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Kiany P, Goharpey F. Surface Morphology Signature of Critical Separated Length and Glass Transition Temperature during Seeded Dispersion Polymerization. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2021; 37:14034-14042. [PMID: 34807618 DOI: 10.1021/acs.langmuir.1c02050] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
The properties of colloids are considerably affected by particles' surface morphology. In this work, for understanding the mechanism of roughness formation in polymeric core-shell (CS) particles, the surface morphology of synthesized CS particles through seeded dispersion polymerization (SDP) in the presence of poly(methyl methacrylate) seeds was investigated. The results revealed that shell polymers with higher solubility parameters (δ) and glass transition temperatures (Tg) had a rougher surface. These parameters directly affect the time needed for chain deformation, which is a critical parameter in controlling the final morphology. We suggested a relation based on these parameters to predict the surface morphology (smoothness or roughness) of CS particles synthesized through SDP in water.
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Affiliation(s)
- P Kiany
- Department of Polymer Engineering, Amirkabir University of Technology, Tehran 15875-4413, Iran
| | - F Goharpey
- Department of Polymer Engineering, Amirkabir University of Technology, Tehran 15875-4413, Iran
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Capsules Rheology in Carreau-Yasuda Fluids. NANOMATERIALS 2020; 10:nano10112190. [PMID: 33153075 PMCID: PMC7692258 DOI: 10.3390/nano10112190] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/12/2020] [Revised: 10/28/2020] [Accepted: 10/28/2020] [Indexed: 11/17/2022]
Abstract
In this paper, a Multi Relaxation Time Lattice Boltzmann scheme is used to describe the evolution of a non-Newtonian fluid. Such method is coupled with an Immersed-Boundary technique for the transport of arbitrarily shaped objects navigating the flow. The no-slip boundary conditions on immersed bodies are imposed through a convenient forcing term accounting for the hydrodynamic force generated by the presence of immersed geometries added to momentum equation. Moreover, such forcing term accounts also for the force induced by the shear-dependent viscosity model characterizing the non-Newtonian behavior of the considered fluid. Firstly, the present model is validated against well-known benchmarks, namely the parabolic velocity profile obtained for the flow within two infinite laminae for five values of the viscosity model exponent, n = 0.25, 0.50, 0.75, 1.0, and 1.5. Then, the flow within a squared lid-driven cavity for Re = 1000 and 5000 (being Re the Reynolds number) is computed as a function of n for a shear-thinning (n < 1) fluid. Indeed, the local decrements in the viscosity field achieved in high-shear zones implies the increment in the local Reynolds number, thus moving the position of near-walls minima towards lateral walls. Moreover, the revolution under shear of neutrally buoyant plain elliptical capsules with different Aspect Ratio (AR = 2 and 3) is analyzed for shear-thinning (n < 1), Newtonian (n = 1), and shear-thickening (n > 1) surrounding fluids. Interestingly, the power law by Huang et al. describing the revolution period of such capsules as a function of the Reynolds number and the existence of a critical value, Rec, after which the tumbling is inhibited in confirmed also for non-Newtonian fluids. Analogously, the equilibrium lateral position yeq of such neutrally buoyant capsules when transported in a plane-Couette flow is studied detailing the variation of yeq as a function of the Reynolds number as well as of the exponent n.
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Küçüksönmez E, Servantie J. Shear thinning and thickening in dispersions of spherical nanoparticles. Phys Rev E 2020; 102:012604. [PMID: 32794894 DOI: 10.1103/physreve.102.012604] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2020] [Accepted: 06/19/2020] [Indexed: 11/07/2022]
Abstract
We present a molecular dynamics study of the flow of rigid spherical nanoparticles in a simple fluid. We evaluate the viscosity of the dispersion as a function of shear rate and nanoparticle volume fraction. We observe shear-thinning behavior at low volume fractions; as the shear rate increases, the shear forces overcome the Brownian forces, resulting in more frequent and more violent collisions between the nanoparticles. This in turn results in more dissipation. We show that in order to be in the shear-thinning regime the nanoparticles have to order themselves into layers longitudinal to the flow to minimize the collisions. As the nanoparticle volume fraction increases there is less room to form the ordered layers; consequently as the shear rate increases the nanoparticles collide more, which results in turn in shear thickening. Most interestingly, we show that at intermediate volume fractions the system exhibits metastability, with successions of ordered and disordered states along the same trajectory. Our results suggest that for nanoparticles in a simple fluid the hydroclustering phenomenon is not present; instead the order-disorder transition is the leading mechanism for the transition from shear thinning to shear thickening.
