Precursor of shish-kebab in isotactic polystyrene under shear flow
Precursor of shish-kebab in isotactic polystyrene under shear flow
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DOI：
10.1016/j.polymer.2009.03.008
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发表时间：
2009-04
期刊：
影响因子：
4.6
通讯作者：
Yuji Hayashi;G. Matsuba;Yunfeng Zhao;K. Nishida;T. Kanaya
中科院分区：
文献类型：
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作者：
Yuji Hayashi;G. Matsuba;Yunfeng Zhao;K. Nishida;T. Kanaya
我们对等规聚苯乙烯（iPS）在低于和高于标称熔融温度 Tm 的剪切流下的结构形成过程或结晶过程进行了偏光光学显微镜（POM）、去偏光散射（DPLS）和小角和广角 X 射线散射测量。研究发现，即使在标称熔化温度以上，也会形成微米级的各向异性取向结构（此处称为线状物体），并稳定超过24小时，但在远高于标称熔化温度的270°C左右熔化。这种绳状物体充当折叠链片状晶体（或烤肉串）的成核剂，并被指定为烤肉串的前体。我们还检查了结构形成的剪切速率依赖性，以找到形成绳状物体的临界剪切速率，这表明链的松弛在结构的形成中起着重要作用。根据结果我们讨论了类绳物体的内部结构。
We performed polarized optical microscope (POM), depolarized light scattering (DPLS) and small- and wide-angle X-ray scattering measurements on the structure formation process or the crystallization process of isotactic polystyrene (iPS) under shear flow below and above the nominal melting temperature Tm. It was found that an anisotropic oriented structure termed here as a string-like object was formed in μm scale even above the nominal melting temperature and stable for more than 24h, but melted at around 270°C far above the nominal melting temperature. The string-like object acts as a nucleation agent for the folded chain lamella crystal (or the kebab), and was assigned to a precursor of the shish–kebab. We also examined the shear rate dependence of the structure formation to find a critical shear rate for the formation of the string-like object, suggesting the relaxation of the chains plays an important role in the formation of the structure. Based on the results we have discussed the inner structure of the string-like object.