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- Rheology (5)
- High-performance concrete (3)
- Internal curing (3)
- Superabsorbent polymer (3)
- Carbon nanotubes (2)
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- Chemical admixtures (2)
- Gels (2)
- Hydrogel particles (2)
- Microscopy (2)
- Microstructure (2)
- Nanosilica (2)
- Strain hardening (2)
- Sustainability (2)
- Transient network (2)
- Adsorption (1)
- Ageing (1)
- Associating polymers (1)
- Atomic force microscope (1)
- Atomic force microscopy (1)
- Autogenous shrinkage (1)
- Bending (1)
- Birefringence (1)
- Block copolymer rheology (1)
- Block copolymers (1)
- Cement (1)
- Cement hydration (1)
- Coalescence (1)
- Colloids (1)
- Comb-polymer adsorption (1)
- Convection (1)
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Articles 1 - 22 of 22
Full-Text Articles in Engineering
Investigation Of Fiber Orientation And Mechanical Properties Of Pyrolysis Recycled Carbon-Fiber Reinforced Thermoset Composite, Reva N. Simmons, Harry Lee, Garam Kim
Investigation Of Fiber Orientation And Mechanical Properties Of Pyrolysis Recycled Carbon-Fiber Reinforced Thermoset Composite, Reva N. Simmons, Harry Lee, Garam Kim
Discovery Undergraduate Interdisciplinary Research Internship
With increasing demand of carbon fiber reinforced fiber thermoset composites, establishing a sustainable cycle for these materials becomes crucial. Pyrolysis is a process of reclaiming carbon fiber from thermoset composites by thermally degrading the polymer at high temperatures allowing the fibers to be extracted. Carbon fiber reclaimed through current pyrolysis processes for thermoset composites typically loses its original shape and orientation, making it difficult to reorganize the fibers. This study investigated the feasibility of maintaining the fiber orientations for continuous fiber reinforced thermoset composite during pyrolysis by stitching the carbon fiber layup to a conformable copper mesh during the manufacturing …
Rheo-Physical Characterization Of Microstructure And Flow Behavior Of Concentrated Surfactant Solutions, Eduard Caicedo Casso, Jason E Bice, Lisa R. Nielsen, Jessica L Sargent, Seth Lindberg, Kendra Erk
Rheo-Physical Characterization Of Microstructure And Flow Behavior Of Concentrated Surfactant Solutions, Eduard Caicedo Casso, Jason E Bice, Lisa R. Nielsen, Jessica L Sargent, Seth Lindberg, Kendra Erk
School of Materials Engineering Faculty Publications
Processing-relevant relationships between the microstructure and flow behavior of concentrated surfactant solutions were determined by a combination of basic rheological experiments, rheo-flow velocimetry tests, and flow birefringence measurements. The most common surfactant microstructures found in liquid soaps and other consumer care products—spherical, worm-like, and hexagonally packed micelles and lamellar structures—were recreated by varying the concentration of sodium laureth sulfate in water from 20 to 70 wt% and adding salt in some cases. It was found that common features of flow curves, such as power-law shear thinning behavior, resulted from a wide variety of material responses including shear-induced wall slip in …
Effect Of Salt Valency And Concentration On Shear And Extensional Rheology Of Aqueous Polyelectrolyte Solutions For Enhanced Oil Recovery, Anna V. Walter, Leidy N. Jimenez, Jelena Dinic, Vivek Sharma, Kendra Erk
Effect Of Salt Valency And Concentration On Shear And Extensional Rheology Of Aqueous Polyelectrolyte Solutions For Enhanced Oil Recovery, Anna V. Walter, Leidy N. Jimenez, Jelena Dinic, Vivek Sharma, Kendra Erk
School of Materials Engineering Faculty Publications
The injection of polymer solutions into an oil basin can lead to enhanced oil recovery (EOR) by increasing the microscopic sweep of the reservoir, improving the water-oil motility ratio, and thus leading to greater yield from oil fields. In this contribution, we characterize both shear and extensional rheological response of aqueous solutions of partially hydrolyzed polyacrylamide (HPAM), the most commonly used polymer for EOR, for velocity gradients in both the flow direction (extensional) and perpendicular to flow (shear) arise in EOR applications. As HPAM is a charged polymer, to better emulate the environment in oil basins, the rheological response was …
