Rheologica Acta最新文献

{"title":"Tuning polymer solution elasticity for electrospinning: effects of molecular weight distribution and elastic doping","authors":"Étienne J. Beaudoin,&nbsp;Ricardo J. Zednik,&nbsp;Nicole R. Demarquette","doi":"10.1007/s00397-025-01541-8","DOIUrl":"10.1007/s00397-025-01541-8","url":null,"abstract":"<div><p>Electrospun nanofibers are used in a wide range of applications, from filtration to biomedical scaffolds, yet their successful formation relies on carefully tuned polymer solution properties. Among these, extensional elasticity plays a central role in stabilizing the fluid jet against capillary breakup. While increasing solution viscosity can modestly delay thinning, it is the presence of entangled high–molecular-weight chains that provides the cohesive elastic stresses needed to sustain a continuous filament until solidification. In this work, the influence of molecular weight distribution (MWD), matrix viscosity, and long-chain content on extensional rheology and electrospinnability was investigated using blends of poly(ethylene glycol) (PEG) and poly(ethylene oxide) (PEO). Shear viscosity and filament thinning dynamics were characterized using rotational rheometry and a custom-built capillary breakup extensional rheometer (CaBER). Initial comparisons confirmed that low molecular weight PEG, despite its high shear viscosity, failed to produce fibers due to the absence of entanglements and extensional elasticity, whereas entangled high molecular weight PEO readily formed uniform nanofibers. MWD was systematically broadened at constant weight-average molecular weight by blending PEO samples of different molecular weights, which increased CaBER-measured relaxation times and led to fibers with larger diameters. Subsequent experiments with Boger-type fluids revealed that shear viscosity alone did not correlate with electrospinning behavior, while relaxation time measured by CaBER remained predictive. Increasing the background matrix viscosity further enhanced extensional elasticity by slowing chain relaxation and filament thinning. Finally, a practical demonstration of elastic doping showed that adding a trace amount of long-chain PEO to an otherwise unspinnable PEG matrix enabled fiber formation and achieved a fivefold increase in polymer throughput. Together, these results establish extensional relaxation time as a robust predictor of electrospinnability and demonstrate that the decoupling of matrix viscosity and chain entanglement offers a versatile strategy for designing high-yield nanofiber formulations.</p><h3>Graphical abstract</h3><div><figure><div><div><picture><source><img></source></picture></div></div></figure></div></div>","PeriodicalId":755,"journal":{"name":"Rheologica Acta","volume":"65 3","pages":"209 - 221"},"PeriodicalIF":3.0,"publicationDate":"2026-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147559022","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}

{"title":"Experimental validation of a magnetorheological fluid activation flow CFD analysis","authors":"Stephen G. Sherman,&nbsp;Min Mao,&nbsp;Young T. Choi,&nbsp;Norman M. Wereley","doi":"10.1007/s00397-025-01540-9","DOIUrl":"10.1007/s00397-025-01540-9","url":null,"abstract":"<div><p>Magnetorheological (MR) fluid-based devices operating at high speeds exhibit a phenomenon termed “high-speed yield force falloff,” characterized by a decrease in the force difference between field-on and field-off states with increasing velocity. This behavior, observed in various applications, contradicts predictions from existing simplified force models that assume constant yield force and employ oversimplified one-dimensional fluid dynamics. Consequently, these models become inaccurate at high speeds due to the increased nonlinearity of the fluid dynamics. This study validates a previously developed two-dimensional computational fluid dynamics (CFD) model, the “activation flow model,” against experimental data obtained from a high-speed MR impact damper. The model accurately predicts the observed yield force falloff, confirming that the primary cause is momentum flux changes within the fluid’s plug region. These findings demonstrate the activation flow model’s potential for accurately predicting high-speed MR device performance, enabling a more robust design of MR impact dampers.</p></div>","PeriodicalId":755,"journal":{"name":"Rheologica Acta","volume":"65 3","pages":"275 - 285"},"PeriodicalIF":3.0,"publicationDate":"2026-01-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00397-025-01540-9.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147559060","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}

