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首页> 外文期刊>Journal of Applied Polymer Science >Capillary Study on Geometrical Dependence of Shear Viscosity of Polymer Melts
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Capillary Study on Geometrical Dependence of Shear Viscosity of Polymer Melts

机译：聚合物熔体剪切粘度的几何相关性的毛细管研究

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摘要

Geometrical dependence of viscosity of polymethylmethacrylate (PMMA) and high density polyethylene (HDPE) are studied by means of a twin-bore capillary rheometer based on power-law model. Contrary geometrical dependences of shear viscosity are observed for PMMA between 210 and 255℃, but similar geometrical dependences are revealed for HDPE between 190 and 260℃. The fact that wall slip can not successfully explain the irregular geometrical dependence of PMMA viscosity is found in this work. Then, pressure effect and dependence of fraction of free volume (FFV) on both pressure and temperature are proposed to be responsible for the geometrical dependence of capillary viscosity of polymers. The dependence of shear viscosity on applied pressure is first investigated based on the Barus equation. By introducing a shift factor, shear viscosity curves of PMMA measured under different pressures can be shifted onto a set of parallel plots by correcting the pressure effect and the less shear-thinning then disappears, especially at high pressure. Meanwhile, the FFV and combining strength among molecular chains are evaluated for both samples based on molecular dynamics simulation, which implies that the irregular geometrical dependence of PMMA viscosity can not be attributed to the wall slip behavior.
机译：借助基于幂律模型的双孔毛细管流变仪，研究了聚甲基丙烯酸甲酯（PMMA）和高密度聚乙烯（HDPE）粘度的几何关系。在210到255℃之间观察到PMMA的剪切粘度具有相反的几何依赖性，而在190到260℃之间的HDPE具有相似的几何依赖性。在这项工作中发现壁滑不能成功解释PMMA粘度的不规则几何依赖性这一事实。然后，提出了压力效应和自由体积分数（FFV）对压力和温度的依赖性，这与聚合物的毛细管粘度的几何依赖性有关。首先基于Barus方程研究了剪切粘度对施加压力的依赖性。通过引入位移因子，可以通过校正压力效应将在不同压力下测得的PMMA的剪切粘度曲线移至一组平行曲线上，然后剪切变稀现象消失了，特别是在高压下。同时，基于分子动力学模拟对两个样品的FFV和结合强度进行了评估，这表明PMMA粘度的不规则几何依赖性不能归因于壁滑行为。

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