Dynamic Wicking Process in Textiles

Abstract

We investigate wicking in textiles using neutron radiography on fabrics of two types, woven and simple jersey knit, and made of yarns of four different materials: cotton, polyethylene terephthalate, polyamide and polypropylene. Moisture distribution in the samples is quantified from the images, and the total mass is compared with gravimetric measurements for validation. The position of the front versus time is obtained from segmented neutron images and backlight images, with good agreement between the two measurement methods. Using a power law to fit the height versus time curves, values for the wicking ratio are found to depart substantially from the 0.5 predicted by the Lucas–Washburn equation. The sharp front approximation is found to be a good approximation for slow wicking fabrics but is an incomplete description of the moisture on high absorbing fabrics such as cotton. The variation of yarn material is the main contributor to the difference of wicking ratio among samples. Finally, neutron moisture profiles complemented with X-ray tomography allow to differentiate two regions in cotton wetted by wicking: intra-yarn wetting and wetting covering the yarns and the inter-yarn voids.