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Relation between configurational entropy and relaxation dynamics of glass-forming systems under volume and temperature reduction

Capaccioli, Simone and Prevosto, Daniele and Lucchesi, Mauro and Amirkhani, Masoud and Rolla, Pierangelo (2009) Relation between configurational entropy and relaxation dynamics of glass-forming systems under volume and temperature reduction. Journal of Non-Crystalline Solids, 355 (10-12). pp. 753-758. ISSN 0022-3093

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    Abstract

    SUMMARY The structural relaxation dynamics of two molecular glass-forming systems have been analyzed by means of dielectric spectroscopy, under cooling and compression conditions. The relation of the dynamic slowing down with the reduction of the configurational entropy, SC, as predicted by Adam and Gibbs (AG), was also investigated. As SC is not directly accessible by experiments, it was estimated, following a common procedure in literature, from the excess entropy Sexc of the supercooled liquid with respect to the crystal, determined from calorimetric and expansivity measurements over the same T–P range of dynamics investigation. The AG relation, predicting linear dependence between the logarithmic of structural relaxation time and the reciprocal of the product of temperature with configurational entropy, was successfully tested. Actually, a bilinear relation between Sexc and SC was found, with different proportionality factors in isothermal and isobaric conditions. Using such results, we derived an equation for predicting the pressure dependence of the glass transition temperature, in good accordance with the experimental values in literature.

    Item Type: Article
    Uncontrolled Keywords: Dielectric properties, relaxation, electric modulus, Glass transition, Pressure effects, Polymers and organics, Pressure effects, Glass transition, Fragility, Structural relaxation
    Subjects: Area02 - Scienze fisiche > FIS/03 - Fisica della materia
    Area02 - Scienze fisiche > FIS/07 - Fisica applicata (a beni culturali, ambientali, biologia e medicina)
    Divisions: Dipartimenti (until 2012) > DIPARTIMENTO DI FISICA " E. FERMI"
    Depositing User: Dr Simone Capaccioli
    Date Deposited: 28 Jul 2009
    Last Modified: 20 Dec 2010 11:50
    URI: http://eprints.adm.unipi.it/id/eprint/613

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