{"title":"Multiscale thermal degradation of phas: kinetic and rheological analysis across processing and decomposition regimes","authors":"Hadis Torabi,&nbsp;Hadis Zarrin,&nbsp;Ehsan Behzadfar","doi":"10.1007/s00397-025-01538-3","DOIUrl":"10.1007/s00397-025-01538-3","url":null,"abstract":"<div><p>The thermal degradation of biopolymers limits their industrial and biomedical applications due to poor stability near processing temperatures. This study integrates thermorheology and thermoanalytical techniques to investigate the multiscale degradation behavior of three polyhydroxyalkanoates (PHAs): poly(3-hydroxybutyrate) (PHB), poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), and poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH). Rheological functions were used to track structural changes during processing. Properties such as mass loss and derivative thermogravimetric curves were monitored to obtain perception of degradation behaviour at decomposition temperature. The findings revealed distinct degradation behaviors across processing and decomposition regimes. In the processing temperature range (160–210 °C), PHBH exhibited the highest resistance to thermal degradation. In contrast, at higher decomposition temperatures (&gt; 250 °C), PHB and PHBV displayed higher activation energies. This combined methodology links structural evolution, degradation mechanisms, and macroscopic flow, providing a unified framework for assessing thermal stability of PHA and can be extended to other biodegradable polymers for process optimization and material design.</p></div>","PeriodicalId":755,"journal":{"name":"Rheologica Acta","volume":"65 3","pages":"223 - 239"},"PeriodicalIF":3.0,"publicationDate":"2025-12-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147561105","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}

{"title":"Rheological response of whey protein deposits forming under shear in concentrated conditions","authors":"Margot Grostete,&nbsp;Jeehyun Lee,&nbsp;Françoise Boissel,&nbsp;Maude Jimenez,&nbsp;Romain Jeantet,&nbsp;Luca Lanotte","doi":"10.1007/s00397-025-01534-7","DOIUrl":"10.1007/s00397-025-01534-7","url":null,"abstract":"<div><p>Dairy fouling consists in the accumulation of whey proteins and minerals on equipment walls. While heat-induced protein denaturation is a primary cause, fouling also occurs below the denaturation threshold (≈ 70 °C). This leads to a renewed interest in other driving forces influencing fouling mechanisms. In this wake, this study investigates the role of shear on the formation of whey protein deposits under sub-denaturation temperature and concentrated conditions. We compared morphology and rheological behavior of shear-induced and unsheared structures formed at 15 and 20 wt% protein concentrations. While unsheared gel-like deposits were compact and stiff, shear led to the formation of weaker, more porous, and highly crosslinked structures. This effect was more pronounced at higher concentrations, where shear counteracted heat-induced aggregation, resulting in an alternative structural organization. These findings provide new insights not only into whey protein gelation but also into dairy fouling mechanisms, highlighting a concentration-dependent shear effect.</p><h3>Graphical Abstract</h3><div><figure><div><div><picture><source><img></source></picture></div></div></figure></div></div>","PeriodicalId":755,"journal":{"name":"Rheologica Acta","volume":"64 12","pages":"745 - 755"},"PeriodicalIF":3.0,"publicationDate":"2025-12-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00397-025-01534-7.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146026964","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}

{"title":"Leveraging viscoelasticity for load enhancement in rotating contacts","authors":"Humayun Ahmed,&nbsp;Luca Biancofiore","doi":"10.1007/s00397-025-01529-4","DOIUrl":"10.1007/s00397-025-01529-4","url":null,"abstract":"<div>\u0000 \u0000 <p>Tribological components such as bearings and gears sustain a tremendous external load and operate at high relative speeds. For hydrodynamically lubricated contacts, subject to these extreme conditions, the lubricating fluid film exhibits non-Newtonian characteristics. In particular, when the ratio of fluid relaxation time to the flow residence time, i.e., the Deborah number (<span>(varvec{De})</span>), becomes appreciable, viscoelastic effects emerge. In this work, we model the effect of viscoelasticity using the viscoelastic Reynolds equation (VR) in cylindrical coordinates under the ultra-dilute limit in which the solvent concentration in terms of viscosity is larger than the polymeric contribution. As such, the velocity field remains Newtonian and the polymer stress constitutive relation is further simplified. We examine the effect of fluid viscoelasticity on the load carrying capacity for two geometries; (i) a conical configuration (that could be aligned or misaligned) and (ii) a flat surface embedded with different kind of textures. Our results show that viscoelasticity can enhance the load carrying capacity in both cases. Small errors in alignment strongly affect the trend in the load versus <span>(varvec{De})</span> and a strong nonlinear trend emerges exhibiting load both saturation and diminishment. Introducing pockets in the surface further improves the load bearing capability beyond the Newtonian values. However, numerical simulation of such textured configurations is challenging and, unlike the inclined asymmetric cone, large values of the Deborah number could not be reached.</p>\u0000 </div>","PeriodicalId":755,"journal":{"name":"Rheologica Acta","volume":"64 12","pages":"729 - 743"},"PeriodicalIF":3.0,"publicationDate":"2025-12-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00397-025-01529-4.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146026757","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}

