Research on Shape Memory Behaviour of Rib Knitted Fabric from Wool Yarn Descaled by Ultrasonic Wave

Abstract

Wool is a special material with the shape memory capability, so it can be used not only for apparel but also for functional applications such as protecting clothes and thermo-regulating clothes. However, wool fibers have a surface structure of overlapping cuticle cells known as scales which significantly affect fiber properties. This research investigated the appearance, strength, extension and the shape memory behavior of the wool yarn and also the wool knitted fabric before and after descaling its cuticle cells using calcium carbonate (CaCO3) powder with the concentration of 5 g/l, 10 g/l, 15g/l, and 20g/l in ultrasonic bath. The results showed that ultrasonic wave and abrasive calcium carbonate powder could reduce the size and the sharpness of wool scale. Wool yarn breaking strength and elongation tended to increase due to the increase of CaCO3 concentration, while the value of CV (%) decreased. The shape memory behavior was evaluated according to the change in length for the wool yarn, and the change in loop dimensions for the knitted fabric in different environmental humidity and temperature. Wool yarn descaled with CaCO3 powder showed more change in length in comparison to original yarn, but the change was a little bit of less than 3%. For the wool rib knitted fabric, the change in vertical direction was negligible, while the change in horizontal direction was significant, especially in the case of rib knitted fabric made of wool yarn descaled with CaCO3 powder. Wool yarn descaled showed a little change in length while the wool knitted fabric showed the more stable in shape by the course direction in comparison to those before descaling treatment.