TIT# Crystallization in partially molten oriented blends of polycondensates
     as revealed by X-ray studies
AUT# Fakirov, Stoyko; Stribeck, Norbert; Apostolov, Anton A.;
     Denchev, Zlatan; Krasteva, Boriana; Evstatiev, Michel; Friedrich, Klaus;
SOU# J. Macromol. Sci. Phys. (2001), 40(5), 935-957
LOC# xv060
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ABS# Oriented fibers or films of binary polymer blends from polycondensates
     were investigated by two-dimensional (2D) wide-angle X-ray scattering
     (WAXS) during the finishing process of microfibrillar reinforced
     composite (MFC) preparation, i.e. heating to a temperature between the
     melting temperatures of the two components, isothermal annealing and
     subsequent cooling. It is shown that the crystallization behavior in
     such MFC from polycondensates depends not only on the blend composition,
     but also on thermal treatment conditions. PET / PA12, PBT / PEE, and
     PET / PA6 composites were prepared in various compositions from the
     components poly(ethylene terephthalate) (PET), polyamide 12 (PA12),
     polyamide 6 (PA6), poly(butylene terephthalate (PBT), and poly(ether ester)
     (PEE). Materials were investigated using rotating anode and synchrotron
     source facilities. The effect of the annealing time on the expected
     isotropization of the lower-melting component was studied in PET / PA6
     blend. It was found that PA6 isotropization takes place after 2 h;
     shorter (up to 30 min) and longer (up to 8 h) melt annealing results in
     oriented crystallization due to different reasons. In PET / PA12
     composites the effect of PA12 transcrystallization with reorientation
     was confirmed for various blend compositions. The relative strength of
     the effect decreases with progressing bulk crystallization. Earlier
     presumed coexistence of isotropic and highly oriented crystallites of
     the same kind with drawn PBT / PEE blend was confirmed by WAXS from
     synchrotron source.