Sock fabrics: The effect of fibre type, yarn type and fabric structure on selected properties

Abstract

Socks are garments which contribute to maintaining the thermal neutrality of the foot, protecting it from blisters, and providing a cushion to absorb energy due to frequent impact. Properties of socks have been investigated previously, most often for comfort, sport or military purposes. The type of fibre used in socks has been a focal point, with differences detected in properties often attributed to the superior characteristics of one fibre type over another. The focus on fibre type has been such that the effects of other sock components (e.g. yarn and fabric structure) have often been overlooked. One reason the effect of fibre type, yarn structure and fabric structure on sock properties is not fully understood is due to the design of experiments which are such to preclude these characteristics to be separated from one another. The difference between this study and previous work is the use of sock fabrics where the manufacturing has been carefully controlled, ensuring that only the variables of interest differ among the fabrics. Three common fibre types (acrylic, fine wool, mid micron wool), yarn structures (single ply, high-twist, low-twist) and fabric structures (single jersey, half-terry, terry) were selected as variables, and the 3 x 3 x 3 experimental design resulted in 27 sock fabrics. Thus, the aim of this thesis was to investigate the effect of fibre type, yarn structure and fabric structure on thermal and moisture properties, frictional properties, compression and recovery from compression of sock fabrics. Standard test methods were used where appropriate. Frictional properties and compression were determined using adapted versions of methods previously reported.

Fabric structure dominated most selected properties, with terry fabrics being thickest, most thermally resistant when dry, most absorbent, most resistant to water vapour transfer and most conductive to heat transfer when damp. Single jersey fabrics had the lowest coefficient of static and dynamic friction, half-terry had the highest. Half-terry fabrics retained the greatest percentage of their original thickness during compression, however single jersey fabrics had the best compression to recovery ratio. When the amount of energy absorbed was standardised for fabric thickness, only the number of compression cycles and whether the fabric was dry or damp had measurable effects. Dry fabrics had a better compression to recovery ratio and absorbed more energy than damp fabrics. Friction between fabric and a synthetic skin was affected most by the applied load, with a higher load resulting in a greater frictional force, and higher coefficients of static and dynamic friction. The overall effect of yarn on properties was less than fabric structure, with small but significant effects on the coefficient of static friction, compression to recovery ratio, thermal resistance and liquid absorption capacity. The effect of fibre type was also minimal, with differences detected among fibre types typically less than differences detected among the fabric structures. The most important effect of fibre was on the static frictional force and coefficient of static friction of damp fabrics, with fabrics composed of fine wool exhibiting lowest friction, and acrylic fabrics the highest.