Browsing by Author "Dr. Timothy Clapp, Committee Member"

Now showing 1 - 7 of 7

Absorbency Characteristics of Kenaf Core Particles
(2004-05-21) Zaveri, Mitul Dilip; Dr.Behnam Pourdeyhimi, Committee Chair; Dr. Medwick V. Byrd, Committee Member; Dr. Donald Shiffler, Committee Member; Dr. Timothy Clapp, Committee Member
Chopped Kenaf Core (2"; to 4" in length), obtained from Greene Natural Fibers — a company located in Snow Hill, North Carolina, was ground into very fine particles (below 1 mm) and categorized into various size ranges. The ground particles were tested for water absorbency and the optimum particle size, giving maximum absorbency, was determined. Experiments revealed that Kenaf Core of size range 106 — 425 microns gave the highest water absorbency at saturation, up to 12 times its weight. The 425 — 840 micron range was the next highest and it absorbed water up to 10 times its weight. Factors leading to this optimum particle size range were determined, the absorption mechanisms taking place were studied and experimental analysis was done to prove the results obtained. Scanning Electron Microscopy (SEM) images were also taken to understand the shape and profile of the granular particles in fine detail. Various chemical treatment and refining experiments were carried out on the highly absorbent particle sizes (106 — 840 microns) to enhance their bonding properties and to make handsheets from them. The highly absorbent Core particles were treated with NaOH in water bath at 90 ° C, Cooked with NaOH and Na2S at 170 ° C in a bomb reactor and treated with water in a water bath at 90 ° C, all for 3 hours. Handsheets were made from the chemically treated particles to determine if there was sufficient bonding between them. To enhance the bonding further, the particles were refined in a blender for one hour. The effect of chemical treatment and refining on the absorbency properties of the Core was determined. SEM analysis of the particles was done to visualize the fibrillation caused due to refining. Handsheets were made with a blend of hardwood and highly absorbent (untreated and water treated 106 — 840 micron) refined Core particles with 50 — 70% of Kenaf Core in them. The absorption properties of these handsheets were determined and compared with the absorption of a handsheet made from fluff pulp (same basis weight). As the final step, the handsheets made from a blend of kenaf core and hardwood pulp were sandwiched between a pair of 17gsm lightly calendared polypropylene spun bond fabrics.
Analysis of an Image-Based Fiber Length Measurement Device
(2004-11-07) Byrd, Thesley Alex; Dr. Timothy Clapp, Committee Member; Dr. Tom Johnson, Committee Member; Dr. Jon Rust, Committee Chair
Previous research by Yuksel Ikiz showed that the use digital imaging could provide more accurate and precise fiber length measurements when compared to current methods. This conclusion sparked the research by Stephen Stroupe, which resulted in the development of a system to deliver individualized cotton fibers to a digital camera for imaging. The system individualized fibers from sliver by utilizing a modified comber roll assembly. These fibers were deposited via a chute to an area between two electrodes, where one of the electrodes was charged with 12 kV. The voltage created an electrostatic field that captured the fibers and straightened them. Fibers would then bound between the plates until coming into contact with a non-conductive conveyor. Once in contact with the conveyor, the fibers remained and were passed over a backlighting source, which provided a silhouette of the fibers to a digital camera. The images were analyzed by using the algorithms that Ikiz had previously developed. Stroupe made some initial evaluations of the system's performance and concluded that further analysis would be necessary. It was the goal of this research to begin the analysis and to develop the system on the basis of increasing measurement precision and accuracy. The specific objectives of this research were to improve image quality, evaluate sample selection, improve fiber presentation, determine measurement accuracy and precision, and compare our results to those of other fiber length measurement devices. These objectives were accomplished by using a variety of statistical, programmatic, and mechanical methods. To improve image quality, a pulsing power supply was used in place of a continuous lighting system and was incorporated with a camera calibration routine. To keep the individualizer airflow from blowing long fibers through the electrodes, the comber roll was slowed, which necessitated the removal of the delivery chute. A belt slot was also milled into one electrode for concealing part of the belt to reduce fiber overlap. An additional experiment was conducted to determine the effect of sample size on the measurement repeatability, and to assess the system's ability to distinguish between two different fiber populations. Cut-length rayon fibers were used to assess measurement accuracy. Through the above methods, the image quality was improved, with the contrast between fibers and the background more than doubling their original values. The number of fiber crossovers and entanglements was reduced by an estimated 9 percent with the removal the delivery chute. After cutting the belt slot, fiber overlapping was reduced to 1 mm on average. Although the fibers did not attach to the belt readily after the slot was milled, moving the system to a conditioned environment helped to increase the rate of fiber removal. After all changes, it was determined that our system showed improved accuracy when compared to other systems. However, the accuracy of the results was dependent upon the sample size and day on which the samples were run. The experiment also showed our system was in reasonable agreement with AFIS regarding the difference between the two fiber populations. The cut-length analysis showed our device's ability to measure individual cut-lengths fairly accurately, with a skew toward the lower tail because of the remaining overlap. Despite the existing issues with fiber overlap and broken skeletons, the system was improved through this research and shows promise of becoming a viable method for the measurement of cotton fiber length.
