Vinylsulphone Dyes Research Articles

Interaction of vinylsulphone reactive dyes with cellulosic fabrics. Part 1 — dyeing mechanism, fibre characterisation and effects of alkaline electrolytes

Two vinylsulphone dyes were studied by an HPLC technique under alkaline conditions in order to evaluate their various chemical forms. Fabrics made from viscose fibres were dyed under controlled conditions, varying the nature and the quantity of electrolyte used. It was found that sodium chloride is the most efficient salt for a short dyeing times (20 min) while lithium chloride yields higher dye uptake over more prolonged dyeing processes (60 min). The effect of the electrolytes on dye uptake was found to be related to the radius of the solvated cation.

The role of vinylsulphonyl reactive dyes in prevention of wool damage

Reactive dyes of the vinylsulphone and α‐bromoacrylamido types inhibit wool fibre degradation during dyeing. The effect is proportional to the amount of dye applied, which may be explained in terms of set inhibition and modification of the cell membrane complex. Reactive dyes are capable of interfering with the fibre thiol‐disulphide interchange reactions, as evidenced by a study of model thiol derivatives of vinylsulphone dyes. H.p.l.c. has been widely employed to separate and assist with identification of these thiol adducts. The role of the cell membrane complex has been clarified using reactive vinylsulphone fluorescent compounds as dye models and following fibre penetration using fluorescence microscopy.

Polymers from acrylonitrile polymerized in the presence of vinylsulphone dyes

The properties of a series of ‘copolymers’ of acrylonitrile and various vinylsulphone dyes are discussed. Information relating to molecular size, the nature of the linkage between the chromophore and the backbone and the reactivity ratios of the two ‘monomers’ is given. These reactivity ratios are calculated from extinction coefficients on the assumption that there is no appreciable breakdown of the chromophore during polymerization. Factors governing the role of the dye in the polymerization process are considered in some detail. Thermal analysis techniques have been used to investigate the thermal stability of the products of polymerization. The thermograms have been used to assess the potential of these materials as pigments and to study the nature of their decomposition.

Polymerization of acrylonitrile in the presence of vinylsulphone dyes

Information regarding the effect of vinylsulphone dyes on the kinetics of polymerization of acrylonitrile is presented in detail. Some of the physical properties of the products, polyacrylonitrile/vinylsulphone dye copolymers, are discussed, although the subject of their thorough characterization is reserved for a later publication. Considerable detail is given concerning the experimental procedures, to ensure ease of understanding of the techniques involved. 60Co γ rays were employed as the polymerization initiator whilst the effect of γ radiation on the chromophore was noted, where relevant.