Pub Date : 2024-04-26DOI: 10.1007/s00397-024-01452-0
Helmut Münstedt
Melt strain hardening is an interesting characteristic property of the elongational flow of polymers. While strain hardening of many unmodified polymer melts has been widely discussed, a comprehensive presentation of the influence of particles on this property is missing. Using literature data and own measurements, the effects of solid particles of various geometries are compared. Micro-sized particles generally reduce melt strain hardening and may even lead to strain thinning. This behavior is postulated to be due to shear flow components around the particles and resulting shear thinning of the polymer matrices that reduces the resistance to flow. More complex is the influence of nano-sized fillers and layered silicate nanoparticles, in particular. Weakly exfoliated particles show effects similar to micro-fillers, but for strongly exfoliated silicates distinct strain hardening is observed that increases with decreasing elongational rate. This behavior is particularly pronounced for polymers modified with maleic anhydrides and thought to be related to electrostatic forces between exfoliated platelets of the silicates and polymer molecules hindering molecular motions.
{"title":"Melt strain hardening of polymeric systems filled with solid particles: review and supplementary experimental results","authors":"Helmut Münstedt","doi":"10.1007/s00397-024-01452-0","DOIUrl":"10.1007/s00397-024-01452-0","url":null,"abstract":"<div><p>Melt strain hardening is an interesting characteristic property of the elongational flow of polymers. While strain hardening of many unmodified polymer melts has been widely discussed, a comprehensive presentation of the influence of particles on this property is missing. Using literature data and own measurements, the effects of solid particles of various geometries are compared. Micro-sized particles generally reduce melt strain hardening and may even lead to strain thinning. This behavior is postulated to be due to shear flow components around the particles and resulting shear thinning of the polymer matrices that reduces the resistance to flow. More complex is the influence of nano-sized fillers and layered silicate nanoparticles, in particular. Weakly exfoliated particles show effects similar to micro-fillers, but for strongly exfoliated silicates distinct strain hardening is observed that increases with decreasing elongational rate. This behavior is particularly pronounced for polymers modified with maleic anhydrides and thought to be related to electrostatic forces between exfoliated platelets of the silicates and polymer molecules hindering molecular motions.</p></div>","PeriodicalId":755,"journal":{"name":"Rheologica Acta","volume":"63 5","pages":"333 - 343"},"PeriodicalIF":2.3,"publicationDate":"2024-04-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00397-024-01452-0.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140802274","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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 : 2024-04-26DOI: 10.1007/s00397-024-01444-0
Pavlos S. Stephanou
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
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。
{"title":"Variable entanglement density constitutive rheological model for polymeric fluids","authors":"Pavlos S. Stephanou","doi":"10.1007/s00397-024-01444-0","DOIUrl":"10.1007/s00397-024-01444-0","url":null,"abstract":"<div><p>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.</p><h3>Graphical abstract</h3>\u0000<div><figure><div><div><picture><source><img></source></picture></div></div></figure></div></div>","PeriodicalId":755,"journal":{"name":"Rheologica Acta","volume":"63 5","pages":"379 - 395"},"PeriodicalIF":2.3,"publicationDate":"2024-04-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140802407","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Increase in viscosity under increasing shear stress, known as shear thickening (ST), is one of the most striking properties of dense particulate suspensions. Under appropriate conditions, they exhibit discontinuous shear thickening (DST), where the viscosity increases dramatically and can also transform into a solid-like state due to shear-induced jamming (SJ). The microscopic mechanism giving rise to such interesting phenomena is still a topic of intense research. A phenomenological model proposed by Wyart and Cates shows that the proliferation of stress-activated interparticle frictional contacts can give rise to such striking flow properties. Building on this model, recent work proposes and verifies a universal scaling relation for ST systems where two different power-law regimes with a well-defined crossover point are obtained. Nonetheless, the difference in the nature of the flow in these two scaling regimes remains unexplored. Here, using rheology in conjugation with high-speed optical imaging, we study the flow and local deformations in various ST systems. We observe that with increasing applied stress, the smooth flow changes into a spatio-temporally varying flow across the scaling crossover. We show that such fluctuating flow is associated with intermittent dilatancy, shear-band plasticity, and fracture induced by system-spanning frictional contacts.
