Thermally stimulated depolarization current studies in pristine and 100 MeV Ni-ion irradiated PET/0.3PHB polymer liquid crystal

Abstract

790-800<span style="font-size: 15.5pt;mso-bidi-font-size:8.5pt;font-family:" times="" new="" roman","serif""="">Thermally stimulated depolarization current (TSDC) characteristics of PET/0.3PHB polymer liquid crystal, a copolymer of polyethylene terephthalate and p-hydroxybenzoic acid, have been studied as a function of the polarizing field (38.5- 192.3 kV /em), polarizing temperature (80-220 °C), heating rate (2-6 °C/min), storage time (0-960 h) and electrode <span style="font-size: 15.5pt;mso-bidi-font-size:8.5pt;font-family:" times="" new="" roman","serif""="">material (Au, AI,Cr). The TSDC spectra in general comprise of three maxima namely β, β' and α with their respective location around 35, 122 and 155 °C. The β-peak has been attributed to the dipolar orientation relaxation of PET rich phase. The α-peak has been ascribed to the space charge relaxation. A major contribution towards a-relaxation comes from PHB-rich phase and the cold crystallization of PET-rich phase. The presence of a rigid amorphous phase (γ-relaxation) appears to <span style="font-size: 15.5pt;mso-bidi-font-size:8.5pt;font-family:" times="" new="" roman","serif""="">affect the true nature of α -peak. A high temperature maxima around 190°C in TSDC spectra of high temperature poled <span style="font-size: 15.5pt;mso-bidi-font-size:8.5pt;font-family:" times="" new="" roman","serif""="">samples is due to melting (δ- relaxation). The β'-peak is ascribed to the extremely fast reacting dipoles of PHB and PET phase. The TSDC spectra of PET/0.3PHB samples irradiated with 100 MeV Ni-ion beam (Fluence: 3.39×1010,8.93× 1010<span style="font-size:13.0pt;mso-bidi-font-size:6.0pt; font-family:" times="" new="" roman","serif""="">, <span style="font-size:15.5pt; mso-bidi-font-size:8.5pt;font-family:" times="" new="" roman","serif""="">3.13× 1011ions/cm2 <span style="font-size:13.0pt;mso-bidi-font-size:6.0pt;font-family: " times="" new="" roman","serif""="">) <span style="font-size:15.5pt;mso-bidi-font-size: 8.5pt;font-family:" times="" new="" roman","serif""="">show the presence of new energy traps (deep/shallow). The peak magnitudes and peak temperatures for <span style="font-size: 15.5pt;mso-bidi-font-size:8.5pt;font-family:" times="" new="" roman","serif""="">β- as well as α- peak increase with fluence. The appearance of new polar groups due to radiation induced cross- linked structure is also possible in the irradiated PET/0.3PHB sample. </span