Modeling of liquid rise in twisted yarns

Abstract

This article presents a mathematical model of liquid transport in twisted yarns, considering that yarn twist determines the pore configuration that ultimately decides the extent to which wicking takes place in a yarn. It is shown that that the equilibrium wicking height of liquid initially increases with the increase of packing density of yarn due to higher capillary pressure resulting from reduction of pore size. A further increase of packing density causes a reduction in equilibrium wicking height. The earlier theory of pore geometry in yarns has been modified by including fibre contacts in yarn cross-section for more realistic estimate of pore shape factor and pore size. Unlike previous studies, the present model is derived through a probabilistic arrangement of fibres in yarns and does not assume any theoretical arrangement. The model developed in this work is found to predict the complete experimental results quite satisfactorily for three structurally disparate variants of polyester filament yarns. Highlights Introducing probabilistic theory for fibre contacts into pore geometry to modify previous theories on pore characteristics Pore size and pore shape factor collectively influence the liquid column height, which varies with packing fraction (or twist) Modified theory of pore geometry predicts an inverted ‘U’ shape curve of wicking as per experimental evidences