Hollow Yarn in Friction Spinning. Part II: Yarn Structure and Deformation Under Axial Tension and Lateral Forces

In Part I of this study, we explained the method of producing a hollow yarn on a friction spinning machine and then considered its tensile properties. In this part of our study, we consider the structural properties of that yarn and the effect of axial and lateral forces on its structure, such as diameter changes, ellipticity, compressibility, and volume. We compare the properties of hollow yarns with those of equivalent 100% cotton yarns. The results indicate that stretching tension may affect the yarn diameter variation but not its linear density. The yarn diameter is bigger than that of conventional cotton yarn, and it decreases with increasing axial tension, which also happens to a conventional cotton yarn. Other results show that the yarn ellipticity ratio is greater than that of the cotton yarn and that it increases with increasing PVA percentage in the hollow yarn. In addition to higher compressibility, the hollow yarn shows better recovery. The volume of hollow yarn after compression is also greater than that of conventional cotton yarn.