The Behaviour of Disperse Dyes at High Temperatures

Investigations on disperse dyes in the vapour phase are described. The various methods of determining the vapour pressure of such dyes at high temperatures are compared. By means of direct spectrophotometric determination, a relation is established between the partial vapour pressure of a disperse dye over its solution in polyester, and its concentration in polyester. It is shown that the heat‐fastness properties of such dyes depend on their vapour pressures, any exceptions being due to the instability of the particular dye under the conditions of testing. Finally, the kinetics of such processes are considered and some attempt is made to analyse practical systems.