Dyeing of a blended knit made of cotton and modified Nitron fibre

Abstract

Dyeing of a blended knit based on cotton fibre and modified Nitron fibre was investigated. The effect of the Nitron fibre modifier on the degree of fixation and sorption of the dye by the fibre was established. Incorporation of up to 50% modified Nitron fibre in the structure of the cotton-fibre knit increases the degree of fixation of active dye.In dyeing blends of polyacrylonitrile (PAN) with natural fibres, important difficulties arise which are primarily a function of the specific properties of the fibre blends. Modification of Nitron fibre with solutions of natural silk wastes (NSW), while improving its hygienic properties and altering the structure (porosity) [1, 2], can affect its dyeability both individually and in blends with other fibres.We investigated the possibility of monochromatic dyeing of a blended knit containing cotton fibre and modified Nitron fibre (MNF). Active, direct, sulfur, vat, and insoluble azo dyes are used to dye cotton fibre. PAN fibres can be dyed with anionic, nonionogenic, and cationic (for Nitron fibre) dyes [3].We investigated Nitron fibre modified with a solution of NSW containing functional groups characteristic of natural silk in the structure. We investigated the possibility of dyeing blended cotton-Nitron samples with an active -dichlorotriazine (DCTA) -dye. Dyeing was conducted with one class of dyes with variation of the temperature, time, and concentration parameters of the process.The first stage of dyeing was conducted in neutral medium in the presence of common salt for 30 min at 30°C, and the second stage was conducted in alkaline medium, adding calcined soda to the dye solution. The duration of the second stage was 60 min. The samples were washed to remove unfixed dye successively in cold and hot water and then in a boiling solution of surfactants. The data on sorption and fixation of the dye by the fibre are reported in Table 1.An analysis of the data in Table 1 demonstrates the difference in dye sorption and fixation for the blended samples as a function of the ratio of components. For a low MNF content in the blends (from 0 to 50%), the degree of fixation of the active dye increased to the sorption values. A further increase in the MNF content decreased the amount of dye fixed in the fibre. This can be attributed to the features of the structure of the blended samples and the related greater accessibility of the active dye to their surface.A small amount of dye was fixed in the samples with an insignificant cotton fibre content and in the sample of 100% MNF. This is because fixation of the dye takes place simultaneously with hydroxyl groups in the cellulose constituent and the functional groups (-NH 2 ) in the Nitron fibre modifier, i.e., the natural silk protein. We conducted an experiment on dyeing of unmodified Nitron fibres with an active dye to confirm this conclusion. The experiment showed that the Nitron fibre was only dyed by the active dye.The periodic methods of dyeing with active dyes are based on the principle of depletion of the dye bath in time. Th...