Pub Date : 2025-09-08DOI: 10.1007/s13367-025-00128-2
Canqi Li, Deshun Yin
Shear banding has been one of the hot issues in polymer science research and hydrogel applications. The universality of transient shear banding has been studied by rheometric characterization and computational simulation of high molecular weight polyacrylamide binary and ternary solutions. The rheological results show that the slope of the steady-state shear stress of the polymer solution in the medium shear rate range decreases with the increase of concentration for both binary and ternary polyacrylamide solutions, while the steady-state shear stress of 500c* polyacrylamide aqueous solution is basically independent of the shear rate, which is a general feature of the existence of the shear banding. Taking the results of the steady-state flow experiment of 500c* as a reference, the simple shear flow simulation study was calculated, and the calculation results found that when the steady-state shear stress is weakly dependent on the shear rate, the velocity field distribution within this shear rate range shows that a transient shear banding is generated, and the existence of the transient shear banding depends on the number of Wi applied. The larger the number of Wi, the longer the transient shear banding will exist.
{"title":"Transient shear banding of highly polydisperse polymer solutions and concentration effects","authors":"Canqi Li, Deshun Yin","doi":"10.1007/s13367-025-00128-2","DOIUrl":"10.1007/s13367-025-00128-2","url":null,"abstract":"<div><p>Shear banding has been one of the hot issues in polymer science research and hydrogel applications. The universality of transient shear banding has been studied by rheometric characterization and computational simulation of high molecular weight polyacrylamide binary and ternary solutions. The rheological results show that the slope of the steady-state shear stress of the polymer solution in the medium shear rate range decreases with the increase of concentration for both binary and ternary polyacrylamide solutions, while the steady-state shear stress of 500<i>c*</i> polyacrylamide aqueous solution is basically independent of the shear rate, which is a general feature of the existence of the shear banding. Taking the results of the steady-state flow experiment of 500<i>c*</i> as a reference, the simple shear flow simulation study was calculated, and the calculation results found that when the steady-state shear stress is weakly dependent on the shear rate, the velocity field distribution within this shear rate range shows that a transient shear banding is generated, and the existence of the transient shear banding depends on the number of <i>Wi</i> applied. The larger the number of <i>Wi</i>, the longer the transient shear banding will exist.</p><h3>Graphical abstract</h3>\u0000<div><figure><div><div><picture><source><img></source></picture></div></div></figure></div></div>","PeriodicalId":683,"journal":{"name":"Korea-Australia Rheology Journal","volume":"37 3-4","pages":"287 - 300"},"PeriodicalIF":2.6,"publicationDate":"2025-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145898490","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-09-04DOI: 10.1007/s13367-025-00130-8
Vahid Rabiei Faradonbeh, Soheil Salahshour, Davood Toghraie
This paper comprehensively investigates integrating surface acoustic waves (SAWs) within microfluidic channels to enhance micromixing efficiency. Utilizing the blood flow flowing through the Carreau–Yasuda non-Newtonian fluid model, we examine the behavior of blood analog fluids under the influence of high-frequency acoustic waves. The study employs advanced computational fluid dynamics (CFD) techniques and perturbation theory to solve the modified continuity and momentum equations, revealing the complex interactions between acoustic streaming and fluid flow. A parametric analysis was conducted for inlet velocities ((text{vel})) ranging from (0.021) to (0.041 text{m}/text{s}) to examine the variations in Reynolds and Peclet numbers. In addition, to evaluate the impact of wave strength on micromixing, the characteristic parameter of the wave generator is considered. ({d}_{0}) was varied between (8) and (14text{ nm}) applied to the system of equations. Our results demonstrate significant improvements in mixing performance, with a remarkable increase in fluid homogenization and reaction rates, thereby underscoring the transformative potential of hydro-acoustofluidic systems in biomedical and bioanalytical applications. One of the key outcomes of the present research is achieving rapid homogeneous mixing of blood flow within an extremely short mixing Length of approximately 2 mm, which offers numerous advantages for biological applications. In addition, the sensitivity of micromixing to variations in Reynolds number, which was previously significant, has been reduced by applying acoustic waves and intensifying the acoustic wave strength.
