ELECTRICAL-CONDUCTION IN POLY(P-HYDROXYBENZOIC ACID-CO-ETHYLENE TEREPHTHALATE) POLYMER LIQUID-CRYSTAL

Electrical conduction behaviour in poly (p-hydroxybenzoic acid-co-ethy lene terephthalate) PET/0.6PHB polymer liquid has been investigated in both transient and steady state conditions. The measurements were mad e in the temperature range of 50 to 250 degrees C at different electri c fields from 3 to 100 kV/cm. The nature of transient currents has mai nly been attributed to the dipolar nature of both PET and PHB. However the transient phenomenon at 250 degrees C seems to be influenced by m -transition (melting). The low field steady state conduction is ohmic in nature. The high field non-linear nature of field-current plots is temperature dependent and an attempt has been made to explain these cu rves taking into account various conduction processes. The ionic jump distances estimation (53-81A) gives little support to ionic conduction process but the Poole-Frenkel and Schottky coefficients estimation sh ows that both Poole-Frenkel and Schottky conduction mechanisms are ope rative in the intermediate field region (12-50 kV/cm) and at high fiel ds (above 50 kV/cm) respectively. The activation energies were determi ned to be 1.0 and 0.6 eV in the temperature region below and above 170 degrees C respectively, indicating the presence of more than one type of trapping levels in PET/0.6PHB in conformity with the multiphasic n ature of this material.