Review
Polymer Science
Yumi Matsumiya, Hiroshi Watanabe
Summary: The rheological behavior of polymeric liquids was traditionally believed to be universally determined by a few time-independent molecular parameters, but recent studies have shown non-universality under extensional flow conditions. A key concept is the reduction of segmental friction of highly oriented/stretched polymer chains, which changes with the chemical structure of the polymer and solvent as well as the polymer concentration.
PROGRESS IN POLYMER SCIENCE
(2021)
Article
Mechanics
Mandi Boudaghi, M. Hadi Nafar Seddashti, Brian J. Edwards, Bamin Khomami
Summary: Dissipative particle dynamics (DPD) simulations replicate the coil-stretch transition (CST) and configurational relaxation of entangled polyethylene melts observed in planar elongational flow (PEF). The width of the CST hysteresis loop is larger for longer molecule liquids. Reducing the flow Deborah number results in a two-stage relaxation process, with initial stratification followed by configurational relaxation.
JOURNAL OF RHEOLOGY
(2022)
Article
Chemistry, Multidisciplinary
Pengyu Liu, Yan Zhang, Ying Guan, Yongjun Zhang
Summary: Hydrogels with ultra-low solid content but good mechanical properties are successfully synthesized using high monomer concentrations and low cross-linker/monomer ratios. The introduction of peptide chains through a poly(l-lysine)-based cross-linker contributes to the gel's excellent mechanical properties, including high stretchability, high tensile strength, superb resilience, high fracture toughness, excellent fatigue resistance, low friction, and high wear resistance. These properties, attributed to the highly entangled structure and a novel energy dissipation mechanism, allow the peptide-crosslinked gel to perform comparably to or better than traditional hydrogels with higher solid content.
ADVANCED MATERIALS
(2023)
Article
Chemistry, Physical
Yedi Li, Hongxia Guo
Summary: In this study, the slip phenomena and individual dynamics of interfacial copolymer chains in entangled polymer-polymer interfaces are analyzed using simulations. The study reveals two distinct power-law regions of slip velocity against interfacial shear stress under fast shear flow. Furthermore, the study investigates the individual chain dynamics of interfacial copolymers under weak and strong incompatibility conditions.
JOURNAL OF PHYSICAL CHEMISTRY B
(2023)
Article
Mechanics
Souta Miyamoto, Takeshi Sato, Takashi Taniguchi
Summary: This study investigated the rheological properties of bidisperse entangled-polymer blends under high-deformation-rate flows using slip-link simulations and a friction reduction mechanism. The incorporation of the friction reduction expression into the Doi-Takimoto slip-link model successfully predicted the data for six experimental bidisperse systems. By statistically averaging the components, the stretch of the longer chains was suppressed, improving the rheological prediction under high elongation rates.
Article
Polymer Science
Diego Becerra, Andres Cordoba, Jay D. Schieber
Summary: The study using the discrete slip-link model (DSM) reveals nonuniversality in the nonlinear rheology of polymer melts at large strain rates during the inception of shear flow, despite the theory predicting universal behavior for maximum shear stress and strain at maximum stress based on entanglement activity and Kuhn steps. Primitive path stretching is shown to correspond to the transition of strain-rate-free values to values that scale with dimensionless strain rate. Additionally, differences in scaling exponents for melt and solution data suggest variations in steady-state shear stress, with DSM showing agreement with melt data.
Article
Polymer Science
Xinlin Zhang, Wei Wei, Huiming Xiong
Summary: The segmental and chain dynamics of type-A polyethers tethered with nonsticky polyhedral oligomeric silsesquioxane molecular nanoparticles (MNPs) were experimentally investigated. It was found that the attachment of MNPs at the chain ends could retard segmental and chain relaxations. The number and position of MNPs also influenced the dynamics of the polymers.
Article
Mechanics
Manfred H. Wagner, Esmaeil Narimissa, Qian Huang
Summary: The study extends the criterion for brittle fracture of entangled polymer liquids by considering the effects of finite chain extensibility and polymer concentration. Experimental data and models support the finding that crack initiation originates from the rupture of C-C bonds, leading to the fracture of polymer chains and crack propagation.
JOURNAL OF RHEOLOGY
(2021)
Article
Polymer Science
Carina D. V. Martinez Narvaez, Jelena Dinic, Xinyu Lu, Chao Wang, Reza Rock, Hao Sun, Vivek Sharma
Summary: This study compared the performance of polysaccharides with hydrophobic modifications and unmodified chains in shear rheology, extensional rheology, and neck dynamics, finding that stickers enhance zero shear viscosity and relaxation time. In sticky polymers, stickers lead to stronger concentration-dependent variations.
