Browsing Hatsopoulos Microfluids Laboratory (HML) by Title
Now showing items 7-26 of 27
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Elongational Viscosity of Monodisperse and Bidisperse Polystyrene Melts
(2007-01-23)The startup and steady uniaxial elongational viscosity have been measured for two monodisperse polystyrene melts with molecular weights of 52 kg/mole and 103 kg/mole, and for three bidisperse polystyrene melts. The ... -
Ex vivo Rheology of Spider Silk
(2005-08-05)We investigate the rheological properties of microliter quantities of the spinning material extracted ex vivo from the major ampullate gland of a Nephila clavipes spider using two new micro-rheometric devices. A sliding ... -
Experimental Investigations of Elastic Tail Propulsion At Low Reynolds Number
(2007-05-04)A simple way to generate propulsion at low Reynolds number is to periodically oscillate a passive flexible filament. Here we present a macroscopic experimental investigation of such a propulsive mechanism. A robotic swimmer ... -
The Flexure-based Microgap Rheometer (FMR)
(2007-01-23)We describe the design and construction of a new microrheometer designed to facilitate the viscometric study of complex fluids with very small sample volumes (1-10 μl)and gaps of micrometer dimensions. The Flexure-based ... -
How Dilute are Dilute Solutions in Extensional Flows?
(2007-01-23)We investigate the concentration-dependence of the characteristic relaxation time of dilute polymer solutions in transient uniaxial elongational flow. A series of monodisperse polystyrene solutions of five different ... -
Inductively Heated Shape Memory Polymer for the Magnetic Actuation of Medical Devices
(2007-01-23)Presently there is interest in making medical devices such as expandable stents and intravascular microactuators from shape memory polymer (SMP). One of the key challenges in realizing SMP medical devices is the implementation ... -
The Inertio-Elastic Planar Entry Flow of Low-Viscosity Elastic Fluids in Micro-fabricated Geometries
(2004-12-17)The non-Newtonian flow of dilute aqueous polyethylene oxide (PEO) solutions through microfabricated planar abrupt contraction-expansions is investigated. The contraction geometries are fabricated from a high-resolution ... -
Iterated Stretching and Multiple Beads-on-a-String Phenomena in Dilute Solutions of Highly-Extensible Flexible Polymers
(2005-04-13)The dynamics of elastocapillary thinning in high molecular weight polymer solutions are re-examined using high-speed digital video microscopy. At long times, the evolution of the viscoelastic thread deviates from self-similar ... -
Iterated Stretching, Extensional Rheology and Formation of Beads-on-a-String Structures in Polymer Solutions
(2005-12-01)The transient extensional rheology and the dynamics of elastocapillary thinning in aqueous solutions of polyethylene oxide (PEO) are studied with high-speed digital video microscopy. At long times, the evolution of the ... -
Linear to Non-linear Rheology of Wheat Flour Dough
(2007-01-23)We provide an overview of transient extensional rheometry techniques for wheat flour doughs in which the deformation and material response is well defined. The behavior of a range of model doughs was explored with a ... -
Miscibility and Viscoelastic Properties of Acrylic Polyhedral Oligomeric Silsesquioxane-Poly(methyl methacrylate) Blends
(2005-04-19)We investigate the miscibility of acrylic polyhedral oligomeric silsesquioxanes (POSS) [characteristic size d ≈ 2 nm] and poly(methyl methacrylate)(PMMA) in order to determine the effect of well-dispersed POSS nanoparticles ... -
Nonlinear Shear and Extensional Flow Dynamics of Wormlike Surfactant Solutions
(2005-10-04)Nonlinear shear and extensional flow dynamics of rheological properties of a wormlike micellar solution based on erucyl bis (2-hydroxyethyl) methyl ammonium chloride, EHAC, are reported here. The influences of surfactant ... -
Peeling, healing and bursting in a lubricated elastic sheet
(PRL, 2004)We consider the dynamics of an elastic sheet lubricated by the flow of a thin layer of fluid that separates it from a rigid wall. By considering long wavelength deformations of the sheet, we derive an evolution equation ... -
Preferential Association of Segment Blocks in Polyurethane Nanocomposites
(2007-01-23)Controlling the level of dispersion of silicate layers in polymer matrices through intermolecular interactions and exploiting these interactions to enhance thermomechanical behavior are key challenges in the field of polymer ... -
Rheology and Dynamics of Associative Polymers in Shear and Extension: Theory and Experiment
(2005-08-22)We investigate the steady and transient shear and extensional rheological properties of a series of model hydrophobically modified ethoxylate-urethane (HEUR) polymers with varying degrees of hydrophobicity. A new nonlinear ... -
Shock Dynamics in Particle-Laden Thin Films
(2005-04-22)We present theory and experiments for thin film particle-laden flow on an incline. At higher particle concentration and inclination angle, a new phenomenon is observed in which a large particle-rich ridge forms at the ... -
Slippage and Migration in Taylor-Couette Flow of a Model for Dilute Wormlike Micellar Solutions
(2005-06-09)In this paper we explore a model, most appropriate for dilute or semi-dilute worm-like micellar solutions, in an axisymmetric circular Taylor-Couette geometry. This study is a natural continuation of earlier work on ... -
Thermorheological Properties Near the Glass Transition of Oligomeric Poly(methyl methacrylate) Blended with Acrylic Polyhedral Oligomeric Silsesquioxane Nanocages
(2005-08-26)Two distinct oligomeric species of similar mass and chemical functionality (Mw ≈ 2,000 g/mol), one a linear methyl methacrylate oligomer (radius of gyration Rg ≈ 1.1 nm) and the other a hybrid organic-inorganic polyhedral ... -
Tuning Gastropod Locomotion: Modeling The Influence Of Mucus Rheology on the Cost of Crawling
(2007-05-04)Common gastropods such as snails crawl on a solid substrate by propagating muscular waves of shear stress on a viscoelastic mucus. Producing the mucus accounts for the largest component in the gastropod’s energy budget, ... -
Two-Dimensional Self-Assembly in Diblock Copolymers
(2005-06-20)Diblock copolymers confined to a two-dimensional surface may produce uniform features of macromolecular dimensions (10 â 100 nm). We present a mathematical model for nanoscale pattern formation in such polymers which ...