Shear thickening in aqueous solutions of hydrocarbon end-capped poly(ethylene oxide)
Shear thickening in aqueous solutions of hydrocarbon end-capped poly(ethylene oxide)
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DOI：
10.1021/ma001772i
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发表时间：
2001-05-08
期刊：
影响因子：
5.5
通讯作者：
Cooper, SL
中科院分区：
文献类型：
--
作者：
Ma, SOX;Cooper, SL
研究了模型疏水端封聚环氧乙烷在水溶液中的剪切增厚行为。以C（12）、C（16）或C（18）烷为端盖的聚环氧乙烷是通过单异氰酸酯与聚乙二醇直接加成制备的。测定了这些聚合物在水溶液中对稳态剪切和振荡剪切的响应。研究了聚合物浓度、温度、缔合强度和聚合物链长对剪切增稠的影响。仅显示分子量较高的PEO（35000）。剪切变薄行为，而分子量较低的peo（10,000和20,000）在一定浓度范围内表现出轻微的剪切增厚。剪切增厚的大小。随结合力的增强而增强，随温度的升高而减弱。随着缔合强度或浓度的增加或温度的降低，发生剪切增厚的临界剪切速率向较低的剪切速率转移。剪切增厚的大小、临界剪切速率和临界剪切应力的比例因子已经用Marrucci等人(1)提出的自由路径模型来解释，该模型表明剪切增厚是由于非高斯链拉伸和解离端基的快速重新捕获。
: The shear thickening behavior in aqueous solutions of model hydrophobically end-capped poly(ethylene oxide) was examined. Poly(ethylene oxide) fully end-capped with C(12), C(16), or C(18) alkanes was prepared by direct addition of monoisocyanate to poly(ethylene glycol). The response of these polymers in aqueous solution to both steady shear and oscillatory shear was determined. The effects of polymer concentration, temperature, association strength, and polymer chain length on shear thickening have been investigated. PEO with higher molecular weight (35 000) shows only. shear thinning behavior whereas PEOs with lower molecular weights (10 000 and 20 000) show mild shear thickening over a range of concentrations. The magnitude of shear thickening. was found to increase with association strength and to decrease with temperature. The critical shear rate at which onset of shear thickening occurs shifted to lower shear rate as the association strength or concentration increases or as temperature decreases. The scaling factors of the magnitude of shear thickening, the critical shear rate, and the critical shear stress have been interpreted in terms of the free path model proposed by Marrucci et al.,(1) which suggests that shear thickening is due to non-Gaussian chain stretching and fast recapture of dissociated end groups.