Structural Studies in Continuous Filament Yarns1

In this, the first of a series of papers on fiber migration in continuous filament yarns, the broad objectives of the entire program of research are described. The experimental investigation included in this entire series is based on yarns produced under carefully controlled conditions which provided a bundle of either parallel filaments, for preparing yarns by the ideal ribbon method, or co-axial filaments, for yarns by the ideal circular method, prior to final twisting. It is shown that by a detailed study of migration in these extreme examples of carefully twisted yarns, it has been possible to obtain a much greater understanding of the nature and origin of migration which is generally observed in commercially prepared yarns than has been possible from the studies described thus far. Some of the important objectives emphasized in this study are: The proportion of total migration which cannot be assigned to any of the known and analysable causes of migration and thus must be of random nature; the extent of migration which can be assigned to the known and analysable causes; and the nature of the local variations in migration. The experimental investigation described in this first paper was restricted to the study of the yarns made by the ribbon method wherein the variables contre the positions of the tracers in the parent sheet of filaments, the initial twist in the strand, and the final twist and the twisting tension of the yarns being produced.