143. More Dominant Shear Flow Effect Assisted by Added Carbon Nanotubes on Crystallization Kinetics of Isotactic Polypropylene in Nanocomposites
writer：Junyang Wang, Jingjing Yang, Liang Deng, Huagao Fang, Yaqiong Zhang, and Zhigang Wang*
keywords：剪切，結晶，聚丙烯，復合材料
source：期刊
specific source：ACS Appl. Mater. Interfaces, 2015, 7 (2), 1364–1375
Issue time：2015年
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dominant shear flow effect with different shear rates and shear time
with assistance of added carbon nanotubes (CNTs) of low amounts on the
crystallization kinetics of isotactic polypropylene (iPP) in CNT/iPP
nanocomposites was investigated by applying differential scanning
calorimetry (DSC), polarized optical microscopy (POM), and rheometer.
CNTs were chemically modified to improve the dispersity in the iPP
matrix. CNT/iPP nanocomposites with different CNT contents were prepared
by solution blending method. The crystallization kinetics for CNT/iPP
nanocomposites under the quiescent condition studied by DSC indicates
that the addition of CNTs of low amounts significantly accelerates
crystallization of iPP due to heterogeneous nucleating effect of CNTs,
whereas a saturation effect exists at above a critical CNT content. The
shear-induced crystallization behaviors for CNT/iPP nanocomposites
studied by POM and rheometry demonstrate the continuously accelerated
crystallization kinetics with assistance from added CNTs, with
increasing CNT content, shear rate, and shear time, without any
saturation effect. The changes of nucleation density for CNT/iPP
nanocomposites under different shear conditions can be quantified by
using a space-filling modeling from the rheological measurements, and
the results illustrate that the combined effects of added CNTs and shear
flow on the acceleration of crystallization kinetics are not additive,
but synergetic. The mechanisms for the synergetic effect of added CNTs
and shear flow are provided.