Article
Mechanics
Ole Hassager, Yanwei Wang, Qian Huang
Summary: Polymeric liquid bridges are prone to failure during extension, but a steady extensional viscosity can still be measured under specific conditions. Additionally, reliable stress measurements can be obtained during a relaxation phase. Various constitutive equations were simulated to draw these conclusions.
Article
Engineering, Biomedical
Fan Yang, Debashish Das, Kathiresan Karunakaran, Guy M. Genin, Stavros Thomopoulos, Ioannis Chasiotis
Summary: This study conducted pure stress relaxation and creep experiments for fully hydrated individual collagen fibrils for the first time, revealing their nonlinear time-dependent behavior consistent with prior studies on macroscale collagenous tissues. This new understanding of the nonlinear viscoelastic behavior of the building blocks of mammalian collagenous tissues may serve as the foundation for improved macroscale tissue models that capture the mechanical behavior across length scales.
ACTA BIOMATERIALIA
(2023)
Article
Mechanics
Simon J. Haward, Stylianos Varchanis, Gareth H. McKinley, Manuel A. Alves, Amy Q. Shen
Summary: Part I presents a microfluidic device for generating near-homogeneous uniaxial and biaxial elongational flows. In Part II, this device is used to examine the extensional rheology of dilute polymer solutions compared to measurements made under planar extension. The extension rate and tensile stress difference generated in the fluid are measured using micro-particle image velocimetry and excess pressure drop measurements. The results show that at higher polymer concentrations, the experimental measurements deviate from the model predictions due to intermolecular interactions as the polymer chains unravel in the extensional flows.
JOURNAL OF RHEOLOGY
(2023)
Article
Chemistry, Multidisciplinary
Yoonyoung Jung, Tae Soup Shim, Ju Min Kim
Summary: In this study, an efficient microfluidic method was proposed to measure the relaxation time of dilute polymer solutions by utilizing elasticity-driven lateral particle migration. The reliability of this method was confirmed by comparing the measured relaxation times with those obtained from Zimm theory. This approach is expected to be useful for characterizing the relaxation times of various polymer solutions.
KOREAN JOURNAL OF CHEMICAL ENGINEERING
(2022)
Article
Polymer Science
Ralm G. Ricarte, Sachin Shanbhag, Dana Ezzeddine, Daniel Barzycki, Kevin Fay
Summary: In this work, the linear rheology of polybutadiene (PB) vitrimers with dioxaborolane metathesis cross-links was investigated. The elastic modulus remained constant while the viscous modulus increased with decreasing angular frequency. The creep behavior deviated from established theoretical models, suggesting that the temperature dependence of cross-linker mobility in vitrimer matrices was not fully captured by these models.
Article
Mechanics
Karen Y. Perez-Salas, Gabriel Ascanio, Leopoldo Ruiz-Huerta, Juan P. Aguayo
Summary: An analytical approximation for the flow of a linear Phan-Thien-Tanner model fluid through an axisymmetric semi-hyperbolic contraction is presented in this study. The semi-analytical solution proposed can accurately represent the exponential version of the viscoelastic model. The flow model equations for both linear and exponential Phan-Thien-Tanner models are solved with the consideration of Navier boundary conditions to account for slip at the geometry wall.
Article
Polymer Science
U. Hyeok Choi, Puji Lestari Handayani, Yeon Hwa Song, Taehoon Kim, Aijie Han, Ralph H. Colby
Summary: The molecular level understanding of ion and polymer dynamics in nanoparticle-coupled hydrogel network polymer electrolytes is studied by dielectric and viscoelastic measurements. Hydrogel polymer electrolytes (HPEs) consisting of Li+ conducting hydrophilic poly(lithium acrylate) (PLiA) and vinyl-functionalized silica nanoparticles (NPs) are prepared. The NP content affects ionic conductivity, dielectric constant, relaxation frequency, and elastic modulus, which are important for ion transport. The presence of NPs leads to higher ion concentration and mobility, resulting in higher ionic conductivity. The incorporation of NPs also affects relaxation and dielectric properties. Time-temperature superposition is applied to construct master curves of viscoelasticity and conductivity.
Article
Polymer Science
Jianshe Xia, Julia Ann Kalow, Monica Olvera de la Cruz
Summary: This study investigates the topological structural changes, microscopic dynamics, and linear rheology of unentangled vitrimers through molecular dynamics simulations. The results show minor variations in topological structure with temperature and increased dynamic heterogeneities near the topological freezing transition temperature. The simulation results are quantitatively consistent with predictions from the sticky Rouse model.
