Pulsed 1H NMR Relaxation in Crystalline Syndiotactic Polystyrene (Articolo in rivista)

Type
Label
  • Pulsed 1H NMR Relaxation in Crystalline Syndiotactic Polystyrene (Articolo in rivista) (literal)
Anno
  • 1991-01-01T00:00:00+01:00 (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#doi
  • 10.1021/ma00002a046 (literal)
Alternative label
  • D. Capitani, A.L. Segre, A. Grassi, S. Sykora (1991)
    Pulsed 1H NMR Relaxation in Crystalline Syndiotactic Polystyrene
    in Macromolecules (Online); American Chemical Society, Washington (Stati Uniti d'America)
    (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#autori
  • D. Capitani, A.L. Segre, A. Grassi, S. Sykora (literal)
Pagina inizio
  • 623 (literal)
Pagina fine
  • 624 (literal)
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  • http://dx.doi.org/10.1021/ma00002a046 (literal)
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  • 24 (literal)
Rivista
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  • 2 (literal)
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  • 2 (literal)
Note
  • ISI Web of Science (WOS) (literal)
  • Scopu (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#affiliazioni
  • Istituto di Metodologie Chimiche Dipartimento di Fisica Università di Salerno Stelar snc, Via E. Fermi 4, Mede (PV) (literal)
Titolo
  • Pulsed 1H NMR Relaxation in Crystalline Syndiotactic Polystyrene (literal)
Abstract
  • A marked shortening of T1 relaxations in solid aromatic polymers can be attributed to O2 adsorbed on the aromatic rings. This effect, observed as a function of temperature, is modulated by the amount of adsorbed O2, which, in turn, varies according to the molecular packing and crystalline/amorphous ratio. Within the temperature range 77-400 K, semicrystalline syndiotactic polystyrenes (s-PS) in the ?, ?, and ? polymorph modifications were studied by pulse 1H NMR at 30 MHz. Due to the presence of many relaxation components, 1,2,2-trideuterio-s-PS was synthesized, crystallized, and characterized by X-ray powder diffraction. At low temperature, when both the O2 diffusion and the spin-diffusion processes are slow enough, the backbone-deuteriated polymers exhibit multiple T1 relaxation: three for ? and ? s-PS and two for ? s-PS. These T1 components are attributed to crystalline and amorphous phases. From the study of these components as a function of temperature and from direct comparison to T1 values in the different phases, the following conclusions were drawn: (i) Clear differentiation was possible between different s-PS polymorphs. (ii) Determination of the crystalline vs amorphous ratio fully consistent with X-ray diffraction data was achieved. (iii) The amorphous component of different semicrystalline s-PS polymorphs could be distinguished. (literal)
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