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Entangled Polymer Melts in Extensional Flow - Characterization by Combined Rheology and Small-Angle Neutron Scattering

机译：扩展流动中的纠缠聚合物熔体 - 组合流变学和小角度中子散射的表征

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Liquid bridges occur in a variety of situations in nature - yet our understanding of the dynamics and stability is very limited. Examples of liquid bridges are the process used byspiders to form draglines and the process used by cats lapping milk. We have an extendedprogram aiming to provide generic knowledge about the process in which macromolecular fluidfilaments are extended and stretched and show how the extensional properties are related to theproperties on individual molecules. We combine structural and rheological studies of a series ofmodel polymers with different composition and architectures. The project entails synthesizingmodel polymer systems of precisely known molecular architecture, subjecting these materials tocontrolled extensional flows and to measure the molecular deformation under controlled flowsituation by SANS. Neutron contrast is obtained using specific deuterium labeled molecules.We have targeted different systems: first a “simple” sample of homogeneous high-molar masspolymers, where only the central part of a fraction of the polymers were D-labelled with the aimto highlight the polymer deformation and avoid influence of fast relaxation near the polymerends [1]. Another example is a bimodal mixture of linear polymer chains with respectively highand low molar mass, and we have studied samples with more complex geometry, includingPOM-POM architecture. The 2D-SANS data have typically Lozenge shaped contour which isanalyzed using the Read- McLeish-model of stretched polymer network [2]. The structure andrheology are measured both as a function of stain flow velocity, final Hencky strain ratio andduring the relaxation after cessation of extensional flow.
机译：在自然界中，液桥发生在各种情况下-但是我们对动力学和稳定性的了解非常有限。液体桥的例子是蜘蛛用来形成拉铲的过程以及猫研磨牛奶所用的过程。我们有一个扩展程序，旨在提供有关大分子流体丝的拉伸和拉伸过程的一般知识，并显示拉伸特性如何与单个分子的特性相关。我们结合了一系列具有不同组成和结构的模型聚合物的结构和流变学研究。该项目需要合成具有精确已知分子结构的模型聚合物系统，使这些材料经受受控的延伸流，并通过SANS在受控的流态下测量分子变形。中子对比是使用特定的氘标记分子获得的。我们针对不同的系统：首先是“简单”的均质高分子量大分子聚合物样品，其中只有一部分聚合物的中心部分被D-标记，目的是突出聚合物变形并避免聚合物末端附近快速松弛的影响[1]。另一个例子是分别具有高摩尔质量和低摩尔质量的线性聚合物链的双峰混合物，并且我们研究了具有更复杂几何形状的样本，包括POM-POM结构。 2D-SANS数据通常具有Lozenge形状的轮廓，可使用拉伸聚合物网络的Read-McLeish模型进行分析[2]。测量结构和流变学与污点流速，最终的汉克应变比以及在停止延伸流后的松弛过程中的函数有关。

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