Article
Chemistry, Multidisciplinary
Junzhe Lou, Sean Friedowitz, Karis Will, Jian Qin, Yan Xia
Summary: The research demonstrates that the terminal relaxation time of dynamic hydrogels is primarily determined by the exchange rate of crosslinks and the number of effective crosslinks per polymer chain, regardless of the network architecture. A universal correlation is identified between the terminal relaxation time and the exchange rate, which can be applied to any viscoelastic hydrogel network. This quantitative correlation facilitates the development of dynamic hydrogels with a variable desired viscoelastic response based on molecular design.
ADVANCED MATERIALS
(2021)
Article
Chemistry, Physical
Yingkang Dai, Runlin Zhang, Weixiang Sun, Tao Wang, Yunhua Chen, Zhen Tong
Summary: This study investigated the gelation process of a hydrophobically modified hyaluronic acid aqueous solution using multi-particle tracking microrheology. The results showed that the linear viscoelasticity of the gelling system transforms at the critical gelling temperature, and the length scale of dynamic heterogeneity monotonically decreases during gelation. The proposed framework and analysis methods in this study can be applied to other microrheological studies.
Article
Construction & Building Technology
Lei Xi, Rong Luo, Qiang Ma, Chongzhi Tu, Yasir Ibrahim Shah
Summary: This study developed an improved method to determine the continuous relaxation spectrum of asphalt materials, demonstrating compliance with LVE theory and physical causality. The generated relaxation spectrum was accurate enough to compare the storage modulus and loss modulus values recalculated by the relaxation spectrum with those predicted by master curve models, highlighting the limitations of the Kramers-Kronig relation for establishing the relaxation spectrum of asphalt materials. Additionally, the generated relaxation spectrum was utilized to construct the relaxation modulus of mixtures and to develop the stiffness modulus of binders, both consistent with LVE theory and physical causality.
CONSTRUCTION AND BUILDING MATERIALS
(2022)
Article
Materials Science, Composites
Liming Wang, Miao Du, Guorong Shan, Qing Lu, Min Zuo, Yihu Song, Qiang Zheng
Summary: This paper investigates the nonlinear viscoelastic behavior of rubber composites. The study finds that frequency sweep tests provide more information about viscoelastic response, and time-temperature superposition is applicable to nonlinear viscoelastic behavior. The behavior of filled vulcanizates is similar to that of unfilled vulcanizates, indicating the same response mechanism.
COMPOSITES SCIENCE AND TECHNOLOGY
(2022)
Article
Polymer Science
Shilong Wu, Huanhuan Yang, Quan Chen
Summary: Molecular theories for dynamics of entangled polymers are based on the number of Kuhn segments per entanglement and the number of entanglements per chain. Linear viscoelasticity can be properly normalized, but normalization fails in the nonlinear extensional rheological properties. This study identifies a suitable model system with fixed parameters and finds that the degree of transient strain hardening during extensional flow increases with alkyl group size, attributed to weaker friction reduction when the main backbones are more separated.
Article
Polymer Science
Hengheng Zhao, Xuefeng Wei, Yue Fang, Ke Gao, Tongkui Yue, Liqun Zhang, Venkat Ganesan, Fanlong Meng, Jun Liu
Summary: This study utilizes coarse-grained molecular dynamics simulations to investigate the effect of bond swap energy barrier (Delta E-sw) on the mechanical properties of vitrimers. The results show that Delta E-sw plays a critical role in the dynamics of linear chains and reactive beads. The study also demonstrates that an intermediate value of Delta E-sw can achieve the best mechanical performance characteristics. Additionally, the study explores the impact of Delta E-sw on stress relaxation, self-healing capability, and extrusion rate of polymer vitrimers.
Article
Polymer Science
Alexis Andre, Taisir Shahid, Filip Oosterlinck, Christian Clasen, Evelyne van Ruymbeke
Summary: The work investigates how steady extensional viscosity of polymer solutions and blends varies with concentration and molecular weight of the chains through well-defined experiments.
Article
Pharmacology & Pharmacy
Annelies Smeets, Ida Lo Re, Christian Clasen, Guy Van den Mooter
INTERNATIONAL JOURNAL OF PHARMACEUTICS
(2020)
Article
Materials Science, Multidisciplinary
Robin Koekoekx, Natalia C. Zawacka, Guy Van den Mooter, Zeger Hens, Christian Clasen
MACROMOLECULAR MATERIALS AND ENGINEERING
(2020)
Article
Polymer Science
Alexis Andre, Taisir Shahid, Filip Oosterlinck, Christian Clasen, Evelyne van Ruymbeke
Summary: The work investigates how steady extensional viscosity of polymer solutions and blends varies with concentration and molecular weight of the chains through well-defined experiments.
