Browsing by Author "Dr. William Oxenham, Committee Member"

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The Application of Hydroentangling to Enhance the Mechanical Properties of Woven Jacquards
(2006-05-09) Kennerly, Paige Stewart; Dr. Behnam Pourdeyhimi, Committee Chair; Dr. William Oxenham, Committee Member; Dr. Tim Clapp, Committee Member
Hydroentangling is traditionally a nonwoven process of manufacturing fabrics through entangling loose webs of fiber using jets of water. This research proposes hydroentangling woven jacquard base fabrics using several speed and pressure combinations to mechanically enhance the structure. It also proposes to hydroentangle a loose web of fibers onto a woven jacquard fabric as a form of mechanically bonding the two structures. By bonding these fibers onto the woven fabric, the structure will be stabilized and mechanical properties will be enhanced. Control fabrics were compared to hydroentangled samples in order to select optimal hydroentangling processing parameters. The effects of these process parameters on fabric properties were studied. The mechanical properties of the woven fabrics before and after hydroentangling were also assessed. One objective of this research is to determine if hydroentangling is a feasible means to overcome certain physical and mechanical shortcomings of jacquard woven fabrics. Test data indicates that certain aspects will be improved, while others may be negatively impacted by hydroentanlging. There are also critical energy points where any further enhancement in properties is diminished. The end use application of the fabric, as well as performance criteria will play a key role in determining if hydroentangling can be used as an alternate means of finishing a jacquard woven fabric, and will be unique to the specific company and production capabilities. A second objective of this research is to determine if hydroentangling is a feasible means of bonding a single fiber carded web onto a base jacquard woven fabric. With the correct combination of base fabric construction and specific energy, bonding is possible. When energy is too high, the design will be jeopardized, while if energy is too low, adequate entanglement will not happen. Test data indicates that certain properties will be improved, while others may be negatively impacted by hydroentanlging. The end use application of the fabric, as well as performance criteria will play a key role in determining if hydroentangling can be used as a feasible means of bonding a jacquard woven fabric with a carded web, and will be unique to the specific company and production capabilities.
Biopolishing Cellulosic Nonwovens
(2005-04-29) Stewart, Melissa Ann; Dr. Leonard Stefanski, Committee Member; Dr. William Oxenham, Committee Member; Dr. Sam Hudson, Committee Member; Dr. Richard Kotek, Committee Member; Dr. Behnam Pourdeyhimi, Committee Chair
Biopolishing refers to the finishing technique of cellulase treatment of a cellulosic fabric, whether a natural or regenerated cellulose, to improve softness and to reduce pilling. The process has been utilized by several sectors of the textile industry, but has yet to be evaluated for hydroentangled nonwoven fabrics. These fabrics can be harsh and often have visible jet streaks on the surface. Traditionally, hydroentangled fabrics are used in disposable applications. The biopolishing treatment offers the potential to improve the appearance and aesthetics of these fabrics, so that they may be used for new, nondisposable applications, such as apparel. With no previous work completed on the effects of biopolishing hydroentangled cellulosic nonwovens, the main goal of this research is to determine if hydroentangled cellulosic fabrics are suitable for biopolishing treatment and will yield promising results. This investigation examines several parameters that impact the resultant properties, such as fabric composition and state, treatment time, and enzyme concentration. Fabric composition varies from 100% cotton, 60/40 cotton/polyester, and 100% Tencel. The state of the fabrics, whether dyed or in a greige state is also examined. Establishing a treatment protocol is of significant interest. Thus, this investigation examines treatment durations varying from 30 to 180 minutes and enzyme concentrations varying from 0.5 to 3.0% o.w.f.. It was found that while the treatment yields a softer, more drapable fabric with reduced pilling, a reduction in physical strength and basis weight was also observed after treatment. The cotton/polyester and the tencel fabrics appear to retain more of their initial physical characteristics than the 100% cotton fabrics. Differences in the substrate compositions and structure account for these results. By examining the resultant properties of all the fabrics, such as flexural rigidity and tensile strength, this research was used to generate a multi-linear model to be used in the prediction of fabric properties following treatment. These models displayed good coefficients of determination for the fabrics used in this investigation. Additionally using these models, a treatment protocol, with variable duration and concentration, can be determined utilizing the resultant properties of interest.
