The influence of acid and direct azo dyes and their intermediates on the degradation of wool keratin. The characterisation by yarn strength measurements of the degradation of wool under conditions relevant to dyeing and of the keratin degradation products, by fractionation, electrophoresis and amino acid analysis.

Abstract

The degradation of wool keratin under conditions relevant to those of wool dyeing was investigated using the techniques of gel permeation chromatography (GPC), ion exchange gel chromatography, and amino acid analysis. Physical testing of the treated and untreated wool was also carried out to determine the physical changes occurring, parameters used being percentage elongation at the break, and the breaking strain of the fibre. Samples of wool keratin were immersed in various aqueous solutions at 1000C for 24 hours and the filtered, aqueous, oxidised extracts were analysed* The solutions used varied only in the dye, or dye intermediate present in the treatment solution. All treatment baths contained 10% owf 1.02 x 10 -2 MSulphuric VI acid; 10%owf 7.04x 10 -3 MSodium sulphate VI ; A 100 :1 liquor ratio was used in each case. Some of the dye intermediates showed a marked catalytic effect, particularly in their effect on breaking strain, a decrease of 40% in some cases. The GPC profiles of the extracted proteins were examined in detail and compared against previous workers' results. An explanation of the behaviour of the dyes and intermediates was proposed. The amino acid composition data of the extracted and fractionated proteins were compared against various morphological components extracted by other workers, as was the total gelatin obtained from each treatment.