The purpose of this research has been to develop a textile finish based on chitosan that is a biopolymer. A fiber-reactive chitosan derivative was synthesized from chitosan with a low molecular weight and a high degree of deacetylation. The synthesis was composed of two steps. As a first step, a water-soluble chitosan derivative was prepared by introducing quaternary ammonium salt groups on the amino groups of chitosan. The derivative was further modified by introducing functional groups (acrylamidomethyl) on the primary alcohol groups of the chitosan backbone, which can form covalent bonds with cotton. The fiber-reactive chitosan derivative (NMA-HTCC) itself showed complete bacterial reduction against Staphylococcus aureus and Escherichia coli at the concentration of 10 ppm. The NMA-HTCC was applied to cotton fabrics by a pad-batch method in the presence of an alkaline catalyst. The 1% NMA-HTCC treated cotton showed 100% bacterial reduction against S. aureus. The fabric maintained over 99% of bacterial reduction even after 50 home launderings. The NMA-HTCC cotton was dyed with direct and reactive dyes without addition of salt. The color yield was higher than that of untreated cotton, which required a large amount salt for dyeing. The NMA-HTCC cotton showed better washfastness than untreated cotton, but the lightfastness was inferior to that of untreated cotton. The antimicrobial activity of the NMA-HTCC cotton was considerablely decreased after dyeing due to the blocking of the cationic groups of the NMA-HTCC by dye molecules.

Poly(ethylene terephthalate) (PET), poly(trimethylene terephthalate) (PTT), poly(ethylene isophthalate) (PEI), and poly(trimethylene isophthalate) (PTI) were synthesized in a Parr reactor and melt-spun. Thermal and physical properties of the as-synthesized polymers and melt-spun fibers were determined. As-synthesized PEI and PTI were amorphous polymers and did not show any melting peaks by DSC analysis. All the polymers were thermally stable (TGA analysis). Amorphous films were made by a melt-press method with PET and PEI for determination of CO2 gas barrier properties. PEI, which has the meta-linkage of ester groups on the phenyl ring, had much lower CO2 gas permeability around one tenth that of PET, which has the para-linkage of ester groups on the phenyl ring. This is because in PET the phenyl rings are substituted in the para (1,4) positions, which allows for their facile flipping, effectively permitting gases to pass through. However, the meta-substituted phenyl rings in PEI do not permit such ring flipping, and thus PEI may be more suitable for barrier applications. The coalesced PEI was prepared from the inclusion compound of PEI with ?×-cyclodextrin. The coalesced PEI may have retained partially highly extended and parallel chains from the narrow channels of the inclusion compound, resulting in better/tighter packing among the PEI chains and exhibited a higher glass-transition temperature. Cyclic oligoesters of PET, PTT, PEI, and PTI were prepared by cyclo-depolymerization of these polyesters. The cyclic oligoesters were mixtures of different sized cyclic oligomers. PET cyclic oligomers showed four melting peaks at 59, 122, 194, and 276 o C. The cyclic oligomers of PTT, PEI, and PTI showed single melting peaks at 241, 335o C and 147o C, respectively. The cyclic oligoesters could be converted to linear polyesters by ring-opening polymerization. PTT was also prepared by ring-opening polymerization of its cyclic dimer obtained as a by-product in the conventional manufacturing plant. Antimony, tin, and titanium catalysts were used with various concentrations. The highest molecular weight, 40,000 g/mol was obtained when 0.25 mol% of titanium(IV) butoxide was used.

<p>HUANG, WENSHENG. Online Characterization of Fabric Compressional Behavior. (Under the direction of Tushar K. Ghosh and Winser E. Alexander)Response of a fabric to applied forces normal to its plane is known as fabric compressional behavior. It is one of the important properties that determine fabric performance in many applications. The principle of a system used to measure fabric compressional characteristics, online, is proposed in this paper. A controllable nip formed by a pair of rollers is employed to apply compressional deformation to a moving fabric while the compression force and displacement are continuously recorded. The influence of various system parameters on the sensitivity of the system has been analyzed. By assuming a stepwise anisotropic behavior in the thickness direction, Incremental Differential Algorithm (IDA) is developed to calculate the pressure-displacement relationship from the measured force-displacement data obtained from the online system. A prototype online measurement system has been developed based on this principle. A number of woven and nonwoven fabrics have been evaluated using the online system as well as a number of other commercially available fabric compression testers. The compressional characteristics obtained from the online measurement system compare well with the same parameters measured using the other commercially available compressional testers.<P>