在剪切应力增加的情况下粘度增加,即剪切增稠(ST),是致密颗粒悬浮液最显著的特性之一。在适当的条件下,它们会表现出不连续剪切增稠(DST)现象,此时粘度会急剧增加,还可能由于剪切诱导堵塞(SJ)而转变为类似固体的状态。导致这种有趣现象的微观机制仍是一个热门研究课题。Wyart 和 Cates 提出的一个现象学模型表明,应力激活的颗粒间摩擦接触的扩散可以产生如此惊人的流动特性。在这一模型的基础上,最近的研究提出并验证了 ST 系统的普遍缩放关系,在这一关系中,得到了两种不同的幂律状态,并有一个明确的交叉点。然而,这两种比例关系中流动性质的差异仍有待探索。在此,我们将流变学与高速光学成像相结合,研究了各种 ST 系统中的流动和局部变形。我们观察到,随着外加应力的增加,平滑的流动会转变为跨越缩放交叉点的时空变化流动。我们发现,这种波动流动与间歇性扩张、剪切带塑性以及系统跨摩擦接触诱发的断裂有关。
{"title":"Role of plasticity in the universal scaling of shear-thickening dense suspensions","authors":"Sachidananda Barik, Akhil Mohanan, Sayantan Majumdar","doi":"10.1007/s00397-024-01443-1","DOIUrl":"10.1007/s00397-024-01443-1","url":null,"abstract":"<div><p>Increase in viscosity under increasing shear stress, known as shear thickening (ST), is one of the most striking properties of dense particulate suspensions. Under appropriate conditions, they exhibit discontinuous shear thickening (DST), where the viscosity increases dramatically and can also transform into a solid-like state due to shear-induced jamming (SJ). The microscopic mechanism giving rise to such interesting phenomena is still a topic of intense research. A phenomenological model proposed by Wyart and Cates shows that the proliferation of stress-activated interparticle frictional contacts can give rise to such striking flow properties. Building on this model, recent work proposes and verifies a universal scaling relation for ST systems where two different power-law regimes with a well-defined crossover point are obtained. Nonetheless, the difference in the nature of the flow in these two scaling regimes remains unexplored. Here, using rheology in conjugation with high-speed optical imaging, we study the flow and local deformations in various ST systems. We observe that with increasing applied stress, the smooth flow changes into a spatio-temporally varying flow across the scaling crossover. We show that such fluctuating flow is associated with intermittent dilatancy, shear-band plasticity, and fracture induced by system-spanning frictional contacts.</p></div>","PeriodicalId":755,"journal":{"name":"Rheologica Acta","volume":"63 4","pages":"291 - 300"},"PeriodicalIF":2.3,"publicationDate":"2024-04-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140578632","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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 : 2024-04-12DOI: 10.1007/s00397-024-01442-2
Tiago Lima de Sousa, Jéderson da Silva, Jucélio Tomas Pereira
Viscoelastic materials (VEMs) have gained increasing popularity for their ability to dampen vibrations in various structural applications in recent years. The mechanical characteristics of VEMs can be effectively described using constitutive models featuring both integer and fractional derivatives. This study examines the mechanical behavior of VEMs using fractional Zener models with four, five, and six parameters, as well as the generalized Maxwell model with 16 parameters, which relies on integer derivatives. To accomplish this, the study formulates an optimization problem with the aim of minimizing an error function defined by the quadratic relative distance between theoretical model responses and experimental data. Solving the optimization problem involves the use of a hybrid optimization technique, which combines genetic algorithms and non-linear programming. After obtaining optimal designs for each viscoelastic model, qualitative assessments demonstrate that all analytical models provide satisfactory fits to the experimental data. Subsequently, a statistical analysis employing Akaike’s Information Criterion is conducted to identify the models that best describe the mechanical behavior of the analyzed VEMs. In this quantitative evaluation encompassing all viscoelastic models, it is noted that the generalized Maxwell model with 16 terms produces a lower relative error and statistically outperforms the fractional Zener models only in a global analysis. However, in a temperature-by-temperature analysis, the GMM16 proves to be inferior to all fractional models. Furthermore, when focusing solely on the fractional models, the five-parameter Fractional Zener Model exhibits the best statistical fit to the experimental data.