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Affiliation(s)
- E Küçüksönmez
- Department of Physics, Istanbul Technical University, Maslak 34469, Istanbul, Turkey
| | - J Servantie
- Department of Physics, Istanbul Technical University, Maslak 34469, Istanbul, Turkey
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Heussinger C. Packings of frictionless spherocylinders. Phys Rev E 2020; 102:022903. [PMID: 32942494 DOI: 10.1103/physreve.102.022903] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Accepted: 07/01/2020] [Indexed: 06/11/2023]
Abstract
We present simulation results on the properties of packings of frictionless spherocylindrical particles. Starting from a random distribution of particles in space, a packing is produced by minimizing the potential energy of interparticle contacts until a force-equilibrated state is reached. For different particle aspect ratios α=10⋯40, we calculate contacts z, pressure as well as bulk and shear modulus. Most important is the fraction f_{0}(α) of spherocylinders with contacts at both ends, as it governs the jamming threshold z_{c}(α)=8+2f_{0}(α). These results highlight the important role of the axial "sliding" degree of freedom of a spherocylinder, which is a zero-energy mode but only if no end contacts are present.
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Affiliation(s)
- Claus Heussinger
- Institute for Theoretical Physics, Georg August University Göttingen, 37077 Göttingen, Germany
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Dekker F, Kuipers BWM, Petukhov AV, Tuinier R, Philipse AP. Scattering from colloidal cubic silica shells: Part I, particle form factors and optical contrast variation. J Colloid Interface Sci 2020; 571:419-428. [PMID: 31813577 DOI: 10.1016/j.jcis.2019.11.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Revised: 10/31/2019] [Accepted: 11/01/2019] [Indexed: 10/25/2022]
Abstract
HYPOTHESIS Colloidal cubic silica shells, prepared from cuprous oxide cubes, with a typical size of 100 nm are promising model particles for scattering studies on dilute, as well as concentrated fluids, of non-spherical colloids. EXPERIMENTS Small angle X-ray scattering, and static light scattering are employed to determine form factors of cubic silica shells and silica covered cuprous oxide cubes. Contrast variation experiments are performed to assess the refractive index and optical homogeneity of the cubic silica shells, which is important for the extension of the scattering study to concentrated dispersions of cubic shells in Part II (Dekker, submitted for publication). RESULTS The experimental form factors, which compare well to theoretical form factors, manifest cubic silica shells that are dispersed as single stable colloids with a shape intermediate between a sphere and a perfect cube. Contrast variation demonstrates that the silica shells are optically homogeneous, with a refractive index that is independent of the shell thickness. The results presented here open up the possibility to extract structure factors from light scattering measurements on concentrated cube dispersions in Part II.
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Affiliation(s)
- F Dekker
- Van't Hoff Laboratory for Physical and Colloid Chemistry, Debye Institute for Nanomaterials Science, Padulaan 8, 3584 CH, Utrecht University, the Netherlands
| | - B W M Kuipers
- Van't Hoff Laboratory for Physical and Colloid Chemistry, Debye Institute for Nanomaterials Science, Padulaan 8, 3584 CH, Utrecht University, the Netherlands
| | - A V Petukhov
- Van't Hoff Laboratory for Physical and Colloid Chemistry, Debye Institute for Nanomaterials Science, Padulaan 8, 3584 CH, Utrecht University, the Netherlands; Laboratory of Physical Chemistry, Department of Chemical Engineering and Chemistry & Institute for Complex Molecular Systems, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, the Netherlands
| | - R Tuinier
- Van't Hoff Laboratory for Physical and Colloid Chemistry, Debye Institute for Nanomaterials Science, Padulaan 8, 3584 CH, Utrecht University, the Netherlands; Laboratory of Physical Chemistry, Department of Chemical Engineering and Chemistry & Institute for Complex Molecular Systems, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, the Netherlands
| | - A P Philipse
- Van't Hoff Laboratory for Physical and Colloid Chemistry, Debye Institute for Nanomaterials Science, Padulaan 8, 3584 CH, Utrecht University, the Netherlands.
