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Title: Dielectric spectroscopy of 100 MeV Ag ion irradiated polyetherimide
Authors: Goyal, Geetika
Quamara, J K
Keywords: High energy heavy ion irradiation;Polyetherimide;Dielectric spectroscopy
Issue Date: Sep-2008
Publisher: CSIR
Abstract: The dielectric constant (′) and loss factor (Ɛ′′) have been measured in pristine and 100 MeV Ag ion irradiated (fluences: 5.610¹⁰, 1.810¹¹ and 1.810¹² ions/cm2) polyetherimide (PEI) in the temperature region 30-250C at different frequencies ranging from 200 Hz to 5 MHz. There is an overall increase in Ɛ′ in irradiated samples. This shows the dominance of interfacial polarization arising from the large number of radiation induced defect sites and free radicals. However, the increase in Ɛ′ is not directly proportional to the fluence of irradiance. There is a sudden decline in ′ at intermediate fluence (1.810¹¹ions/cm²) which is due to the occurrence of new secondary radiation induced crystalline (SRIC) phase. In the low temperature region 30-100C, the Ɛ′ follows the Kirkwood model. Above 100C, the Ɛ′ is almost temperature independent. The radiation induced free radical cross-linking and formation of free radicals have been held responsible for this behaviour. Various relaxation processes revealed their presence in the form of loss peaks in Ɛ′′-T curves appearing around 40-50C, 120-130C and 180-220C associated to the dipolar nature of ether linkages, carbonyl groups and space charge relaxation processes, respectively.
Page(s): 660-666
ISSN: 0019-5596
Appears in Collections:IJPAP Vol.46(09) [September 2008]

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