FRAGILITY AND ANHARMONICITY IN INTERPENETRATING POLYMER NETWORKS (Contributo in volume (capitolo o saggio))

Type
Label
  • FRAGILITY AND ANHARMONICITY IN INTERPENETRATING POLYMER NETWORKS (Contributo in volume (capitolo o saggio)) (literal)
Anno
  • 2010-01-01T00:00:00+01:00 (literal)
Alternative label
  • A. Bartolotta; G. Carini; G. D'Angelo, A. Fainleib (2010)
    FRAGILITY AND ANHARMONICITY IN INTERPENETRATING POLYMER NETWORKS
    in Thermostable Polycyanurates: Synthesis, Modification, Structure and Properties, 2010
    (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#autori
  • A. Bartolotta; G. Carini; G. D'Angelo, A. Fainleib (literal)
Pagina inizio
  • 143 (literal)
Pagina fine
  • 159 (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#titoloVolume
  • Thermostable Polycyanurates: Synthesis, Modification, Structure and Properties (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#pagineTotali
  • 17 (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#affiliazioni
  • Istituto per i Processi Chimico-Fisici del C. N. R., Sezione di Messina, Italy Dipartimento di Fisica, Università di Messina, Salita Sperone 31, I-98166 Messina, Italy Institute of Macromolecular Chemistry, National Academy of Sciences of Ukraine, Kharkivske shose, 48, 02160 Kyiv, Ukraine (literal)
Titolo
  • FRAGILITY AND ANHARMONICITY IN INTERPENETRATING POLYMER NETWORKS (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#isbn
  • 978-1-60876-907-0 (literal)
Abstract
  • An intriguing aspect of the dynamic behaviour of polymers is the understanding of the microscopic mechanisms regulating the temperature dependence of cooperative segmental relaxations. Polymers exhibit a complex molecular structure characterized by different intra- and inter-molecular forces, so that the chain environment gives rise to significant deviations from linearity and exponentiality of the cooperative primary or ?-relaxation over the glass-rubber transition region. From this point of view the \"fragility\" of a glass-forming liquid, a concept introduced by C.A. Angell, is an important property which measures the departure from the Arrhenius behaviour of its viscosity ?. \"Fragile\" liquids, such as polymers, are substances with non-directional intermolecular bonds which permit drastic changes in the local order at the glass transition leading to pronounced deviations from the Arrhenius behaviour for the viscosity. Interpenetration of a polycyanurate network with linear polyurethane leads to the formation of semi-interpenetrating polymer networks (semi-IPNs) which exhibit an increasing dynamic fragility and a nearly constant thermodynamic fragility (measured by Cpl/Cpg, the ratio of the liquid to glassy specific heat capacities at Tg). These findings raise some doubts about the existence of a correlation between the cooperative molecular mobility and the variations of the configurational entropy at Tg characterizing the system, when it goes through the glass-rubber transition. (literal)
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