Flow-induced crystallization precursor structure in high molecular weight isotactic polypropylene (HMW-iPP)/low molecular weight linear low density polyethylene (LMW-LLDPE) binary blends
Flow-induced crystallization precursor structure in high molecular weight isotactic polypropylene (HMW-iPP)/low molecular weight linear low density polyethylene (LMW-LLDPE) binary blends
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DOI：
10.1016/j.polymer.2012.12.067
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发表时间：
2013-02
期刊：
影响因子：
4.6
通讯作者：
J. Keum;Y. Mao;F. Zuo;B. Hsiao
中科院分区：
文献类型：
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作者：
J. Keum;Y. Mao;F. Zuo;B. Hsiao
以高相对分子质量等规聚丙烯(HMW-IPP)和低相对分子质量线性低密度聚乙烯(LMW-LLDPE)共混物为模型体系，采用基于同步加速器的广角和小角X射线散射技术(WAXS/SAXS)研究了流动诱导初始结晶前驱体的形成。其主要成分为LMW-LLDPE，为非晶态基质。在高于共混物浊点的温度下，以时间分辨的方式研究了三种不同HMW-iPP浓度，即3，6和9wt%的共混物的结晶行为。研究发现，共混物中HMW-iPP的浓度对流动诱导结晶前驱体的形成有很大影响。HMW-iPP含量较低(3wt%)的共混物不能形成剪切诱导结晶结构。随着HMW-iPP浓度的增加，结晶动力学、结晶度和片层取向都大大提高。
The formation of initial crystallization precursor induced by flow was investigated by synchrotron-based wide- and small-angle X-ray scattering techniques (WAXS/SAXS), using polymer blends consisting of high molecular weight isotactic polypropylene (HMW-iPP) and low molecular weight linear low density polyethylene (LMW-LLDPE) as model systems. LMW-LLDPE, the dominant component, served as the amorphous matrix. Crystallization behavior of the blends with three different HMW-iPP concentrations, i.e., 3, 6 and 9 wt%, were examined at temperatures higher than the blends' cloud points, in a time-resolved manner. It was found that the formation of a flow-induced precursor of crystallization was strongly influenced by the concentration of HMW-iPP in the blends. The blend with low HMW-iPP content (3 wt%) was not able to form a shear-induced crystalline structure. As the concentration of HMW-iPP increased, crystallization kinetics, crystallinity, and lamellar orientation were greatly enhanced.