Static Generation and Dissipation in Textiles

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Title: Static Generation and Dissipation in Textiles
Author: Suh, Minyoung
Advisors: A. M. Seyam, Committee Co-Chair
William Oxenham, Committee Co-Chair
Abstract: Static charge has been a major source of problem in textile industry as well as consumers. During textile manufacturing process, there is a potential of static charge generation when fibers are extruded, and yarns are woven or knitted, and finished. This gives spinners and weavers much trouble in terms of productivity, and can lead malfunction of electronic equipments. Static problems in textile industry have become more serious as synthetic fibers and higher processing speeds are met. More or less, natural fibers are not as susceptible to static problems as synthetics. Synthetics such as nylon or polyester are so hydrophobic that they are easy to accumulate electrostatic charges. This research was undertaken to gain better understanding of static generation and dissipation on continuous yarn surface in terms of environmental conditions (temperature and relative humidity), yarn tension, yarn speed, and fiber type. Four experiments were conducted: (1) effect of environmental conditions, yarn tension, and yarn speed on static generation/dissipation of continuous filament polyester yarn, (2) effect of charging pin material (stainless steel, nylon, polyester, polypropylene, and Teflon) on static generation/dissipation of continuous filament polyester yarn, (3) effect of fiber type (polyester, nylon, and polypropylene) on static generation/dissipation of finish free continuous filament yarns, and (4) effect of humidity, yarn tension, and yarn speed on yarns of different fiber types with different filament count. The assessment of static generation/dissipation was done by using a device equipped with winder, two potential probes, charge pin, tension and speed controllers, and data acquisition system. The device was housed in an environmental room where relative humidity and temperature can be precisely controlled. Potentials collected by the two probes at two different positions on a running yarn in real time were used to calculate initial potential (at the point of separation of yarn and charge pin) and characteristic decay time. The independent parameters of the experimental designs were broad to include the conditions practiced by the textile industry. The results of the first experiment indicated that temperature, humidity, yarn tension and speed had significant effects on static generation, while only temperature and yarn speed showed statistically significant effects on static dissipation. More charge was created with lower temperature and humidity, and higher yarn tension and speed. At a temperature of 35°the charge on the polyester yarn increased as the yarn moved from first probe to the second probe while at lower temperatures the charge was dissipated. It was also found that high yarn speed promoted the charge dissipation (shorter decay time). The results of the second experiment showed that different charging materials affected static generation, but not static dissipation. The charge materials showed the following polarity categorized into three groups; stainless steel (gave negative charge on the polyester yarn), nylon (gave positive charge on the polyester yarn), and polyester (gave positive charge on the polyester yarn). The polypropylene and Teflon charge materials exhibited almost no polarity (charge on the yarn is almost zero). Charge polarity generated on the polyester sample yarn did not coincide with tribo-electric series due to the presence of spin finish. The results of the third experiments, however, showed that finish-free yarn materials followed tribo-electric series. The stainless steel charge pin caused the polyester and polypropylene to be charged negatively, whereas nylon was positively charged. Finish-free yarns had potential as high as 8,000 volts. Polypropylene yarns showed relatively smaller static charges than polyester and nylon yarns, and nylon yarns were characterized by the slowest charge decay. The results of the last experiment exhibited that humidity, yarn tension and speed showed significant effect on static generation of multifilament yarns, while none of them were significant in case of monofilament yarns. For the multifilament yarns, more charge was generated with lower humidity, and higher yarn tension and speed. Static dissipation was influenced only by yarn speed for both multifilament and monofilament yarns. The effect of yarn speed on decay time for multifilament and monofilament yarns was the same in terms of trend, where high yarn speed promoted the charge dissipation (shorter decay time).
Date: 2009-04-28
Degree: MS
Discipline: Textile and Apparel, Technology and Management
URI: http://www.lib.ncsu.edu/resolver/1840.16/2780


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