Comparative Analysis of Compact Spun Yarns and Ring Spun Yarns
(2008-06-09) Rajaney, Pooja Jaswant; Dr. William Oxenham, Committee Member; Dr. Tim Clapp, Committee Chair; Dr. Jon P. Rust, Committee Member; Dr. Jeff Thompson, Committee Member
De-bottlenecking the Electrospinning Process Using Superparamagnetic Particles
(2006-07-23) Satcher, Melinda Renee; Dr. Lei Qian, Committee Member; Dr. William Oxenham, Committee Member; Dr. Saad Khan, Committee Co-Chair; Dr. Juan Hinestroza, Committee Co-Chair
Nanocomposite polyethylene oxide (PEO) fibers containing magnetic domains were produced using parallel plate electrospinning. The fibers were spun from solutions dosed with nanoparticles of magnetite (Fe3O4) in 2wt% PEO in water. Solution parameters like viscosity, conductivity, and surface tension were measured and correlated to final fiber diameter. Increased amounts of magnetic nanoparticles produced higher conductivity, higher viscosity, and lower surface tension solutions. Transmission electron microscopy and energy dispersive spectroscopy were used to analyze the diameters of the nanofibers as well as the distribution of the magnetic nanoparticles inside the PEO matrix. A SQUID magnetometer was applied to determine the AC and DC magnetic susceptibility of the fibers. The resultant nanofibers had diameters as low as 100 nm and exhibited unique AC susceptibility patterns and magnetic responses making them excellent for anti-counterfeiting applications.
Electrostatic Self-assembled Nanolayers on Textile Fibers
(2006-04-19) Hyde, Gary Kevin; Dr. Lei Qian, Committee Member; Dr. Juan Hinestroza, Committee Chair; Dr. William Oxenham, Committee Member; Dr. Peter Hauser, Committee Member
This project reports the deposition of nanolayers of poly(sodium 4-styrene sulfonate) (PSS) and poly(allylamine hydrochloride) (PAH) over cotton fibers using the electrostatic self-assembly method (ESA). While glass, silicon wafers, gold coated particles, quartz and mica have dominated the choice of substrates for ESA, the use of textile fibers has been rarely considered. Cotton, in particular, offers a unique challenge to the deposition of nanolayers because of its unique cross section as well as the chemical heterogeneity of its surface. The deposition of the nanolayers involved the preparation of cotton substrates via immersion in 2,3-epoxypropyltrimethylammonium chloride solutions to produce cotton with a high density of cationic groups. The cationic cotton was processed further by repeated sequential dipping into aqueous solutions of PSS and PAH with rinsing between each deposition step. Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy (FTIR), X-ray Photoelectron Spectroscopy (XPS), and Transmission Electron Microscopy (TEM) were used to verify the presence of deposited nanolayers. This research work demonstrates the possibility of using the ESA method to tailor the surface of textile fibers at the molecular level by depositing nanolayers of biocidal, charged nanoparticles, non-reactive dyes, and polyelectrolytes in a controlled manner. Preliminary results indicate that the thickness and sequence of the nanolayers can be controlled to tailor and enhance the selectivity, diffusivity, and permeability of the textile fibers while maintaining their comfort and physical properties.
Hydroentanglement Process as a Finishing Treatment for the Enhancement of Knitted Fabrics
(2006-04-23) Williams, Stephannia P; Dr. Tim Clapp, Committee Member; Dr. William Oxenham, Committee Member; Dr. Behnam Pourdeyhimi, Committee Chair
This research involves the application of hydroentangling technology as a means of significantly improving knitted fabric properties. In the past, various efforts have been made, directed at improving the dimensional stability and physical properties of woven and knitted fabrics through the finishing technique of hydroentanglement. In such applications, warp and filling fibers in fabrics are hydroentangled at crossover points to effect enhancement in fabric cover. The process parameters of hydroentangling are investigated and optimized to achieve desired results. Potential benefits include enhanced fabric durability, stability, and appearance.
Incorporating Carbon Nanotubes into Polypropylene Fibers
(2003-12-02) Erickson, Jody Ann; Dr. Timothy Clapp, Committee Member; Dr. Behnam Pourdeyhimi, Committee Co-Chair; Dr. Trevor Little, Committee Co-Chair; Dr. William Oxenham, Committee Member
Carbon nanotubes (CNT) are an exciting new carbon based material discovered in 1991 by Iijima. The size, crystalline structure and conductivity make them an exciting choice for use in a composite fiber. The purpose of this study is to explore the possibilities of melt spinning carbon nanotubes compounded in polypropylene (PP) using conventional spinning equipment. Carbon Nanotubes, pre-compounded in 30 melt flow rate polypropylene, were purchased from Hyperion Catalysis International at 15% concentration. Let downs from this concentration were spun into fibers using a single screw extruder. However, the resultant fibers exhibited a rough texture and distinct lumps of aggregated carbon nanotubes due to inadequate mixing and dispersion of the concentrated CNT/PP and virgin PP. To address this issue a twin screw extruder was used to compound the polymer into several lower concentrations and a second attempt at spinning yielded greater success. Fibers containing up to 3% CNT were spun as well as some bicomponent fibers. The fibers spun were slightly smoother than those of the initial trial although lumps along the fiber surface are still evident, especially at higher loadings. Imaging the fibers under optical and scanning electron microscope reveals the extent of the nanotube agglomerate formation and the severe deformation of the fibers. The aggregates of carbon nanotubes appear in all composite fibers and cause the tensile properties to suffer by acting as stress concentration sites, leading to fiber failure. Conductivity is not achieved even with the highest loading of 3% carbon nanotubes. A uniform distribution of the nanotubes in the polypropylene is believed to be critical to spinning uniform fibers with good mechanical characteristics and to reaching percolation at low loading. CNT aggregation remains a challenge to the processing of these composite fibers.
