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Fast Dynamics in Glass-Forming Polymers Revisited

Published online by Cambridge University Press:  10 February 2011

J. Colmenero ,
A. Arbe ,
C. Mijangos  and
H. Reinecke
J. Colmenero
Affiliation:
Departamento de Física de Materiales, Facultad de Química, Apdo. 1072, 20080 San Sebastián, Spain, [email protected]
A. Arbe
Affiliation:
Departamento de Física de Materiales, Facultad de Química, Apdo. 1072, 20080 San Sebastián, Spain, [email protected]
C. Mijangos
Affiliation:
CSIC, Instituto de Ciencia y Tecnología de Polímeros, Juan de la Cierva 3, 28006 Madrid, Spain
H. Reinecke
Affiliation:
CSIC, Instituto de Ciencia y Tecnología de Polímeros, Juan de la Cierva 3, 28006 Madrid, Spain
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Abstract

The so called “fast-dynamics” of glass-forming systems as observed by time of flight (TOF) neutron scattering techniques is revisited. TOF-results corresponding to several glass-forming polymers with different chemical microstructure and glass-transition temperature are presented together with the theoretical framework proposed by us to interpret these results. The main conclusion is that the TOF-data can be explained in terms of quasiharmonic vibrations and the particular short time behavior of the segmental dynamics. The segmental dynamics display in the very short time range (t ≈ 2 ps) a crossover from a simple exponential behavior towards a non-exponential regime. The first exponential decay, which is controlled by C-C rotational barriers, can be understood as a trace of the behavior of the system in absence of the effects (correlations, cooperativity, memory effects…) which characterize the dense supercooled liquid like state against the normal liquid state. The non-exponential regime at t > 2 ps corresponds to what is usually understood as α and β relaxations. Some implications of these results are also discussed.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 455: Symposium T – Glasses and Glass Formers–Current Issues , 1996 , 17
Copyright
Copyright © Materials Research Society 1997

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References

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