{"title":"Special issue devoted to the XVIII Italian society of rheology conference (SIR 2024)","authors":"Sergio Caserta,&nbsp;Claudia Carotenuto,&nbsp;Gaetano D’Avino,&nbsp;Giovanna Tomaiuolo","doi":"10.1007/s00397-025-01539-2","DOIUrl":"10.1007/s00397-025-01539-2","url":null,"abstract":"","PeriodicalId":755,"journal":{"name":"Rheologica Acta","volume":"64 12","pages":"687 - 689"},"PeriodicalIF":3.0,"publicationDate":"2025-12-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146027096","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}

{"title":"Rheology of silica nanoparticle-stabilized pickering emulsions","authors":"Ruihui Yun,&nbsp;Yue Liang,&nbsp;Jiaxin Wu,&nbsp;Lesen Ma,&nbsp;Florian J. Stadler","doi":"10.1007/s00397-025-01532-9","DOIUrl":"10.1007/s00397-025-01532-9","url":null,"abstract":"<div><p>We investigated structure–rheology relationships in oil-in-water Pickering emulsions stabilized by hydrophilic fumed silica (Aerosil) with a cationic co-emulsifier (didodecyldimethylammonium bromide, DDAB). A systematic composition matrix (Aerosil 2–6 wt%; DDAB 1–9 mg per 3 mL oil) decouples particle from surfactant effects. Optical microscopy and SEM/EDS confirm silica-armored droplets; morphological stability requires sufficiently high particle loading and modest DDAB, whereas low Aerosil or very low DDAB leads to merged “lakes”. Steady flow shows strong shear-thinning and a pronounced first-interval effect: the initial high-rate sweep erases the rested structure, after which start-up curves become reproducible. Oscillatory tests establish weak-gel signatures (G’ &gt; G”, weak frequency dependence), with strain sweeps revealing a clear elastic plateau and a G” peak near yield. Increasing Aerosil elevates the modulus scale, broadens the linear-viscoelastic window, and delays softening; increasing DDAB at fixed particle fraction softens the emulsion and advances yielding. Multiple-interval thixotropic tests (miTT) quantify flow-history memory: the recovered small-amplitude moduli G’(γ̇_prev) and G”(γ̇_prev) decrease monotonically with prior shear rate, recover only partially between pulses, and—when normalized—show greater resilience at higher Aerosil but heightened sensitivity with surplus DDAB. These insights provide a practical formulation window for tunable, robust emulsions.</p></div>","PeriodicalId":755,"journal":{"name":"Rheologica Acta","volume":"65 1","pages":"13 - 30"},"PeriodicalIF":3.0,"publicationDate":"2025-12-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146026754","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}

