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Multiple Relaxations in Poly (p-hydroxybenzoic acid-CO-ethylene terephthalate) Liquid Crystal Polymer: TSD Current Investigations

Published online by Cambridge University Press:  01 February 2011

Jitendra Kumar Quamara ,
Sridharbabu Yarramaneni  and
Geetika Goyal
Jitendra Kumar Quamara
Affiliation:
jkquamara@yahoo.com, National Institute of Technology, Deptt. of Applied Physics, NIT Kurukshetra, Kurukshetra, N/A, India, 91 1744 238470, 91 1744 238050
Sridharbabu Yarramaneni
Affiliation:
sridharsridharsridhar@yahoo.com, National Institute of Technology, Department of Applied Physics, Kurukshetra, N/A, India
Geetika Goyal
Affiliation:
smart_geetu@yahoo.com, National Institute of Technology, Department of Applied Physics, Kurukshetra, N/A, India
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Abstract

The PET/x.PHB samples were polarized at different temperatures (30-250°C) under various biasing fields ranging from 40 to 200 kV/ cm. The TSD currents were obtained at a heating rate of 2 °C/min in the temperature range (15-250)°C. The TSD current spectra in general comprise of three maxima namely β, α and δ in ascending order of temperature. However number of peaks actually appearing in these spectra, their location, height and sharpness are governed by polarization/depolarization parameters as well as the value of ‘x’ in a particular sample. The β peak appearing around (110-140°C) has been recognized as a dipolar relaxation process and is due to PET rich phase. The α- peak (160-180°C) recognized as space charge process is due to PHB rich phase and cold crystallization of PET rich phase. The δ peak (190-210°C) is a melting process due to the movement of large segments leading to Smectic-E like phase. In addition PET/x.PHB also exhibit a weak low temperature dipolar relaxation process β′ peak around (30-40)°C. In the vicinity of α-relaxation a rigid amorphous phase dipolar relaxation process γ relaxation is also observed.

Keywords

dielectric propertiesthermally stimulated currentpolymer
Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 949: Symposium C – Smart Dielectric Polymer Properties, Characterization and Their Devices , 2006 , 0949-C03-20
Copyright
Copyright © Materials Research Society 2007

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