Ionomers are interesting due to their applications in coatings, adhesives, films and packaging materials. A study of the underlying mechanisms for fracture in ionomers is consequently of both practical as well as theoretical interest. In this study, we employ high speed imaging coupled with uniaxial extensional rheometry to delineate the mechanics leading to the brittle fracture of ionomer melt...

Birefringent strands are key to understanding polymeric non-Newtonian flows, especially in extension. Utilising microfluidic extensional flow oscillatory rheometry coupled with microvelocimetry (μ-PIV), we report experiments on the genesis, steady state and decay of such strands, together with rheological consequences. For closely monodisperse atactic polystyrene, we report massive effects of t...

We use a differential constitutive equation to model the flow of a viscoelastic flow in a cross-slot geometry, which is known to exhibit bistability above a critical flow rate. The novelty lies in two asymmetric modifications to the geometry, which causes a change in the bifurcation diagram such that one of the stable solutions becomes disconnected from the solution at low flow speeds. First we...

1. Introduction: Surface tension driven break-up of cylindrical fluid elements into droplets plays a crucial role in the use or processing of many multicomponent complex fluids like paints, inks, insecticides, cosmetics, food, etc [1, 2]. These industrial fluids are typically formulated using dilute polymer solutions, and are exposed to a wide range of shear and extension rates. Since the polym...

Mamaku gum is a polysaccharide extracted from the fronds of the black tree fern found in New Zealand. The cooked pith has traditionally been used for various medicinal purposes and as a food source by the Maori people of New Zealand. It has potential applications as a thickener in the food industry and as a palliative for patients with dysphagia. Studies on the shear rheology of Mamaku gum have...

We measure the viscoelastic properties of a highly entangled narrow molecular weight polyisoprene melt with approximately 280 entanglements per chain in steady and transient shear and in elongational ows. The storage and loss moduli of the melt are found to be well described by the Milner and McLeish model. The relaxation modulus G(t, γ) is measured using stress relaxation after a sudden sheari...

We show that poly(ethylene oxide) (PEO) solutions formulated using solvent mixtures of acetonitrile (AcN) and water can be centrifugally spun into fibers. find spinnability fiber morphology depend on choice if polymer concentration, solution shear rheology, the number entanglements, extensional relaxation time, parameters for centrifugal spinning are nearly matched. obtain an intrinsic map vola...

© Appl. Rheol. 19 (2009) 41969 Abstract: Filament breakup of high viscosity fluids with apparent yield stress has been investigated and strategies for an appropriate characterization of their behavior in CaBER experiments are discussed. Filament profiles of such fluids exhibit significant concave curvature. Accurate determination of filament shape is mandatory for understanding deformation beha...