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.
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Showing 1 to 18 of 18 for “"fiber spinning"”.
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Fiber spinning and rheology of liquid-crystalline polymers
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, 1994.
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Image processing for in-situ feedback control of fiber spinning of carbon nanotubes
… first one determines the absolute size of the fiber, and the second one relates to the elongational force that the fiber feels. [2] The LabVIEW VI successfully identified and measured the CNT strand 80% of the time, and the unsuccessful cases were examined to determine solutions for improving …
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Statistical Electron Microscopy, Rheometric Studies of Carbon Nanotube Solutions in Chlorosulfonic Acid and Characterization of Wire, Planar Antennas Manufactured from Macroscopic Carbon Nanotube Materials
… wire and planar antennas manufactured from fiber spinning and shear-coating of these CNT solutions are designed and their performance is shown to match that of equivalent copper antennas at frequencies suited for wireless communication.
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Electrospinning of polymeric nanofiber materials : process characterization and unique applications
Electrospinning or electrostatic fiber spinning employs electrostatic force to draw a fiber from a spinneret. This fiber solidifies and lies down on a collector in the form of a non-woven fiber mat. Electrospinning has attracted much attention recently due to the ease with which fine fibers about …
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Processing of composite fibers based on polypropylene and a thermotropic liquid crystalline polymer
… liquid crystalline polymer (TLCP), in two novel fiber spinning processes. In one process, a single VB melt stream was surrounded by a sheath of PP in a manner comparable to a wire coating process just prior to melt spinning to generate fibers possessing a sheath-core structure. The other process …
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Biomimicry of the spider silk spinning apparatus
… both very strong and extensible. Even though the fibers outperform many synthetic and natural materials, it is impractical to collect industrial amounts of silk from spiders due to their cannibalistic and venomous nature; they cannot be farmed like the commercial silk worm Bombyx mori. Thus, …
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The stability of viscoelastic fluids in complex flows : the role of shear and extensional rheology
… processes such as injection molding and fiber spinning. The combination of streamwise curvature and elastic normal stresses can lead to the onset of elastic flow instabilities, severely rate-limiting such processes. This thesis focuses on the stability of two complex non-Newtonian flows …
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Highly productive ester crosslinkable composite hollow fiber membranes for aggressive natural gas separations
… with high feed pressures. Dual-layer hollow fiber spinning can be used to reduce the cost of membrane production by integrating a low-cost supporting core polymer with the expensive crosslinkable sheath polymer. However, the complexity of interfacial interaction between the sheath/core layers …
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Development of Liquid Crystalline Elastomers as Soft Mechanical Actuators
… patterns. The thesis introduced a scalable fiber spinning process that can cross-link the material on the fly to achieve a massive rate of production. The thesis also demonstrated how the spun LCE fibers are suitable to be made into smart fabrics using a common weaving machine. Finally, the …
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The incorporation of electrohydrodynamics and other modifications into a dry spinning model to develop a theoretical framework for electrospinning
… of a mathematical model of the electrospinning process using dry spinning modeling principles as a basis. This model is directed at the identification of parameters which influence final fiber characteristics, e.g., solvent concentration, temperature, spin line tension, and electric …
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Extrusion Printing of Carbon Nanotube Inks, from Rheology to Electronics
… imbibition. Next, taking inspiration from wet fiber-spinning processes, a method of extruding CNT inks into a coagulating liquid bath of non-solvent is introduced, generating rapidly solidifying, lightweight fibers with specific conductivity up to 7,000 S.m^2/kg, comparable with copper (6,600 …
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The Manufacture and Mechanical Properties of Poly(ethylene terephthalate) Fibers Filled with Organically-Modified Montmorillonite
… to poly(ethylene terephthalate), PET, fibers by the addition of layered silicate nanoparticles and by drawing the un-oriented nanocomposite filaments in a second step. No previous studies on PET fibers filled with montmorillonite (MMT) nanoclay examined fiber drawability at temperatures …
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Elongational Flows in Polymer Processing
The production of long, thin polymeric fibers is a main objective of the textile industry. Melt-spinning is a particularly simple and effective technique. In this work, we shall discuss the equations of melt-spinning in viscous and viscoelastic flow. These quasilinear hyperbolic equations model the …
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The linear and nonlinear rheology of multiscale complex fluids
… important in applications such as spraying and fiber spinning, is relatively poorly understood. The primary contribution of this thesis is the development of a compact constitutive modeling framework to quantitatively describe the rheology of multiscale complex fluids. In the linear limit of …
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Processing-Structure-Property Studies of: I) Submicron Polymeric Fibers Produced By Electrospinning and II) Films Of Linear Low Density Polyethylenes As Influenced By The Short Chain Branch Length In Copolymers Of Ethylene/1-Butene, Ethylene/1-Hexene & Ethylene/1-Octene Synthesized By A Single Site Metallocene Catalyst
… relationships for submicron polymeric fibers produced by electrospinning (Part I) and to ascertain whether or not the length of the short chain branch has any effect on the physical properties of films of linear low-density polyethylenes (LLDPEs) (Part II). Electrospinning is a unique …
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Injection Molding of Pregenerated Microcomposites
One portion of this work was concerned with injection molding pregenerated microcomposites composed primarily of poly(ethylene terephthalate) (PET) as the matrix and HX1000 as the thermotropic liquid crystalline polymer (TLCP). Several factors were examined to maximize the mechanical properties of …
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Synthetic vascular materials via a vaporization of sacrificial component (VaSC) approach
… necessitated the development of PLA sacrificial fibers, and three distinct production techniques for producing the desired PLA fibers were explored (chemical modification of commercial PLA fibers, homespun PLA fibers, and micro-structuring of a PLA film). The dissertation also discusses the …