Article
Mechanics
Mohammad Hadi Nafar Sefiddashti, Brian J. Edwards, Bamin Khomami
Summary: This study investigates the flow-induced phenomena in entangled solutions of linear, monodisperse C1000H2002 polyethylene dissolved in benzene. The simulations reveal that the solution exhibits phase separation and crystallization under specific flow conditions.
Article
Chemistry, Multidisciplinary
Kristina Maria Zentel, Paul Severin Eselem Bungu, Jonas Degenkolb, Harald Pasch, Markus Busch
Summary: This study fractionated well-defined mini-plant low density polyethylene samples preparatively and characterized their rheology properties. The impact of molecular weight and long chain branching on different fractions was observed in rheology measurements. The experimental trends were consistent with the model predictions, showing an acceptable overall agreement between the two approaches.
Article
Mechanics
Sami Yamani, Gareth H. McKinley
Summary: The FENE-P dumbbell constitutive equation is commonly used for simulating viscoelastic shear flows and predicting macroscopic properties of dilute polymer solutions. By evaluating steady material functions, universal master curves for these functions, as well as the corresponding stress ratio, can be constructed, which helps in understanding the effects of finite extensibility of polymer chains.
JOURNAL OF NON-NEWTONIAN FLUID MECHANICS
(2023)
Article
Mechanics
Joshua David John Rathinaraj, Gareth H. McKinley
Summary: Oscillatory rheometric techniques are widely used to characterize the viscoelastic properties of complex fluids. However, conventional Fourier transforms for analyzing oscillatory data are limited in studying shear-induced microstructural changes in time-evolving materials. In this study, the Gabor transform is explored as a more advanced signal processing technique to extract time-resolved frequency information from oscillatory data. The Gabor transform enables accurate measurement of rapid changes in storage and loss modulus, extraction of characteristic thixotropic/aging time scale, and extraction of useful viscoelastic data from initial transient response. The resulting test protocol, Gaborheometry, reduces the number of required experiments and data postprocessing time significantly.
JOURNAL OF RHEOLOGY
(2023)
Article
Mechanics
Esteban F. Medina-Banuelos, Benjamin M. Marin-Santibanez, Emad Chaparian, Crystal E. Owens, Gareth H. McKinley, Jose Perez-Gonzalez
Summary: It has been discovered that the steady fractal vane-in-cup (fVIC) flow of complex fluids using vanes with fractal cross sections can produce an almost axisymmetric flow field and rotation rate-independent effective radius, making it a reliable measurement tool for complex fluids. However, axial shearing/compression during the insertion of the rheometric tool in the sample also accelerates syneresis, leading to shear banding for Couette and fVIC flows.
JOURNAL OF RHEOLOGY
(2023)
Article
Polymer Science
Gauthier Legrand, Sebastien Manneville, Gareth H. McKinley, Thibaut Divoux
Summary: Nanocomposite gels formed by mixing hydrophobic colloidal soot particles and a sodium salt of carboxymethylcellulose (CMC), known as cellulose gum, exhibit different mechanical behaviors depending on the relative content of the two components. At low CMC concentration, the gel shows electric conductivity and glassy-like viscoelastic behavior, while at higher CMC concentration, the gel becomes nonconductive and displays power-law viscoelastic behavior. The CMC plays a crucial role in the gel's viscoelastic properties. These findings provide valuable insights for designing nanocomposite gels based on hydrophobic interactions.
Article
Physics, Multidisciplinary
Minaspi Bantawa, Bavand Keshavarz, Michela Geri, Mehdi Bouzid, Thibaut Divoux, Gareth H. McKinley, Emanuela Del Gado
Summary: Soft particulate gels consist of a small amount of particulate matter dispersed in a continuous fluid phase. The mechanical response and gel elasticity are determined by the particle volume fraction. However, the diverse range of functional dependencies reported experimentally has made it difficult to identify general scaling laws.
Article
Mechanics
Jelle J. J. Schoppink, Keerthana Mohan, Miguel A. A. Quetzeri-Santiago, Gareth McKinley, David Fernandez Rivas, Andrew K. K. Dickerson
Summary: By selectively coating hydrophobic strips on hydrophilic glass capillaries, the trajectory and characteristics of the microjet can be influenced and controlled.