{"title":"Enhancement of micromixing efficiency in non-Newtonian blood flow using surface acoustic waves: a study based on the Carreau–Yasuda model","authors":"Vahid Rabiei Faradonbeh, Soheil Salahshour, Davood Toghraie","doi":"10.1007/s13367-025-00130-8","DOIUrl":"10.1007/s13367-025-00130-8","url":null,"abstract":"<div><p>This paper comprehensively investigates integrating surface acoustic waves (SAWs) within microfluidic channels to enhance micromixing efficiency. Utilizing the blood flow flowing through the Carreau–Yasuda non-Newtonian fluid model, we examine the behavior of blood analog fluids under the influence of high-frequency acoustic waves. The study employs advanced computational fluid dynamics (CFD) techniques and perturbation theory to solve the modified continuity and momentum equations, revealing the complex interactions between acoustic streaming and fluid flow. A parametric analysis was conducted for inlet velocities (<span>(text{vel})</span>) ranging from <span>(0.021)</span> to <span>(0.041 text{m}/text{s})</span> to examine the variations in Reynolds and Peclet numbers. In addition, to evaluate the impact of wave strength on micromixing, the characteristic parameter of the wave generator is considered. <span>({d}_{0})</span> was varied between <span>(8)</span> and <span>(14text{ nm})</span> applied to the system of equations. Our results demonstrate significant improvements in mixing performance, with a remarkable increase in fluid homogenization and reaction rates, thereby underscoring the transformative potential of hydro-acoustofluidic systems in biomedical and bioanalytical applications. One of the key outcomes of the present research is achieving rapid homogeneous mixing of blood flow within an extremely short mixing Length of approximately 2 mm, which offers numerous advantages for biological applications. In addition, the sensitivity of micromixing to variations in Reynolds number, which was previously significant, has been reduced by applying acoustic waves and intensifying the acoustic wave strength.</p><h3>Graphical Abstract</h3>\u0000<div><figure><div><div><picture><source><img></source></picture></div></div></figure></div></div>","PeriodicalId":683,"journal":{"name":"Korea-Australia Rheology Journal","volume":"37 3-4","pages":"253 - 271"},"PeriodicalIF":2.6,"publicationDate":"2025-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145898410","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-09-04DOI: 10.1007/s13367-025-00129-1
Seung Chang Lee, Jun Seo Lee, Seong Jae Lee
Lithium-ion batteries (LIBs) are widely employed across various applications due to their high operating voltage, energy density, and extended cycle life. This study investigated the effect of carboxymethyl cellulose (CMC) molecular weight (MW), a commonly utilized LIB binder, on the rheological properties of anode slurries. Steady shear and creep tests revealed an increase in the viscosity and yield stress of the slurries with increasing CMC MW. The temporal stability of the slurries, evaluated through a hysteresis loop test, showed significant thixotropic phenomenon up to shear rate of 10 s−1 regardless of MW. Although the temperature stability of the slurry improved with increasing MW, the viscosity as a function of temperature at a given shear rate exhibited markedly different behavior depending on the MW. Small-amplitude oscillatory shear tests confirmed that both the crossover frequency and elasticity increased with increasing MW. Additionally, in suspensions composed of carbon black (CB) and binder, the size of conductive particle aggregates was observed to increase with increasing MW. This is inferred to contribute to the formation of an efficient graphite/CB network structure, thereby enhancing the rheological properties and stability. This study is expected to contribute to establishing suitable processing conditions for stable LIB manufacturing by analyzing the rheological properties of anode slurry and predicting its internal structure.
{"title":"Influence of carboxymethyl cellulose molecular weight on anode slurry rheology for lithium-ion batteries","authors":"Seung Chang Lee, Jun Seo Lee, Seong Jae Lee","doi":"10.1007/s13367-025-00129-1","DOIUrl":"10.1007/s13367-025-00129-1","url":null,"abstract":"<div><p>Lithium-ion batteries (LIBs) are widely employed across various applications due to their high operating voltage, energy density, and extended cycle life. This study investigated the effect of carboxymethyl cellulose (CMC) molecular weight (MW), a commonly utilized LIB binder, on the rheological properties of anode slurries. Steady shear and creep tests revealed an increase in the viscosity and yield stress of the slurries with increasing CMC MW. The temporal stability of the slurries, evaluated through a hysteresis loop test, showed significant thixotropic phenomenon up to shear rate of 10 s<sup>−1</sup> regardless of MW. Although the temperature stability of the slurry improved with increasing MW, the viscosity as a function of temperature at a given shear rate exhibited markedly different behavior depending on the MW. Small-amplitude oscillatory shear tests confirmed that both the crossover frequency and elasticity increased with increasing MW. Additionally, in suspensions composed of carbon black (CB) and binder, the size of conductive particle aggregates was observed to increase with increasing MW. This is inferred to contribute to the formation of an efficient graphite/CB network structure, thereby enhancing the rheological properties and stability. This study is expected to contribute to establishing suitable processing conditions for stable LIB manufacturing by analyzing the rheological properties of anode slurry and predicting its internal structure.