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Glass Transition and Ultrasonic Relaxation in Polystyrene

Published online by Cambridge University Press:  10 February 2011

A. Sahnoune  and
L. Piché
A. Sahnoune
Affiliation:
National Research Council Canada, Industrial Materials Institute, 75, de Mortagne, Boucherville, Québec J4B 6Y4 CANADA, abdelhadi.sahnoune@nrc.ca
L. Piché
Affiliation:
National Research Council Canada, Industrial Materials Institute, 75, de Mortagne, Boucherville, Québec J4B 6Y4 CANADA, abdelhadi.sahnoune@nrc.ca
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Abstract

We present measurements of the glass transition and the ultrasonic relaxation modulus in a series of monodisperse polystyrenes. The temperature dependence of the modulus was analyzed using Havriliak-Negami relaxation model (HN) and Vogel-Tammann-Fulcher equation (VTF) for the relaxation time. The results allowed us to determine the fragility index, m, which decreases with increasing molecular weight, Mn. Furthermore, the relaxation time was found to saturate at high molecular weights and varies as Mnp, in the low molecular weight region. The exponent is p≈2 at high temperatures and p ≈ 7 at low temperatures close to Tg.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 455: Symposium T – Glasses and Glass Formers–Current Issues , 1996 , 183
Copyright
Copyright © Materials Research Society 1997

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References

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