<p>IKIZ, YUKSEL. Fiber Length Measurement by Image Processing. (Under the direction of Dr. Jon P. Rust.) This research studied the accuracy and feasibility of cotton fiber length measurement by image processing as an alternative to existing systems. Current systems have some weaknesses especially in Short Fiber Content (SFC) determination, which is becoming an important length parameter in industry. Seventy-two treatments of five factors were analyzed for length and time measurements by our own computer program. The factors are: Sample preparation (without fiber crossover and with fiber crossover), lighting (backlighting and frontlighting), resolution (37-micron, 57-micron, 106-micron, and 185-micron), preprocessing (4-neighborhood and 8-neighborhood), and processing (outlining, thinning, and adding broken skeletons). The best results in terms of accuracy, precision and analysis time for images without fiber crossovers were: 106-micron resolution with frontlighting using an 8-neighborhood thresholding algorithm and using an outline algorithm for length determination. With fiber crossovers, 57-micron resolution with backlighting using an 8-neighborhood thresholding algorithm and using a thinning algorithm combined with an adding algorithm for combining broken skeletons. Using the above conditions, 1775 area can be analyzed using our current equipment in 15 seconds. In the case of images with crossovers, only 117 can be analyzed in 15 seconds. This research demonstrates that successful sample preparation without fiber crossovers would create the best fiber length measurement technique, however with fiber crossovers the system efficiency has been proven as well.<P>

<p>Bauer-Kurz, Ina. Fiber Crimp and Crimp Stability in Nonwoven Fabric Processes. (Under the direction of Dr. William Oxenham and Dr. Donald A. Shiffler.)In nonwovens, crimp characteristics of synthetic fibers are, along with finish, major contributors to processing efficiency, web cohesion, fabric bulk and bulk stability. However, the meaning of measurable crimp parameters and their influence on processing and fabric characteristics has not been quantified. The purpose of this study is to quantify the mechanical fiber behavior during crimp removal, and relate it to fundamental fiber properties, nonwoven fabric properties, and processibility in nonwoven equipment.Single fiber tensile tests in the crimp removal region have been performed on various fibers with the Textechno FAVIMAT and have also been monitored optically. Based on empirical evidence, a basic understanding of the physical crimp removal mechanism is obtained. A methodology is developed, to identify the true crimp removal region of the whole single fiber load-extension curve during a tensile test. A mechanical model accounting for the nonlinear load-deflection behavior during crimp removal is developed. According to this model, a logarithmic function can be used to describe the material behavior in the crimp node during crimp removal. This function is fit to experimental data and delivers two fitting parameters that characterize the shape of the experimental load-extension curve in the crimp region.The extracted characteristic crimp parameters are being evaluated in terms of fiber material characteristics, such as fiber type, crimp processing settings and carding performance during nonwoven production. A dependence of the shape of the crimp removal curve on crimping settings during crimp production is established. The characteristic crimp parameters are also correlated to the sequence of processing stages during nonwoven production and cylinder speed during carding.<P>

Thesis (M.Ch.E.)--University of Delaware, 2006. / Principal faculty advisor: Eric W. Kaler, College of Engineering. Includes bibliographical references.

In this research, influence of different levels of Closite Na+ additives on the microstructure, morphology and mechanical properties of polymer products was studied. Importance was given to understand the additive level, extent of dispersion in matrix, change in microstructure and respective property observed in the end product. Polypropylene spunbond and meltblown web samples with various levels of Closite Na+ additives were produced and characterized. Injection molded polypropylene nanocomposite with 1 to 15 wt% nanoclay additives were also prepared and characterized for microstructure and mechanical properties. Crystallization kinetics studies showed significant increase in crystallization rates on nylon 6 even at 0.25 wt % additives. Near surface and bulk stiffness of the film significantly increased in the presence of nanoclay additives. Intercalated and flocculated morphology was observed for all the polypropylene concentrate and the same morphology was retained in spunbond fibers also. About 25 to 30 % increase in cross direction tear strengths were observed for 1 to 2 wt % clay loading. Fibers with even as low as 1 % clay retains their morphology and integrity in bond point after thermal bonding. At higher weight percentage, stiffness of webs significantly increased and tear strength of webs decreased due to exclusion of excess clay platelets in the interspherulite regions. Property benefits were not observed in the case of melt blown samples with nanoclay additives, but the additives were well dispersed in the fiber web. Compared to control meltblown webs, stiff and open web structure with high irregularity was obtained for samples with clay additive. In case of injection-molded polypropylene composite, significant increase in breaking energy was observed for sample with just with 1 wt % clay additive. At higher weight percentage, segregation was observed in the inter-spherulitic region and failure mode shifted from ductile to brittle.