</p><h3>Graphical Abstract</h3>\u0000<div><figure><div><div><picture><source><img></source></picture></div></div></figure></div></div>","PeriodicalId":683,"journal":{"name":"Korea-Australia Rheology Journal","volume":"37 3-4","pages":"273 - 285"},"PeriodicalIF":2.6,"publicationDate":"2025-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145898492","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Dynamic oscillatory shear rheology (OSR) is a powerful technique for characterizing the viscoelastic behavior of complex fluids and soft materials. However, existing software tools for analyzing such data are limited in availability, accessibility, and scope. Moreover, most require nontrivial technical knowledge—such as software installation and programming skills—restricting their widespread use in research and industry. To address this gap, we developed OSR-Tool, a web-based application for the analysis of oscillatory shear data and extraction of meaningful material parameters. Accessible through modern web browsers at https://edufyx.com/OSR without the need for additional installations or specialized expertise, OSR-Tool integrates the most frequently used analysis methods—Fourier transform (FT) rheology, Lissajous curve analysis, stress decomposition (SD), Chebyshev parameters, and sequence of physical processes (SPP) techniques—within a unified interface. The tool enables efficient processing and interpretation of both linear and nonlinear oscillatory shear data and offers features, such as bulk file import, export capabilities, and an intuitive user interface. OSR-Tool is expected to significantly broaden the adoption of advanced oscillatory shear methods in the rheological characterization of complex fluids and soft materials.
{"title":"Oscillatory shear rheology (OSR)-tool: a web-based platform for analyzing oscillatory shear rheological data","authors":"Tochukwu Olunna Nnyigide, Hyeong Yong Song, Uzodinma Ndibe, Osita Sunday Nnyigide, Kyu Hyun","doi":"10.1007/s13367-025-00127-3","DOIUrl":"10.1007/s13367-025-00127-3","url":null,"abstract":"<p>Dynamic oscillatory shear rheology (OSR) is a powerful technique for characterizing the viscoelastic behavior of complex fluids and soft materials. However, existing software tools for analyzing such data are limited in availability, accessibility, and scope. Moreover, most require nontrivial technical knowledge—such as software installation and programming skills—restricting their widespread use in research and industry. To address this gap, we developed OSR-Tool, a web-based application for the analysis of oscillatory shear data and extraction of meaningful material parameters. Accessible through modern web browsers at https://edufyx.com/OSR without the need for additional installations or specialized expertise, OSR-Tool integrates the most frequently used analysis methods—Fourier transform (FT) rheology, Lissajous curve analysis, stress decomposition (SD), Chebyshev parameters, and sequence of physical processes (SPP) techniques—within a unified interface. The tool enables efficient processing and interpretation of both linear and nonlinear oscillatory shear data and offers features, such as bulk file import, export capabilities, and an intuitive user interface. OSR-Tool is expected to significantly broaden the adoption of advanced oscillatory shear methods in the rheological characterization of complex fluids and soft materials.</p>","PeriodicalId":683,"journal":{"name":"Korea-Australia Rheology Journal","volume":"37 3-4","pages":"235 - 251"},"PeriodicalIF":2.6,"publicationDate":"2025-08-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145898348","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-08-20DOI: 10.1007/s13367-025-00126-4
Dongkeun Yu, Minhyuk Im, Jaewook Nam
Understanding the extensional rheology of viscoelastic fluids is fundamental to advancing a wide array of modern technologies, from precision inkjet printing and high-speed spraying to the controlled formation of droplets in microfluidic devices. In this study, we employ the dripping-onto-substrate capillary breakup extensional rheometry (DoS-CaBER) technique to investigate the capillary thinning dynamics of polymer solutions composed of varying ratios of Newtonian and viscoelastic components. By applying a physically grounded modeling approach, we develop an automated method to identify the transition point between the visco-capillary and elasto-capillary regimes, enabling robust extraction of key rheological parameters. Our results show that increasing the glycerine content leads to higher extensional viscosity, longer relaxation times, and an extended elasto-capillary regime, reflecting enhanced viscous drag and polymer entanglement. Notably, the extensional viscosity in the visco-capillary regime approaches the Newtonian Trouton ratio as the solvent fraction increases, indicating a shift toward solvent-dominated flow behavior. These findings provide new insights into the interplay between viscous and elastic forces in capillary thinning and offer practical guidance for the design and control of extensional flow processes in complex fluids.
