Now You Know Treatment of Cotton Fiber with Chitosan for the Improvement of Exhaustion during Dyeing with Reactive Dye (Part-5)

Treatment of Cotton Fiber with Chitosan for the Improvement of Exhaustion during Dyeing with Reactive Dye (Part-5)

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

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CHAPTER 4
RESULTS AND DISCUSSIONS

4.1. Measurement of Dye Exhaustion
Dye exhaustion may define as the leaving of a dye from the dye bath and attachment to the fiber being dyed. For instance, 70% exhaustion would mean that 70% of the total amount of dye has attached to the fiber, and 30% is still in solution. Dyebath exhaustion can be calculated as the mass of dye taken up by the material divided by the total initial mass of dye in the bath, for a bath of constant volume [21].

Where, C0 and Cs are the concentrations of dye in the dyebath initially and at some time during the process, respectively.

Figure: 4.1 Dye exhaustion percentage of chitosan treated and untreated samples.

The treatment of fabric with chitosan has enhanced the dyesite in cellulose macromolecule of cotton fiber. As a result, the treated fabric absorbed more dyestuff than the untreated sample and this absorption has increased the exhaustion percentage of dye in the treated fabric. The improved dyebath exhaustion has shown by the longer bar diagram in Figure 4.1 where all the chitosan treated fabric samples have shown longer bar than the untreated fabric sample. From the statistical analysis, it has been found that, the values of exhaustion percentages of chitosan treated fabric has fluctuated more than the un- treated fabric sample, resulting higher bar in the bar diagram. One possible reason for comparatively higher bar in treated fabric may be the unequal chitosan absorption by different samples.

4.2 Depth of Shade
Color depth of the dyed fabrics was analyzed by meauring the K/S values of samples. Higher the value of K/S more dye will absorb in the fabric. Color measuring instrument (spectrophotometer) determines the K/S value of a given fabric through Kubelka-Munk equation as follows [21].

S = scattering of dyes. The values found for all the dyed fabrics are shown in Figures 4.2

Figure: 4.2 the gradual increment of dye absorption (K/S value) with the increment of chitosan concentration.

It has been found that the chitosan treated fabric samples have absorbed significantly higher amount of dyes than normal untreated fabric. The dyebath parameters such as shade %, amount of salt and alkali, dyeing time and temperature were constant for all the samples. The increased K/S value in the chitosan treated fabric indicates the presence of higher amount of the dye absorbed in the chitosan treated fabric.

4.3 Color Fastness properties

Table: 4.1 Fastness Rating of Rubbing.

Fabric Type	Rubbing Fastness
	Dry	Wet
U	4/5	4
A	4/5	3/4
B	4/5	3/4
C	4/5	3/4
D	4/5	3
E	4/5	3

Table: 4.1 Fastness Rating of washing.

Fabric Type	Washing fastness	Color staining
	Color change	Acetate	Cotton	Nylon	Poly:	Acrylic	Wool
U	4/5	4/5	4/5	4/5	4/5	4/5	4/5
A	5	4/5	4/5	4/5	4/5	4/5	4/5
B	5	4/5	4/5	4/5	4/5	4/5	4/5
C	5	4/5	4/5	4/5	4/5	4/5	4/5
D	4/5	4/5	4	4/5	4/5	4/5	4/5
E	4/5	4/5	4	4/5	4/5	4	4/5

Table: 4.2 Code of test samples

Test fabric type	Code
Normal fabric without any chitosan treatment	U
Fabric treated with 0.5% Chitosan solution	A
Fabric treated with 1% Chitosan solution	B
Fabric treated with 1.5% Chitosan solution	C
Fabric treated with 2.5% Chitosan solution	D
Fabric treated with 3% Chitosan solution	E

CHAPTER 5
CONCLUSION

5.1 Conclusion
Reactive dyeing process has been completed at 600C and the added time remains 60 mins. Fixation and exhaustion have been completed at 600c. The addition of glubar’s salt is necessary as it increase the exhaustion of the dye bath. This study is intended to improve the absorption of reactive dye by cotton fiber after treating with chitosan. The application of chitosan on cotton fiber enhances the dye adsorption and also increases the hydroxyl group for fixation. Accordingly, dye exhaustion and depth of shade improve in the treated fabric compared to the untreated fabric. Though the fastness rating is lower in case of wet rubbing fastness, the overall fastness rating is satisfactory. In all cases, the pre-dyeing method in which the fabrics were treated with chitosan solutions prior to dyeing produced the optimum K/S value. An increase in chitosan concentration resulted in an increase in the dyeability of dye. This effect was associated with the presence of bonded chitosan through the chemical reaction of the chitosan aldehyde group with cellulose. Due to high absorbency, hydrolysis of dye is reduced which is helpful to protect the environment from pollution. So the treatment of cotton with chitosan can be an effective way for this purpose.

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