Synthesis And Characterization Of Polymer-Silica Composite Hydrogel Particles And Influence Of Hydrogel Composition On Cement Paste Microstructure, Matthew J. Krafcik, B Bose, Kendra Erk
Synthesis And Characterization Of Polymer-Silica Composite Hydrogel Particles And Influence Of Hydrogel Composition On Cement Paste Microstructure, Matthew J. Krafcik, B Bose, Kendra Erk
School of Materials Engineering Faculty Publications
The objective of this research is to define the fundamental structure-property relationships of water-swollen polymer hydrogel particles that are employed as internal curing agents in cementitious mixtures, in addition to reporting a novel synthesis procedure for combining pozzolanic materials with hydrogel particles. Solution polymerization was performed to incorporate amorphous nanosilica particles within acrylic-based polymer hydrogel particles of varying chemical compositions (i.e., monomer ratio of acrylic acid (AA) to acrylamide (AM)). Experiments were designed to measure the absorption capacity and kinetics of hydrogel particles immersed in pure water and cementitious pore solution, as well as determine the impact of particles on …
A Rheometry Method To Assess The Evaporation-Induced Mechanical Strength Development Of Polymer Solutions Used For Membrane Applications, Eduard Caicedo Casso, Jessica L Sargent, Rachel M. Dorin, Ulrich B. Wiesner, William A. Phillip, Bryan M. Boudouris, Kendra Erk
A Rheometry Method To Assess The Evaporation-Induced Mechanical Strength Development Of Polymer Solutions Used For Membrane Applications, Eduard Caicedo Casso, Jessica L Sargent, Rachel M. Dorin, Ulrich B. Wiesner, William A. Phillip, Bryan M. Boudouris, Kendra Erk
School of Materials Engineering Faculty Publications
Rotational and oscillatory shear rheometry were used to quantify the flow behavior under minimal and significant solvent evaporation conditions for polymer solutions used to fabricate isoporous asymmetric membranes by the self-assembly and non-solvent induced phase separation (SNIPS) method. Three different A-B-C triblock terpolymer chemistries of similar molar mass were evaluated: polyisoprene-^-polystyrene-6-poly(4-vinylpyridine) (ISV); polyisoprene-6- polystyrene-6-poly(V,A-dimethylacrylamide) (ISD); and polyisoprene-Z>-polystyrene-h-poly(fer/- butyl methacrylate) (ISB). Solvent evaporation resulted in the formation of a viscoelastic film typical of asymmetric membranes. Solution viscosity and film viscoelasticity were strongly dependent on the chemical structure of the triblock terpolymer molecules. A hierarchical magnitude (ISV>ISB>ISD) was observed …
Controllable Internal Mixing In Coalescing Droplets Induced By The Solutal Marangoni Convection Of Surfactants With Distinct Headgroup Architectures, Jerome J. Nash, Patrick T. Spicer, Kendra Erk
Controllable Internal Mixing In Coalescing Droplets Induced By The Solutal Marangoni Convection Of Surfactants With Distinct Headgroup Architectures, Jerome J. Nash, Patrick T. Spicer, Kendra Erk
School of Materials Engineering Faculty Publications
Through several complementary experiments, an investigation of the bulk and interfacial flows that emerged during the coalescence of two water-in-oil droplets with asymmetric compositional properties was performed. By adding surfactant to one of the coalescing droplets and leaving the other surfactant-free, a strong interfacial tension gradient (i.e., solutal Marangoni) driving energy between the merging droplets generated pronounced internal mixing. The contributions of two distinct types of surfactant, anionic ammonium lauryl sulfate (ALS) and cationic cetyltrimethylammonium bromide (CTAB) on the rate of coalescence bridge expansion and on the generation of opposing flows during coalescence were investigated. All coalescence experiments supported the …
Synthesis And Characterization Of Polymer-Silica Composite Hydrogel Particles And Influence Of Hydrogel Composition On Cement Paste Microstructure, Matthew J. Krafcik, B Bose, Kendra Erk
Synthesis And Characterization Of Polymer-Silica Composite Hydrogel Particles And Influence Of Hydrogel Composition On Cement Paste Microstructure, Matthew J. Krafcik, B Bose, Kendra Erk
School of Materials Engineering Faculty Publications