{"title":"Visco-elastic transition in capillary thinning of complex fluids","authors":"Dongkeun Yu, Minhyuk Im, Jaewook Nam","doi":"10.1007/s13367-025-00126-4","DOIUrl":"10.1007/s13367-025-00126-4","url":null,"abstract":"<div><p>Understanding the extensional rheology of viscoelastic fluids is fundamental to advancing a wide array of modern technologies, from precision inkjet printing and high-speed spraying to the controlled formation of droplets in microfluidic devices. In this study, we employ the dripping-onto-substrate capillary breakup extensional rheometry (DoS-CaBER) technique to investigate the capillary thinning dynamics of polymer solutions composed of varying ratios of Newtonian and viscoelastic components. By applying a physically grounded modeling approach, we develop an automated method to identify the transition point between the visco-capillary and elasto-capillary regimes, enabling robust extraction of key rheological parameters. Our results show that increasing the glycerine content leads to higher extensional viscosity, longer relaxation times, and an extended elasto-capillary regime, reflecting enhanced viscous drag and polymer entanglement. Notably, the extensional viscosity in the visco-capillary regime approaches the Newtonian Trouton ratio as the solvent fraction increases, indicating a shift toward solvent-dominated flow behavior. These findings provide new insights into the interplay between viscous and elastic forces in capillary thinning and offer practical guidance for the design and control of extensional flow processes in complex fluids.</p><h3>Graphical abstract</h3>\u0000<div><figure><div><div><picture><source><img></source></picture></div></div></figure></div></div>","PeriodicalId":683,"journal":{"name":"Korea-Australia Rheology Journal","volume":"37 3-4","pages":"223 - 233"},"PeriodicalIF":2.6,"publicationDate":"2025-08-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s13367-025-00126-4.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145898491","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-08-04DOI: 10.1007/s13367-025-00125-5
Xuesi Gao, Nam Sub Woo, Wook Ryol Hwang
Flows in a blade free planetary mixer with a free surface were investigated numerically with the moving coordinate system, considering both Coriolis and centrifugal forces, to incorporate the revolutionary and rotational motions together. The level-set method was employed to describe the free surface, and surface tension was incorporated through the continuous surface stress model. Both Newtonian and non-Newtonian fluids (power-law and Herschel-Bulkley models) were employed to investigate the mixing mechanism and performance with free-surface evolution, shear rate distribution, power consumption, and dynamical systems structures. The results show that the free surface shape is primarily affected by gravity and two centrifugal (rotation and revolution) accelerations. The free surface shape appears independent of revolution speed at speeds exceeding 1000 RPM, where the effect of gravity can be neglected. Using the Poincaré map, the dynamical systems structures were analyzed within the mixer and it was observed that the size of coherent structures reduces with increasing revolution speed, indicating enhancement of mixing performance. High shear rate regions appear locally near the vessel walls, and the dimensionless maximum shear rate was expressed as a function of the Reynolds number and the vessel size. Power draw depends strongly on revolution speed, particularly on rheological behaviors at a low revolution speed; but it becomes independent of rheological properties at a high revolution speed due to formation of inertia-dominated flow. A flow quantification framework is proposed, achieving power number predictions in terms of the Reynolds number for a given fixed ratio between rotation and revolution at high speed.
