Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
Results
Showing 1 to 20 of 26 for “"particle volume fraction"”.
-
Experimental and numerical investigation of steady-state and transient ultrasound directed self-assembly of spherical particles in a viscous medium
… a standing ultrasound wave field to organize particles dispersed in a fluid medium into specific patterns. The ability to tailor the organization and packing density of spherical particles using ultrasound DSA in a viscous fluid medium is crucial in the context of (additive) manufacturing of …
-
Laser Doppler velocimetry measurements of particle velocity fluctuations in a concentrated suspension
… spheres in Newtonian fluids suggest that the particles nijgrate in response to gradients in "suspension temperature," defined as the average kinetic energy contained in the particle velocity fluctuations. These models have not yet been compared systematically with experimental data. In …
-
The effects of concentration, interaction, size distribution and shape anisotropy on rheology of colloidal mixtures
… Particular interest is focused on the role of volume fraction and strength of interactions that lead to glass or gel formation. Variables studied include particle concentration, strength of attraction, particle size distribution, and particle shape, which have effects on dynamic arrest …
-
Micro/nanoscale modeling of anisotropic mechanical properties of polymer/layered-silicate nanocomposites
… with relatively low filler loadings (1-4 percent volume fraction). These property enhancements have been speculated to be a result of the change in polymer morphology and properties within the polymer/particle interfacial regions, due to the nanometer length scale and the large interface area/unit …
-
Mechanical and physical properties of particulate reinforced composites
The effect of particle size matching and mismatching on the processability, and the mechanical and physical properties of particulate reinforced composites is investigated in this study. These composites were made from dry powder-powder blends. Polymer and reinforcement materials were chosen, …
-
Shear behavior and microstructures of confined colloidal suspensions
… confined to gap sizes on the order of a few particle diameters are investigated by molecular dynamics computer simulations. Suspensions of uniform spheres at volume fractions ranging from 0.28 to 0.53 covering the crystalline phase are studied. The suspensions are modeled as spheres …
-
Phase Behavior, Fluid Structure, and Slow Dynamics in Polymer -Colloid Mixtures: Novel Liquid State Theory and Its Applications
… 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 suspensions. The calculated ""transient gel lines"" are in semi-quantitative agreement with measurements in deep quenched …
-
Physical mechanisms controlling the pre-failure stress-strain behavior of frozen sand
… the dependency of these two parameters on volume fraction, stress level, strain rate, and temperature, as well as on particle size, stiffness, roughness, shape, and interfacial bond strength. Theories for composite material behavior are employed to analyze the observed …
-
Mesoscale Computational Analysis on the Reactivity of Heterogeneous Energetic Materials with Electromechanical Properties
… a composite film consisting of nanoaluminum particles embedded within PVDF-TrFE binder) possessing flexoelectric and piezoelectric properties. The attainment of sufficient E-field intensity within the material is then used as part of the input for the subsequent analysis, wherein dielectric …
-
Particle microstructure and polymer dynamics in concentrated polymer solutions
The states of nanoparticle dispersions in concentrated polymer solutions are studied with extensive small angle scattering and NMR experiments. Silica nanoparticles are suspended in polymer-solvent mixtures. The effects of polymer induced interactions on the particle microstructure are examined …
-
Multiscale micromechanical modeling of the thermal/mechanical properties of polymer/clay nanocomposites
… thermal/mechanical properties at low weight fractions (We) of clay. Continuum-based composite modeling reveals that the enhanced properties are strongly dependent on particular features of the second-phase "particles"; in particular, the particle volume fraction (f,), the particle aspect …
-
Phase Behavior, Microstructure and Mechanics of Colloid -Polymer Mixtures
… as a function of the strength and range of interparticle interactions. In particular, we establish links between the suspension microstructure and the mechanical response of gels formed via short-range depletion attractions. First we highlight the failure of extant classical models to capture the …
-
Micromechanical modeling of the toughening mechanisms in particle-modified semicrystalline polymers
… phase. In particular, when the average interparticle matrix ligament thickness, A, of the blend is reduced below a critical length parameter, Ac, dramatic jumps in toughness levels are observed. This critical parameter is a specific material characteristic of the base polymer and can be …
-
Laminar viscous resuspension in two-dimensional channels
The laminar viscous resuspension of sphere particles in two-dimensional channel with gravity and electrostatic effects is studied numerically. The constitutive equation for particles include the shear-induced diffusion flux, gravitational sedimentation flux and electro-static diffusion flux. In …
-
A Numerical Evaluation of Thermotropic Materials for Polymer Solar Thermal Collectors
… thickness τL, the scattering albedo ω, and the particle size parameter x. The study demonstrates that to achieve ≥85% transmittance in the clear state, the optical thickness must be low. To achieve ≥50% reflectance in the translucent state necessitates a significant increase in optical thickness …
-
Synthesis and study of crystalline hydrogels, guided by a phase diagram.
Monodispersed nanoparticles of poly-N-isopropylacrylamide-co-allylamine (PNIPAM-co-allylamine) and PNIPAM-co-acrylic acid (AA) have been synthesized and used as building blocks for creating three-dimensional networks. The close-packed PNIPAM-co-allylamine and PNIPAM-co-AA nanoparticles were …
-
Rheology and Microstructure of Filled Polymer Melts
The states of particle dispersion in polymer nanocomposite melts are studied through rheological characterization of nanocomposite melt mechanical properties and small angle X-ray scattering measurement of the particle microstructure. The particle microstructure probed with scattering is related to …
-
Hydrodynamics and heat transfer in shallow fluidized beds
… probe has been developed for measurements of particle volume-fraction distribution and its statical fluctuation (standard deviation). These data have been shown to quantitatively define: (1) different types of shallow beds; (2) relative magnitude of solid mixing; (3) bed surface and bed …
-
Polymer Nanocomposites: Polymer And Particle Dynamics And Its Application As Lubricant
… entitled 'Polymer Nanocomposites: Polymer and Particle Dynamics' where I investigate dynamics of polymer and particle upon their mixing. On second part of the thesis, I present one of the application of polymer nanocomposites (PNC) entitled 'Nanoscale Organic-Inorganic Hybrid Lubricants'. …
-
Microscopic theory for dynamics in entangled polymer nanocomposites
… long-time and intermediate-time dynamics of nanoparticles in entangled and unentangled polymer melts for dilute particle concentrations. Using a combination of mode-coupling, Brownian motion, and polymer physics ideas, the nanoparticle long-time diffusion coefficients is formulated in terms of …
Page 1 of 2