The objective of this research is to define the fundamental structure-property relationships of water-swollen polymer hydrogel particles that are employed as internal curing agents in cementitious mixtures, in addition to reporting a novel synthesis procedure for combining pozzolanic materials with hydrogel particles. Solution polymerization was performed to incorporate amorphous nanosilica particles within acrylic-based polymer hydrogel particles of varying chemical compositions (i.e., monomer ratio of acrylic acid (AA) to acrylamide (AM)). Experiments were designed to measure the absorption capacity and kinetics of hydrogel particles immersed in pure water and cementitious pore solution, as well as determine the impact of particles on …
Comparing Laser Diffraction And Optical Microscopy For Characterizing Superabsorbent Polymer Particle Morphology, Size, And Swelling Capacity, Cole R. Davis, Stacey L. Kelly, Kendra Erk
Comparing Laser Diffraction And Optical Microscopy For Characterizing Superabsorbent Polymer Particle Morphology, Size, And Swelling Capacity, Cole R. Davis, Stacey L. Kelly, Kendra Erk
School of Materials Engineering Faculty Publications
In this study, we determined the accuracy and practicality of using optical microscopy (OM) and laser diffraction (LD) to characterize hydrogel particle morphology, size, and swelling capacity (Q). Inverse-suspension-polymerized polyacrylamide particles were used as a model system. OM and LD showed that the average particle diameter varied with the mixing speed during synthesis for the dry (10–120 lm) and hydrated (34–240 lm) particles. The LD volume and number mean diameters showed that a few large particles were responsible for the majority of the water absorption. Excess water present in the gravimetric swelling measurements led to larger Qs (8.2 6 0.37 …
Influence Of Adsorbed And Nonadsorbed Polymer Additives On The Viscosity Of Magnesium Oxide Suspensions, Lisa R. Murray, Jason E Bice, Emily G. Soltys, Christopher Perge, Sebastien Manneville, Kendra Erk
Influence Of Adsorbed And Nonadsorbed Polymer Additives On The Viscosity Of Magnesium Oxide Suspensions, Lisa R. Murray, Jason E Bice, Emily G. Soltys, Christopher Perge, Sebastien Manneville, Kendra Erk
School of Materials Engineering Faculty Publications
Adsorbed polymer additives have been employed to reduce water content and improve cement workability through lowering viscosity, but the influence of over-dosage and the presence of nonadsorbed chains have yet to be fully understood. Model magnesium oxide (MgO) suspensions were used to investigate the potential processing effect of “free” chain concentration on cementitious mixtures. The rheological impact of the free chains was measured through incorporation of nonadsorbing poly(ethylene glycol) (PEG) to suspensions stabilized with an adsorbed comb-polymer superplasticizer. Analyses of the rheological data, that showed viscosity-increases and viscosity-reduction due to free PEG concentrations revealed a transition from depletion flocculation to …
The Impact Of Damage Accumulation On The Kinetics Of Network Strength Recovery For A Physical Polymer Gel Subjected To Shear Deformation, Travis Thornell, Krithika Subramaniam, Kendra Erk
The Impact Of Damage Accumulation On The Kinetics Of Network Strength Recovery For A Physical Polymer Gel Subjected To Shear Deformation, Travis Thornell, Krithika Subramaniam, Kendra Erk
School of Materials Engineering Faculty Publications
Shear rheophysical experiments were used to quantify the kinetics of strength recovery of model thermoreversible polymer gels that were fractured and ultimately sheared to different total magnitudes of strain (700 and 4000%) before resting for set periods of time. Relationships between the amount of strength recovered and the normalized ratio of resting times to characteristic relaxation times were developed. It was found that gels displayed fully healed networks within timescales that were 2-3 orders of magnitude greater than the gel’s characteristic relaxation time. Gels deformed to 700% applied strain either healed slower at lower gel concentrations as compared to experiments …
Characterization Of Superabsorbent Poly(Sodium-Acrylate Acrylamide) Hydrogels And Infuence Of Chemical Structure On Internally Cured Mortar, Matthew J. Krafcik, Kendra Erk
