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Title: Thermally stimulated depolarization current studies in pristine and 100 MeV Ni-ion irradiated PET/0.3PHB polymer liquid crystal
Authors: Quamara, J K
Sridharbabu, Y
Keywords: Polymer;Relaxation;Ion irradiation
Issue Date: Oct-2003
Publisher: NISCAIR-CSIR, India
Abstract: 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 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 affect the true nature of α -peak. A high temperature maxima around 190°C in TSDC spectra of high temperature poled 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, 3.13× 1011ions/cm2 ) show the presence of new energy traps (deep/shallow). The peak magnitudes and peak temperatures for 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.
Page(s): 790-800
ISSN: 0975-1041 (Online); 0019-5596 (Print)
Appears in Collections:IJPAP Vol.41(10) [October 2003]

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