observed above 150°C. Saturation in the TSP current around 220°C reveals the presence of a relaxation process owing to the movement of large segmental groups in LC phase.