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Singh A, Ness C, Seto R, de Pablo JJ, Jaeger HM. Shear Thickening and Jamming of Dense Suspensions: The "Roll" of Friction. PHYSICAL REVIEW LETTERS 2020; 124:248005. [PMID: 32639825 DOI: 10.1103/physrevlett.124.248005] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/24/2020] [Accepted: 05/20/2020] [Indexed: 06/11/2023]
Abstract
Particle-based simulations of discontinuous shear thickening (DST) and shear jamming (SJ) suspensions are used to study the role of stress-activated constraints, with an emphasis on resistance to gearlike rolling. Rolling friction decreases the volume fraction required for DST and SJ, in quantitative agreement with real-life suspensions with adhesive surface chemistries and "rough" particle shapes. It sets a distinct structure of the frictional force network compared to only sliding friction, and from a dynamical perspective leads to an increase in the velocity correlation length, in part responsible for the increased viscosity. The physics of rolling friction is thus a key element in achieving a comprehensive understanding of strongly shear-thickening materials.
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Affiliation(s)
- Abhinendra Singh
- Pritzker School of Molecular Engineering, University of Chicago, Chicago, Illinois 60637, USA
- James Franck Institute, University of Chicago, Chicago, Illinois 60637, USA
| | - Christopher Ness
- School of Engineering, University of Edinburgh, Edinburgh EH9 3FG, United Kingdom
| | - Ryohei Seto
- Wenzhou Institute, University of Chinese Academy of Sciences, Wenzhou, Zhejiang 325000, China
| | - Juan J de Pablo
- Pritzker School of Molecular Engineering, University of Chicago, Chicago, Illinois 60637, USA
- Materials Science Division, Argonne National Laboratory, Lemont, Illinois 60439, USA
| | - Heinrich M Jaeger
- James Franck Institute, University of Chicago, Chicago, Illinois 60637, USA
- Department of Physics, University of Chicago, Chicago, Illinois 60637, USA
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Hayakawa H. Simulation of dense non-Brownian suspensions with the lattice Boltzmann method: shear jammed and fragile states. SOFT MATTER 2020; 16:945-959. [PMID: 31845696 DOI: 10.1039/c9sm00850k] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Dense non-Brownian suspensions, including both hydrodynamic interactions and frictional contacts between particles, are numerically studied under simple and oscillatory shears in terms of the lattice Boltzmann method. We successfully reproduce the discontinuous shear thickening (DST) under a simple shear for bulk three-dimensional systems. For our simulation of an oscillatory shear in a quasi-two-dimensional system, we measure the mechanical response after the reduction of the strain amplitude from the initial oscillations. Here, we find the existence of a shear-jammed state under this protocol in which the storage modulus G' is only finite for high initial strain amplitude γI0. We also find the existence of a fragile state in which both fluid-like and solid-like responses can be detected for an identical area fraction and an initial strain amplitude γI0 depending on the initial phase Θ (or the asymmetricity of the applied strain) of the oscillatory shear. We also observe a DST-like behavior under the oscillatory shear in the fragile state. Moreover, we find that the stress anisotropy becomes large in the fragile state. Finally, we confirm that a stress formula based on the angular distribution of the contact force recovers the contact contributions to the stress tensors for both simple and oscillatory shears with large strains.
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Affiliation(s)
- Hisao Hayakawa
- Yukawa Institute for Theoretical Physics, Kyoto University, Kitashirakawaoiwake-cho, Sakyo-ku, Kyoto 606-8502, Japan.
