writer：Changyan Zhang, Bo Wang, Jingjing Yang, Guoqiang Zheng(通讯作者), Daowei Ding, Xingru Yan, Kun Dai, Chun
keywords：b-nucleating agent, Phase, Self-assembly
source：期刊
Issue time：2015年

The impacts of both shear temperature and shear rate on both the self-assembled bnucleating agent (bNA) in the hosting isotactic polypropylene (iPP) matrix and the subsequent crystallization of the hosting iPP matrix were investigated by polarized optical microscopy (POM) and wide-angle X-ray diffraction (WAXD), and small-angle X-ray scattering (SAXS) measurements, respectively. Under static condition, bNA could self-assemble into snowflake like aggregate. Once shear was applied, three kinds of selfassembled aggregates could be developed prior to the crystallization of matrix depending on the applied shear temperatures, that is, snowflake-like self-assembled aggregate at 200 ^oC, deformed snowflake-like one with smaller branches at 180 ^oC, tiny and dense needle-like one if shear temperature was further decreased to 160 ^oC. Since b-NA with various self-assembled aggregates can act as nucleating templates for the subsequent nucleation of iPP matrix, it is conceivable that the crystallization behavior of the iPP matrix can be altered. As expected, b-phase crystallinity, long period and lamellar thickness are steadily dependent on the shear temperature and shear rate. That is, when shear was applied at 200 ^oC, b-phase crystallinity, long period and lamellar thickness keeps almost constant regardless of the shear rate. If melt was sheared at 180 ^oC, b-phase crystallinity was decreased while long period and lamellar thickness remained unchanged with elevating shear rate. At lower shear temperature (i.e., 160 ^oC), bphase crystallinity, long period and lamellar thickness were further decreased with increasing the shear rate. These results are of practical significance to understand the long-term ignored issue: apart from the loading of b-NA, different self-assembled aggregates formed in flow field are another crucial factor in determining the microstructure development of matrix.