{"title":"Statistical analysis of identification of linear viscoelastic models","authors":"Tiago Lima de Sousa, Jéderson da Silva, Jucélio Tomas Pereira","doi":"10.1007/s00397-024-01442-2","DOIUrl":"10.1007/s00397-024-01442-2","url":null,"abstract":"<div><p>Viscoelastic materials (VEMs) have gained increasing popularity for their ability to dampen vibrations in various structural applications in recent years. The mechanical characteristics of VEMs can be effectively described using constitutive models featuring both integer and fractional derivatives. This study examines the mechanical behavior of VEMs using fractional Zener models with four, five, and six parameters, as well as the generalized Maxwell model with 16 parameters, which relies on integer derivatives. To accomplish this, the study formulates an optimization problem with the aim of minimizing an error function defined by the quadratic relative distance between theoretical model responses and experimental data. Solving the optimization problem involves the use of a hybrid optimization technique, which combines genetic algorithms and non-linear programming. After obtaining optimal designs for each viscoelastic model, qualitative assessments demonstrate that all analytical models provide satisfactory fits to the experimental data. Subsequently, a statistical analysis employing Akaike’s Information Criterion is conducted to identify the models that best describe the mechanical behavior of the analyzed VEMs. In this quantitative evaluation encompassing all viscoelastic models, it is noted that the generalized Maxwell model with 16 terms produces a lower relative error and statistically outperforms the fractional Zener models only in a global analysis. However, in a temperature-by-temperature analysis, the GMM16 proves to be inferior to all fractional models. Furthermore, when focusing solely on the fractional models, the five-parameter Fractional Zener Model exhibits the best statistical fit to the experimental data.</p></div>","PeriodicalId":755,"journal":{"name":"Rheologica Acta","volume":"63 4","pages":"301 - 318"},"PeriodicalIF":2.3,"publicationDate":"2024-04-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140578623","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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 : 2024-04-11DOI: 10.1007/s00397-024-01446-y
Guinevere Tillinghast, Kevin L. Sánchez-Rivera, George W. Huber, H. Henning Winter, Jonathan P. Rothstein
There is high market demand for increasing the viability of current plastic recycling processes. In this work rheology is used to evaluate the mechanical properties of a solvent dissolution recycled polymer compared to its virgin untreated precursor. Solvent dissolution and precipitation are used to target multi-layer, multi-component, industry films, which cannot be mechanically recycled. Polyethylene was chosen as the primary polymer of interest. Polymer thermal stability was monitored via time-resolved rheology; consecutive frequency sweeps over the course of an hour while under isothermal conditions. Additional rheological experiments were performed within the identified thermally stable conditions. Small-angle oscillatory shear was complemented with steady shear viscosity experiments over a wide range of shear rates. Extensional rheology was used to determine changes in molecular weight and cross link density. Rheological characterization is supplemented with gas chromatography–mass spectrometry of the solvent wash to determine components stripped from the virgin polymers during solvent treatment.
