Long chain branching and polydispersity effects on the rheological properties of polyethylenes
Long chain branching and polydispersity effects on the rheological properties of polyethylenes
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DOI：
10.1002/pen.11360
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发表时间：
2000-11-01
影响因子：
3.2
通讯作者：
Hatzikiriakos, SG
中科院分区：
文献类型：
--
作者：
Hatzikiriakos, SG
研究了线性和支化聚乙烯的流变行为作为重均分子量 (M-W) 及其分布 (MWD) 以及长链支化水平的函数，试图确定长链支化、多分散性和流变性能之间的相关性。研究发现，利用时间-温度叠加原理获得主曲线需要对粘弹性模量数据进行垂直平移，这与聚合物结构中长链支化的存在有关。发现垂直位移的程度与长链支化的水平相关。这种相关性证实了长链支化与活化的水平流能相关的观察结果。 atan(G " /G') 与 G* 的图（称为 Van Gurp 图）还揭示了一些重要的特征，这些特征可用作聚合物结构中特定特征的标志。更具体地说，Van Gurp 曲线下方的面积与长链支化和多分散性指数的水平相关。这些相关性以图形形式呈现，它们可用于将流变特性与长链支化和/或多分散性的存在关联起来。
The rheological behavior of linear, and branched polyethylenes is studied as a function of the weight average molecular weight (M-W) and its distribution (MWD) as well as the level of long chain branching in an attempt to identify correlations between long chain branching, polydispersity and rheological properties. It is found that a need for vertical shift of the viscoelastic moduli data to obtain the master curves using the time-temperature superposition principle is associated with the existence of long chain branching in the structure of the polymer. The degree of vertical shift is found to correlate with the level of long chain branching. This correlation corroborates with the observation that long chain branching correlates with the horizontal flow energy of activation. Plots of atan(G " /G') vs. G* (known as Van Gurp plots) also reveal some important features that can be used as signs of specific features in the structure of polymers. More specifically, the area included below the Van Gurp curves correlates with the level of long chain branching and polydispersity index. The correlations are presented in graphical form and they can be used to associate rheological properties with the presence of long chain branching and/or polydispersity.