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Rheological and mechanical properties of cellulose/LDPE composites using sustainable and fully renewable compatibilisers. J Appl Polym Sci 2019. [DOI: 10.1002/app.48744] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Jamali S, Brady JF. Alternative Frictional Model for Discontinuous Shear Thickening of Dense Suspensions: Hydrodynamics. PHYSICAL REVIEW LETTERS 2019; 123:138002. [PMID: 31697551 DOI: 10.1103/physrevlett.123.138002] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/02/2019] [Revised: 07/24/2019] [Indexed: 06/10/2023]
Abstract
A consensus has emerged that a constraint to rotational or sliding motion of particles in dense suspensions under flow is the genesis of the discontinuous shear thickening (DST) phenomenon. We show that tangential fluid lubrication interactions due to finite-sized asperities on particle surfaces effectively provide these constraints, changing the dynamics of particle motion. By explicitly resolving for the surface roughness of particles, we show that, while smooth particles exhibit continuous shear thickening, purely hydrodynamic interactions in rough particles result in DST. In contrast to the frictional contact model, the hydrodynamic model predicts negative first and second normal stress differences for dense suspensions in the shear thickened state.
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Affiliation(s)
- Safa Jamali
- Mechanical and Industrial Engineering Department, Northeastern University, Boston, Massachusetts 02115, USA
| | - John F Brady
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, USA
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Shakor P, Nejadi S, Paul G. A Study into the Effect of Different Nozzles Shapes and Fibre-Reinforcement in 3D Printed Mortar. MATERIALS 2019; 12:ma12101708. [PMID: 31130708 PMCID: PMC6567183 DOI: 10.3390/ma12101708] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/26/2019] [Revised: 05/19/2019] [Accepted: 05/22/2019] [Indexed: 11/16/2022]
Abstract
Recently, 3D printing has become one of the most popular additive manufacturing technologies. This technology has been utilised to prototype trial and produced components for various applications, such as fashion, food, automotive, medical, and construction. In recent years, automation also has become increasingly prevalent in the construction field. Extrusion printing is the most successful method to print cementitious materials, but it still faces significant challenges, such as pumpability of materials, buildability, consistency in the materials, flowability, and workability. This paper investigates the properties of 3D printed fibre-reinforced cementitious mortar prisms and members in conjunction with automation to achieve the optimum mechanical strength of printed mortar and to obtain suitable flowability and consistent workability for the mixed cementitious mortar during the printing process. This study also considered the necessary trial tests, which are required to check the mechanical properties and behaviour of the proportions of the cementitious mix. Mechanical strength was measured and shown to increase when the samples were printed using fibre-reinforced mortar by means of a caulking gun, compared with the samples that were printed using the same mix delivered by a progressive cavity pump to a 6 degree-of-freedom robot. The flexural strength of the four-printed layer fibre-reinforced mortar was found to be 3.44 ± 0.11 MPa and 5.78 ± 0.02 MPa for the one-layer. Moreover, the mortar with different types of nozzles by means of caulking is printed and compared. Several experimental tests for the fresh state of the mortar were conducted and are discussed.
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Affiliation(s)
- Pshtiwan Shakor
- Centre for Built Infrastructure Research, School of Civil and Environmental Engineering, Faculty of Engineering and Information Technology, University of Technology Sydney, Ultimo, NSW 2007, Australia.
| | - Shami Nejadi
- Centre for Built Infrastructure Research, School of Civil and Environmental Engineering, Faculty of Engineering and Information Technology, University of Technology Sydney, Ultimo, NSW 2007, Australia.
| | - Gavin Paul
- Centre for Autonomous Systems, School of Mechanical and Mechatronic Engineering, Faculty of Engineering and Information Technology, University of Technology Sydney, Ultimo, NSW 2007, Australia.
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Denn MM, Morris JF, Bonn D. Shear thickening in concentrated suspensions of smooth spheres in Newtonian suspending fluids. SOFT MATTER 2018; 14:170-184. [PMID: 29239446 DOI: 10.1039/c7sm00761b] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Shear thickening is a phenomenon in which the viscosity of a suspension increases with increasing stress or shear rate, sometimes in a discontinuous fashion. While the phenomenon, when observed in suspensions of corn starch in water, or Oobleck, is popular as a science experiment for children, shear thickening is actually of considerable importance for technological applications and exhibited by far simpler systems. Concentrated suspensions of smooth hard spheres will exhibit shear thickening, and understanding this behavior has required a fundamental change in the paradigm of describing low-Reynolds-number solid-fluid flows, in which contact forces have traditionally been absent. Here, we provide an overview of our understanding of shear thickening and the methods that have been developed to describe it, as well as outstanding questions.