The Effects of Batting Materials on the Performance of Turnout Thermal Liners
(2007-05-04) Heniford, Ryan C; Dr. Jeffrey W. Eischen, Committee Member; Dr. Roger L. Barker, Committee Chair; Dr. Behnam Pourdeyhimi, Committee Co-Chair; Dr. Timothy Clapp, Committee Member
The effects of fiber and constructional variables on the properties of hydroentangled nonwovens important to their performance when used as batting components in firefighter turnout systems are investigated. Para-aramid, meta-aramid and oxidized PAN constructions are characterized on the basis of thermal insulation, flexibility and durability performance. The contribution of batting properties to the thermal protective performance provided by multilayer turnout systems is examined for selected turnout lay ups. Optimized thermal liner systems are suggested based on layered constructions including the properties of the face cloth components.
Evaluation of Army Battle Dress Uniform Fabric Containing an Electrically Conductive Network
(2010-08-07) Charette, Christine DiSanto; Dr. Timothy Clapp, Committee Member; Dr. Trevor Little, Committee Member; Dr. Abdel-Fattah Seyam, Committee Chair
Technology is being developed to add a conductive network to the Army Battle Dress Uniform (BDU). To embed the network within the BDU fabric, electronically conductive yarns are located at every ripstop location. To optimize conductivity, fabric construction had to be modified from MIL DTL 44436 requirements. The primary objective of this research was to determine how the addition of the electrically conductive network would change the comfort and durability properties of the BDU. To accomplish this, eleven fabrics of varying fabric constructions with and with and without the network were woven at the College of Textiles, NC State University. These fabrics were then evaluated for any changes in performance in the properties of breaking force and elongation, tearing strength, stiffness, thermal resistance, air permeability and abrasion resistance. The results from each of these tests were statistically analyzing using SAS JMPÂ® software to reveal any property changes as a result of the fabric changes of yarn type, float length and location that were necessary to allow the addition of the network.
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
The Mechanical Behavior of Air Textured Aramid Yarns in Thermoset Composites.
(2004-06-05) Langston, Thomas Brice; Dr. Yiping Qiu, Committee Chair; Dr. Abdel Fahmy, Committee Member; Dr. Timothy Clapp, Committee Member
The purpose of this study was to investigate the properties of air-textured aramid yarn (ATAY), in a single yarn composite (SYC), in a 3D woven fabric preform, and in a 3D preform composite. Yarn tensile tests demonstrated textured yarn was 70-77% lower in tensile strength, 82-85% lower in tensile modulus, and 60-190% higher in breaking strain than those of the control yarn. The results of SYC testing illustrated that the control yarn composite had only a 5% higher tensile strength, a 27% higher modulus, and 11% lower energy to break than the textured single yarn composite. Fabric tensile tests demonstrated a low initial modulus and a much larger secondary modulus for all 3D woven preforms. The ATAY fabric had a similar initial modulus and a much lower secondary modulus in the weft direction compared to the control fabric. The ATAY fabric had a significantly higher yield shear stress and strain, primary and secondary shear moduli, energy to yield point, and total energy absorbed to 4° than those of the control. With the same fiber volume fraction, the ATAY composite had a slightly lower tensile strength and modulus, but a 120% higher shear modulus, than the regular aramid yarn (RAY) composite. Unlike the RAY composite brittle failure behavior, the ATAY composite failed in a ductile manner with multiple diverting cracks propagating during failure. The ATAY composite had a much higher yield point in the 45° direction tensile test, a much higher softening point in the warp direction tensile test, and increased the interlaminar shear strength of a laminated composite by 37% as compared with the control.