Article
Materials Science, Ceramics
Glenn Beersaerts, Anja Vananroye, Dimitrios Sakellariou, Christian Clasen, Yiannis Pontikes
Summary: The flow behavior of alkali-activated Fe-rich slag suspensions was studied, with modifications to the activator SiO2/Na2O molar ratio and H2O content to determine their impact on rheology. Changes in these parameters led to variations in yield stress and elasticity, with higher ratios resulting in more complex silicate structures and lower ratios leading to increased monomers. The AAS exhibited a yield stress fluid-like behavior driven by strong physical interactions between slag particles.
JOURNAL OF NON-CRYSTALLINE SOLIDS
(2021)
Article
Mechanics
Celine Hannecart, Taisir Shahid, Dimitris Vlassopoulos, Filip Oosterlinck, Christian Clasen, Evelyne van Ruymbeke
Summary: A new alternative approach is proposed to explain the peculiar behavior of polymer chains under uniaxial extensional flow, taking into account chain stretching, orientation, and a rate-dependent blob picture. This method introduces an additional parameter for describing stretch relaxation time, but results are in good agreement with experimental observations.
JOURNAL OF RHEOLOGY
(2022)
Article
Instruments & Instrumentation
E. Persembe, C. Parra-Cabrera, C. Clasen, R. Ameloot
Summary: The limited control over the printing process in commercial powder bed 3D printers hampers the exploration of novel materials and applications. A custom binder-jetting 3D printer was developed in this study to enable fine-grained control over the printing process. An optimized protocol was developed for new build materials and binders, with resolution tests used as a guideline for improving dimensional accuracy. The demonstration of printing a functionally graded object showcased the voxel-based control over the printing process.
REVIEW OF SCIENTIFIC INSTRUMENTS
(2021)
Article
Mechanics
Jasper Van Aeken, Luca Passaro, Christian Clasen
Summary: This article introduces a novel device for directly measuring the axial force evolution during the pinching of fluid filaments. By fitting the bending curve of the fluid filament using a tilted-CaBER, the axial force can be extracted accurately from a single fitting parameter. The new setup has been validated to approach the theoretical factor X=1.5 for dilute polymer solutions in the form of a Boger fluid.
Article
Mechanics
Joshua David John Rathinaraj, Jan Hendricks, Gareth H. McKinley, Christian Clasen
Summary: Shear-induced microstructural changes are commonly observed in various materials. Superposition rheometry, particularly orthogonal superposition, is used to study these changes and avoid non-linear coupling between steady shear and small amplitude oscillatory deformation. This study demonstrates the potential to investigate shear-induced microstructural anisotropy by superimposing fast deformations orthogonally to steady shearing deformation. The changes are evaluated by measuring the damping function and shear-induced changes in orthogonal moduli.
JOURNAL OF NON-NEWTONIAN FLUID MECHANICS
(2022)
Article
Chemistry, Physical
Gilles Van Eygen, Daan Marien, Anja Vananroye, Christian Clasen, Bart Van der Bruggen, Anita Buekenhoudt, Joao A. P. Coutinho, Patricia Luis
Summary: This study explores the use of in-situ product removal via supported liquid membranes (SLM) to improve the synthesis of chiral amines. A screening of 400 ionic liquids (ILs) using COSMO-RS led to the selection of 14 ILs, and their properties were compared experimentally and in simulations. Further liquid-liquid extraction (LLE) and membrane extraction (ME) tests identified [P6,6,6,14][N(Tf)2] as the most selective and stable IL for the process.
JOURNAL OF MOLECULAR LIQUIDS
(2023)
Article
Acoustics
Aniket Pradip Udepurkar, Christian Clasen, Simon Kuhn
Summary: An ultrasonic microreactor with rough microchannels is used to generate oil in water emulsion in this study. The study shows that the surface pits or imperfections in the microchannels enhance cavitation activity. High-speed imaging is used to investigate the influence of cavitation bubble size and oscillation intensity on the emulsification mechanism, and the effect of emulsification modes on droplet size distribution is demonstrated for different surface roughness and frequency. The study also demonstrates the successful generation of high dispersed phase volume fractions up to 20% using microreactor systems.
