writer：Yamin Pan, Suyu Shi, Wenzhong Xu, Guoqiang Zheng(通讯作者), Kun Dai, Chuntai Liu, Jingbo Chen, Changyu S
keywords：micro-injection-molding
source：期刊
specific source：Journal of Materials Science
Issue time：2014年
In this paper, injection-molded isotactic polypropylene
(iPP) microparts and macroparts were respectively
fabricated by the molds with different thickness
under the same processing conditions. Comparative study
on microstructure and mechanical property was carried out
by means of scanning electron microscopy (SEM), twodimensional
wide-angle X-ray diffraction (2D-WAXD),
two-dimensional small-angle X-ray scattering (2D-SAXS),
differential scanning calorimetry (DSC) and tensile test.
SEM images reveal that the two parts show distinctly different
hierarchical structure. An obvious ‘skin–core’
structure is present for the macroparts, while a wide distribution
of shish-kebab structure develops in both shear
and core layer for microparts, exhibiting a specific ‘corefree’
morphology. 2D-WAXD, 2D-SAXS and DSC results
show that microparts have higher orientation degree and
crystallinity as compared to macroparts, which are
responsible for the remarkably high tensile strength and
modulus. Our work provides a good example for better
understanding processing structure–property relationship
of iPP through tuning their internal microstructure.