{"title":"Numerical simulations for flows in a blade free planetary mixer: dynamical systems and flow quantification","authors":"Xuesi Gao, Nam Sub Woo, Wook Ryol Hwang","doi":"10.1007/s13367-025-00125-5","DOIUrl":"10.1007/s13367-025-00125-5","url":null,"abstract":"<div><p>Flows in a blade free planetary mixer with a free surface were investigated numerically with the moving coordinate system, considering both Coriolis and centrifugal forces, to incorporate the revolutionary and rotational motions together. The level-set method was employed to describe the free surface, and surface tension was incorporated through the continuous surface stress model. Both Newtonian and non-Newtonian fluids (power-law and Herschel-Bulkley models) were employed to investigate the mixing mechanism and performance with free-surface evolution, shear rate distribution, power consumption, and dynamical systems structures. The results show that the free surface shape is primarily affected by gravity and two centrifugal (rotation and revolution) accelerations. The free surface shape appears independent of revolution speed at speeds exceeding 1000 RPM, where the effect of gravity can be neglected. Using the Poincaré map, the dynamical systems structures were analyzed within the mixer and it was observed that the size of coherent structures reduces with increasing revolution speed, indicating enhancement of mixing performance. High shear rate regions appear locally near the vessel walls, and the dimensionless maximum shear rate was expressed as a function of the Reynolds number and the vessel size. Power draw depends strongly on revolution speed, particularly on rheological behaviors at a low revolution speed; but it becomes independent of rheological properties at a high revolution speed due to formation of inertia-dominated flow. A flow quantification framework is proposed, achieving power number predictions in terms of the Reynolds number for a given fixed ratio between rotation and revolution at high speed.</p><h3>Graphical Abstract</h3>\u0000<div><figure><div><div><picture><img></picture></div></div></figure></div></div>","PeriodicalId":683,"journal":{"name":"Korea-Australia Rheology Journal","volume":"37 3-4","pages":"207 - 222"},"PeriodicalIF":2.6,"publicationDate":"2025-08-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145898463","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-06-03DOI: 10.1007/s13367-025-00124-6
Hyeong Yong Song, Hyo Jae Kong, Seung Hak Lee, Min Chan Kim, Gyungbok Kim, Nakyong Yun, Kyu Hyun
This study investigated the rheological properties of thermoplastic elastomer (TPE) foams filled with thermally expandable microcapsules by dynamic oscillatory shear tests. While linear viscoelastic data of the foams showed simple elastic-dominant behavior, nonlinear viscoelastic parameters obtained from Fourier-transform rheology exhibited two-step developments resulting from cell interfacial contribution at lower strain amplitude and macroscopic structural changes at higher strain amplitude. Intriguingly, the displacement component of normal stress difference exhibited its sign change from positive to negative right before the second development of shear nonlinearity started. The sign change of normal stress difference is speculated to be due to compressibility feature of foam cells and unknown interaction between matrix and cells. The shear nonlinear properties were correlated with cell structural factors in a power law manner. Using power law relationships, all shear nonlinearities of the foams could be reconstructed into a single master curve as a function of strain units rescaled by cell structural factors, indicating the universality of nonlinear rheological properties of polymer foams produced using TEMs.
{"title":"Viscoelastic properties of thermoplastic elastomer (TPE) foams measured by oscillatory shear tests","authors":"Hyeong Yong Song, Hyo Jae Kong, Seung Hak Lee, Min Chan Kim, Gyungbok Kim, Nakyong Yun, Kyu Hyun","doi":"10.1007/s13367-025-00124-6","DOIUrl":"10.1007/s13367-025-00124-6","url":null,"abstract":"<div><p>This study investigated the rheological properties of thermoplastic elastomer (TPE) foams filled with thermally expandable microcapsules by dynamic oscillatory shear tests. While linear viscoelastic data of the foams showed simple elastic-dominant behavior, nonlinear viscoelastic parameters obtained from Fourier-transform rheology exhibited two-step developments resulting from cell interfacial contribution at lower strain amplitude and macroscopic structural changes at higher strain amplitude. Intriguingly, the displacement component of normal stress difference exhibited its sign change from positive to negative right before the second development of shear nonlinearity started. The sign change of normal stress difference is speculated to be due to compressibility feature of foam cells and unknown interaction between matrix and cells. The shear nonlinear properties were correlated with cell structural factors in a power law manner. Using power law relationships, all shear nonlinearities of the foams could be reconstructed into a single master curve as a function of strain units rescaled by cell structural factors, indicating the universality of nonlinear rheological properties of polymer foams produced using TEMs.</p><h3>Graphical abstract</h3>\u0000<div><figure><div><div><picture><source><img></source></picture></div></div></figure></div></div>","PeriodicalId":683,"journal":{"name":"Korea-Australia Rheology Journal","volume":"37 3-4","pages":"193 - 206"},"PeriodicalIF":2.6,"publicationDate":"2025-06-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145898462","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-05-07DOI: 10.1007/s13367-025-00123-7
Elliza Tri Maharani, Jong-Seok Oh, Seung-Bok Choi
Magnetorheological (MR) elastomer is classified as a smart material whose mechanical properties, such as stiffness, natural frequency, and damping capacity are tunable and controllable under the influence of magnetic field. This tunability makes it suitable for various engineering applications that require adjustable devices. Generally, MR elastomer contains magnetic particles and a matrix. Iron particles are typically used as magnetic particles in MR elastomer because of their low residual magnetism and high magnetization. Nevertheless, iron particles are prone to oxidation in a practical environment that can weaken the effectiveness of MR elastomer in terms of its field-dependent viscoelasticity. As an alternative, MR elastomer contains cobalt particles that offer better oxidative resistance and favorable electrical properties, yet their properties under oxidation have not been explored. In this work, we conducted an oxidation process using diluted 5vol% hydrochloric acid (5 vol% HCl). Two different magnetic particles (iron particles and cobalt particles) were used and tested to identify the better filler for MR elastomer subjected to oxidation conditions. The characterizations of magnetic particles were accomplished using high-resolution field emission scanning electron microscopy and energy dispersive X-ray spectroscopy (HR-FESEM and EDS) to observe the morphology and elemental compositions, and X-ray diffraction (XRD) to determine the crystallinity of magnetic particles. In addition, Fourier-transform infrared (FTIR) analysis was conducted to identify the molecular compounds of the MR elastomers. A vibrating sample magnetometer (VSM) was also utilized to obtain magnetic properties and a rheometer to measure rheological properties. The oxidation on the layer of the magnetic particles undoubtedly affected the MR elastomers’ properties showing the degradation of magnetic properties and rheological properties (storage modulus and loss modulus) for both iron particles and cobalt particles. However, cobalt particles exhibit greater oxidation resistance. It is shown that MR elastomers with cobalt particles showed a higher storage modulus and loss modulus compared to MR elastomers with iron particles both before and after oxidation. Specifically, MR elastomers with cobalt particles and MR elastomers with iron particles showed a decrement of the MR effect by 119.36% and 139.26%, respectively.
