Polyamide 66 (PA 66) nanofiber bundles were
first electrospun and then introduced into isotactic polypropylene
(iPP) melts to prepare nanofiber bundle/iPP composites.
To reveal the influences of matrix molecular weight
(Mn) on the transcrystalline layer, three kinds of iPP with
different Mn were adopted. Polarized optical microscope
was employed to investigate the transcrystallinity. In the
presence of PA 66 nanofiber bundle, the heterogeneous
nucleation distinctly happened in iPP melts. Moreover, the
higher the iPP Mn, the denser the nuclei. Both a decrease in
matrix Mn and an increase in isothermal crystallization
temperature led to an increase in the induction time. The
maximum temperature at which the transcrystalline layer
can be optically observed increased with the increase of
Mn. The growth rate of transcrystallinity decreased with
the increasing Mn and crystallization temperature. Moreover,
selective melting of the transcrystalline layers confirmed
that it was merely composed of α form crystal for
all composites.
