Abstract:

In this paper, the orthogonal analysis method was adopted to analyse the optimal mordanting condition for the bleaching of black yak fibres. Without changing the subsequent oxidative/reducing bleaching technology, the optimal mordanting condition was as follows: per weight of water, the ferrous ion concentration is 16%, the sodium bisulfate concentration 3 g/l, the mordanting temperature 60 °C and the liquor pH value is 2. Based on the optimal mordanting condition, yak fibres were bleached. The properties of bleached and untreated yak fibres and yarns were tested by a fibre tensile tester, scanning electron microscopy, yarn strength tester, USTER Tester 5 and so on. By comparing the properties of untreated and bleached yak fibres and yarns, the effects of optimal mordanting on the bleaching and spinning of black yak fibres were presented. The results show that bleached yak fibres have poorer mechanical and morphology properties, and it is harder to felt for bleached fibres. For the spinning of 16.7 tex yarn, a complete condensing spinning system was adopted, and the performances of bleached fibre yarn decreased in the permissible range compared with the untreated fibre yarn.