Exploring the melting of a semirigid-chain polymer with temperature-resolved small-angle X-ray scattering
Laboratoire de Physique des Polyméres, CP 223, Université Libre de Bruxelles, Boulevard du Triomphe, B-1050, Brussels, Belgium
2 Laboratoire de Physicochimie des Polyméres, Université de Mons-Hainaut, Place du Parc 20, B-7000, Mons, Belgium
3 European Molecular Biology Laboratory, Hamburg Outstation, EMBL c/o DESY, Notkestrasse 85, D-22603, Hamburg, Germany
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The thermal behavior of semirigid semicrystalline polymers differs significantly from that of flexible-chain polymers. The origin of the differences is believed to lie in the higher energy expenditure associated with the formation of adjacent re-entry folds at the crystalline surface in the case of semirigid chains. The effect of constraints imposed by the interlamellar amorphous regions on the neighboring crystals was studied with temperature-resolved synchrotron radiation small-angle X-ray scattering (SAXS). The analysis of SAXS patterns with a generalized paracrystalline lamellar stack model indicates that melting of a semirigid-chain polymer is not a random process but that the crystals grown in the smallest amorphous gaps melt first. This suggests that the hitherto largely neglected geometrical confinement effects may play an important role in determining the thermodynamic stability of semirigid-chain polymer crystals.
© EDP Sciences, Società Italiana di Fisica, and Springer-Verlag, 2004