Characterization Of Superabsorbent Poly(Sodium-Acrylate Acrylamide) Hydrogels And Infuence Of Chemical Structure On Internally Cured Mortar, Matthew J. Krafcik, Kendra Erk
School of Materials Engineering Faculty Publications
Internal curing of mortar through superabsorbent polymer hydrogels is explored as a solution to self-desiccation. Four different hydrogels of poly(sodium-acrylate acry- lamide) are synthesized and the impact of chemical composition on mortar is assessed with relative humidity and autogenous shrinkage testing. The hydrogels are characterized with swelling tests in different salt solutions and compression tests. Chemical composition af- fected both swelling kinetics and gel network size. Mortar containing these hydrogels had increased relative humidity and markedly reduced autogenous shrinkage. Additionally, the chemical structure of the hydrogels was found to signifcantly impact the mortar’s shrink- age. Hydrogels that quickly released most …
Lignopolymers As Viscosity-Reducing Additives In Magnesium Oxide Suspensions, Lisa R. Murray, Chetali Gupta, Newell R. Washburn, Kendra Erk
Lignopolymers As Viscosity-Reducing Additives In Magnesium Oxide Suspensions, Lisa R. Murray, Chetali Gupta, Newell R. Washburn, Kendra Erk
School of Materials Engineering Faculty Publications
Lignopolymers are a new class of polymer additives with the capability to be used as dispersants in cementitious pastes. Made with kraft lignin cores and grafted polymer side- chains, the custom-synthesized lignopolymers were examined in terms of the molecular architecture for viscosity reducing potential in inert model suspensions. Lignin-poly(acrylic acid) (LPAA) and lignin-polyacrylamide (LPAm) have been found to vary the rheology of magnesium oxide (MgO) suspensions based on differences in chain architecture and particle- polymer interactions. A commercial comb-polymer polycarboxylate ester was compared to LPAA and LPAm at 2.7 mg/mL, a typical dosage for cement admixtures, as well as 0.25 …
Nanohub.Org: A Gateway To Undergraduate Simulation-Based Research In Materials Science And Related Fields, Tanya A. Faltens, Peter A. Bermel, Amanda Buckles, K Anna Douglas, Alejandro H. Strachan, Lynn K. Zentner, Gerhard Klimeck
Nanohub.Org: A Gateway To Undergraduate Simulation-Based Research In Materials Science And Related Fields, Tanya A. Faltens, Peter A. Bermel, Amanda Buckles, K Anna Douglas, Alejandro H. Strachan, Lynn K. Zentner, Gerhard Klimeck
Birck and NCN Publications
Our future engineers and scientists will likely be required to use advanced simulations to solve many of tomorrow's challenges in nanotechnology. To prepare students to meet this need, the Network for Computational Nanotechnology (NCN) provides simulation-focused research experiences for undergraduates at an early point in their educational path, to increase the likelihood that they will ultimately complete a doctoral program. The NCN summer research program currently serves over 20 undergraduate students per year who are recruited nationwide, and selected by NCN and the faculty for aptitude in their chosen field within STEM, as well as complementary skills such as coding …
Effect Of Ionic Crosslinking On The Swelling And Mechanical Response Of Model Superabsorbent Polymer Hydrogels For Internally Cured Concrete, Qian Zhu, Christopher W. Barney, Kendra Erk
Effect Of Ionic Crosslinking On The Swelling And Mechanical Response Of Model Superabsorbent Polymer Hydrogels For Internally Cured Concrete, Qian Zhu, Christopher W. Barney, Kendra Erk
School of Materials Engineering Faculty Publications
The chemical and physical structure-property relationships of model superabsorbent polymer (SAP) hydrogels were characterized with respect to swelling behavior and mechanical properties in different ionic solutions (Na+, Ca2+, and Al3+). The model hydrogels were composed of poly(sodium acrylate-acrylamide) (PANa-PAM) copolymer with varying concentrations of PANa (0, 17, 33, 67, and 83 wt.%) and covalent crosslinking densities of 1, 1.5, and 2 wt.%. By synthesizing the hydrogels in-house, systems with independently tunable amounts of covalent crosslinking and anionic functional groups were created, allowing for the relative effects of covalent and ionic crosslinking on the properties of the hydrogels to be directly …
