A positron lifetime study of structural relaxation in UV irradiated poly (ethylene terephthalate)

Sathyanarayana, P. M. and Shariff, G. and Thimmegowda, M. C. and Ashalatha, M. B. and Ramani, R. and Ranganathaiah, C. (2002) A positron lifetime study of structural relaxation in UV irradiated poly (ethylene terephthalate). POLYMER DEGRADATION AND STABILITY, 78 (3). pp. 449-458.

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Official URL: http://dx.doi.org/10.1016/S0141-3910(02)00183-0


Structural relaxation in UV irradiated poly (ethylene terephthalate) (PET-UV) has been investigated using positron lifetime techniques. Positron lifetime results show that the structural relaxation processes in PET-UV encompass three different time regimes, unlike the unirradiated poly (ethylene terephthalate) (PET) where only two relaxation times were observed. The relaxation functions constructed from the measured ortho positronium intensity, I-3, exhibit non-exponential character that can be best fitted with two additive exponentials. To determine the extent of deviation from exponential relaxation, we have used the Narayanaswamy model (KWW function) and evaluated the stretching parameter beta. From the relaxation times derived from the exponential decay curves, the. activation energies have been calculated and from these activation energies it seems possible to label the different kinetic units of the UV irradiated poly (ethylene terephthalate) structure participating in the relaxation processes. (C) 2002 Elsevier Science Ltd. All rights reserved.

Item Type: Article
Uncontrolled Keywords: poly (ethylene terephthalate); UV irradiation; structural relaxation; free volume; relaxation time; activation energy
Subjects: Physical Sciences > Physics
Divisions: PG Campuses > Manasagangotri, Mysore > Physics
Depositing User: Users 11 not found.
Date Deposited: 17 Apr 2013 04:53
Last Modified: 14 May 2013 11:49
URI: http://eprints.uni-mysore.ac.in/id/eprint/4386

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