Europhys. Lett.
Volume 66, Number 2, April 2004
Page(s) 239 - 245
Section Condensed matter: structure, mechanical and thermal properties
Published online 01 April 2004
Europhys. Lett., 66 (2) , pp. 239-245 (2004)
DOI: 10.1209/epl/i2003-10180-5

Direct observation of the crossover from ${\alpha}$-relaxation to Rouse dynamics in a polymer melt

D. Richter1, M. Monkenbusch1, L. Willner1, A. Arbe2, J. Colmenero2, 3, 4 and B. Farago5

1  Institut für Festkörperforschung, Forschungszentrum Jülich GmbH D-52425 Jülich, Germany
2  Unidad Física de Materiales (CSIC-UPV/EHU) Apartado 1072, 20080 San Sebastián, Spain
3  Departamento de Física de Materiales (UPV/EHU) Apartado 1072, 20080 San Sebastián, Spain
4  Donostia International Physics Center - Apartado 1072, 20080 San Sebastián, Spain
5  Institut Laue-Langevin - BP 156, 38042 Grenoble Cedex 9, France

(Received 4 December 2003; accepted in final form 4 February 2004)

In this letter we report a large experimental effort exploring the dynamics of poly(vinyl ethylene) on length scales covering Rouse dynamics and below. The results establish the simultaneous existence of a generic sublinear diffusion regime which underlies the ${\alpha}$-process in addition to the Rouse process. Both regimes are separated by a well-defined dynamic crossover. From that the size of the Gaussian blobs making up the Rouse model is determined directly. Following this observation, we may identify the universal glassy dynamics with subdiffusive motions occurring within these Gaussian blobs.

61.41.+e - Polymers, elastomers, and plastics.
83.80.Sg - Polymer melts.
64.70.Pf - Glass transitions.

© EDP Sciences 2004