Jamming Rheology Of Model Cementitious Suspensions Composed Of Comb-Polymer Stabilized Magnesium Oxide Particles, Lisa R. Murray, Kendra Erk
Jamming Rheology Of Model Cementitious Suspensions Composed Of Comb-Polymer Stabilized Magnesium Oxide Particles, Lisa R. Murray, Kendra Erk
School of Materials Engineering Faculty Publications
The colloidal microstructure of concentrated suspensions containing anionic comb- polymer-stabilized magnesium oxide (MgO) particles in water was analyzed by shear rheometry for indications of changes in particle microstructure based on particle size and comb-polymer usage. As the suspensions were sheared at different rates, jamming in the sheared MgO suspensions was observed as shear stress overshoots. The shear-induced evolution of the suspension’s microstructure was strongly related to the perceived interactions between neighboring MgO particles in the suspension. In the jammed state, interactions are believed to be enhanced by the formation of entanglements between opposing comb-polymer side-chains. Steric repulsion between side-chains was …
Extreme Strain Localization And Sliding Friction In Physically Associating Polymer Gels, Kendra Erk, Jeffrey D. Martin, Y. Thomas Hu, Kenneth R. Shull
Extreme Strain Localization And Sliding Friction In Physically Associating Polymer Gels, Kendra Erk, Jeffrey D. Martin, Y. Thomas Hu, Kenneth R. Shull
School of Materials Engineering Faculty Publications
Model physically associating gels deformed in shear over a wide range of reduced rates displayed evidence of strain localization. The non-linear stress responses and inhomogeneous velocity profiles observed during shear rheometry coupled with particle tracking velocimetry were associated with the occurrence of rate-dependent, banding and fracture-like responses in the gel. Scaling law analysis from traditional sliding friction studies suggests that at the molecular level, deformation is confined to a shear zone with thickness comparable to the gel’s mesh size, the smallest structurally relevant length scale in the gel.
Shear And Dilational Interfacial Rheology Of Surfactant-Stabilized Droplets, Kendra Erk, Jeffrey D. Martin, Jonathan T. Schwalbe, Frederick R. Phelan Jr., Steven D. Hudson
Shear And Dilational Interfacial Rheology Of Surfactant-Stabilized Droplets, Kendra Erk, Jeffrey D. Martin, Jonathan T. Schwalbe, Frederick R. Phelan Jr., Steven D. Hudson
School of Materials Engineering Faculty Publications
A new measurement method is suggested that is capable of probing the shear and dilational interfacial rheological responses of small droplets, those of size comparable to real emulsion applications. Freely suspended aqueous droplets containing surfactant and non-surface-active tracer particles are transported through a rectangular microchannel by the plane Poiseuille flow of the continuous oil phase. Optical microscopy and high-speed imaging record the shape and internal circulation dynamics of the droplets. Measured circulation velocities are coupled with theoretical descriptions of the droplet dynamics in order to determine the viscous (Boussinesq) and elastic (Marangoni) interfacial effects. A new Marangoni-induced stagnation point is …
Interfacial Effects On Droplet Dynamics In Poiseuille Flow, Kendra Erk, Jonathan T. Schwalbe, Frederick R. Phelan Jr., Petia M. Vlahovska, Steven D. Hudson
Interfacial Effects On Droplet Dynamics In Poiseuille Flow, Kendra Erk, Jonathan T. Schwalbe, Frederick R. Phelan Jr., Petia M. Vlahovska, Steven D. Hudson
School of Materials Engineering Faculty Publications
Many properties of emulsions arise from interfacial rheology, but a theoretical understanding of the effect of interfacial viscosities on droplet dynamics is lacking. Here we report such a theory, relating to isolated spherical drops in a Poiseuille flow. Stokes flow is assumed in the bulk phases, and a jump in hydrodynamic stress at the interface is balanced by Marangoni and surface viscous forces according to the Boussinesq–Scriven constitutive law. Our model employs a linear equation of state for the surfactant. Our analysis predicts slip, cross-stream migration and droplet-circulation velocities. These results and the corresponding interfacial parameters are separable: e.g., cross-stream …
