Thesis (Ph. D.)--Polymer, Textile & Fiber Engineering, Georgia Institute of Technology, 2007. / Karl I. Jacob, Committee Chair ; Youjiang Wang, Committee Member ; Mary Lynn Realff, Committee Member ; Arun Gokhale, Committee Member ; Rami Haj-Ali, Committee Member.

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Xyloglucan is a hemicellulose found in the primary cell walls of many plant species. Found adjacent to the cellulose, it is believed to function as a cementing material which contributes crosslinks and rigidity to the cellulose framework. The only noncovalent linkage reported in the primary cell wall cellulose-hemicellulose-pectic polysaccharide matrix of the cultured tissues is that between xyloglucan and cellulose. Therefore, the xyloglucan:cellulose association has been of great interest to researchers. Xyloglucan can be bound to cellulose in vitro to simulate this in vivo relationship. Previously, the sorption of xyloglucan fragments onto cellulose under non-physiological conditions had been studied, but little information was available on xyloglucan polymer sorption onto cellulose under more natural conditions. This thesis examined the sorption of the xyloglucan polymer isolated from Tamarindus indica onto cellulose fibers (cotton linters) in an aqueous environment. The structure of the xyloglucan isolated from Tamarindus indica in this thesis resembled that of other tamarind xyloglucans reported in the literature. Due to the milder isolation procedure employed, the molecular weight of this polymer was much larger than those previously found. No acetyl, pyruvate, methoxyl, or carboxyl groups were found. The molecular weight and certain structural features (e.g., no fucose units) also differed from the xyloglucan found in plant primary cell walls. When sorbed onto well characterized cotton linters, this xyloglucan exhibited equilibrium sorption within 24 hours. The equilibrium adsorption isotherm was defined. Monolayer sorption occurred. A maximum specific sorption value of 3.9 milligrams of xyloglucan sorbed per gram of cotton linters was calculated using Langmuir's adsorption isotherm theory. This value was compared with other values found in the literature for similar polymer adsorption studies. The effect of molecular weight on sorption equilibrium was also examined and found to be insignificant over the molecular weight range of the polymer isolated in this thesis.

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Thesis (Ph.D)--Polymer, Textile and Fiber Engineering, Georgia Institute of Technology, 2009. / Committee Chair: Cook, Fred; Committee Member: Beckham, Haskell; Committee Member: Bottomley, Lawrence; Committee Member: Carr, Wallace; Committee Member: Etters, Nolan. Part of the SMARTech Electronic Thesis and Dissertation Collection.

Thesis (M.S. in Aeronautical Engineering)--Naval Postgraduate School, June 1990. / Thesis Advisor(s): Wu, Edward M. "June 1990." Description based on signature page as viewed on October 21, 2009. DTIC Identifier(s): Graphite fiber strength testing, graphite fiber statistical evaluation. Author(s) subject terms: Graphite fiber strength testing, graphite fiber statistical evaluation, composite reliability predictions. Includes bibliographical references (p. 78-79). Also available in print.

Many commercial and laboratory applications of fiber optics require an ability to manipulate, change and control the state of polarization of light. This is usually accomplished with bulk-optic wave plates which are inherently narrowband, bulky, and often require careful manual tuning and adjustments. H.C. Huang has recently proposed that a variably spun birefringent fiber with spin rate slowly varying from zero to very fast (or vice versa) will transform the state of polarization (SOP) from linear to circular (and vice versa). The most remarkable feature of a Huang fiber is that the transformation from linear to circular polarization is independent of wavelength over entire single mode range of the fiber. In this thesis, using simulations and experiments we explore the properties of such a fiber element and investigate its similarities and differences as compared to a bulk-optic quarter-wave plate. In the simulations, we modeled the Huang fiber as a stack of birefringent waveplates and used this model verify the theoretically predicted polarization transformation behavior and the wideband nature of the Huang fiber. We analyzed the dependence of the polarization transformation by this device on various structural parameters and showed that while the fiber has loose tolerances with respect to the fiber length and the spin variation, it has a strong dependence on the maximum spin rate at the high-spun end. We investigated the PMD characteristics of the Huang fiber for short pulse applications. Using simulations we also verified that two such quarter wave-transforming fibers can be appropriately cascaded to obtain half-wave and full-wave transformation, analogous to bulk optics half wave and full wave plate respectively. In the experiments we studied the polarization transformation behavior of a Huang fiber sample when it is excited by different input states of polarization both from the un-spun end and the high-spun end. We found that the results from the experiments strongly support the simulation results. The experiment was performed at 1310 nm and 1550 nm to verify the wideband nature of the Huang fiber sample. We found that the Huang fiber indeed performs the prescribed state of polarization transformation over a wide band. / Master of Science

A generalized analysis of multiple-clad cylindrical dielectric structures with step-index profiles is presented. This analysis yields unified expressions for fields, dispersion equation and cutoff conditions for weakly guiding optical fibers with step-index but otherwise arbitrary profiles. The formulation focuses on triple-clad fibers, but can accommodate single and double-clad fibers as special limiting cases. Using the generalized solutions, transmission properties of several types of specialty fibers for broadband applications, including dispersion-shifted, dispersion-flattened, and dispersion compensating fibers, are studied. Improved designs for dispersion-shifted and dispersion compensating fibers are achieved. Fiber parameters and material compositions for the improved designs are provided. The proposed design for the dispersion-shifted fiber yields zero second-order as well as third-order dispersion at the 1.55 micrometer wavelength. The dispersion compensating fiber proposed here provides a large negative dispersion of about -400 ps/nm.km at the 1.55 micrometer wavelength for the fundamental mode. Numerical results for dispersion characteristics, cutoff wavelengths, and radial field distributions are provided. / Master of Science