Correlation of structural and Johari-Goldstein relaxations in systems vitrifying along isobaric and isothermal paths (Articolo in rivista)

Type
Label
  • Correlation of structural and Johari-Goldstein relaxations in systems vitrifying along isobaric and isothermal paths (Articolo in rivista) (literal)
Anno
  • 2007-01-01T00:00:00+01:00 (literal)
Alternative label
  • Capaccioli, S; Kessairi, K; Prevosto, D; Lucchesi, M; Rolla, PA (2007)
    Correlation of structural and Johari-Goldstein relaxations in systems vitrifying along isobaric and isothermal paths
    (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#autori
  • Capaccioli, S; Kessairi, K; Prevosto, D; Lucchesi, M; Rolla, PA (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#numeroVolume
  • 19 (literal)
Note
  • ISI Web of Science (WOS) (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#affiliazioni
  • Univ Pisa, Dipartimento Fis, I-56127 Pisa, Italy; CNR, INFM, CRS, SOFT, I-00185 Rome, Italy; CNR, PolyLab, I-56127 Pisa, Italy (literal)
Titolo
  • Correlation of structural and Johari-Goldstein relaxations in systems vitrifying along isobaric and isothermal paths (literal)
Abstract
  • The effect of isobaric cooling ( over the range 190 - 350 K) and isothermal compression (up to 700 MPa) on structural alpha- and secondary beta-relaxations has been studied for low molecular weight glass-forming systems. The shape of the a- loss peak was found to change with temperature T and pressure P but to be constant for a combination of T and P giving the same tau(alpha)(T, P). The invariance of shape at constant tau(alpha)(T, P) involved also the excess wing, i.e. the process showing up at the high-frequency tail of the alpha-loss peak in systems with no well-resolved beta-process. Likewise, systems where the excess wing evolved to a well-resolved beta-peak showed that the timescale of the beta-process was strongly related to that of the alpha-peak. Also in this case, once a given value tau(alpha)(T, P) was fixed, a corresponding value tau beta(T, P) was found for different T and P. Same results were found also for a binary mixture of a polar rigid molecule dissolved in an apolar solvent, i.e. a model system for Johari-Goldstein intermolecular relaxation. These evidences imply that a strong correlation exists between structural alpha- and Johari-Goldstein relaxation over a wide interval of temperature and density. (literal)
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