Wicking in Ring-spun vis-a-vis Rotor-spun Yarns

Wicking is the ability of water, dye, etc. to move through textile structures. Many researchers 1-4 are of the opinion that wicking is carried on mainly in the capillaries formed by the fibres in yarns. According to Norman:', the speed of water in the capillaries is reduced by the presence of randomly-arranged fibres in the yarn, and it is this factor rather than the nature of the fibre material that accounts for the wide range of water-transportation properties. Whenever a liquid is taken up by a yarn, the amount of liquid absorbed per unit of surface of mass and the velocity of absorption are measurable. De Boer! suggests three types of measuring methods, viz. (i) vertical wicking test, (ii) determination of saturation value, and (iii) drop test, all of which cover both the parameters. Norman" analyzed the movement of water in fibre assemblies in terms of fibre properties and yarn structure in nylon, wool, and wool-blended yarns. According to him, the measurement of water transport rates in yarn is sensitive to the properties of fibre arrangement and yarn roughness in textile assemblies. Lord? suggests various methods for determining the relative moisture uptake of ring-spun and open-end yarns. According to him, the wicking height is 'not greatly sensitive to changes in twist in open-end yarns. The test procedures adopted by the above authors differ. Norman mounted the yarns on a microscope stage parallel to a stainless-steel rule. A drop of a blue dye solution (0.05 /'~)was placed on one end ofthe yarn, and the position of the head of the liquid flow was noted as a function of time. De Boer's wicking test was confined to the fabric strips of 25 x 2 em. Lord wound cotton yarns -ring-spun and open-end -on a strip of cardboard at uniform tension; one end of each was immersed in a dye liquor for 15 s and the wicking height was determined. This study was aimed at developing a simple, vertical wicking height test suitable for all types of single-end yarns to help assess the relative yarn structures. More specifically, the effect of twist on the comparative wicking in ring-spun and open-end yarns was studied.