Rate-Dependent Stiffening And Strain Localization In Physically Associating Solutions, Kendra Erk, Kenneth R. Shull
Rate-Dependent Stiffening And Strain Localization In Physically Associating Solutions, Kendra Erk, Kenneth R. Shull
School of Materials Engineering Faculty Publications
Model physically associating solutions of acrylic triblock copolymer molecules in a midblock-selective solvent displayed non-linear strain-stiffening behavior which transitioned to rapid strain softening during shear start-up experiments at reduced rates spanning almost four orders of magnitude. Softening was believed to result from the shear-induced formation of highly localized regions of deformation in the macromolecular network. This behavior was accurately captured by a model that incorporated the strain energy and relaxation behavior of individual network strands in the solution. Flow curves predicted from the model were non-monotonic, consistent with the onset of flow instabilities at high shear rates. The non-linear stress …
Strain-Stiffening In Synthetic And Biopolymer Networks, Kendra Erk, Kevin J. Henderson, Kenneth R. Shull
Strain-Stiffening In Synthetic And Biopolymer Networks, Kendra Erk, Kevin J. Henderson, Kenneth R. Shull
School of Materials Engineering Faculty Publications
Strain-stiffening behavior common to biopolymer networks is difficult to reproduce in synthetic networks. Physically associating synthetic polymer networks can be an exception to this rule and can demonstrate strain-stiffening behavior at relatively low values of strain. Here, the stiffening behavior of model elastic networks of physically associating triblock copolymers is characterized by shear rheometry. Experiments demonstrate a clear correlation between network structure and strain-stiffening behavior. Stiffening is accurately captured by a constitutive model with a single fitting parameter related to the midblock length. The same model is also effective for describing the stiffening of actin, collagen, and other biopolymer networks. …
Strain Energy And Lateral Friction Force Distributions Of Carbon Nanotubes Manipulated Into Shapes By Atomic Force Microscopy, Mark C. Strus, Roya R. Lahiji, Pablo Ares, Vincente Lopez, Arvind Raman, Ron R. Reifenberger
Strain Energy And Lateral Friction Force Distributions Of Carbon Nanotubes Manipulated Into Shapes By Atomic Force Microscopy, Mark C. Strus, Roya R. Lahiji, Pablo Ares, Vincente Lopez, Arvind Raman, Ron R. Reifenberger
Other Nanotechnology Publications
The interplay between local mechanical strain energy and lateral frictional forces determines the shape of carbon nanotubes on substrates. In turn, because of its nanometer-size diameter, the shape of a carbon nanotube strongly influences its local electronic, chemical, and mechanical properties. Few, if any, methods exist for resolving the strain energy and static frictional forces along the length of a deformed nanotube supported on a substrate. We present a method using nonlinear elastic rod theory in which we compute the flexural strain energy and static frictional forces along the length of single walled carbon nanotubes (SWCNTs) manipulated into various shapes …
Interfacial Energy Between Carbon Nanotubes And Polymers Measured From Nanoscale Peel Tests In The Atomic Force Microscope, Mark C. Strus, Camilo I. Cano, R. Byron Pipes, Cattien V. Nguyen, Arvind Raman
Interfacial Energy Between Carbon Nanotubes And Polymers Measured From Nanoscale Peel Tests In The Atomic Force Microscope, Mark C. Strus, Camilo I. Cano, R. Byron Pipes, Cattien V. Nguyen, Arvind Raman
Other Nanotechnology Publications
The future development of polymer composite materials with nanotubes or nanoscale fibers requires the ability to understand and improve the interfacial bonding at the nanotube-polymer matrix interface. In recent work [Strus MC, Zalamea L, Raman A, Pipes RB, Nguyen CV, Stach EA. Peeling force spectroscopy: exposing the adhesive nanomechanics of one-dimensional nanostructures. Nano Lett 2008;8(2):544–50], it has been shown that a new mode in the Atomic Force Microscope (AFM), peeling force spectroscopy, can be used to understand the adhesive mechanics of carbon nanotubes peeled from a surface. In the present work, we demonstrate how AFM peeling force spectroscopy can be …