Estimation of Bleaching Effect on Cotton Fabric by Measurement of Reflectance

Estimation of Bleaching Effect on Cotton Fabric by Measurement of Reflectance

Mustaque Ahammed Mamun
Department of Textile Engineering
Dhaka University of Engineering & Technology (DUET)
Cell: +8801723300703 
Email: mamuntex09@gmail.com

Introduction
Bleaching is the process by which natural color of cotton fabric aredestroyed. So that fabric will be more bright& light reflectance will be more before one. Also absorbency is increased because sodium hydroxide is used to increase the pH value and which remove oil, fat wax etc. The bleaching effect is measured by two ways-

1. Measurement of reflectance.
2. Measurement of whiteness.

Measurement of whiteness in case of hypochlorite bleaching.But we used hydrogen peroxide so we will measured only Measurement of reflectance.

Objectives

• To know about the bleaching process.
• To know about the estimation of bleaching effect.
• To know about the Measurement of reflectance.
• To know about the process of estimation.

At first fabric have to be Bleached.

Bleaching Recipe:

• H2O2————————————————-9gm/L
• Stabilizer ——————————————- 4.5 gm/L
• NaoH ———————————————— 8 gm/L
• Na2CO3 —————————————— 5gm/L
• Detergent —————————————— 1 gm/L
• Anticreasing —————————————1 gm/L
• Sequestering agent —————————- 1 gm/L
• Wetting agent ———————————— 1 gm/L
• M t L ————————————————-1 t 10 
• Temp x time —————————————1000c x 30′

Calculation:

Sample weight = 9.64gm

Total liquor = 9.64 x 10 = 96.4 ml

Water =96.4- (8.676+4.338+7.112+4.82+1+1+1+1) = 67.454≈68 ml

ESTIMATION OF BLEACHING EFFECT
Measurement of Reflectance: when a fabric is bleached, its light reflecting capacity increases. The reflectance of a bleached fabric is measured by spectrometer. It can measured light reflectance of fabric and can give reflectance curve.

Standard range of reflectance 85% (84%-86%) up to 90%.

A range of 90-94% reflectance is also possible in a high temperature treatment in a kier (120oc). In high temperature bleaching, we can get high range of bleaching but high temperature bleaching is a risky.

Reflectance Curve & % of Reflectance:

Figure: Reflectance curve & % of Reflectance

We see that from above chart of reflectance of scoured and non-scoured sample are increased at small amount. And amount of hydrogen per-oxide reflectance are increased respectively but we see that there are vary difference of last person experiment i.e. amount of hydrogen per-oxide 11gm/L used and reflectance is less than from all but there would be more reflectance from others. So I think that there may be problem in his experiment. So we should that, more attention have to be maintain during experiment.

Also in most case, scouring is above 85 at 700 nm which can be said good scouring.

Conclusion
At last we can say that, how to estimate of bleaching effect is known by this experiment. Knowledge is gained from this experiment which is very helpful in our practical life. Special thanks to our honorable teacher who has been help us to complete this experiment.

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