Interfacial Nucleation in iPP/PB-1 Blends Promotes the Formation of Polybutene-1 Trigonal Crystals
Interfacial Nucleation in iPP/PB-1 Blends Promotes the Formation of Polybutene-1 Trigonal Crystals
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iPP/PB-1 共混物中的界面成核促进聚丁烯-1 三角晶体的形成
DOI：
10.1016/j.polymer.2018.01.078
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发表时间：
2018
期刊：
影响因子：
4.6
通讯作者：
Dujin Wang
中科院分区：
文献类型：
--
作者：
Zefan Wang;Xia Dong;Guoming Liu;Qian Xing;Dario Cavallo;Qianhong Jiang;Alej;ro J. Müller;Dujin Wang
在过去的几十年里，聚丁烯-1(PB-1)直接从熔体中形成三角晶型的I‘晶体引起了人们的极大关注。在本研究中，我们在SituSynchrotron WAXD和FT-IR中用DSC、SEM和FT-IR研究了PB-1与过量等规聚丙烯(IPP)共混形成的液滴中PB-1的分级结晶行为。当PB-1分散成大量的小尺寸液滴时，可以抑制第二种形态晶体的异相形核，因为液滴的数量多于第二种形态的活性形核位置(即原来存在于块体PB-1中的活性异质相)。细小分散的PB-1液滴的成核不是均匀的，而是发生在与iPP基体的界面上，导致液滴结晶成I‘型。用傅里叶变换红外光谱测定了I‘晶型在不同温度下的结晶速率。结果表明，共混物中PB-1含量越低，三方晶型I‘结晶越快，界面比表面积越大。在亚稳II形成的动力学过程中观察到了相反的效应。因此，认为第一种晶型的结晶是由PB-1在iPP晶面成核所驱动的，而这种晶化与第二种晶型的结晶是由PB-1液滴中存在的成核不均匀所引起的。
The formation of trigonal Form I′ crystals of polybutene-1 (PB-1) directly from melt has drawn much attention in past decades. In this study, we investigate the fractionated crystallization behavior of PB-1 within droplets formed by blending PB-1 with an excess of isotactic polypropylene (iPP) employing DSC, SEM,in situsynchrotron WAXD and FT-IR. When PB-1 is dispersed into a large number of small size droplets, the heterogeneous nucleation of Form II crystals can be inhibited because the number of droplets is larger than that of active nucleation sites for Form II (i.e., active heterogeneities originally present in bulk PB-1). The nucleation of the finely dispersed PB-1 droplets does not occur homogenously, but at the interface with the iPP matrix, which induces the crystallization of the droplets into Form I′. The crystallization rate of Form I′ at different temperatures was determined by Fourier transform infrared spectroscopy. It was found that trigonal Form I′ crystallizes faster when the content of PB-1 in the blend is lower, and the specific interfacial surface area is larger. The opposite effect has been observed for the kinetics of the metastable Form II formation. It is therefore suggested that Form I′ crystallization is driven by the nucleation of PB-1 at the crystalline iPP surface, which competes with the crystallization of Form II induced by nucleating heterogeneities present in PB-1 droplets.