{"title":"Nonlinear modification of the Rouse model constraining volume conservation of deforming chains","authors":"Youngdon Kwon","doi":"10.1007/s00397-023-01424-w","DOIUrl":null,"url":null,"abstract":"<div><p>Recent experimental observation in fast extensional flow of polymer melts and solutions displayed as presence and absence of viscosity thinning, respectively, has necessitated and also initiated nonlinear modification of the Rouse model, the fundamental molecular model for unentangled polymeric liquids. On that account, concept of reduction of bead friction is introduced in the form of variable friction coefficient <span>\\(\\zeta (t)\\)</span> sometimes with corresponding variation of the Brownian force. This work presents mathematical constraint based on reasonable assumptions for volume conservation of deforming chains and accordingly formulates the rheological constitutive equation. The equation of constraint for volume conservation possibly relieves in part the complication introduced by the friction reduction and intrinsic flow-induced anisotropy in nonlinear modification of the Rouse model. The suggested constitutive equation expresses description in simple rheometric flows quite similar to that of the previous model with B-variation given by Sato et al. (2021) when both are formulated with effects of finite extensibility (FENE) and friction reduction. In addition, the molecular dynamics simulation demonstrates possible validity of the current hypothesis, the constraint of chain volume conservation.</p><h3>Graphical abstract</h3>\n<div><figure><div><div><picture><source><img></source></picture></div></div></figure></div></div>","PeriodicalId":755,"journal":{"name":"Rheologica Acta","volume":"63 1","pages":"79 - 91"},"PeriodicalIF":2.3000,"publicationDate":"2023-12-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Rheologica Acta","FirstCategoryId":"5","ListUrlMain":"https://link.springer.com/article/10.1007/s00397-023-01424-w","RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"MECHANICS","Score":null,"Total":0}
引用次数: 0
Abstract
Recent experimental observation in fast extensional flow of polymer melts and solutions displayed as presence and absence of viscosity thinning, respectively, has necessitated and also initiated nonlinear modification of the Rouse model, the fundamental molecular model for unentangled polymeric liquids. On that account, concept of reduction of bead friction is introduced in the form of variable friction coefficient \(\zeta (t)\) sometimes with corresponding variation of the Brownian force. This work presents mathematical constraint based on reasonable assumptions for volume conservation of deforming chains and accordingly formulates the rheological constitutive equation. The equation of constraint for volume conservation possibly relieves in part the complication introduced by the friction reduction and intrinsic flow-induced anisotropy in nonlinear modification of the Rouse model. The suggested constitutive equation expresses description in simple rheometric flows quite similar to that of the previous model with B-variation given by Sato et al. (2021) when both are formulated with effects of finite extensibility (FENE) and friction reduction. In addition, the molecular dynamics simulation demonstrates possible validity of the current hypothesis, the constraint of chain volume conservation.
最近对聚合物熔体和溶液快速延伸流动的实验观察分别表明，存在和不存在粘度变薄现象，这就有必要对单缠聚合物液体的基本分子模型--劳斯模型进行非线性修正。因此，以可变摩擦系数（\zeta (t)\）的形式引入了珠子摩擦力减小的概念，有时布朗力也会发生相应的变化。本研究基于变形链体积守恒的合理假设，提出了数学约束条件，并据此制定了流变构成方程。体积守恒的约束方程可能会部分缓解在非线性修正 Rouse 模型时由摩擦减少和内在流动引起的各向异性所带来的复杂性。当 Sato 等人（2021 年）提出的具有 B 变量的简单流变流模型和具有有限延伸性（FENE）和摩擦减小效应的模型时，所建议的构成方程所表达的描述非常相似。此外，分子动力学模拟还证明了当前假设--链体积守恒约束--的可能有效性。
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."
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