TIT# Transcrystallisation with reorientation of polypropylene in drawn PET/PP
     and PA66/PP blends. Part 1. Study with WAXS of synchrotron radiation
AUT# Apostolov, A.A.; Samokovlijski, O.; Fakirov, S.; Stribeck, N.;
     Denchev, Z.; Evstatiev, M.; Friedrich, K.; Funari, S. S.;
SOU# Progr. Coll. Polym. Sci. (2005), in print
LOC# xv090
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ABS# Transcrystallisation induced by annealing in the polypropylene (PP) component
     of nanostructured polymer-polymer composites (NPC) was studied for two
     different polymeric fillers. In contrast to the typical narrow columnar
     transcrystalline regions around filler fibres in common glass-fibre
     reinforced PP, volume-filling transcrystallisation was observed for both
     the polymer fillers, thus resulting in reorientation of the PP matrix
     crystals instead of an expected isotropisation.
     Two cold-drawn blends of PP with poly(ethylene terephthalate) (PET) or
     polyamide 66 (PA66), respectively, namely PET/PP and PA66/PP both in a
     ratio of 50/50 wt.% were investigated by means of wide angle X-ray
     scattering (WAXS) of synchrotron radiation during heating, melting of
     only the low-melting component (PP) at 200°C yielding an isotropic melt,
     and subsequent crystallisation upon cooling. A strong epitaxial effect of
     the persistent embedded microfibrillar component (PET or PA66) on the
     non-isothermal crystallisation behaviour of PP during its cooling to
     room temperature was found. The composites obtained after such thermal
     treatment represented anisotropic semi-crystalline nanocomposites, in
     which the PP crystallites were reoriented. The ultimate structure for
     the PET/PP blend exhibited crystals with their molecular axis tilted at
     approx. 49° with respect to their initial orientation (parallel to the
     fibre axis). In the PA66/PP blends the ultimate structure returned to
     the initial orientation of the PP chains parallel to the fibre axis, but
     with a broadened orientation distribution. Results of similar studies
     on other blends are reviewed.