We
report on the role of temperature and shear on the melt behavior
of iPP in the presence of the organic compound N1,N1′-(propane-1,3-diyl)bis(N2-hexyloxalamide) (OXA3,6). It is demonstrated
that OXA3,6 facilitates a viscosity suppression when
it resides in the molten state. The viscosity suppression is attributed
to the interaction of iPP chains/subchains with molten OXA3,6 nanoclusters. The exact molecular mechanism has not
been identified; nevertheless, a tentative explanation is proposed.
The observed viscosity suppression appears similar to that encountered
in polymer melts filled with solid nanoparticles, with the difference
that the OXA3,6 compound reported in this study facilitates
the viscosity suppression in the molten state. Upon cooling, as crystal
growth of OXA3,6 progresses, the decrease in viscosity
is suppressed. Retrospectively, segmental absorption of iPP chains on the surface of micrometer-sized OXA3,6 crystallites
favors the formation of dangling arms, yielding OXA3,6 crystallites decorated with partially absorbed iPP chains. In other words, the resulting OXA3,6 particle
morphology resembles that of a hairy particle or a starlike polymer
chain. Such hairy particles effectively facilitate a viscosity enhancement,
similar to branched polymer chains. This hypothesis and its implications
for the shear behavior of iPP are discussed and supported
using plate–plate rheometry and slit-flow experiments combined
with small-angle X-ray scattering analysis.