Polyvinyl alcohol gelling systems. I. Congo red and related dyes

Abstract Azo dyes of the Congo Red type are known to be amount the most effective gelling agents for polyvinyl alcohol. It has been shown by means of measurements of dilute solution viscosities that all of the dyes effective as gelling agents associate strongly with polyvinyl alcohol, as well as other hydroxylated water‐soluble polymers. This association is not, however, a sufficient condition for the promotion of gelation. Measurements of gel properties of aqueous systems consisting of polyvinyl alcohol and Congo Red or other related dyes have been made. From these measurements it has been possible to draw some conclusions pertaining to the nature of the crosslinks which contribute to the gel structure.