Wide-Range Tunable Dynamic Property of Carbon Nanotube-Based Fibers

Carbon nanotube (CNT) fiber is formed by assembling millions of individual tubes. The assembly feature provides the fiber with rich interface structures and thus various ways of energy dissipation, as reflected by the non-zero loss tangent (>0.028--0.045) at low vibration frequencies. A fiber containing entangled CNTs possesses higher loss tangents than a fiber spun from aligned CNTs. Liquid densification and polymer infiltration, the two common ways to increase the interfacial friction and thus the fiber's tensile strength and modulus, are found to efficiently reduce the damping coefficient. This is because the sliding tendency between CNT bundles can also be well suppressed by the high packing density and the formation of covalent polymer cross-links within the fiber. The CNT/bismaleimide composite fiber exhibited the smallest loss tangent, nearly as the same as that of carbon fibers. At a higher level of the assembly structure, namely a multi-ply CNT yarn, the inter-fiber friction and sliding tendency obviously influence the yarn's damping performance, and the loss tangent can be tuned within a wide range, as similar to carbon fibers, nylon yarns, or cotton yarns. The wide-range tunable dynamic properties allow new applications ranging from high quality factor materials to dissipative systems

Assessing cotton maturity from fiber cross-section measurements

textThe previous Fiber Image Analysis System (FIAS-I) is not reliable enough to detect fibers, especially for the immature fibers. It yields a systematic bias in the maturity distribution. Furthermore, the maturity distributions are often assumed to be normal without any normality tests in many previous studies, and those distributions are commonly measured by a sole parameter, e.g., the mean maturity value. In fact, those statistical inferences on cotton maturity may not be valid when cotton maturity does not follow a normal distribution. In light of the complexity of maturity distributions, the sole-parameter approach does not appear to be reliable and rational to rank the maturity among different samples. In this thesis, modified algorithms are made in the previous Fiber Image Analysis System (FIAS-I) to improve the number and accuracy of detected cross-sections and reduce the bias on immature fiber. The normality of cotton maturity distributions are analyzed through multiple parameters and patterns of cotton maturity distributions, and the experimental results on the cross section images selected from seven cotton varieties are displayed. Finally, several normality tests are introduced, and the Box-Cox transformation is applied to the maturity distribution, which makes the comparisons among the mean maturity feasible.Textile and Apparel Technolog

Factors Affecting Within-plant Variation of Cotton Fiber Quality and Yield

Cotton is sold by weight, but a bale’s lint price per pound is determined by its fiber quality profile. Cotton quality is defined by a set of standardized properties (length, strength, elongation, uniformity, color, trash, and micronaire) collected on every United States bale. Each cotton fiber is the remnant of a single cell which upon harvest exists as a dry, hollow tube of crystalline cellulose. The length, perimeter, and thickness are a fiber’s physical dimensions. These dimensions influence both the mechanics involved in yarn spinning and the quality of the yarn produced. Genetic and environmental factors affect the development and consequently, the final properties of cotton crops. However, information is lacking about the degree of influence they impart, especially on fiber perimeter (fineness) and cell wall thickness (maturity), both components of micronaire. The goals of this dissertation were to: 1) Summarize and review the techniques available to industry to measure fiber perimeter and maturity in order to discuss their advantages and limitations, 2) Validate the use Cottonscope to measure fiber quality variation, 3) Determine the significance of within-plant yield variation, and 4) Determine the significance of within-plant quality variation. Small differences in micronaire are often indistinguishable, making breeding efforts difficult. With new instruments, selecting for the components of micronaire may increase selection efficiency and genetic gain compared to breeding for micronaire directly. In addition, these results show that yield and quality within genotypes are highly variable, and a significant amount of the variation is attributable to a boll’s fruiting site. Substantial bias can be introduced if boll sampling does not consider fruiting position. The results show that plot sampling techniques can greatly influence fiber quality testing results and as a result the effectiveness of genetic selection. The Cottonscope is a very accurate and precise tool for measuring fiber fineness and maturity ratio and improving the interpretation of micronaire. Micronaire had strong correlation with fiber fineness data. Breeding for lower micronaire would be a useful strategy to improve fiber fineness in environments where low fiber maturity is not a problem

Design and construction of new central and forward muon counters for CDF II

New scintillation counters have been designed and constructed for the CDF upgrade in order to complete the muon coverage of the central CDF detector, and to extend this coverage to larger pseudorapidity. A novel light collection technique using wavelength shifting fibers, together with high quality polystyrene-based scintillator resulted in compact counters with good and stable light collection efficiency over lengths extending up to 320 cm. Their design and construction is described and results of their initial performance are reported.Comment: 20 pages, 15 figure

Forensic Significance of Teal Colored Cashmere and Black Acrylic Fibers

Textile fibers are a valuable type of trace evidence within forensic cases. They have the ability to connect a perpetrator to a victim and or a crime scene. Some types of fibers are more prevalent than others. The purpose of this research was to conduct a target fiber study in order to determine the significance of the selected fibers in a forensic case. Two fibers were selected from two different garments, black acrylic fiber and a teal colored cashmere fiber. Unknown fibers were collected from three local clothing stores and counted. Using light microscopy, all 20,164 fibers were eliminated as a potential match to the black acrylic target fiber. Microscopic comparison of the unknown fibers to the teal colored cashmere target fiber, produced two potential matches, which were further eliminated by microspectrophotometric analysis. Therefore, of the 20,164 unknown fibers, comparison to both target fibers resulted in no potential matches. It can be concluded that these target fibers may have potential forensic evidential value within a criminal case in the Erie County area