Interactions between polysaccharide polymer thickener and bifunctional bireactive dye in the presence of nonionic surfactants. Part 1: surface tension and rheological behavior of different polysaccharide solutions

The quality of textile printing is closely related to the rheological characteristics of the printing paste which depend on the chemical structure of the thickener used, its concentration and physico-chemical interactions with other paste components. The undesired interactions between the polysaccharide guar gum thickener and the bifunctional bireactive dye after the addition of a nonionic surfactant were investigated as a function of the degree of carboxymethylation (DS) of the guar gum polymer, the hydrophilic/hydrophobic structure of the surfactant, and the concentration of the surfactant and the reactive dye. The rheological investigations show that the destroying of the primary polymer cross-linked structure leads to stronger pseudoplasticity/elasticity of the paste due to hydrogen and covalent ether bonds of surfactants as individual molecules (below critical micelle concentration (CMC)), or as micelle aggregates (above CMC) with the –OH groups of the thickener. The interactions increase with the increasing HLB value and the surfactant concentration, and with the decreasing DS of the polymer. A highly hydrophilic surfactant produced a strong drop of viscosity and leads to phase separation. The addition of the reactive dye diminishes the hydrophilic interactions between the surfactant and the guar gum thickener probably due to interactions between the reactive dye and the surfactant. The micellization process of the surfactant is not influenced by the presence of reactive dye or guar gum molecules.