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首页> 外文期刊>Bulletin of the American Physical Society >APS -APS March Meeting 2017 - Event - Fingerprinting molecular deformation of entangled polymers by small-angle neutron scattering
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APS -APS March Meeting 2017 - Event - Fingerprinting molecular deformation of entangled polymers by small-angle neutron scattering

机译：APS -APS 2017年3月会议-活动-通过小角度中子散射指纹图谱分析纠缠聚合物的分子变形

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During the last several decades, the study of the dynamics of entangled polymers has been focusing on the application of the tube model. Despite the tremendous success of this theoretical approach, a key hypothesis of the tube model concerning nonlinear viscoelasticity has not been fully validated by experiments. In this work, we critically examine the molecular deformation of entangled polymers by small-angle neutron scattering (SANS) experiments. A new approach, based on spherical harmonic expansion analysis, has been developed to decompose the 2D anisotropic scattering pattern. This development makes it possible to unambiguously examine the deformation mechanism predicted by statistical and molecular models of entangled polymers at the microscopic level. Our SANS measurements on uniaxially stretched polystyrene melts show that the tube model could not describe the extit{Q}-dependent spherical harmonic expansion coefficients determined from experiments, as it significantly overestimates the deformation anisotropy. The failure of the model stems from its assumption of extit{chain retraction within an affinely-deformed tube}. New insights for understanding the nonlinear flow behavior of entangled polymers will be discussed in this talk.
机译：在过去的几十年中，对纠缠聚合物动力学的研究一直集中在管模型的应用上。尽管这种理论方法取得了巨大的成功，但是关于非线性粘弹性的管模型的关键假设尚未通过实验得到充分验证。在这项工作中，我们通过小角度中子散射（SANS）实验来严格检查缠结聚合物的分子变形。已经开发了一种基于球谐展开分析的新方法来分解二维各向异性散射图。这种发展使得有可能在微观水平上明确地检查由缠结聚合物的统计模型和分子模型预测的变形机理。我们对单轴拉伸聚苯乙烯熔体的SANS测量表明，管模型无法描述由实验确定的依赖于ext {Q}的球谐谐波膨胀系数，因为它大大高估了变形各向异性。该模型的失败源于其存在的假设{仿射变形管中的链缩回}。在本讲座中将讨论用于理解纠缠聚合物的非线性流动行为的新见解。

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