Importance of cotton fiber elongation in fiber processing

Developing cotton fibers with improved tensile properties is important because fiber breakage during processing from field to yarn can impart imperfections in the finished product by degrading fiber quality. Cotton fiber strength is often the focus of germplasm development while the degree of fiber elongation before rupture under load has been neglected. Nevertheless, the degree of fiber bundle elongation is reported to be heritable. Isolating the importance of a particular mechanical property in resisting breakage during processing is difficult in a naturally produced fiber whose quality attributes depend on genetics and environment. Therefore, it is unknown how much improvement might be achieved by integrating fiber elongation into germplasm improvement efforts. A set of thirty-two samples were recently identified that belonged to two families where, within a family, all fiber properties except elongation were similar. Fiber bundle elongation ranged from 7.7 % to 8.8 % for the low elongation lines, and 9.9%–11% among the high elongation lines. This unique sample set was used in this research to isolate the importance of fiber elongation in processing. Fiber quality was evaluated before and after mechanical processing with the Microdust and Trash Analyzer (MDTA3). Lower elongation fibers break more frequently during processing and yarns made from these lower elongation samples exhibit a work to break as much as 32.3 % lower than the paired high elongation sample. Similarly, yarns from the low elongation samples have as many as 46 more thick and thin places per kilometer, a type of yarn imperfection, in comparison with the paired high elongation sample. These results suggest improving the degree of fiber elongation reduces fiber breakage during processing and should be considered an important target for improvement alongside fiber bundle strength.