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首页> 外文期刊>The Journal of Chemical Physics >RESPONSE OF A SINGLE GRAFTED POLYETHYLENE CHAIN TO SIMPLE SHEAR FLOW - A BROWNIAN DYNAMICS SIMULATION STUDY
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RESPONSE OF A SINGLE GRAFTED POLYETHYLENE CHAIN TO SIMPLE SHEAR FLOW - A BROWNIAN DYNAMICS SIMULATION STUDY

机译：单接枝聚乙烯链对简单剪切流的响应-布朗动力学模拟研究。

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The behavior of a single polyethylene chain grafted to an impenetrable surface, under shear flow, is investigated using Brownian dynamics simulations. Both short-range conformational energies and excluded volume effects are included in the model. Simulations are performed in good and poor solvent conditions in order to explore the effect of solvent quality. The shear flow is represented by the superposition of a force profile increasing linearly with the distance from the surface. Distribution of relational angles, chain dimensions, components of the radius of gyration, segment density distribution, average layer thickness, and average orientation of bond vectors with respect to flow direction are determined and compared with other studies. Above a certain value of the shear rate, a significant increase in chain dimensions is observed for both good and poor solvents, the transition from coiled to stretched state being sharper in poor solvent. In good solvent, chain dimensions along the two perpendicular directions to the flow direction diminish with increasing shear rate. On the other hand, in poor solvent, there is an overall expansion in chain dimensions in all directions at low shear rates, which is subsequently followed by the orientation and alignment of the chain along the direction of flow. The experimentally observed increase in chain dimensions normal to the flow field at low shear rates is evidenced for the first time by simulations. (C) 1996 American Institute of Physics. [References: 30]
机译：使用布朗动力学模拟研究了在剪切流下接枝到不可渗透表面的单个聚乙烯链的行为。该模型包括短程构象能量和排除的体积效应。为了研究溶剂质量的影响，在良好和不良溶剂条件下进行了模拟。剪切流由力分布的叠加表示，该力分布随与表面的距离线性增加。确定了关系角，链尺寸，回转半径的分量，段密度分布，平均层厚度以及键合矢量相对于流向的平均方向的分布，并与其他研究进行了比较。高于一定的剪切速率值时，对于良溶剂和不良溶剂，均观察到链尺寸的显着增加，在不良溶剂中，从卷曲状态到拉伸状态的过渡更为明显。在良好的溶剂中，沿垂直于流动方向的两个垂直方向的链尺寸随剪切速率的增加而减小。另一方面，在不良溶剂中，在低剪切速率下，链的尺寸在所有方向上都有整体膨胀，随后沿流动方向定向和对齐链。实验首次观察到在低剪切速率下垂直于流场的链尺寸增加。 （C）1996年美国物理研究所。 [参考：30]

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