6/6/12

Exhaust Dyeing

Exhaust dyeing is one of the most popular dyeing methods. Most of the dyes could be used for exhaust dyeing of textile material. The exhaust dyeing process is used for staple fibre dyeing. Yarn and fabric could be dyed by exhaust dyeing method. Dye solution or dye bath is produced by dissolving the dyestuff according to required liquor ratio. Then Textile material is immersed in to the dye solution. Initially the surface of the fibre is dyed when dyes contact with the fibre, then the dyes are entered in the core of fibre. Proper temperature and time is maintained for diffusion and penetration of dyes molecule in the fibres core. During the process, kinetic and thermodynamic reactions interact.

Exhaustion 
In exhaust dyeing, all the textile material contacts all the dye liquor and the fibres absorb the dyes. The concentration of the dye in the dye bath therefore gradually decreases. The degree of dyebath exhaustion as a function of time describes the rate and extent of the dyeing process. For a single dye, the exhaustion is defined as the mass of dye taken up by the material divided by the total initial mass of dye in the bath, but for a bath of constant volume:





Where Co and Cs are the concentrations of dye in the dyebath initially and at some time during the process,
respectively.

Dyeing Theory of exhaust dyeing: 
The dyeing process is a chemical reaction occurring between the dye molecule and the fibre molecule: 





The kinetics (process speed) and thermodynamic (balance) relationships both could be examined to evaluate the dyeing process.
Application of kinetics and thermodynamics to exhaust dyeing process:
When the textile material is immersed in to the disperse dye solution, a complex bio-chemical reaction is occurred between the dyes molecule and fibers. The exhaust dyeing process is carried out at particular process stages.
Application of kinetics and thermodynamics to exhaust dyeing process: When the textile material is immersed in to the disperse dye solution, a complex bio-chemical reaction is occurred between the dyes molecule and fibers. The exhaust dyeing process is carried out at particular process stages.







To gain the proper knowledge of the exhaust dyeing theory, it is fundamental to divide it into various stages (even if sometimes there is a time overlapping) and learn each of them individually from different points of view:
-Kinetics of dyeing (study of the reaction rate or speed).
-Thermodynamics (study of balance of reaction).
Hydrokinetics (influence on kinetics of the liquor and/or material turbulence, depending on the dyeing machine used). This is an important aspect not only for exhaust dyeing.
Steps involve with Exhaust Dyeing:
1. First stage (dissolving and dispersion of the dye)
2. Second stage (adsorption)
3. Third stage (Diffusion) 
4. Fourth stage (migration)

2 comments:

  1. Exhaust dyeing is one of the most popular dyeing methods. Most of the dyes could be used for exhaust dyeing of textile material. The exhaust dyeing process is used for staple fibre dyeing. Yarn and fabric could be dyed by exhaust dyeing method. Dye solution or dye bath is produced by dissolving the dyestuff according to required liquor ratio. Then Textile material is immersed in to the dye solution. Initially the surface of the fibre is dyed when dyes contact with the fibre, then the dyes are entered in the core of fibre. Proper temperature and time is maintained for diffusion and penetration of dyes molecule in the fibres core. During the process, kinetic and thermodynamic reactions interact.

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  2. this is really a best post on exhaust dyeing

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