{"title":"Shear and extensional rheology of polyethylenes recycled using a solvent dissolution process","authors":"Guinevere Tillinghast, Kevin L. Sánchez-Rivera, George W. Huber, H. Henning Winter, Jonathan P. Rothstein","doi":"10.1007/s00397-024-01446-y","DOIUrl":"10.1007/s00397-024-01446-y","url":null,"abstract":"<div><p>There is high market demand for increasing the viability of current plastic recycling processes. In this work rheology is used to evaluate the mechanical properties of a solvent dissolution recycled polymer compared to its virgin untreated precursor. Solvent dissolution and precipitation are used to target multi-layer, multi-component, industry films, which cannot be mechanically recycled. Polyethylene was chosen as the primary polymer of interest. Polymer thermal stability was monitored via time-resolved rheology; consecutive frequency sweeps over the course of an hour while under isothermal conditions. Additional rheological experiments were performed within the identified thermally stable conditions. Small-angle oscillatory shear was complemented with steady shear viscosity experiments over a wide range of shear rates. Extensional rheology was used to determine changes in molecular weight and cross link density. Rheological characterization is supplemented with gas chromatography–mass spectrometry of the solvent wash to determine components stripped from the virgin polymers during solvent treatment.</p><h3>Graphical abstract</h3>\u0000<div><figure><div><div><picture><source><img></source></picture></div></div></figure></div></div>","PeriodicalId":755,"journal":{"name":"Rheologica Acta","volume":"63 5","pages":"345 - 360"},"PeriodicalIF":2.3,"publicationDate":"2024-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140578730","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The present work explores the shear and extensional rheology of immiscible multi-micro/nanolayered systems comprising low-density polyethylene (LDPE) paired with polystyrene (PS) and polycarbonate (PC) obtained from forced-assembly multilayer coextrusion. Firstly, miscible multilayer references based on LDPE/LLDPE layers were prepared with their miscibility characterized by shear and elongational measurements. Their strain hardening behaviors were found to be intricately linked to the number of layers and confinement. Secondly, for immiscible LDPE/PS and LDPE/PC multilayers with symmetric (50/50) and asymmetric (10/90) compositions, negative deviation of complex viscosities from neat polymers was highlighted because of the heightened confinement of LDPE chains by PS or PC and reduced entanglements at polymer–polymer interfaces. Intriguingly, LDPE/PC systems exhibited no strain hardening irrespective of layer configuration, while the geometric confinement imposed by PS layers facilitated interactions between single chains with long-chain branching (LCB), leading to strain hardening under specific conditions. Furthermore, the extensional viscosities were predicted using the Macosko model (C.W. Macosko et al. Journal of Rheology. 63 2019), accurately describing the behavior of 1024 layered films for both asymmetric (10/90) LDPE/PS and LDPE/PC systems, but not for 32 layers due to a limited number of interfaces. This study provides insights into quantifying interfacial tension properties in micro/nano-layered systems with high mismatched viscoelastic polymers, shedding light on their strain hardening properties in the presence of increased interfacial area.
{"title":"Interfacial shear and elongational rheology of immiscible multi-micro-nanolayered polymers: contribution for probing the effect of highly mismatched viscoelastic properties and modeling interfacial tension properties","authors":"Jixiang Li, Ibtissam Touil, Bo Lu, Huagui Zhang, Abderrahim Maazouz, Khalid Lamnawar","doi":"10.1007/s00397-024-01445-z","DOIUrl":"10.1007/s00397-024-01445-z","url":null,"abstract":"<div><p>The present work explores the shear and extensional rheology of immiscible multi-micro/nanolayered systems comprising low-density polyethylene (LDPE) paired with polystyrene (PS) and polycarbonate (PC) obtained from forced-assembly multilayer coextrusion. Firstly, miscible multilayer references based on LDPE/LLDPE layers were prepared with their miscibility characterized by shear and elongational measurements. Their strain hardening behaviors were found to be intricately linked to the number of layers and confinement. Secondly, for immiscible LDPE/PS and LDPE/PC multilayers with symmetric (50/50) and asymmetric (10/90) compositions, negative deviation of complex viscosities from neat polymers was highlighted because of the heightened confinement of LDPE chains by PS or PC and reduced entanglements at polymer–polymer interfaces. Intriguingly, LDPE/PC systems exhibited no strain hardening irrespective of layer configuration, while the geometric confinement imposed by PS layers facilitated interactions between single chains with long-chain branching (LCB), leading to strain hardening under specific conditions. Furthermore, the extensional viscosities were predicted using the Macosko model (<i>C.W. Macosko </i>et al<i>. Journal of Rheology. 63 2019</i>), accurately describing the behavior of 1024 layered films for both asymmetric (10/90) LDPE/PS and LDPE/PC systems, but not for 32 layers due to a limited number of interfaces. This study provides insights into quantifying interfacial tension properties in micro/nano-layered systems with high mismatched viscoelastic polymers, shedding light on their strain hardening properties in the presence of increased interfacial area.</p><h3>Graphical abstract</h3>\u0000<div><figure><div><div><picture><source><img></source></picture></div></div></figure></div></div>","PeriodicalId":755,"journal":{"name":"Rheologica Acta","volume":"63 5","pages":"361 - 377"},"PeriodicalIF":2.3,"publicationDate":"2024-04-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140578728","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Understanding and controlling the rheology of electrode slurries for lithium-ion batteries is critical both for improving their manufacturing efficiency and for achieving desirable battery performance. Here, we show drastic “slurry-preparation-dependent” rheology in an anode slurry for lithium-ion batteries, focusing on the behaviour of carboxymethyl cellulose (CMC), which is the most popular dispersant for graphite particles in anode slurries. Slurry preparation with dry-state mixing, where water is added to a dry mixture of graphite and CMC powder, results in much higher viscosity, yield stress, and elastic modulus than those achieved with conventional wet-state mixing, where graphite is added to a CMC solution. Cryogenic scanning electron microscopy reveals strange CMC “clumps” formed among the graphite particles in the slurry prepared with dry-state mixing. We attribute the increases in viscosity, yield stress, and elastic modulus for the slurries prepared with dry-state mixing to these clumps of CMC, which can enhance the adhesion between graphite particles and thereby constrain their motion. We also show that pre-shearing irreversibly decreases viscosity, yield stress, and elastic modulus, suggesting that the clumps of CMC are irreparably broken down by applied shear. The influence of the slurry preparation method on the rheological properties of anode slurries has not received attention in previous studies. Hence, we believe that our results might provide new strategies for controlling the rheology of the anode slurry in the manufacturing process for lithium-ion batteries.
