Shear-Induced Crystallization Precursor Studies in Model Polyethylene Blends by in-Situ Rheo-SAXS and Rheo-WAXD
Shear-Induced Crystallization Precursor Studies in Model Polyethylene Blends by in-Situ Rheo-SAXS and Rheo-WAXD
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DOI：
10.1021/ma049925f
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发表时间：
2004-06
期刊：
影响因子：
5.5
通讯作者：
Ling Yang;R. Somani;I. Šics;B. Hsiao;R. Kolb;H. Fruitwala;C. Ong
中科院分区：
文献类型：
--
作者：
Ling Yang;R. Somani;I. Šics;B. Hsiao;R. Kolb;H. Fruitwala;C. Ong
采用原位流变- saxs（小角x射线散射）和流变- waxd（广角x射线衍射）技术，研究了高分子量聚乙烯和低分子量聚乙烯二元共混聚合物在标称熔点（120℃）附近剪切诱导结晶前驱体结构的发展。采用两种低分子量聚乙烯共聚物作为非结晶基体，共含2 mol %己烯，分子量（Mw）分别为50 000 （MB-50K）和10 000 (MB-100K)，多分散度约为2。采用分子量为250000 Mw (MB-250K)，多分散度约为2的高分子量聚乙烯均聚物作为结晶次要组分。通过溶液共混制备MB-50K/MB-250K和MB-100K/MB-250K两个系列的模型共混物，其质量比分别为100/0、97/3、95/5和90/10，以确保在分子水平上充分混合。在剪切速率为60 s-1，持续时间为5 s，温度为120℃的条件下，无流致结构。
Development of shear-induced crystallization precursor structure was studied by in-situ rheo-SAXS (small-angle X-ray scattering) and rheo-WAXD (wide-angle X-ray diffraction) techniques using binary polymer blends of high and low molecular weight polyethylenes near their nominal melting temperatures (120 °C). Two low molecular weight polyethylene copolymers, containing 2 mol % hexene, with weight-average molecular weights (Mw) of 50 000 (MB-50K) and 100 000 (MB-100K), and polydispersity of about 2, were used as the noncrystallizing matrices. A high molecular weight polyethylene homopolymer with Mw of 250 000 (MB-250K) and polydispersity of about 2 was used as the crystallizing minor component. Two series of model blends, MB-50K/MB-250K and MB-100K/MB-250K, each containing weight ratios of 100/0, 97/3, 95/5, and 90/10, were prepared by solution blending to ensure thorough mixing at the molecular level. At the chosen shear conditions (rate = 60 s-1, duration = 5 s, T = 120 °C), while no flow-induced structur...