Fiber Surface Properties in Relation to Linear Assemblies During Processing1

Abstract

This paper reports the results of processitig on the worsted system. Two model fiber samples, which differed only in surface roughness, were specially prepared and cut into lengths suitable for processing on the worsted yarn system (also for the cotton and woolen yarn systems). Static and dynamic cohesion tests on sliver and roving samples indicated that geometrically smoother fibers (those having fewer asperities on the surface) lead to greater cohesion in fiber assemblies. Similarly, in blends of smooth and rough fibers in slivers, the cohesion was found to increase consistently with increas ing percentage of smooth fibers. As indicated by performance during opening processes, geometrically smooth fibers were found to be more difficult to separate from one another. The rougher fiber samples appeared to open much more easily and more thoroughly than the smooth sam ples in the same number of operations. In subsequent processes, the greater cohesion of the smooth samples was found to lead to reduced actual drafts under certain processing conditions. It was found that the degree of twist normally used in staple yarns itself sufficiently restricts the relative movement of fibers to mask the direct effects of fiber surface properties under tensile load. However, results indicated that twist masks the direct effects of fiber surface properties in the yarns (at near optimum twist), but the yarns reflect in evenness, average tensile properties, and actual draft—features introduced in earlier processing.