Changes in Anisotropic Elastic Moduli of Wool Fibres during Worsted Spinning, Weaving and Finishing

Abstract

The mechanical properties of wool fibres are altered by the mechanical actions which are applied to the fibres during the worsted spinning, weaving and finishing processes. The processing of wool fibres with average diameters of 17, 19 and 22 μm were investigated, respectively. The test fibres were sampled at each processing stage and the elastic moduli of these fibres measured by the direct measurement of the mechanical properties of a single fibre by using a new measuring system which has recently been developed[1,2]. The parameters of washed wool fibre were used as the base and the changes in the test-fibre's parameters during processing were compared with these base parameters. The following results were identified: the longitudinal modulus - E_L, exhibited a small increase during the processing and decreased when the fabric was finished. As a result, the value of the fibre in finished form, and therefore the E_Lvalue of the fibre in the finished fabric was slightly less than the original figure. The shear modulus - G_LTand the transverse modulus - E_T, fell during the drawing process, and also, during both the fine spinning and weaving processes. In this case, the decrease in the G_LTof 17-μm wool fibre seemed to be somewhat less than that of the 19- and 22-μm wool fibres. The G_LTand E_Trecovered at the finished stage to some extent; however, the recovery of G_LTwas smaller than that of E_Tand remained at about 7.5% less than the original value. The observation of these processed fibres by optical microscope showed many thin shades inside the fibre along the fibre axis. There may be two reasons for the reduction of G_LT: firstly, the rupture of the bonding between fibrils by the mechanical actions applied to the fibres during processing and, secondly, the crack damage of the fibre skin also caused by the mechanical action.