We investigate the concentration dependence of characteristic relaxation time dilute polymer solutions in transient uniaxial elongational flow. A series monodisperse polystyrene five different molecular weights (1.8×106⩽M⩽8.3×106g∕mol) with concentrations spanning orders magnitude were dissolved two solvents differing solvent quality (diethylphthalate and oligomeric styrene). Optical measurements a capillary breakup extensional rheometer rate filament thinning to each fluid are used...

By adding minute concentrations of a high-molecular-weight polymer, liquid jets or bridges collapsing under the action surface tension develop characteristic shape uniform threads connecting spherical fluid drops. In this paper, high-precision measurements beads-on-string structure are combined with theoretical analysis limiting case large polymer relaxation times and high extensibilities, for which evolution can be divided into two distinct regimes. For smaller than time over develops, we...

Nonlinear rheological properties are often relevant in understanding the response of a material to its intended environment. For example, many gastropods crawl on thin layer pedal mucus using technique called adhesive locomotion, which gel structure is periodically ruptured and reformed. We present mechanical model that captures key features this process suggests most important for optimal inclined locomotion large, reversible yield stress, followed by small shear viscosity short thixotropic...

Abstract Rheological effects may complicate the dispensing of complex fluids, when compared to their Newtonian counterparts. In this work, fluids with tailored rheological properties have been studied using high‐speed video‐microscopy. The level viscosity, degree shear thinning, and elasticity varied independently. At low‐flow rates, droplets are formed that pinch off. drop volumes, breakup mechanisms, times identified. higher‐flow a continuous jet is observed, transition depending on...

An ultrasonic microreactor with rough microchannels is presented in this study for oil-in-water (O/W) emulsion generation. Previous accounts have shown that surface pits or imperfections localize and enhance cavitation activity. In bubbles are localized on the of a borosilicate glass microreactor. The microchannel primarily responsible emulsification We investigate mechanism employing high-speed imaging to reveal different modes influenced by size oscillation intensity bubbles. effect O/W...

In this paper, hydrophilic polymer membranes based on macromolecular chitosan networks have been synthesized and characterized. The structure of the membrane has altered in several ways during formation to adjust properties, particularly with regard elasticity, tensile strength, permeability, surface structure. An alteration network was achieved by addition flexibilizer, cross-linking dialdehydes, symplex polyanion sulfoethyl cellulose, introduction artificial pores micro- nanometer scale...

A simple and versatile method for making chemically patterned anisotropic colloidal particles is proposed demonstrated two different types of patterning. Using a combination thermo/mechanical stretching followed by wet chemical treatment sterically stabilized latex, both patchy ellipsoidal with sticky interactions near the tips as well tunable fluorescent patterns could be easily produced. The potential such model demonstrated, specifically case directed self-assembly.

The hydrophilic nature of graphene oxide sheets can be tailored by varying the carbon to oxygen ratio. Depending on this ratio, particles deposited at either a water-air or water-oil interface. Upon compression thus-created Langmuir monolayers, cover entire interface, assembling into strong, compact layer tiled sheets. With further compression, particle forms wrinkles that are reversible upon expansion, resembling behavior an elastic membrane. In present work, we investigate under which...

We study the mechanism of depletion stabilization and resultant microstructure aqueous suspensions nanosized silica poly(vinyl alcohol) (PVA). Rheology, small-angle light scattering (SALS), X-ray (SAXS) techniques enable us to analyze at broad length scale from single particle size a cluster aggregated particles. As PVA concentration increases, evolves bridging flocculation, steric stabilization, flocculation stabilization. To our surprise, when occurs, suspension shows scale, while...

SUMMARY We investigate the rheological properties of microliter quantities spinning material extracted ex vivo from major ampullate gland a Nephila clavipes spider using two new micro-rheometric devices. A sliding plate micro-rheometer is employed to measure steady-state shear viscosity ∼1 μl samples silk dope individual biological specimens. The steady solution found be highly shear-thinning, with power-law index consistent values expected for liquid crystalline solutions. Calculations show...

Abstract Summary: Membranes of bacterial cellulose produced by Gluconacetobacter xylinus show a high water and gas permeability that can be altered different drying techniques. It could shown freeze‐drying reduces the swellability polymer membranes factor 5 while evaporation causes reduction 50. The strong decrease for an dried membrane correlated with absolute number strands form network structure membrane, determined oscillatory shear rheological experiments. removal meshes complete...

This paper discusses the breakup of capillary jets dilute polymer solutions and dynamics associated with transition from dripping to jetting. High-speed digital video imaging reveals a new scenario via periodic growth detachment large terminal drops. The underlying mechanism is discussed basic theory for also presented. drop trajectory prove be governed primarily by mass momentum balances involving capillary, gravity inertial forces, whilst event controlled kinetics thinning process in...

Lightweight graphene structures have promising applications, for example as separation media, microreactor environments, use in energy storage or microelectronics. The assembly of its derivatives into such frameworks typically requires rather elaborate and expensive methods which are moreover difficult to scale up. In the present work we propose a simpler route is based on arresting temperature induced phase water–lutidine mixture containing oxide particles. 2D nature sheets, combined with...