Yarn porosity and its relationship with the dyeing behavior

Porosity is one of the most important properties for the textile substrate. It can influence comfort of a garment by affecting its breathability and thermal conductivity. During the process of dyeing the dye liquor comes in contact with the substrate, the absorption of the dye liquor into the substrate will be dependent on its porosity. The concept of porosity between the yarns of a fabric is a common phenomenon, however the porosity between the fibers in the yarn can also influence the dyeing behavior of fabric.
In this research work; ring and rotor yarns of 25/s and 30/s counts are considered as textile substrates. The porosity of yarns was determined theoretically and experimentally using image analysis method. It was found that theoretical porosity is independent of the yarn manufacturing method. 30/s yarn was more porous as compared to 25/s yarn having higher pore area. Rotor yarns had higher porosity as compared to ring yarns because of higher pore area.
Dyeing behavior is influenced by the porosity of yarn. Rotor yarns have higher dye fixation as compared to ring yarns. These yarns were also dyed with deeper shades showing higher K/S values as compared to ring yarns.
Dyeing behavior was also dependent on the count of yarn. 30/s yarns have higher dye fixation as compared to 25/s yarns. However 25/s yarns were dyed with deeper shades showing higher K/S values. 25/s yarns are coarser than 30/s yarns having higher diameters and cross sectional area thus resulting in deeper shades and higher K/S values.
Keeping all the other conditions constant; deeper shades can be achieved with rotor yarn as compared to ring yarns. Deeper shades can also be achieved with coarser yarns as compared to finer yarns.