Browsing by Author "Dr. Behnam Pourdeyhimi, Committee Chair"

Now showing 1 - 9 of 9

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.
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.
The Manufacturing of Wet-laid Hydroentangled Glass Fiber Composites For Industrial Applications
(2002-08-01) Vaidya, Neha; Dr. Melur Ramasubramanian, Committee Member; Dr. Behnam Pourdeyhimi, Committee Chair; Dr. Donald Shiffler, Committee Member
The main focus of this research is to make a composite of sufficient strength from glass fibers using low melt polyester or bicomponent (polyester/polyethylene sheath/core) fibers as binder fibers for nonwoven preforms. A wet-laid hydroentangled sheet consisting of a blend of glass and low melt binder fibers is used to make compression molded composite. An appropriate white water recipe for dispersing glass and binder fibers was obtained after personal conversation with Owens Corning Company and after image analysis of the trial sheets. The amount of defects in the fabric was analyzed and optimum time of dispersion was established. 6 layers of wet lay sheets were stacked and hydroentangled to get a high weight per unit length single hydroentangled sheet that is then heat pressed. When heat pressed, the binder fibers in the blend melt, adhere to the glass fibers and form a composite. These composites were tested for stiffness, toughness and flexural strength. An instron machine was used for tensile and 4-point bending tests. Stress strain curves were obtained and the secant modulus at breaking strain was determined. The area under the curve was measured determine the toughness of the material. The tensile strength and toughness increased significantly with increasing glass fiber content of up to 30-40%, after which the strength of the composite decreases. This may be caused by the reduction in binding points and lower adhesion between the glass fibers resulting in lower tensile and flexural strength. The innovative aspect of this research is in the manufacturing of composites using glass fibers along with binder fibers. Some of the current composite manufacturing techniques use resin to bind the fibers/sheets. Resins are costly and also, not environment friendly. By using binder fibers, the need of using resin is eliminated. Elimination of resin and manufacture of high strength low cost composites with more process flexibility is an imperative objective of this research.
Mechanisms in Bicomponent Fiber Spinning During Melt Blown Process
(2009-02-23) Zapletalova, Terezie; Dr. Saad Khan, Committee Member; Dr. Stephen Michielsen, Committee Member; Dr. Eunkyoung Shim, Committee Member; Dr. Jan Genzer, Committee Co-Chair; Dr. Behnam Pourdeyhimi, Committee Chair
ZAPLETALOVA, TEREZIE. Mechanisms in Bicomponent Fiber Spinning During Melt Blown Process (Under the direction of Dr. Behnam Pourdeyhimi and Dr. Jan Genzer) A series of melt blown bicomponent webs made with various grades of polypropylene and polyethylene were evaluated in terms of influence of process and polymer properties on fiber morphology and web mechanical properties. This study utilized full quadratic model with continuous factors of temperature and component ratio. We were able to obtain the effects these parameters on fiber and substrate properties with high statistical significance. Overall fiber crystallinity content as well as crystallinity content of each separate component can be well explained linked with a high degree of confidence to the processing temperature, component ratio, and several polymer component properties, including, enthalpy of melting, zero shear viscosity, activation energy of flow, and highest crystallization rate temperature. Fabric mechanical properties can also be correlated with the same structural parameters. Bicomponent fiber diameter could not be satisfactorily explained in terms of the same parameters, which indicates that there is another mechanism not described by the studied process and polymer data that largely influences substrate fiber diameter.
Method for Measuring Static Potential on Moving Fabrics
(2005-08-08) Ercan, Erkmen; Dr. Perry L. Grady, Committee Member; Dr. Donald Shiffler, Committee Member; Dr. Behnam Pourdeyhimi, Committee Chair
There is no clear explanation for static potential generation. There are many factors that affect charge generation such as environment (temperature, humidity), structural (polymer type, structure of fabric) and working factors (fabric speed, tension, and contact area between fabric and machine parts, material type that is in contact with fabric). With a good knowledge of these parameters, generation of static charge can be minimized. During production, static potential on a moving web can cause web breakage, ignition of flammable atmosphere, or shock risk. The main objective of this research is to develop a method to measure static electricity on moving nonwoven machine belts. In this project the instruments to measure and eliminate static potential on moving fabrics, design of test apparatus, relationship between charge decay values and charge generation of different fabrics, static potential measurements under different conditions are discussed. Spunbond technology is one of the nonwoven production methods have a high static charge generation problem; tests were done by using a spunbond belt on an actual spunbond machine. These belts are mostly made of woven fabrics with different structures (different number of layers, fabric design, structure of polymers used). A goal of manufacturing these belts is to reduce static electricity during production. Among all parameters that cause static charge generation, tension is the most important one. A small amount of increase in tension can double the charge on belt. Separation is also a reason for charge generation and as roller-fabric friction increases —because of the increased contact area- more charge will be generated during separation. A new parameter, contact area, also needs to be considered. Static charge generation may not be same at cross direction on a belt. As all areas are in the same situation (working and environment conditions) the only thing that was different was the tension. Because of the spunbond machine setup, tension —for this reason, static charge- was different in cross direction. The effect of this and other parameters can be seen more clearly when a non-conductive belt is used.
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.
Surface Modification of Polypropylene Nonwovens to Improve Adhesion to Elastomers
(2009-02-25) Paul, Shreya; Dr. Saad Khan, Committee Member; Dr. Jan Genzer, Committee Member; Dr. Behnam Pourdeyhimi, Committee Chair; Dr. Eunkyoung Shim, Committee Co-Chair
This study addresses how one can use blending, grafting and UV radiation techniques to make polar or hydrophilic polypropylene (PP) to overcome the shortcomings of the inert (hydrophobic) nature of the PP surface. For this purpose a functional monomer, glycidyl methacrylate (GMA), was chosen as the modifier. Moreover, the similarity and differences in results between the different techniques are reported. For both blending and grafting techniques a range of weight percentage of GMA was added to the base polymer PP and it was observed that even low amounts of GMA (0.5 wt %) was sufficient to modify the surface property of the PP and produce enhanced adhesion to elastomeric polymers such as thermoplastic polyurethane (TPU) and Pebax. Increased adhesion up to 300% has been reported in this work. The physical modification of PP using UV irradiation also proved effective and has improved the hydrophilicity of PP. The laminated samples of modified PP and elastomeric polymers were subjected to barrier and moisture transport tests. Under specific conditions of lamination, these composites have proved to be an effective barrier to water but at the same time can provide comfort property by maintaining the moisture vapor transfer through them.
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.