The Stability of Flowing Dispersions

Presented at the 13th Congress of the International Federation of Associations of Textile Chemists and Colourists in London on 20th September 1984. Within a package-dyeing machine the danger of dye agglomeration is always greatest in regions where the shear rate is high. Therefore, in modern circulation machines the dye tends to agglomerate mainly within the yarn package, thus hindering the throughput of dye liquor. However, the degree of hindrance to liquor throughput has only a very limited value as a criterion of dispersion stability. Provided certain precautionary measures are adhered to, the bath depletion due to coagulation during the heating phase is readily reproducible. From this it is possible to calculate the coagulation constant, i.e. stability criterion independent of test conditions. Conversely, if a stability constant for a given product is available, then the bath exhaustion and thus stability of the product for any desired process can also be computed