Thesis Details

Thesis Title: The effect of polyester staple length on evenness of yarns spun on ring, rotor, and air-jet spinning systems
Thesis Author: Mary-Melissa LeBlanc Sladick
Abstract: A method currently being used to define yarn evenness is a Uniformity Index (also known as an Irregularity Index). This can be defined as the ratio between the actual, measured %CV of the yarn to the ideal %CV. Past research has determined the Ideal CV to be 100/JN, N being the number of fibers possible of fitting into a given cross-section. However the ideal CV formula only considers denier as having an effect on yarn evenness, not including any effect of staple length. For this work eight specifications of fiber were spun; two deniers and four staple lengths on an open-end, air-jet and ring spinning frame. Once the yarn was spun, statistical regression equations were generated to determine how much of an effect staple length had on actual yarn Uster %CV. The regression equations relating changes in Uster %CV to changes in denier and staple length showed a strong indication that staple length does have an effect on yarn evenness in two of the three spinning systems. As fiber length was increased from 1.0" to 2.0", ring spun yarn became more even. A parabolic shaped curve best represents the effect of length on open-end yarn evenness. Yarns spun with 1.0" and 2.0" fibers are significantly less even than yarns spun with 1.25" and 1.5" fiber lengths. Uster %CV of air-jet spun yarns was not influenced by changes in fiber length in this work. Therefore, the Ideal %CV calculation of 100/jN may need modification to include a factor of staple length that more fairly represents the practical ideal yarn evenness capability.