https://doi.org/10.1007/s100510070105
Very fast relaxation in polycarbonate glass
1
Laboratoire de PhysicoChimie des Matériaux
LuminescentsUMR-CNRS 5620, Université Lyon I,
69622 Villeurbanne Cedex, France
2
Département de Physique des MatériauxUMR-CNRS 5586,
Université Lyon I, 69622 Villeurbanne
Cedex, France
3
Institut Laue-Langevin, 38042 Grenoble Cedex, France
Received:
29
February
2000
Revised:
13
June
2000
Published online: 15 October 2000
Relaxations in amorphous bis-phenol A polycarbonate are studied by neutron scattering, as a function of temperature below the glass transition. Two different processes are observed. One is very fast, with a characteristic time (~ 0.3 ps), that is independent of temperature and momentum transfer. Conversely the other is slower, with a time which is dependent on temperature and momentum transfer. The very fast localized anharmonic motion is interpreted by the overdamping of low-frequency vibrational modes, by nearby dynamic holes. The slower relaxation is thermally activated and momentum transfer dependent. It corresponds to molecular group motions and possibly to the short-time regime of the segmental relaxation.
PACS: 61.41.+e – Polymers, elastomers, and plastics / 61.12.Ex – Neutron scattering techniques (including small-angle scattering) / 64.70.Pf – Glass transitions
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2000
