Influence of Fiber Geometry on the Mechanical Properties of Assemblies During Processing

Samples of polyester fibers have been processed on the worsted system from raw stock through the 4th pin-drafting stage. The samples consisted of all combinations of two widely-differing levels of each of the following fiber variables: (a) surface roughness, (b) cross-sectional shape, (c) linear density, (d) crimp, and (e) staple length. Laboratory evaluations were conducted the cohesion, elasticity, and resilience of card webs, and for the static and dynamic cohesion, evenness, and fiber orientation of slivers. In general, the important conclusions were that staple length and crimp are the most highly significant factors controlling the cohesion and related properties of the fiber assemblies; the other variables are statisti cally significant at lower levels. Additionally, three pertinent fiber properties were measured on specimens removed from a number of subsample assemblies. The results of tests on specimens removed from 4th pin-drafting slivers showed that the rough and smooth fibers retain their distinctive surface characteristics through the successive stages of drafting. Crimp measurements indicated that this characteristic is retained through the opening and carding operations, but is substantially removed during pin drafting. Length analysis of fibers from 4th pin-drafting slivers showed that some breakage occurred in 6-in. samples during processing.