ULTRASONICS SONOCHEMISTRY
(2023)
Article
Polymer Science
Celine Hannecart, Christian Clasen, Evelyne van Ruymbeke
Summary: Despite extensive experimental data and numerous studies, the quantitative description of relaxation mechanisms in bidisperse blends is still debated. This study aims to discuss different approaches for determining the release time and compare them to experimental viscoelastic data. Based on a large set of data, it is found that the release time follows a power law close to 2.5, rather than the previously proposed 3. Finally, a new description of the release time is proposed and implemented in a tube-based model, providing a good starting point for extension to self-entangled binary blends.
Article
Chemistry, Physical
Iurii Alekseevich Babkin, Aniket Pradip Udepurkar, Hannes Van Avermaet, Rodrigo de Oliveira-Silva, Dimitrios Sakellariou, Zeger Hens, Guy van den Mooter, Simon Kuhn, Christian Clasen
Summary: Quantum dots (QDs) are semiconductor nanocrystals used in optoelectronic applications. Most modern QDs are based on toxic metals and do not comply with EU regulations. However, there are promising developments in safer QD alternatives based on elements from the III-V group. This study focuses on encapsulating InP-based QDs in polymer microbeads for improved photostability.
Article
Chemistry, Physical
Alina Arslanova, Ine Matthe, Olivier Deschaume, Carmen Bartic, Wouter Monnens, Erwin Konrad Reichel, Naveen Reddy, Jan Fransaer, Christian Clasen
Summary: The motion of self-propelling microswimmers is affected by liquid-liquid interfaces (LLI), which can enhance or reduce their mobility and also steer the direction of their propulsion. In this study, the adsorption and motion of bimetallic Janus sideways propelled rods were studied at the interface between an aqueous solution of hydrogen peroxide and oil. It was found that the wetting properties of the rods result in a wide distribution of their velocities at the LLI, with a significant enhancement of motility compared to near a solid wall.
Article
Acoustics
Aniket Pradip Udepurkar, Wim Dermaut, Christian Clasen, Simon Kuhn
Summary: In this article, a new system combining an ultrasonic microreactor with a tubular reactor is introduced for the continuous production of polymer nanoparticles. The system demonstrates the continuous generation of cross-linked polymer nanoparticles using the monomer butyl methacrylate and the cross-linker ethylene glycol dimethacrylate. The article investigates the miniemulsion polymerization of a monomer-in-water miniemulsion in a batch system and then utilizes a coiled tubular reactor for the continuous polymerization. The study also examines the impact of monomer volume fraction and surfactant concentration on the synthesized nanoparticles. The system showcased in this research successfully synthesizes polymer particles ranging from 50 to 250 nm in size and achieves a high polymerization conversion.
ULTRASONICS SONOCHEMISTRY
(2023)
Article
Chemistry, Physical
Alina Arslanova, Venkateshwar Rao Dugyala, Erwin Konrad Reichel, Naveen Reddy, Jan Fransaer, Christian Clasen
Summary: The use of Janus rods propelled perpendicular to their long axis can maximize the efficiency of collecting and transporting microscopic cargo.
Article
Mechanics
Chen Liu, Jianzhong Lin, Zhenyu Ouyang
Summary: This study simulated the locomotion state and motion type of elliptical squirmers in a channel flow of power-law fluids. The influence of different parameters on the squirmers was explored, and it was found that coupled structures are prone to break and viscosity significantly affects the flow velocity and motion type of squirmers.
Article
Mechanics
E. E. Herrera-Valencia, M. L. Sanchez-Villavicencio, C. Soriano-Correa, O. Bautista, L. A. Ramirez-Torres, V. J. Hernandez-Abad, F. Calderas
Summary: This study investigated the electroosmotic flow of a viscoelastic fluid in a capillary system. The rheology of the fluid was characterized by a novel generalized exponential model equation, and the effect of charge density on the double-layer field and electrical forces was analyzed. Mathematical models were used to describe the rheological properties and flow performance of the fluid, and experimental data were used to make predictions. The study also examined the influence of applied forces on the structure of the fluid.
Article
Mechanics
Stefano Amadori, Giuseppe Catania
Summary: This article presents a multi-step, iterative technique for locally non-parametric identification of the standard linear solid (SLS) material model using fractional order time differential operators. Test input data consists of a set of identified material complex modulus values estimated at different frequency values obtained from input-output experimental measurements and quasi-static relaxation measurements on the same specimen. The proposed technique is based on an algebraic procedure to solve an overdetermined system of linear equations in order to obtain optimal values for the unknown parameters of the model. The procedure is non-parametric, as the order of the SLS model is initially unknown.