{"title":"The material characterization of magnetorheological elastomers consisting of oxidized iron particles and cobalt particles","authors":"Elliza Tri Maharani, Jong-Seok Oh, Seung-Bok Choi","doi":"10.1007/s13367-025-00123-7","DOIUrl":"10.1007/s13367-025-00123-7","url":null,"abstract":"<div><p>Magnetorheological (MR) elastomer is classified as a smart material whose mechanical properties, such as stiffness, natural frequency, and damping capacity are tunable and controllable under the influence of magnetic field. This tunability makes it suitable for various engineering applications that require adjustable devices. Generally, MR elastomer contains magnetic particles and a matrix. Iron particles are typically used as magnetic particles in MR elastomer because of their low residual magnetism and high magnetization. Nevertheless, iron particles are prone to oxidation in a practical environment that can weaken the effectiveness of MR elastomer in terms of its field-dependent viscoelasticity. As an alternative, MR elastomer contains cobalt particles that offer better oxidative resistance and favorable electrical properties, yet their properties under oxidation have not been explored. In this work, we conducted an oxidation process using diluted 5vol% hydrochloric acid (5 vol% HCl). Two different magnetic particles (iron particles and cobalt particles) were used and tested to identify the better filler for MR elastomer subjected to oxidation conditions. The characterizations of magnetic particles were accomplished using high-resolution field emission scanning electron microscopy and energy dispersive X-ray spectroscopy (HR-FESEM and EDS) to observe the morphology and elemental compositions, and X-ray diffraction (XRD) to determine the crystallinity of magnetic particles. In addition, Fourier-transform infrared (FTIR) analysis was conducted to identify the molecular compounds of the MR elastomers. A vibrating sample magnetometer (VSM) was also utilized to obtain magnetic properties and a rheometer to measure rheological properties. The oxidation on the layer of the magnetic particles undoubtedly affected the MR elastomers’ properties showing the degradation of magnetic properties and rheological properties (storage modulus and loss modulus) for both iron particles and cobalt particles. However, cobalt particles exhibit greater oxidation resistance. It is shown that MR elastomers with cobalt particles showed a higher storage modulus and loss modulus compared to MR elastomers with iron particles both before and after oxidation. Specifically, MR elastomers with cobalt particles and MR elastomers with iron particles showed a decrement of the MR effect by 119.36% and 139.26%, respectively.</p><h3>Graphical Abstract</h3>\u0000<div><figure><div><div><picture><source><img></source></picture></div></div></figure></div></div>","PeriodicalId":683,"journal":{"name":"Korea-Australia Rheology Journal","volume":"37 2","pages":"129 - 144"},"PeriodicalIF":2.6,"publicationDate":"2025-05-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s13367-025-00123-7.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145163137","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-04-17DOI: 10.1007/s13367-025-00120-w
Anirban Ghosh, Raghav Kumar, Indranil Saha Dalal
It is well known from existing literature that the molecular constitutive models face convergence issues in CFD simulations at higher flow rates. Hence, this article investigates the viability of a numerically efficient approximation that potentially replaces such models by a GNF-based approach, by closely mimicking flow and stress profiles. As a test case, we use the flow of polymer solutions, modelled by FENE-P, around a sphere. Note, the FENE-P is frequently used as a constitutive model for polymer solutions. First, the flow fields predicted by FENE-P are compared with an equivalent GNF model (with the Carreau-Yasuda serving as the representative GNF in this study). Despite efforts to align the viscosity-shear rate dependence and thus creating equivalent models, the GNF model exhibits notable shortcomings, particularly due to neglect of chain stretching, especially near the stagnation points. Subsequently, an attempt is made to address this limitation by introducing extensional components to the local viscosity. Various inelastic models exist in literature for this aspect, among which the most recent one, the GNF-X formulation [Journal of Rheology 64, 493 (2020)] is selected. However, this formulation predicts significantly large stresses at the stagnation regions relative to FENE-P as well as fails to exhibit the asymmetry in stress and flow profiles. Consequently, we propose appropriate corrections to be added (termed as GNF-XM), which enables successful predictions. The asymmetry and drag coefficients from the GNF-XM agree well with the predictions from FENE-P across all flow rates. Notably, being inelastic and easier to converge, computational times are significantly lower than those for FENE-P, particularly at higher flow rates. This suggests a promising, highly efficient GNF-based approximation to FENE-P, with potential applicability to other complex constitutive models. Note, such an inelastic model would be helpful for polymer processing applications, particularly for faster design estimates. The corrections are physical in origin and independent of the details of the GNF-X formulation, which can be added to any given inelastic mixed-viscosity formulation.
