Temperature-dependent β-crystal growth in isotactic polypropylene with β-nucleating agent after shear flow
Temperature-dependent β-crystal growth in isotactic polypropylene with β-nucleating agent after shear flow
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DOI：
10.1007/s10118-017-1990-x
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发表时间：
2017-06
影响因子：
4.3
通讯作者：
Yanhui Chen;Hao Yang;Song Yang;Qiuyu Zhang;Zhong‐Ming Li
中科院分区：
文献类型：
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作者：
Yanhui Chen;Hao Yang;Song Yang;Qiuyu Zhang;Zhong‐Ming Li
在我们目前的工作中，通过原位二维广角X射线衍射（2D-WAXD）研究了剪切温度对β-成核剂等规聚丙烯（iPP）中β-晶体生长的影响。在低剪切温度下，由于分子链的移动性较弱，形成的剪切诱导取向前驱体很难松弛回到随机卷曲状态。因此，剪切诱导的取向前驱体诱导了大量取向的α-晶体，而β-晶体则大大凹陷。随着剪切温度的升高，取向的β晶逐渐增多，而α晶逐渐减少。由此推论，β晶含量增加到静态结晶时的（最大）值时的剪切温度与完全消除流动对结晶动力学的加速作用时的剪切温度几乎相同。我们的工作体现了其在调节β-晶体以及iPP的结构和性质操纵方面的重要性。
In our current work, the effect of the shear temperature on the growth ofβ-crystal in isotactic polypropylene (iPP) withβ-nucleating agent is investigated by means ofin situtwo-dimensional wide-angle X-ray diffraction (2D-WAXD). At low shear temperatures, the formed shear-induced oriented precursors are hard to relax back to random coiled state due to the weak mobility of molecular chains. Therefore, plenty of orientedα-crystals are induced by shear-induced oriented precursors, whileβ-crystal is greatly depressed. As the shear temperature increases, orientedβ-crystal gradually increases along with the decrease ofα-crystal. It is deduced that the shear temperature at which the content ofβ-crystal increases to the (maximum) value found in quiescent crystallization is almost the same as that at which the accelerating effect of flow on crystallization kinetics is completely erased. Our work manifests its significance in regulatingβ-crystal and thus in the structure and property manipulation ofiPP.