An Investigation of the Influence of Nozzle Geometry in the Hydroentangling Process
(2007-08-18) Anantharamaiah, Nagendra; Dr. Hooman Vahedi Tafreshi, Committee Co-Chair; Dr. Behnam Pourdeyhimi, Committee Co-Chair; Dr. Hassan A. Hassan, Committee Member; Dr. Timothy Clapp, Committee Member; Dr. William Oxenham, Committee Member
An Investigation on Fluid Flow in Fibrous Materials via Image-Based Fluid Dynamics Simulations
(2009-11-03) Jaganathan, Sudhakar; Dr. Joel Pawlak, Committee Member; Dr. Behnam Pourdeyhimi, Committee Co-Chair; Dr. Eunkyoung Shim, Committee Member; Dr. William Oxenham, Committee Member; Dr. David Dickey, Committee Member; Dr. Hooman Vahedi Tafreshi, Committee Co-Chair
While there are a large number of analytical studies dedicated to developing permeability equations for a 2-D and 3-D models of fibrous disordered structures, there are only few numerical work that compares these models with real counterparts. For the first time, we present a series of numerical simulations performed on real fibrous media obtained via Digital Volumetric Imaging technique. An efficient procedure is presented for reconstructing 3-D images from the 2-D images of real fibrous media and processing them (meshing them) for performing fluid flow simulations. Permeability values obtained from these simulations are compared with those obtained from analytical equations given in the literature. We also present two scale modeling technique to predict macro scale permeability of fibrous structures. Second part of this thesis deals with unsaturated flow through the fibrous media. We start our study by computing the pore size distribution of typical hydroentangled nonwoven materials and present a theoretical model for their geometric pore size distributions based on Poisson line network model of the fibrous media. We also study connectivity of the pore space in fibrous media by computing and comparing the accessible and allowed pore volumes in the form of access function graphs. We also present a novel image-based technique to study the changes in the pore size distribution of a fibrous material exposed to compressive load. A combined micro- and macroscale modeling is presented to simulate the fluid infiltration in fibrous media. The RichardsÃ¢â‚¬â„¢ equation of two-phase flow in porous media is used here to model the fluid absorption in un-saturated fibrous thin sheets. The required consecutive equations, relative permeability and capillary pressure as functions of mediumÃ¢â‚¬â„¢s saturation, are obtained via microscale modeling and long column experiment, respectively. The RichardsÃ¢â‚¬â„¢ equation together with the above consecutive correlations is simultaneously solved for fibrous media inclined with different angles. To validate our simulations, we compared our numerical results with those of our long column experiment and observed good agreement.
Non-Chemical Insecticidal Textiles
(2008-03-26) Collins, Lynda E.; Dr. William Oxenham, Committee Member; Prof. Nancy B Powell, Committee Member; Dr. Marian G McCord, Committee Co-Chair; Dr. Behnam Pourdeyhimi, Committee Chair
Mosquito-borne malaria threatens 40% of the world's population, killing at least one million people each year. Efforts to control mosquito populations with chemicals and habitat elimination are often beyond the means of many nations. In addition, both mosquitoes and the diseases they carry are becoming resistant to common chemical and medical interventions. In most cases vaccines are not available. Novel insecticidal textiles were created by binding safe, food-grade diatomaceous earth to fabrics with three different structures including: a 100% polypropylene 200 holes per inch mosquito netting, a 100% cotton terry cloth, and a knit fabric of unknown fiber content with an unusual texture on one side similar to a shag carpet. Mortality in mosquitoes of 86.1% was seen 24 hours after the initial exposure of 15 minutes to the mosquito netting loaded with 98.5 gm DE⁄g fabric. No significant difference in mortality was seen between the different fabric structures. The mechanical nature of the killing mechanism should exclude cross resistance that has developed from the use of chemical insecticides.