{"title":"Three-dimensional tracking of particle migration in viscoelastic fluids via oscillatory microfluidics","authors":"Daniele Tammaro,&nbsp;Federica Ida Borrata,&nbsp;Gaetano D’Avino,&nbsp;Pier Luca Maffettone","doi":"10.1007/s00397-025-01535-6","DOIUrl":"10.1007/s00397-025-01535-6","url":null,"abstract":"<div><p>We present an experimental microfluidic platform capable of reconstructing full three-dimensional trajectories of single particles in viscoelastic fluids by exploiting oscillatory flow. The system combines synchronized high-speed imaging from orthogonal perspectives with a custom-fabricated square microchannel and optical correction techniques, enabling high-resolution, time-resolved observation of particle dynamics. The device is applied to study the migration of spherical particles in Polyethylene Oxide solutions, providing the first complete measurements of particle trajectories in such flows. The effects of initial particle position, flow rate, oscillation period, and fluid rheology are systematically analyzed.</p></div>","PeriodicalId":755,"journal":{"name":"Rheologica Acta","volume":"65 1","pages":"1 - 12"},"PeriodicalIF":3.0,"publicationDate":"2025-12-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00397-025-01535-6.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146027084","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}

{"title":"Synergistic improvement in flowability and rheological properties of waxy oil by graphene","authors":"Jiaqiang Jing,&nbsp;Qiuyue Wang,&nbsp;Junyu Pu,&nbsp;Rinat Karimov,&nbsp;Xinyu Luo,&nbsp;Jie Sun","doi":"10.1007/s00397-025-01530-x","DOIUrl":"10.1007/s00397-025-01530-x","url":null,"abstract":"<div><p>The poor low-temperature flowability of waxy crude oil poses significant challenges for pipeline transportation. To address the issue, this study systematically investigates the potential of graphene materials as novel flow improvers, utilizing steady and dynamic rheology in conjunction with microstructural characterization techniques. Rheological analyses demonstrate that graphene at an optimal concentration of 400 ppm reduces the viscosity of the oil by 23.43% and lowers the pour point by 5.1 ± 0.5 °C in oil with 7.4 wt% wax. The graphene weakens the gel structure’s strength, decreasing the thixotropic loop area by 22.63% and the critical shear stress from 63 Pa to 16 Pa. The addition of graphene substantially reduced the median wax crystal length from 39.15 μm to 18.77 μm and enhanced structural disorder. These findings establish a relationship between graphene modification, wax crystal evolution, and improved flowability, thereby providing fundamental insights into the application of graphene for enhancing the flow assurance of waxy crude oil in pipeline transportation.</p></div>","PeriodicalId":755,"journal":{"name":"Rheologica Acta","volume":"65 1","pages":"51 - 63"},"PeriodicalIF":3.0,"publicationDate":"2025-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146026740","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}

{"title":"Modelling sol-gel transition and mechanical properties of hydrogels using statistical learning","authors":"Enrique Manso Castillo,&nbsp;Williams Brett,&nbsp;Javier Tarrio Saavedra,&nbsp;Salvador Naya Fernández,&nbsp;Jorge Lopez Beceiro,&nbsp;Alain Ponton","doi":"10.1007/s00397-025-01528-5","DOIUrl":"10.1007/s00397-025-01528-5","url":null,"abstract":"<div><p>The present study reports a quantitative analysis of the gelation kinetics and mechanical behaviour of chitosan-based hydrogels chemically crosslinked with glyoxal. Time-resolved mechanical spectroscopy (TRMS) was coupled with non-parametric generalised additive models (GAM) to accurately model the evolution of viscoelastic moduli and determine statistically key parameters at the gel point, including gel time (t_g), gel stiffness (S), and relaxation exponent (Δ). The effect of polymer and crosslinker concentrations on these parameters was established with the use of GAM and validated by multivariate linear regression, yielding interpretable parametric models. In a similar way, a detailed statistical analysis of oscillatory and uniaxial compression measurements of fully gelled hydrogels in both swollen and dry states revealed distinct trends in mechanical response: crosslinker concentration enhanced stiffness in the swollen state but exhibited a saturation effect in the dry state. Convolutional neural network (U-Net) analysis of scanning electron microscopy (SEM) images was, finally, able to provide structural insight correlating pore morphology with mechanical properties. The findings demonstrate the utility of statistical learning tools in increasing knowledge of the mechanical and morphological properties of hydrogels.</p><h3>Graphical Abstract</h3><div><figure><div><div><picture><source><img></source></picture></div></div></figure></div></div>","PeriodicalId":755,"journal":{"name":"Rheologica Acta","volume":"65 1","pages":"31 - 50"},"PeriodicalIF":3.0,"publicationDate":"2025-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146027095","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}