| Numéro |
J. Phys. Colloques
Volume 42, Numéro C5, Octobre 1981
ICIFUAS-7Seventh International Conference on Internal Friction and Ultrasonic Attenuation in Solids |
|
|---|---|---|
| Page(s) | C5-563 - C5-568 | |
| DOI | https://doi.org/10.1051/jphyscol:1981586 | |
Seventh International Conference on Internal Friction and Ultrasonic Attenuation in Solids
J. Phys. Colloques 42 (1981) C5-563-C5-568
DOI: 10.1051/jphyscol:1981586
THERMOSTIMULATED CREEP FOR THE STUDY OF MECHANICAL ENERGY LOSSES IN POLYMERS
P. Demont1, D. Chatain1, T. Elsayed1, C. Lacabanne1, D. Ronarc'h2 et J.L. Moura31 Solid State Physics Laboratory, Université Paul Sabatier, 118 Route de Narbonne, 31062 Toulouse Cedex, France
2 CNET Centre Lannion B, TIC Department, B.P. n° 40, Route de Trégastel, 22301 Lannion, France
3 Atochimie, Usine de Mont, 64300 Orthez, France
Abstract
A detailed study of molecular motions has been performed by Thermostimulated Creep (TSC). The great advantage of the TSC technique for this investigation is its high resolving power. Data obtained on polypropylene will be presented as example. Between -30 °C and +40 °C, two retardation modes can be distinguished. The one observed around the glass transition temperature is characterized by mechanical retardation times following an Arrhenius equation. They have the peculiarity to take the same value -τc = 2.8 sec. - at the "compensation temperature" -Tc = 23 °C-. This behavior has been found to be characteristic of the glass transition ; it may arises from amorphous chains free from restraints caused by the presence of crystallites. Another retardation mode is observed 50° above the glass transition temperature. It has also been, experimentally, resolved into "elementary" processes but, contrarily to the preceeding ones, the corresponding retardation times do not follow an Arrhenius equation. As they can be described by a Vogel equation, they have been assigned to the fluidification of the amorphous chains.