Question 65 (Textile Technology & Fibre Science)
A polyester fabric is dyed till equilibrium with a disperse dye at two temperatures, T1 and T2 (T2 > T1). At T1 and T2, the partition coefficient is K1 and K2 and the equilibrium dye uptake is D1 and D2, respectively. The correct option is
| (A) | K1 > K2 and D1 >D2 |
| (B) | K1 > K2 and D1 < D2 |
| (C) | K1 < K2 and D1 > D2 |
| (D) | K1 < K2 and D1 < D2 |
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Frequently Asked Questions | FAQs
How does a disperse dye work ?
Disperse dyes are a class of synthetic dyes that are used to dye synthetic fabrics such as polyester, nylon, and acetate. These dyes are insoluble in water and require a special dyeing process to achieve uniform dyeing.
In the dyeing process, disperse dyes are first dispersed in a hot liquid medium, such as water, by the use of dispersing agents. The fabric to be dyed is then immersed in the dye bath and the temperature is raised to near boiling point. At this temperature, the dispersed dye molecules penetrate the fiber structure of the synthetic fabric and become trapped inside the fibers. The dyeing process is typically followed by a rinsing and washing step to remove any unattached dye molecules.
Disperse dyes are known for their excellent light fastness and color retention, making them ideal for outdoor applications and clothing that is frequently exposed to sunlight. They are also known for their ability to produce bright and vibrant colors on synthetic fabrics.