Variable entanglement density constitutive rheological model for polymeric fluids

IF 2.3 3区工程技术 Q2 MECHANICS

Rheologica Acta Pub Date : 2024-04-26 DOI:10.1007/s00397-024-01444-0

Pavlos S. Stephanou

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Abstract

A variable-entanglement density constitutive model is developed for the description of the rheological properties of entangled polymer melts and concentrated polymer solutions using non-equilibrium thermodynamics (NET). It proposes two evolution equations: one for the average number of entanglements per chain and one for the orientation of entanglement strands. Direct comparison with non-equilibrium molecular dynamics simulation data shows that the model can accurately describe the loss of entanglements due to the applied flow for three molecular weights by using the same value for the convective constraint release (CCR) parameter. The CCR relaxation time depends on the trace of the inverse of the orientation tensor instead of an explicit dependency on the velocity gradient. Finally, the stress tensor contains an additional contribution inspired by the Curtiss-Bird or tumbling snake model. Overall, the model proposed here carefully derives via NET and builds upon the work of Ianniruberto-Marrucci when stretching is not considered.

Graphical abstract

Abstract Image

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聚合物流体的可变纠缠密度构成流变模型

利用非平衡热力学（NET）建立了一个可变纠缠密度构成模型，用于描述纠缠聚合物熔体和浓缩聚合物溶液的流变特性。该模型提出了两个演变方程：一个是每条链的平均纠缠数方程，另一个是纠缠链的取向方程。与非平衡分子动力学模拟数据的直接比较表明，该模型可以通过使用相同的对流约束释放（CCR）参数值，准确地描述三种分子量的外加流动造成的纠缠损失。CCR 松弛时间取决于取向张量的逆迹线，而不是明确取决于速度梯度。最后，受柯蒂斯-伯德（Curtiss-Bird）或翻滚蛇模型的启发，应力张量包含了额外的贡献。总之，本文提出的模型是通过 NET 精心推导出来的，并在不考虑拉伸的情况下，以 Ianniruberto-Marrucci 的工作为基础。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Rheologica Acta 物理-力学

CiteScore

4.60

自引率

8.70%

发文量

审稿时长

3 months

期刊介绍： "Rheologica Acta is the official journal of The European Society of Rheology. The aim of the journal is to advance the science of rheology, by publishing high quality peer reviewed articles, invited reviews and peer reviewed short communications. The Scope of Rheologica Acta includes: - Advances in rheometrical and rheo-physical techniques, rheo-optics, microrheology - Rheology of soft matter systems, including polymer melts and solutions, colloidal dispersions, cement, ceramics, glasses, gels, emulsions, surfactant systems, liquid crystals, biomaterials and food. - Rheology of Solids, chemo-rheology - Electro and magnetorheology - Theory of rheology - Non-Newtonian fluid mechanics, complex fluids in microfluidic devices and flow instabilities - Interfacial rheology Rheologica Acta aims to publish papers which represent a substantial advance in the field, mere data reports or incremental work will not be considered. Priority will be given to papers that are methodological in nature and are beneficial to a wide range of material classes. It should also be noted that the list of topics given above is meant to be representative, not exhaustive. The editors welcome feedback on the journal and suggestions for reviews and comments."