Polyester fibre generally consisting of linear chain polymers containing ester groups1 and is derived from dicarboxylic acids and diols. 2 It is the highest volume synthetic fiber produced globally due to its unique end use and easy care properties. 3, 4 The polyester fibres are highly crystalline and are usually even and rod like shapes. 5 Owing to their hydrophobic nature they are therefore difficult to dye at low temperatures and dyeing is usually carried out at high temperatures, regularly around 130 C. 6, 7

Disperse dyes usually used to dye polyester fibres which are non-ionic in nature and have limited water solubility even at high dyeing temperatures. 8 Therefore, require the presence of a dispersing agent, which improves their solubility. 9 These agents produce energy barriers maintaining dispersions in their meta-stable condition, thus, avoiding the aggregation of dispersed particles thus improves the dispersion stability, solubility, leveling, and fastness properties. 10 Since the dispersion of disperse dyes is thermodynamically unstable, the particle sizes tend to increase due to the decreased free energy of the system. 11 The stability of the dye dispersion and the rate of dyeing are all affected by the type and concentration of the dispersing agents. 8