Graphical abstract
现有文献表明，分子本构模型在大流速下的CFD模拟中存在收敛问题。因此，本文研究了数值有效近似的可行性，该近似有可能通过基于gnf的方法取代这些模型，通过密切模拟流动和应力剖面。作为一个测试案例，我们使用了由FENE-P模拟的聚合物溶液绕球体流动。注意，FENE-P经常被用作聚合物溶液的本构模型。首先，将FENE-P预测的流场与等效GNF模型（本文以careau - yasuda为代表的GNF）进行比较。尽管努力调整黏度-剪切率的依赖关系，从而创建等效模型，但GNF模型显示出明显的缺点，特别是由于忽略了链拉伸，特别是在停滞点附近。随后，尝试通过向局部粘度引入拉伸分量来解决这一限制。关于这方面的非弹性模型已有多种文献，其中选择了最新的GNF-X公式[Journal of Rheology 64, 493(2020)]。然而，该公式预测相对于FENE-P的滞止区有明显较大的应力，并且未能表现出应力和流动剖面的不对称性。因此，我们建议添加适当的修正（称为GNF-XM），从而实现成功的预测。GNF-XM的不对称性和阻力系数与FENE-P在所有流速下的预测结果吻合得很好。值得注意的是，由于非弹性且易于收敛，计算时间明显低于FENE-P，特别是在高流速下。这表明，一个有前途的，高效的基于gnf的近似FENE-P，具有潜在的适用性，其他复杂的本构模型。请注意，这种非弹性模型将有助于聚合物加工应用，特别是对于更快的设计估计。校正是物理上的，与GNF-X配方的细节无关，可以添加到任何给定的非弹性混合粘度配方中。图形抽象
{"title":"Necessary corrections to an inelastic mixed-viscosity model to efficiently and accurately solve for the flow of polymer solutions around a sphere","authors":"Anirban Ghosh, Raghav Kumar, Indranil Saha Dalal","doi":"10.1007/s13367-025-00120-w","DOIUrl":"10.1007/s13367-025-00120-w","url":null,"abstract":"<div><p>It is well known from existing literature that the molecular constitutive models face convergence issues in CFD simulations at higher flow rates. Hence, this article investigates the viability of a numerically efficient approximation that potentially replaces such models by a GNF-based approach, by closely mimicking flow and stress profiles. As a test case, we use the flow of polymer solutions, modelled by FENE-P, around a sphere. Note, the FENE-P is frequently used as a constitutive model for polymer solutions. First, the flow fields predicted by FENE-P are compared with an equivalent GNF model (with the Carreau-Yasuda serving as the representative GNF in this study). Despite efforts to align the viscosity-shear rate dependence and thus creating equivalent models, the GNF model exhibits notable shortcomings, particularly due to neglect of chain stretching, especially near the stagnation points. Subsequently, an attempt is made to address this limitation by introducing extensional components to the local viscosity. Various inelastic models exist in literature for this aspect, among which the most recent one, the GNF-X formulation [Journal of Rheology 64, 493 (2020)] is selected. However, this formulation predicts significantly large stresses at the stagnation regions relative to FENE-P as well as fails to exhibit the asymmetry in stress and flow profiles. Consequently, we propose appropriate corrections to be added (termed as GNF-XM), which enables successful predictions. The asymmetry and drag coefficients from the GNF-XM agree well with the predictions from FENE-P across all flow rates. Notably, being inelastic and easier to converge, computational times are significantly lower than those for FENE-P, particularly at higher flow rates. This suggests a promising, highly efficient GNF-based approximation to FENE-P, with potential applicability to other complex constitutive models. Note, such an inelastic model would be helpful for polymer processing applications, particularly for faster design estimates. The corrections are physical in origin and independent of the details of the GNF-X formulation, which can be added to any given inelastic mixed-viscosity formulation.