Saminathan Ratnapandian

Dye (10 g/l)
Chitosan added to pad liquor (%)
Caspian	Thar	0	0.05
Reduction in CFU (%)	0	0	Control	100

This study is the first reported instance where chitosan was applied simultaneously with the pad-dyeing liquor on cotton fabric to produce shades with acceptable fastness. The single-bath approach was probably rejected by earlier researchers because during exhaust dyeing chitosan agglomerated the dye in the dye bath and hindered colouration. This impediment was avoided in padding by 1) the low chitosan concentration employed; and 2) curing the fabric sample instead of steaming. The present findings are indicative of a simpler and more efficient process. Further, the excellent antimicrobial attributes acquired by the dyed fabric may be exploited in the specialty application area of medical textiles for use as bed linen.

6. Conclusions

This investigation demonstrates that chitosan could be utilised to improve dye uptake by cotton fabrics during padding with natural dyes. Incorporating 0.05% chitosan achieved a maximum increase of 37.9% in the depth of shade obtained from the Acacia plant family. Excess chitosan limited the reactivity between the dye-mordant complex and the fabric, consequently reducing the final colour yield. The propensity of chitosan
to increase the depth of shade was more pronounced when iron (II) sulfate was the mordant. The fastness properties of the dyed fabrics were not affected by chitosan. All samples dyed in the presence of chitosan showed excellent antimicrobial properties.
Thus such materials dyed in the presence of chitosan have the potential for application in medical textiles as hospital linen.

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Chapter 6