The addition of macromolecules to solvent, even in dilute quantities, can significantly alter a fluid's response in an extensional, or stretching, flow. When high-molecular-weight polymers are extended in solution, extensional thickening can result, yielding viscosities that are orders of magnitude larger than values found in shear. Examples of applications where...
Polyethylene terephthalate (PET) polymer has been the material of choice for packaging industry as a result of its excellent mechanical and physical properties. These properties are highly dependent on the microstructure, chemistry, and processing conditions of this material. PET is often oriented in the machine direction (MD), the transverse direction...
Additive manufacturing and 3D printing have become household names as both hobbyistsand industrial manufacturers utilize fast, inexpensive prototyping and production of functionalparts. Additive manufacturing is being revolutionized with 3D printers such as theMulti Jet Fusion 3D from HP, Inc., where each volume pixel, or voxel, can be independentlyfunctionalized. Voxel-by-voxel printing...
Seed shattering is a constraint to improvement of seed yield in Lolium perenne L. and as a result, seed retention is an essential trait for this valuable crop. Field studies were conducted near Corvallis, OR in two years (2017-2018 and 2018-2019) to identify genetic variation for seed retention and to...
Extending rheological characterization methods to very small length scales is of interest. AC susceptometry using magnetic nanoparticle probes has been proposed for measurement of frequency-dependent rheological properties at the nanoscale. As this technique has been primarily used for ideally Newtonian fluids, this research aimed to extend this technique to viscoelastic...
This project discuses the design of a novel apparatus for measuring the interfacial rheological properties of a complex interface while measuring the concentration of redox species within the sub-phase. Preliminary measurements made using the apparatus are also presented. The objective of the preliminary experimentation was to simultaneously measure the interfacial...
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Travis W. Walker
This project discuses the design of a novel apparatus for measuring the
Insoluble surfactants are unique molecules that have the ability to manipulate interfacial properties, becoming useful in numerous applications such as detergents, wetting agents, emulsifiers, foaming agents, dispersants, and more. Interfacial rheology is a field that attempts to characterize the flow properties of insoluble surfactants by exerting a stress on the...
The Brownian motion of micron-scale particles reflects the viscoelastic response of the local environment of the medium. Tracking the thermal fluctuations of these particles is a measure of the rheology of the material at the microscopic scale. This technique is called passive microrheology. Microrheology has been developed to assess the...
Highly elastic solutions have been shown to increase contaminant removal from silicon wafers, indicating the possibility for reduced reliance upon hazardous chemicals and expensive technologies during the fabrication of semiconductor devices. The onset of this enhanced removal is explored using rinsing and siphoning experimentswith polymer fluids of high molecular weights...
Xanthan gum, a naturally produced polysaccharide, is biocompatible, and it is commonly used as a food additive. When combined with trivalent ions, such as chromium (III), a gel can form. Various concentrations of xanthan gum and chromium (III) nitrate were combined to evaluate the sol-gel transition of this system. Samples...