The roles of polymer relaxation phenomena, aqueous dye solubility and the physical properties of water in the mechanism of adsorption of a disperse dye on poly(ethylene terephthalate) fibres: Part 2 dye solubility

Abstract

The marked temperature‐dependent uptake of a commercial disperse dye on poly(ethylene terephthalate) fabric achieved during an aqueous high temperature dyeing process is the likely amalgamation of at least two separate, but intrinsically inter‐related, thermally activated processes, namely, poly(ethylene terephthalate) structural relaxations, as articulated in terms of polymer chain segmental mobility and available free volume, in which glass transition adopts a principal role, as well as disperse dye aqueous solubility. Both polymer relaxation times and disperse dye solubility therefore assume crucially important roles in the mechanism of adsorption of disperse dyes on poly(ethylene terephthalate) fibres.

The roles of polymer relaxation phenomena, aqueous dye solubility and the physical properties of water in the mechanism of adsorption of a disperse dye on poly(ethylene terephthalate) fibres: Part 3 physical properties of water and water‐derived fibre properties

“…However, as mentioned, the results obtained for the commercial dye Teratop Yellow HL‐G 150%/PET fabric presented in the previous part of the paper 2 clearly showed that the aqueous solubility of the dye adopts a very important mechanistic role in the aqueous HT dyeing process employed. From this, it follows that despite the innate hydrophobicity of both PET fibres and disperse dyes, water must undertake fundamentally important functions in aqueous, HT dyeing processes.…”

“…As previously discussed, 2 the structure of liquid water (eg 3–7 ) is of major significance in all exhaust dyeing processes 8–11 in view of the manifold, but inherently complex, interactions that this most exquisite of solvents undertakes with each of the many, varied dyebath components (eg, dye molecules, fibre macromolecules, dispersing agents, buffers and levelling agents, etc. ).…”

“…Subsequent investigations 2 revealed that the pronounced temperaturedependent uptake of the commercial disperse dye on PET fabric presented in Figure 1 was the consequence of at least two separate, but inherently inter‐related, thermally regulated processes, namely, structural relaxation phenomena within the PET substrate, which are dominated by glass transition, and the aqueous solubility of the disperse dye.…”

“…From the viewpoint of the mechanism by which the Teratop Yellow HL‐G 150% was adsorbed on the PET fabric used, it was concluded 2 that the thermally regulated processes of poly(ethylene terephthalate) polymer chain segmental mobility and disperse dye solubility assume profoundly important roles.…”

“…In view of the important contribution that the pronounced thermal dependency of disperse dye solubility likely makes towards the mechanism of adsorption of Teratop Yellow HL‐G 150% on PET fabric, 2 the purpose of this part of the paper is to consider the extent to which the temperaturedependent physical properties of water in the guise of water saturation vapour pressure, and several temperature dependent water‐derived PET fibre properties, namely, the extents of water molecule diffusivity and water sorption, as well as water‐induced polymer swelling and water‐induced plasticisation, may augment the important roles assumed by PET relaxation phenomena and disperse dye solubility in the uptake of the commercial dye on PET fabric.…”