The plasticisation model of dye diffusion: Part 4

Abstract Previously published data reported for the temperature dependency of the diffusion of an organic acid within PA 6 film, as well as the desorption of three acid dyes from dyed nylon 66 fabric, diffusion of an acid dye within nylon 6 film and the adsorption of a sulphur dye onto nylon 66 fabric, over a diverse range of application/washing/dyeing temperatures and conditions, were re‐evaluated using the Williams‐Landel‐Ferry (WLF) equation. As the experimentally observed diffusion/desorption/adsorption of the organic acid, each of the anionic dyes and the sulphur dye within/from/onto each of the respective polyamide substrates adhered to a WLF relationship, the thermally activated diffusivity of the various anionic species is governed by the thermally regulated structural relaxation times of the water‐saturated, water‐swollen, water‐plasticised, poly(ε‐caprolactam) or poly(hexamethylene) adipamide macromolecules. The plasticisation model of dye diffusion seems to offer a reasonable explanation of the observed temperature dependency of the diffusivity of the simple organic acid, each of the four acid dyes and the sulphur dye within both types of aliphatic polyamide.