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The role of the amorphous phase in the recrystallization process of cold-crystallized poly(ethylene terephthalate) (Articolo in rivista)
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- Label
- The role of the amorphous phase in the recrystallization process of cold-crystallized poly(ethylene terephthalate) (Articolo in rivista) (literal)
- Anno
- 2008-01-01T00:00:00+01:00 (literal)
- Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#doi
- 10.1140/epje/i2008-10389-0 (literal)
- Alternative label
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- Pieruccini M.; Flores A.; Nochel U.; Di Marco G.; Stribeck N.; Balta Calleja F.J. (literal)
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- ISI Web of Science (WOS) (literal)
- Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#affiliazioni
- Pieruccini M. e Di Marco G. CNR-IPCF
Flores A e Baltà-Calleja F.J. Instuto de Estructura de la Materia CSIC, Madrid, Spagna
Noechel U. e Stribeck N. Institut fur Technische und Makromolekulare Chemie, Universitat Hamburg (literal)
- Titolo
- The role of the amorphous phase in the recrystallization process of cold-crystallized poly(ethylene terephthalate) (literal)
- Abstract
- Abstract. The process of re-crystallization in poly(ethylene terephthalate) is studied by means of X-ray
diffraction (SAXS and WAXS) and dynamical mechanical thermal analysis. Samples cold-crystallized for
9h at the temperatures Tc = 100o C and Tc = 160o C, i.e. in the middle of the relaxation region and
close to its upper bound, respectively, are analyzed. During heating from room temperature, a structural
rearrangement of the stacks is always found at Tr ? Tc +20o C. This process is characterized by a decrease
of the linear crystallinity, irrespective of Tc ;on the other hand, the WAXS crystallinity never increases with
T below Tc +30o C. The lamellar thickness in the low-Tc sample decreases significantly after the structural
transition, whereas in the high-Tc sample the lamellar thickness remains almost unchanged. In both, high-
and low-Tc , the interlamellar thickness increases above Tr . Moreover, the high-Tc sample shows a lower rate
of decrease of the mechanical performance with increasing T as the threshold Tr is crossed. This result is
interpreted in terms of the formation of rigid amorphous domains where the chains are partially oriented.
The presence of these domains would determine i) the stabilization of the crystalline lamellae from the
thermodynamic point of view and ii) the increase of the elastic modulus of the amorphous interlamellar
regions. This idea is discussed by resorting to a phase diagram. An estimation of the chemical-potential
increase of the interlamellar amorphous regions, due to the enhancement of the structural constraints
hindering segmental mobility, is offered. Finally, previous calculations developed within the framework of
the Gaussian chain model (F.J. Balt´a Calleja et al., Phys. Rev. B 75, 224201 (2007)) are used here to
estimate the degree of chain orientation induced by the structural transition of the stacks. (literal)
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