Outcomes of Private Label Programs: Brand Loyalty, Supply Chain, & Cost Management
(2006-11-07) Bruer, Shanna Michelle; Mark Messura, Committee Member; Dr. Barry Goodwin, Committee Member; Dr. William Oxenham, Committee Member; Dr. Michelle Jones, Committee Co-Chair; Dr. Nancy Cassill, Committee Co-Chair
Private labels have become an increasingly important part of the retail apparel industry; however, the reason(s) for which they have been added to firms' portfolios has not been thoroughly researched or discussed in the academic or industry literature. The motivation for and outcomes of private label implementation at retail was therefore the focus of this study. The purpose of this research was to determine the reasons for which private label, programs are employed by retailers. The research focused on two potential rationales: 1) internal outcomes, which are defined by the researcher as those that are primarily controlled by the firm through internal actions that seek such results as greater control over the supply chain and costs, and 2) external outcomes, though influenced by the firm, are ultimately determined by the consumer as brand loyalty. The review of literature offered an explanation of the progression of logic used in the conceptual framework for this study. Additionally, it examined the current literature available in academia and industry. The conceptual model began with the generic competitive strategies offered by Porter (1990), was narrowed to a single strategy through Aaker's (1998) success factors of differentiation and Barney's (2002) differentiation tools, finally the focus of the study was on the potential outcomes of a brand offered by Keller (1998). The methodology used in this study consisted of three phases. Phase I used a deductive research design (quantitative). The goal of the deductive analysis was to determine the level of, and differences between, the loyalty associated with national and private label brands. In order to accomplish this goal, STS longitudinal panel data was employed. The sample consisted of 12,254 denim jean purchasers. Phase II used an inductive research design (qualitative). The inductive phase was used to expand upon the findings from phase one, as well as gain data on the internal outcomes associated with private label brands. In order to accomplish Phase II a case study methodology was employed. The two-page discussion guide was developed by the researcher and was used to acquire depth of information on the three outcomes, as well as uncover potential rationales for program implementation. The sample consisted of thirty companies from the following five sectors: fiber, fabric, apparel manufacturing/marketing, apparel agents, and retail. The information collected from industry interviews brought a deeper level of understanding as to why private label programs are implemented at retail. Phase III was a co-interpretation of analyses from Phases I and II. The goal of this section was to visually depict the motivations for private label program implantation, relationships and communication within the supply chain, and outcomes of program participation for each sector. Quantitative results indicated that there is no greater loyalty associated with private label product than that of national brand. Further exploration of private label program drivers found that retailers and manufacturers were driven to private label programs by two additional motivations — supply chain management and cost management. From these results a private label apparel model was developed containing drivers for programs, communication amongst supply chain members, and outcomes of program implementation. The findings of this study are significant to both industry and academia when determining the best strategy for entering and improving private label programs.
Three Dimensional Structures from Nonwovens
(2004-04-08) Grissett, Gregory Aaron; Dr. William Oxenham, Committee Member; Dr. Jason Osborne, Committee Member; Dr. Behnam Pourdeyhimi, Committee Chair
The purpose of this research was to assess molding or thermoforming nonwoven webs into a three-dimensional fiber network without the use of resin or binders via the SpaceNet Formed Fiber System ¬Æ. We define this network as a deep-draw structure with projections and/or depressions rising from an initial plane, providing a grid-domed structure. The research is comprised of three experimental components: the first concerned with moldability of nonwovens on the SpaceNet System. The second component comprised an evaluation of the effect process parameters on substrate deformation, and the third concerned with an investigation the effect of mold geometry on compressive properties. Concerning the moldability of nonwovens, eight-nonwoven webs (six spunbond, two hydroentangled) were processed using the SpaceNet formed fiber system. Nonwovens comprised of a uniform fiber orientation and isotropic mechanical properties were found to process more efficiently in the SpaceNet system. Given this conclusion, spunbond nonwovens were selected for the remainder of the research described herein. Different mold geometries were used to make three-dimensional structures from spunbond nonwovens and their respective compressive properties were evaluated. It was observed that decreases in pin diameter increased the compressive stress in all samples produced. It was also found that compressive resilience is not necessarily associated with changes in mold geometry but rather inherent fabric properties i.e. stiffness and level of bonding. The effect of preheating and temperature on formed product dimensions was also evaluated. A split-plot factorial design was used and it was determined that temperature alone influences maximum deformation. Preheating (residence time) was observed to be insignificant including all interactions.