Analysis of changes in mechanical and deformation properties of yarn by sizing

Abstract

The purpose of this paper is to show the degree of changes in mechanical and deformation properties of single cotton yarn after sizing depending on their fineness, size concentration and the structure created by the type of yarn spinning. The properties of ring and rotor-spun yarns were analyzed before and after sizing with a PVA sizing agent, using the same recipe, but with two different size concentrations — 7.5% and 5.0%. Standardized methods for determining the mechanical properties were used, as well as a modified method for cyclic testing to determine areas of elastic, viscoelastic and plastic yarn deformations. There are no significant differences in yarn properties after sizing with lower and higher size concentrations, which leads to the conclusion that it is a greater advantage to use a lower concentration, in order to achieve better economic and environmental effects. By sizing, a ring-spun yarn achieves major improvements, particularly in more refined yarns (20, 30 tex), which is positive because improvements in mechanical properties of these yarns are more necessary. Contrary to this, with a rotor-spun yarn the improvements are relatively low, due to its structure. Cyclic loading of yarn showed a difference in changes of deformation areas of unsized and sized yarns, primarily in the way of reducing the elastic area of deformation, depending on yarn structure. Information obtained by this analysis can improve the quality of sizing with possible cost savings and contribute to a better regulation of weaving conditions and thus to an increase in the quality and performance of weaving.