Premium
The short time regime of segmental dynamics of glass‐forming polymers
Author(s) -
Colmenero Juan,
Arbe Arantxa
Publication year - 1997
Publication title -
macromolecular symposia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.257
H-Index - 76
eISSN - 1521-3900
pISSN - 1022-1360
DOI - 10.1002/masy.19971210113
Subject(s) - glass transition , supercooling , cooperativity , exponential function , polymer , materials science , neutron scattering , diffusion , thermodynamics , exponential decay , chemical physics , condensed matter physics , scattering , optics , physics , chemistry , mathematics , composite material , nuclear physics , mathematical analysis , biochemistry
The short time regime (10 −13 s ≤ t ≤ 10 −11 s) of the segmental dynamics of several glass‐forming polymers with different chemical microstructure and glass‐transition temperature has been investigated by means of time of flight (TOF) neutron scattering techniques. In this paper we present a summary of the main results obtained as well as the theoretical framework proposed by us to interpret these results. The main conclusion is that the segmental dynamics of glass‐forming polymers display in the very short time range (t = 2 ps) a crossover from a simple exponential behaviour 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 behaviour of the system in absence of the effects (correlations, cooperativity, memory effects…) which characterise 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.