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Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 85 for “"polymer concentration"”.
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Determination of the Mechanical Properties of Electrospun Gelatin Based on Polymer Concentration and Fiber Alignment
… as fiber diameter and porosity are affected by polymer concentration. However, the affects of fiber alignment upon the material properties of electrospun scaffolds remains unclear. The purpose of this study is to determine how the material properties of electrospun gelatin scaffolds are affected …
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Effects of polymer concentration and molecular weight on the dynamics of visco-elasto-capillary breakup
Capillary-break-up measurements of viscoelastic polymer solutions are performed using a Capillary Breakup Extensional Rheometer (CABER). The device consists of two coaxial plates which are used to form and hold a liquid bridge of the test fluid. An axial step strain is applied to the fluid by …
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Influence of Solvent Removal Rate and Polymer Concentration on Ordering Kinetics of Block Copolymers in Solution
An examination of the ordering process of block copolymer microstructure with respect to concentration was performed. Specifically, the process of solution casting block copolymer films was studied using small-angle X-ray scattering (SAXS). A method for determining the volume fraction of ordered …
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High-pressure viscosity and density of polymer solutions at the critical polymer concentration in near-critical and supercritical fluids
… for the determination of the viscosity of polymer solutions in dense fluids at the critical polymer concentration stems from the need to understand the factors that influence the time scale of phase separation in systems that undergo spinodal decomposition upon a pressure quench. In a …
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Structure, Dynamics and Rheology of Polymer Solutions from Coarse-Grained Molecular Dynamics: Effects of Polymer Concentration, Solvent Quality and Geometric Confinement
… in the design and optimization of ubiquitous polymer processing operations.</p> <p>Further, such interactions are routinely encountered in separation of biopolymer mixtures</p> <p>using gel electrophoresis and microfluidic technologies, manufacturing of polymer-based</p> <p>functional …
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Phase Behavior, Fluid Structure, and Slow Dynamics in Polymer -Colloid Mixtures: Novel Liquid State Theory and Its Applications
… order parameter S(k* ≈ 7 D) with increasing polymer concentrations. Accurate, no adjustable parameter predictions of the fluid structure are combined with a single particle version of idealized mode coupling theory to predict the gelation boundaries and elastic shear moduli for Rg/R < 0.1 …
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Development and characterization of edible films made from four dietary fibers -pectin, guar gum, locust bean gum, and hydroxypropyl methylcellulose
… This research aims to determine the effect of polymer concentration of 4 dietary fibers, e.g., guar gum, locust bean gum, pectin, and hydroxypropyl methylcellulose, and glycerol concentration to the mechanical properties and dissolution/ partial dissolution time of their films and the viscosity …
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Equilibrium and Dynamic Phase Behavior in Thin Films of Cylinder-Forming Block Copolymers
… in thin films of cylinder-forming block copolymers has been studied. The results range from an extension of an advanced strong segregation theory to the treatment of cylindrical microdomains in a thin film, over the detailed analysis of the phase behavior and the microdomain dimensions of a …
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Regulated release of a novel non-viral gene delivery vector from electrospun coaxial fiber mesh scaffolds
… tissue engineering entails the evolution of biopolymers into multifunctional constructs that can support the proliferation of cells and stimulate their differentiation into functional tissues. With that in mind, biocompatible polymers were fabricated into a novel gene delivery agent as well as …
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Synthesis and Environmental Applications of Mesoporous Alumina
… oxide)-poly(ethylene oxide) triblock copolymer and aluminum isopropoxide in the presence of nitric acid. This synthesis afforded mesoporous alumina materials with high specific surface area, large pore volume, and large pore width. This study showed that the specific surface area and …
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Liquid State Theory of Equilibrium Structure and Thermodynamics of Block Copolymer Melts and Solutions
… and structures of fluids of multiblock polymers both with nonpolar and strongly attracting groups. The physical clustering/aggregation process is probed via the calculation of small and wide angle scattering patterns, real space intermolecular radial distribution functions, and …
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Chemi-code : an innovative method for wood product tracking
… method using the innate IR signatures of polymeric compounds, varied by compound and concentration to develop millions of potential combinations, and consequently millions of unique identities. The combined variation of multiple IR peak frequencies and magnitudes provide the conceptual …
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Characterization of Friction Reducer Properties in Oil-Field Operations
… to identify the specific parameters that affect polymeric friction reduction. This research uses friction flow loop experiments to characterize the performance of partially hydrolyzed polyacrylamide friction reducers in conditions relevant to the oil field. Polymer concentration and degree of …
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Soft hydrated sliding interfaces as complex fluids
… aqueous component. Recent studies have shown polymer concentration gradients resulting in a less dense region in the top micrometers of the surface. Under shear, this gradient is hypothesized to drive lubrication behavior due to its rheological similarity to a semi-dilute polymer solution. In …
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Depletion Attractions Between Hard Spheres: Comparisons of Theory and Experiment
… over nearly two orders of magnitude in polymer/colloid size asymmetry. Fluid-gel, fluid-crystal, and fluid-fluid transitions are observed as Rg, the polymer radius of gyration, increases. Based on the polymer concentration relative to the dilute-semidilute crossover density, cp/cp*, as …
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Self-Assembly of Block Copolymers in External Fields
… fields on the microdomain structure of block copolymers has been studied. Both surface fields and electric fields have been considered. External electric fields are used to create macroscopically oriented bulk samples. In order to circumvent limitations associated with the application of …
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Single polymer dynamics in semi-dilute solutions: linear and ring polymers
"Synthetic and biological polymers are ubiquitous in nature and modern technologies. Traditional characterization methods of polymeric materials rely on bulk level measurements that can provide useful information on material properties. However, these methods generally cannot access underlying …
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pH-Responsive Polymers for Biosurfaces: An Investigation of Solution Properties and Surface Modifying Performance
<p>Gantrez® copolymers are used widely in the personal care industry, but their mechanisms of interaction with dental surfaces are poorly understood. In this study, we determined a number of the solution and polymer properties that control deposition, adsorption and adhesion in Gantrez® polymer …
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Dilute Non-Newtonian Particle Suspension Rheology And Microstructure
The study of polymeric particle suspensions has been the subject of a number of past experimental and theoretical studies. However, fundamental questions about suspension rheology and shear flow-induced microstructural effects remain. First, a quasi-analytical study is presented that gives the first …
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Twofold switchable block copolymers based on new polyzwitterions
… sulfobetaine monomers were synthesized and polymerized by reversible addition-fragmentation chain transfer (RAFT) polymerization, using a fluorophore labeled RAFT agent. The polyzwitterions of systematically varied molar mass were characterized with respect to their solubility in water, …
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