Volume 71, Number 2, July 2005
|Page(s)||262 - 268|
|Section||Condensed matter: structural, mechanical and thermal properties|
|Published online||10 June 2005|
The decisive influence of local chain dynamics on the overall dynamic structure factor close to the glass transition
Unidad Física de Materiales (CSIC–UPV/EHU) - Apartado 1072 E-20080 San Sebastián, Spain
2 Departamento de Física de Materiales (UPV/EHU) - Apartado 1072 E-20080 San Sebastián, Spain
3 Donostia International Physics Center - Apartado 1072 E-20080 San Sebastián, Spain
4 Institut für Festkörperforschung, Forschungszentrum Jülich GmbH D-52425 Jülich, Germany
Accepted: 23 May 2005
We present molecular-dynamics simulations on 1,4-polybutadiene performed above the glass transition Tg and relate them to measurements of the dynamic structure factor obtained by neutron spin echo spectroscopy. In real space the simulation data display two well-separated dynamical processes: anomalous diffusion and local hopping. A real-space analysis allows a unique identification of both processes. The obtained results lead to a rationalization of most of the various and very different experimental results reported so far in this system and facilitate a general understanding of why close to Tg the local dynamics may globally dominate the dynamic structure factor.
PACS: 64.70.Pf – Glass transitions / 83.10.Rs – Computer simulation of molecular and particle dynamics / 61.12.Ex – Neutron scattering (including small-angle scattering)
© EDP Sciences, 2005
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