Fast dynamics in glass-forming polymers revisited
- Univ. del Pais Vasco, San Sebastian (Spain). Dept. de Fisica de Materiales
- CSIC, Madrid (Spain). Inst. de Ciencia y Tecnologia de Polimeros
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 the authors 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 {approx} 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 {hor_ellipsis}) 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 {alpha} and {beta} relaxations. Some implications of these results are also discussed.
- OSTI ID:
- 580846
- Report Number(s):
- CONF-961202-; ISBN 1-55899-359-2; TRN: IM9807%%56
- Resource Relation:
- Conference: 1996 Fall meeting of the Materials Research Society (MRS), Boston, MA (United States), 2-6 Dec 1996; Other Information: PBD: 1997; Related Information: Is Part Of Structure and dynamics of glasses and glass formers; Angell, C.A. [ed.] [Arizona State Univ., Tempe, AZ (United States)]; Ngai, K.L. [ed.] [Naval Research Lab., Washington, DC (United States)]; Kieffer, J. [ed.] [Univ. of Illinois, Urbana, IL (United States)]; Egami, T. [ed.] [Univ. of Pennsylvania, Philadelphia, PA (United States)]; Nienhaus, G.U. [ed.] [Univ. of Ulm (Germany)]; PB: 530 p.; Materials Research Society symposium proceedings, Volume 455
- Country of Publication:
- United States
- Language:
- English
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