The crystallization behavior, the physical properties and the
crystal morphology of b-NA nucleated iPP were investigated in
the current research. Experimental results indicated that the crystallization
temperature of iPP was raised to about 120 C upon the
addition of b-NA by only 0.20 wt%. Double DSC melting peaks verified
the existence of both b and a phase in the b-NA modified iPP.
XRD patterns confirmed the predominant existence of the b-crystal
phase by around 0.85 (or 85%) when 0.10 wt% of b-NA was employed.
The transformation of b to a phase, indicated by the lowered
Kb, was observed upon re-heating by re-extrusion. The
average crystal size of the b-NA modified iPP was remarkably decreased
compared to that of the iPP. Microscopic observation revealed
that the iPP crystals grew very slowly with sizes ranging
from 100–200 lm. The presence of the nano-scaled b-NA led to
higher population of nuclei and a dramatic decrease in the sizes
of the spherulites; the crystals grew very rapidly, leading to extremely
fine morphology. The impact strength of the iPP/b-NA improved
substantially when 0.10–0.20 wt% b-NA was employed;
this was due to the predominant existence of the b-crystals in
the crystal morphology. The color measurement implied that the
clarity of the iPP/b-NA blends was reduced with greater b-NA content.
Injection molding products is a good application of the bnucleated
iPP due to its rapid crystallization rate and requirements
of shorter time in the mold. Hence, the cycle time for injection
molding can be reduced significantly.