Date of Award

12-2009

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Legacy Department

Materials Science and Engineering

Advisor

Brown, Philip J

Committee Member

Cole , Christine

Committee Member

Hirt , Douglas

Committee Member

Luzinov , Igor

Abstract

This work investigated the production and characterization of novel shaped fibers for fluid adsorption and transport. Shaped fibers such as Y, H, and octolobal, as well as conventional round fibers, were extruded using a research melt extruder. The fibers were extruded from 18 melt flow index (MFI) polypropylene (PP) and blends of 18 MFI PP and 400 MFI PP. Hydrophilic spin finish Bozzetto Favorol SF2 was applied to the surface of extruded fibers and hydrophilic polyester additive LB-100 was included in the blend of some H fibers to increase the hydrophilicity of the fiber surface. The geometric shape retention of the extruded fibers was evaluated using scanning electron microscopy. The fluid adsorption and transport properties of the fibers were investigated using a low surface tension liquid and a high surface tension liquid. The shaped fibers were shown to have improved geometric shape retention with the addition of 400 MFI PP and were shown to have twice the fluid adsorption and transport capacities of the round fibers.
Micrographs of the fiber cross-sections obtained with a scanning electron microscope were used to visually determine the geometric shape retention of the fiber with respect to the spinneret hole design. While round, Y and octolobal fibers had excellent geometric shape retention regardless of polymer blend, H fibers showed improving geometric shape retention with increasing amounts of 400 MFI PP in the fiber blend. The perimeter and area of the fiber cross-section were measured from the micrograph and were used to calculate the shape factor for each shaped fiber.
The oil adsorption properties of the 18 MFI PP shaped and round fibers was evaluated using ASTM F-726. During the oil adsorption short test, the shaped fibers adsorbed more than twice the oil that the round fibers adsorbed. The Y fibers were shown to be the most effective at oil adsorption and retention. The dynamic degradation test evaluated the ability of the fibers to adsorb oil in the presence of water. The shaped fibers again adsorbed twice the amount of oil that the round fibers adsorbed, with the Y and H fibers adsorbing the highest amounts of oil from the water. A comparison of the oil adsorption properties of Y and round fibers of increasing dpf showed that the Y fibers formed a cooperative structure that increased the oil adsorption beyond the adsorption of oil to the surface of the fibers.
Vertical wicking tests were used to investigate the wicking properties of the shaped and round fibers extruded with hydrophilic spin finish. When packed to have equal channel size, the shaped fibers wicked twice the amount of water the round fibers wicked. Second insult wicking tests on the H fibers showed that the improvement of geometric shape retention caused by adding 400 MFI PP to the fiber blend actually decreased the wicking properties of the fiber. The combination of the hydrophilic polyester additive LB-100 and the 400 MFI PP in the polymer blend, however, increased the wicking properties of the fiber as increasing amounts of 400 MFI PP were included.

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