Complex description and measurement of two-ply yarn transversal proportions

Abstract

A diameter of single yarn is well known as one of the main geometrical descriptive characteristics of yarn formation. Many experimental methods also measure and define this parameter while assuming cylindrical shape of a single yarn. Very rare information exists in the case of two-ply yarn geometrical parameters. This paper, in its first part, introduces the geometrical parameters of two-ply yarn from a mathematical ideas point of view. The second part presents the longitudinal view method of their measurement. The longitudinal view method is functional also for single yarn diameter evaluation. Contribution proves the method on a set of five single polypropylene yarns variable in fineness and on a set of five polypropylene two-ply yarns different in ply twists, while two-ply yarn fineness stays constant. The third part of this paper presents a cross-sectional method of linear textiles, here of two-ply yarn and single yarn. Images of two-ply yarn and additionally single yarn cross-sections are used to measure transversal proportions of two-ply yarn and single yarn equivalent diameter. Results are discussed in terms of the set of five two-ply polypropylene yarns and some outputs are compared to those from the longitudinal view method.