{"title":"Impact of slurry preparation method on the rheological behaviour of dense anode slurries for lithium-ion batteries","authors":"Soichiro Makino, Yusuke Akimoto, Masahiko Ishii, Hiroshi Nakamura","doi":"10.1007/s00397-024-01440-4","DOIUrl":"10.1007/s00397-024-01440-4","url":null,"abstract":"<div><p>Understanding and controlling the rheology of electrode slurries for lithium-ion batteries is critical both for improving their manufacturing efficiency and for achieving desirable battery performance. Here, we show drastic “slurry-preparation-dependent” rheology in an anode slurry for lithium-ion batteries, focusing on the behaviour of carboxymethyl cellulose (CMC), which is the most popular dispersant for graphite particles in anode slurries. Slurry preparation with dry-state mixing, where water is added to a dry mixture of graphite and CMC powder, results in much higher viscosity, yield stress, and elastic modulus than those achieved with conventional wet-state mixing, where graphite is added to a CMC solution. Cryogenic scanning electron microscopy reveals strange CMC “clumps” formed among the graphite particles in the slurry prepared with dry-state mixing. We attribute the increases in viscosity, yield stress, and elastic modulus for the slurries prepared with dry-state mixing to these clumps of CMC, which can enhance the adhesion between graphite particles and thereby constrain their motion. We also show that pre-shearing irreversibly decreases viscosity, yield stress, and elastic modulus, suggesting that the clumps of CMC are irreparably broken down by applied shear. The influence of the slurry preparation method on the rheological properties of anode slurries has not received attention in previous studies. Hence, we believe that our results might provide new strategies for controlling the rheology of the anode slurry in the manufacturing process for lithium-ion batteries.</p></div>","PeriodicalId":755,"journal":{"name":"Rheologica Acta","volume":"63 4","pages":"319 - 331"},"PeriodicalIF":2.3,"publicationDate":"2024-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140170118","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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 : 2024-03-13DOI: 10.1007/s00397-024-01439-x
Thomas Larsen, John R. Royer, Fraser H. J. Laidlaw, Wilson C. K. Poon, Tom Larsen, Søren J. Andreasen, Jesper de C. Christiansen
The ability to manipulate rheological and electrical properties of colloidal carbon black gels makes them attractive in composites for energy applications such as batteries and fuel cells, where they conduct electricity and prevent sedimentation of ‘granular’ active components. While it is commonly assumed that granular fillers have a simple additive effect on the composite properties, new phenomena can emerge unexpectedly, with some composites exhibiting a unique rheological bi-stability between high-yield-stress and low-yield-stress states. Here we report such bi-stability in suspensions of non-Brownian graphite and colloidal carbon black in oil, a model system to mimic composite suspensions for energy applications. Steady shear below a critical stress elicits a transition to a persistent mechanically weak and poorly conducting state, which must be ‘rejuvenated’ using high-stress shear to recover a stronger, high-conductivity state. Our findings highlight the highly tunable nature of binary granular/gel composite suspensions and present new possibilities for optimising mixing and processing conditions for Li-ion battery slurries.
