Behaviour of Bifunctional and Polyfunctional Reactive Dyes Applied to Cotton Cellulose

Analytical techniques, viz. electron microscopy, surface area determination, and swelling in cadoxen solvent, have been used to obtain results which provide positive evidence for the formation of crosslinks between adjacent cellulose chains in cotton dyed with different classes of bi‐ and poly‐functional reactive dyes. Reactive dyes selected include those where either the reactive groups are present in the same nucleus (dichlorotriazinyl, monomethoxymonochlorotriazinyl, dichloroquinoxaline, trichloropyrimidinyl and difluoromonochloropyrimidinyl) or where the two reactive groups are present at different positions in the dye molecule (Procion HE (ICI) and Procion Supra (ICI)). The extent of changes observed in the morphology of cotton fibre as a result of dyeing with bi‐ and poly‐functional reactive dyes has been found to depend on the amount of dye present in the fibre and the conditions of application.