Article
Materials Science, Biomaterials
Mario Milazzo, Vincent Fitzpatrick, Crystal E. Owens, Igor M. Carraretto, Gareth H. McKinley, David L. Kaplan, Markus J. Buehler
Summary: This study investigates the rheology, printability, and prosthetic mechanical properties of HA and HA-silk protein composites, highlighting the roles of composition and water content. The inclusion of silk improves the quality of printed items by reducing underextrusion and slumping. A printing map is constructed to guide the manufacturing of HA-based inks for biomedical applications requiring sub-millimetric features.
ACS BIOMATERIALS SCIENCE & ENGINEERING
(2023)
Article
Physics, Fluids & Plasmas
Sami Yamani, Yashasvi Raj, Tamer A. Zaki, Gareth H. McKinley, Irmgard Bischofberger
Summary: The interplay between viscoelasticity and inertia in dilute polymer solutions can lead to inertioelastic instabilities, resulting in elastoinertial turbulence (EIT) with distinct spatiotemporal features compared to Newtonian turbulence. Our study on a submerged planar jet of a dilute polymer solution in a quiescent water tank reveals that fluid elasticity has a nonmonotonic effect on the jet stability, creating two different regimes. At low levels of elasticity, an inertioelastic shear-layer instability emerges, destabilizing the flow and causing a turbulence transition closer to the nozzle. Increasing fluid elasticity merges the shear-layer instability into a bulk instability, partially stabilizing the flow and retarding the transition to turbulence. The fully turbulent state exhibits unique spatiotemporal features associated with EIT, characterized by self-similar evolution of jet spreading angle, entrainment, and coherent structures elongated in the streamwise direction. LDV measurements show a frequency spectrum with a -3 power-law exponent, different from Newtonian turbulence's well-known -5/3 exponent.
PHYSICAL REVIEW FLUIDS
(2023)
Article
Nanoscience & Nanotechnology
Jake Song, Sungjin Kim, Olivia Saouaf, Crystal Owens, Gareth H. McKinley, Niels Holten-Andersen
Summary: This study presents a novel design strategy for the synthesis of high-concentration soft magnetic hydrogels by in situ mineralization of iron oxide nanoparticles within polymer hydrogels. The resulting hydrogels exhibit softness, viscoelasticity, and strong magnetic actuation, making them suitable for biomedical applications.
ACS APPLIED MATERIALS & INTERFACES
(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
Mechanics
San To Chan, Simon J. Haward, Eliot Fried, Gareth H. Mckinley
Summary: Saltwater taffy exhibits critical gel-like behavior and obeys time-temperature superposition principle. Its rheological properties can be described by the fractional Maxwell gel model. Minor ingredients like flavorings and colorings have little impact on the rheology of taffy.
Article
Multidisciplinary Sciences
Kyle R. Lennon, Gareth H. McKinley, James W. Swan
Summary: The development of data-driven models for complex fluid mechanics is essential for designing soft materials. This study presents a framework that allows rheologists to construct learnable models incorporating important physical information, without being dependent on specific experimental protocols or flow kinematics. These models enable rapid discovery of accurate constitutive equations from limited data and can describe more complex flows. The flexibility of this framework enables its application to a wide range of material systems and engineering problems.
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
(2023)
Article
Chemistry, Physical
Rishabh V. More, Reid Patterson, Eugene Pashkovski, Gareth H. McKinley
Summary: By studying the rod-climbing effect, we can measure the elasticity of complex fluids, including factors such as rotation rate, fluid elasticity, surface tension, and inertia. Our results show that by combining small amplitude oscillatory shear flow measurements and commercial rheometer measurements, we can accurately measure the normal stress differences of complex fluids.
Article
Chemistry, Physical
Joshua David John Rathinaraj, Kyle R. Lennon, Miguel Gonzalez, Ashok Santra, James W. Swan, Gareth H. McKinley
Summary: Clay slurries are widely used in the oil exploration industry as drilling fluids. However, modeling the rheological behavior of these suspensions is challenging due to their thermal-driven evolution and non-linear viscoelastic properties. This study presents a new approach for modeling the linear viscoelastic response of aging bentonite suspensions, which effectively solves the problem by transforming the time domain and material domain. Experimental measurements support the validity of this model.
Review
Chemistry, Physical
Jake Song, Niels Holten-Andersen, Gareth H. Mckinley
Summary: This study introduces the non-Maxwellian linear stress relaxation observed in soft matter systems and discusses its physical origins. Suitable mathematical models are proposed to describe this phenomenon. The research is important for understanding and modeling the mechanical relaxation of soft materials.