{"title":"Controlling the rheo-electric properties of graphite/carbon black suspensions by ‘flow switching’","authors":"Thomas Larsen, John R. Royer, Fraser H. J. Laidlaw, Wilson C. K. Poon, Tom Larsen, Søren J. Andreasen, Jesper de C. Christiansen","doi":"10.1007/s00397-024-01439-x","DOIUrl":"10.1007/s00397-024-01439-x","url":null,"abstract":"<p>The ability to manipulate rheological and electrical properties of colloidal carbon black gels makes them attractive in composites for energy applications such as batteries and fuel cells, where they conduct electricity and prevent sedimentation of ‘granular’ active components. While it is commonly assumed that granular fillers have a simple additive effect on the composite properties, new phenomena can emerge unexpectedly, with some composites exhibiting a unique rheological bi-stability between high-yield-stress and low-yield-stress states. Here we report such bi-stability in suspensions of non-Brownian graphite and colloidal carbon black in oil, a model system to mimic composite suspensions for energy applications. Steady shear below a critical stress elicits a transition to a persistent mechanically weak and poorly conducting state, which must be ‘rejuvenated’ using high-stress shear to recover a stronger, high-conductivity state. Our findings highlight the highly tunable nature of binary granular/gel composite suspensions and present new possibilities for optimising mixing and processing conditions for Li-ion battery slurries.</p>","PeriodicalId":755,"journal":{"name":"Rheologica Acta","volume":"63 4","pages":"283 - 289"},"PeriodicalIF":2.3,"publicationDate":"2024-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00397-024-01439-x.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140128865","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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 : 2024-03-06DOI: 10.1007/s00397-024-01441-3
Clément Berger, David Coulette, Paul Vigneaux
{"title":"Correction to: A metamodel for confined yield stress flows and parameters’ estimation","authors":"Clément Berger, David Coulette, Paul Vigneaux","doi":"10.1007/s00397-024-01441-3","DOIUrl":"10.1007/s00397-024-01441-3","url":null,"abstract":"","PeriodicalId":755,"journal":{"name":"Rheologica Acta","volume":"63 4","pages":"265 - 265"},"PeriodicalIF":2.3,"publicationDate":"2024-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140077907","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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 : 2024-03-02DOI: 10.1007/s00397-024-01438-y
Mahesh T, Satyananda Panda
The long-wave theory is used to model the thin film flow of a generalized second-grade fluid (GSGF) down a tilted plate with a bump topography. The derived single non-linear partial differential equation for the film thickness describes the surface wave generated by the bump, which disturbs the uniform flow. The model involves the non-Newtonian and geometrical parameters that investigate the wave’s shape and amplitude. The model equation is strongly non-linear due to the GSGF’s constitutive equations, and it is solved numerically using the finite volume method, where the flux function is approximated implicitly using the upwind scheme. The simulation reveals that the bump creates the surface wave, it splits and propagates, and its shape and size are influenced by the bump’s height and the non-Newtonian fluid properties.
{"title":"Generalized second-grade fluid flow over a tilted plate with bump topography","authors":"Mahesh T, Satyananda Panda","doi":"10.1007/s00397-024-01438-y","DOIUrl":"10.1007/s00397-024-01438-y","url":null,"abstract":"<div><p>The long-wave theory is used to model the thin film flow of a generalized second-grade fluid (GSGF) down a tilted plate with a bump topography. The derived single non-linear partial differential equation for the film thickness describes the surface wave generated by the bump, which disturbs the uniform flow. The model involves the non-Newtonian and geometrical parameters that investigate the wave’s shape and amplitude. The model equation is strongly non-linear due to the GSGF’s constitutive equations, and it is solved numerically using the finite volume method, where the flux function is approximated implicitly using the upwind scheme. The simulation reveals that the bump creates the surface wave, it splits and propagates, and its shape and size are influenced by the bump’s height and the non-Newtonian fluid properties.</p></div>","PeriodicalId":755,"journal":{"name":"Rheologica Acta","volume":"63 4","pages":"267 - 282"},"PeriodicalIF":2.3,"publicationDate":"2024-03-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140018069","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}