Thesis Details

Thesis Title: The effects of polyester fiber variants and spinning parameters on lint shedding and knittability of polyester/cotton open end and ring spun yarns
Thesis Author: Sidney Attaway
Abstract: Yarn manufacturers and knitters are constantly looking for ways to reduce the amount of lint shedding at knitting. Lint that is shed creates difficulty for knitters by collecting on the surfaces of the machinery and being transferred into the knitting area of the machine. This results in lower quality fabric, broken knitting elements, and costly downtime. These problems originally were caused mainly as a result of natural fibers such as cotton, which contain more immature and short fibers. As fiber manufacturers began to produce synthetic fibers, chiefly polyester, with lower pilling tendencies by changing the fiber structure, the occurrence of lint shedding from yarns made using synthetic fibers began to increase. Machinery manufacturers have taken action to reduce the amount of lint shedding by developing enclosed creels with humidity control to keep the yarn conditions consistently maintained. Other machinery implementations such as enclosed yarn guides from the creel to the knitting machine, strategically placed fans to circulate the air, and decreasing the number of friction points the yarn contacts have helped control the lint. However, no solution has been found to eliminate the problems caused by lint shedding. The objective of this thesis was to determine the effects upon lint shedding and yarn knittability of polyester fiber variants and spinning parameters of open end and ring spun yarns. The fiber variants under study were fiber length and denier. The open end parameters were combing roll speed (7500 and 8500 rpm), navel type (ceramic and steel), rotor speed (90,000 and 96,000 rpm), and rotor groove configuration (G and T groove). The parameters were spindle speed and traveler weight in ring spinning. To accomplish this work, a 0.9 and 1.2 denier polyester fiber were obtained. Using three pass drawing, a 45 grain sliver for open end and a 55 grain sliver for ring spinning were produced. The slivers were spun into 28/1 Ne yarns under various spinning settings. All yarns were tested for lint generation, knittability, blend analysis, and hairiness. This data was analyzed using analysis of variance and linear regression. The following general results were noted: In open end spinning it was generally found that increasing combing roll speed and rotor speed had a detrimental effect on the amount of lint shedding exhibited by the yarn. Yarns spun using G-groove rotors also exhibited a higher percentage of shedding. Open end spinning using steel navels had a positive influence on reducing lint. The lint shedding from open end yarns contained nearly 83 % polyester while approximately 18 % polyester resulted from ring yarns. Knittability of open end yarns decreased as rotor speed and fiber denier increase. An increase in fiber length helped reduce the number of knittability stops. Lower spindle speeds shed more lint than higher speeds but a trend appeared which showed there may be an increase in shedding as spindle speed continues to increase. However, spindle speed and traveler weight both affected knittability of the yarns. In conclusion, slower rotor and combing roll speeds produced yarns of superior quality in regard to lint shedding and knittability. Conversely, ring yarns result in lower shedding at higher spindle speeds and better knittability with lighter traveler weights.