The study of strain proprieties of woolen yarns mixed with elastomer, bleached and coloured

Textile yarns have mechanical properties that enable their transformation using woven, knitted structures or other procedures into textile products. Tensile strength is one of the basic features of the yarn because it influences the behaviour of yarns in processing (preparation for weaving, weaving, knitting) determining the technological parameters of equipment adjustment, and their productivity. Also, the breaking strength of yarns is a qualitative characteristic because its value depends on its quality and the product. For these reasons the characteristic mentioned above is established by internal norms and STAS by the minimum permissible value, depending on the feedstock, production technology and destination. In this paper there were analysed the woolen yarns 75% mixed with elastomer 25%, fineness of 34/1 Nm and torque of 470 twists/m using the device USTER® TENSOJET 4. The comparative study in terms of breaking strength of these yarns was conducted for two groups of yarns, the first batch being bleached yarns and the second batch, colour yarns (dyed) for knitting. From a practical standpoint, the resistance is evaluated by the average value and the coefficient of variation.