Effects of radiation (gamma and proton) on Ultra High Molecular Weight Polyethylene (UHMWPE) is studied for prosthetic joints and for radiation shielding for manned space missions. The first section of the dissertation will cover gamma radiation effects on UHMWPE by means of solubility, hardness, three-phase model, crystallite thickness, and molecular mobility studies. The second part will cover proton radiation effects on UHMWPE by means of solubility, three-phase crystallite model, and crystallite thickness study. The combined studies of the gamma irradiated samples shows that chain scission occurs on the surface and crosslinking in the center. The combined studies of the proton irradiated samples show that crosslinking occurs in the amorphous region and breaking of the tie chains and loops causes the growth of the already existing crystals. A new method has been developed to analyze DSC data based on crystallite thickness that generates crystallite thicknesses (number-average, weight-average, and z-average) and the lamella thickness polydispersity index, PDI (lw/ln and lz/ln). This new analysis method agrees with all other experiments conducted on the samples (solubility, molecular mobility, and three-phase model analysis).

In some breeds of dog, specifically the Yorkshire Terrier, a genetic defect exists that causes a hepatic portosystemic shunt to form. A hepatic portosystemic shunt is a vessel that when present cause blood to bypass the liver, which is responsible for filtering waste from the digestive system and moving it out of the body. An implantable polymeric device was constructed that would slowly occlude the hepatic portosystemic shunt and force the blood to stop flowing through the bypassing vessel and flow through the vessel to the liver over 3-4 months time. The portosystemic shunt occluder device consist of three polyoxymethylene components, a swelling hydrogel (poly (acrylic acid)), and a degrading copolymer – (Poly (lactide-co-caprolactone)). The poly (acrylic acid) was used to move the piston component of the device upward to constrict the portosystemic shunt placed inside the device. Eight milligrams of poly (acrylic acid) had a swelling ratio of 20.10 ± 1.63, a swelling rate of 0.071 mm/s2, and generated 25mN of force. Eight milli-Newtons is the amount of force that is produced by blood flowing in a four milli-meter diameter vessel. The degradation properties of two compositions of poly (lactide-co-caprolactone) (40 percent lactide and 60 percent caprolactone; 86 percent lactide and 14 percent caprolactone) were analyzed and relationships were developed that would aid in determining the degradation rate of the copolymers in respect to the copolymer composition and the environmental temperature. The poly (lactide-co-caprolactone) controlled the rate that the piston moved by providing a counter force to the poly (acrylic acid). The poly (lactide-co-caprolactone) (40:60), when loaded into the device, degraded in 86 days in a phosphate buffered saline solution at a temperature of 37oC.

Cotton based highloft nonwovens have been used in consumer goods such as pillows, upholstered furniture and mattresses for years. Cotton provides comfort, soft hand and cost effectiveness to these products. In contrast to its desirable properties, cotton products have a higher proneness to burning and are characterized as highly flammable materials. During the last decade, the fire safety has been an important issue, and there has been increasing focus on approaches to reduce hazardous fire risks and effects. Incorporating flame resistant (FR) chemicals and fibers is one of the most effective methods to improve thermal resistance of cotton to ignition, and provide high degree of flame retardancy performance in the final product. The major aim of using flame retardants is to provide more time for people to escape from fire and reduce death and injuries. Most of the approaches to produce FR cotton based nonwovens are for applications where durability is not important. For some of the applications wash durability is desired and needed. The focus of this research was to develop semi-durable and durable FR treatments for cotton rich nonwovens in an economical way using a binder fiber, going through-air bonding process and treating them with commercially available FR chemicals in the presence of a chemical binder. These FR treated webs have been evaluated for their FR performance before and after washing. Selected FR chemicals and binder types have effect on the wash durability of the produced webs. Selection of appropriate chemicals and binders in the right combination is important so that desired degree of flame resistancy can be achieved. A neural network model was used to understand these effects, so it can help in selecting the best combination for optimum FR performance and reveal the unknown behavior of FR characteristics. Also, importance of FR chemical type, chemical binder type, chemical add on level and binder percentage based on flammability results was revealed through a statistical analysis.