</p><h3>Graphical abstract</h3>\u0000<div><figure><div><div><picture><source><img></source></picture></div></div></figure></div></div>","PeriodicalId":683,"journal":{"name":"Korea-Australia Rheology Journal","volume":"37 2","pages":"91 - 119"},"PeriodicalIF":2.6,"publicationDate":"2025-04-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145166950","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We investigated a composite hydrogel composed of bovine serum albumin (BSA) and xanthan gum (XG). Using small-amplitude oscillatory shear (SAOS) and large-amplitude oscillatory shear (LAOS) tests, we explored the effects of both BSA and XG concentrations on the BSA-XG composite hydrogel across linear and nonlinear deformation length scales. In the SAOS tests, an increase in XG concentration, at a constant BSA content, resulted in a linear increase in the storage modulus (({G}^{prime})) and loss modulus (({G}^{{prime}{prime}})) of the hydrogel. The power-law viscoelastic frequency dependence of the BSA-XG hydrogel increased with higher XG concentrations, indicating a denser crosslinking network. The LAOS behavior, analyzed through storage modulus (({G}^{prime})) and loss modulus (({G}^{{prime}{prime}})) via Fourier transform rheology, revealed that the critical yielding strain amplitudes decreased as the XG concentration increased. Additionally, intra- and intercycle analyses were performed using Lissajous plots in conjunction with the stress decomposition method, stiffening and thickening ratios, and the sequence of physical processes technique. Strong elastic strain-stiffening was identified as the dominant nonlinear behavior at large strain amplitudes. Moreover, at higher XG concentrations, the strain-stiffening response was better preserved beyond the first critical yield strain amplitude. Fourier transform infrared spectra confirmed that the unfolding and crosslinking intensity of BSA was proportional to the XG concentration.
{"title":"Rheological characterization of a novel synergistic bovine serum albumin–xanthan gum composite hydrogel","authors":"Tochukwu Olunna Nnyigide, Osita Sunday Nnyigide, Kyu Hyun","doi":"10.1007/s13367-025-00121-9","DOIUrl":"10.1007/s13367-025-00121-9","url":null,"abstract":"<div><p>We investigated a composite hydrogel composed of bovine serum albumin (BSA) and xanthan gum (XG). Using small-amplitude oscillatory shear (SAOS) and large-amplitude oscillatory shear (LAOS) tests, we explored the effects of both BSA and XG concentrations on the BSA-XG composite hydrogel across linear and nonlinear deformation length scales. In the SAOS tests, an increase in XG concentration, at a constant BSA content, resulted in a linear increase in the storage modulus (<span>({G}^{prime})</span>) and loss modulus (<span>({G}^{{prime}{prime}})</span>) of the hydrogel. The power-law viscoelastic frequency dependence of the BSA-XG hydrogel increased with higher XG concentrations, indicating a denser crosslinking network. The LAOS behavior, analyzed through storage modulus (<span>({G}^{prime})</span>) and loss modulus (<span>({G}^{{prime}{prime}})</span>) via Fourier transform rheology, revealed that the critical yielding strain amplitudes decreased as the XG concentration increased. Additionally, intra- and intercycle analyses were performed using Lissajous plots in conjunction with the stress decomposition method, stiffening and thickening ratios, and the sequence of physical processes technique. Strong elastic strain-stiffening was identified as the dominant nonlinear behavior at large strain amplitudes. Moreover, at higher XG concentrations, the strain-stiffening response was better preserved beyond the first critical yield strain amplitude. Fourier transform infrared spectra confirmed that the unfolding and crosslinking intensity of BSA was proportional to the XG concentration.</p><h3>Graphical abstract</h3>\u0000<div><figure><div><div><picture><source><img></source></picture></div></div></figure></div></div>","PeriodicalId":683,"journal":{"name":"Korea-Australia Rheology Journal","volume":"37 2","pages":"169 - 191"},"PeriodicalIF":2.6,"publicationDate":"2025-04-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145164999","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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