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Affiliation(s)
- Morton M Denn
- Benjamin Levich Institute and Department of Chemical Engineering, Steinman Hall, City College of New York, CUNY, New York, NY 10031, USA.
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Hsiao LC, Saha-Dalal I, Larson RG, Solomon MJ. Translational and rotational dynamics in dense suspensions of smooth and rough colloids. SOFT MATTER 2017; 13:9229-9236. [PMID: 29199309 DOI: 10.1039/c7sm02115a] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
We demonstrate that colloidal particles with surface roughness exhibit hindered rotational diffusion in quiescent dense suspensions. This is accomplished by the use of confocal microscopy and particle tracking to follow the translational and rotational dynamics of smooth and rough colloids suspended in a refractive index and density matched organic solvent. Measurement of the three-dimensional rotational diffusion is enabled by the addition of inert Janus tracers made of native colloids coated with a thin layer of aluminum. These experiments show that the mean square displacement (MSD) is unaffected by particle roughness, while the mean square angular displacement (MSAD) decreases for rough colloids at high volume fractions. Our results quantify the slowdown in the rotational dynamics of rough colloids, which is evidently due to steric frustration caused by the surface topography of the particles.
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Affiliation(s)
- Lilian C Hsiao
- Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, NC 27695, USA.
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Malmir H, Sahimi M, Rahimi Tabar MR. Statistical characterization of microstructure of packings of polydisperse hard cubes. Phys Rev E 2017; 95:052902. [PMID: 28618643 DOI: 10.1103/physreve.95.052902] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2017] [Indexed: 06/07/2023]
Abstract
Polydisperse packings of cubic particles arise in several important problems. Examples include zeolite microcubes that represent catalytic materials, fluidization of such microcubes in catalytic reactors, fabrication of new classes of porous materials with precise control of their morphology, and several others. We present the results of detailed and extensive simulation and microstructural characterization of packings of nonoverlapping polydisperse cubic particles. The packings are generated via a modified random sequential-addition algorithm. Two probability density functions (PDFs) for the particle-size distribution, the Schulz and log-normal PDFs, are used. The packings are analyzed, and their random close-packing density is computed as a function of the parameters of the two PDFs. The maximum packing fraction for the highest degree of polydispersivity is estimated to be about 0.81, much higher than 0.57 for the monodisperse packings. In addition, a variety of microstructural descriptors have been calculated and analyzed. In particular, we show that (i) an approximate analytical expression for the structure factor of Percus-Yevick fluids of polydisperse hard spheres with the Schulz PDF also predicts all the qualitative features of the structure factor of the packings that we study; (ii) as the packings become more polydisperse, their behavior resembles increasingly that of an ideal system-"ideal gas"-with little or no correlations; and (iii) the mean survival time and mean relaxation time of a diffusing species in the packings increase with increasing degrees of polydispersivity.
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Affiliation(s)
- Hessam Malmir
- Mork Family Department of Chemical Engineering and Materials Science, University of Southern California, Los Angeles, California 90089-1211, USA
| | - Muhammad Sahimi
- Mork Family Department of Chemical Engineering and Materials Science, University of Southern California, Los Angeles, California 90089-1211, USA
| | - M Reza Rahimi Tabar
- Department of Physics, Sharif University of Technology, Tehran 11365-9161, Iran
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15
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Cwalina CD, Harrison KJ, Wagner NJ. Rheology of cubic particles in a concentrated colloidal dispersion suspending medium. AIChE J 2016. [DOI: 10.1002/aic.15443] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Colin D. Cwalina
- Dept. of Chemical and Biomolecular Engineering, Center for Molecular Engineering and Thermodynamics; University of Delaware; Newark DE 19716
| | - Kelsey J. Harrison
- Dept. of Chemical and Biomolecular Engineering, Center for Molecular Engineering and Thermodynamics; University of Delaware; Newark DE 19716
| | - Norman J. Wagner
- Dept. of Chemical and Biomolecular Engineering, Center for Molecular Engineering and Thermodynamics; University of Delaware; Newark DE 19716
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