Although the synthetic fibers have dominated the textile market, consumer has still preference towards cotton. Today cotton can be manufactured but the natural merits obtained in cotton cultivated in different areas of the country cannot be underestimated.
A number of research studies are reported on the chemical modification of cotton using types of agents. In this regard, the present study considers the affect of reducing agent on the fabric properties.
The starting material was 30sX20s single sheeting fabric producing normally in most acceptable widths. The fabric was desized, scoured, bleached before dyeing with vat dyes. During dyeing hydros, glucose and sucrose were used as reducing agent. The fabric was tested for air permeability, fabric thickness , tearing strength, bending length and crease recovery from grey to dyed state using standard methods as prescribed by IS Hand book.
[...] When air is beaten into the solution, the indican combines with oxygen to produce indigotin or “indigo blue.” Indigo blue is insoluble and settles out of the solution to produce the blue indigo dyestuff Application of vat dye involves five stages: AQUEOUS DISPERSION: The insoluble vat dye is dispersed in water. VATTING: This step involves the chemical reduction of the vat dye to produce the soluble, reduced or leuco form of the dye. This is achieved by sodium hydro sulphite, sodium hydroxide and water. [...]
[...] The reductive decomposition of the excessive dye by sodium hydrosulfite improves the color fastness. Sodium hydrosulfite's reduction reaction removes residual oxide and wrong pigments. Sodium hydrosulfite is a reductive bleaching agent. It reduces carbonyl and alcohol groups, which function as colorants of the substances Dyeing mechanism with Hydros: Na2S2O4 +2H2O 2NaHSO + 2 H 2 >C=OH 2 >C=OH+2 2 >C-ONa + H2O 2 NaHSO3 + 2 2 Na2SO3 +2H2O 1.4 Glucose: Glucose a monosaccharide (or simple sugar), is an important carbohydrate in biology. [...]
[...] Sucrose is a disaccharide that yields 1 equiv of glucose and 1 equiv of fructose on acidic hydrolysis. This 1:1 mixture of glucose and fructose is often referred to as invert sugar, since the sign of optical rotation changes (inverts) during the hydrolysis from sucrose ([alpha] D = + 66.5 to a glucose fructose mixture ([alpha] D = - 22.0 o). Certain insects, particularly honeybees, have enzymes called invertases that catalyze the hydrolysis of sucrose to a glucose-fructose mixture. Honey, in fact, is primarily a mixture of these three sugars. [...]
[...] On comparing between three reducing agents glucose bending length is lesser than other in both the directions, this indicate glucose act as smooth reducing agent than hydros. Effect on Crease Recovery: From grey to bleached its values is increased and after dyeing also its value is increased. On comparing the three reducing agents glucose value was found to be higher than the hydros value. This indicates that glucoses effect on fabric is lesser than that of hydros. Effect of Air Permeability: From grey to scoured its value is decreased and than increased. [...]
[...] Table 3.5 : Treatment conditions for dyeing with hydros : liquor used concentration ratio Dyeing of the fabric with vat dyes using glucose: The fabric after bleaching is dyed using glucose as a reducing agent under the same conditions as followed in hydros and same amount of glucose as hydros show in the table 3.6 Table 3.6 : Treatment conditions for dyeing with glucose : liquor used concentration ratio Dyeing of the fabric with vat dyes using sucrose: The fabric after bleaching is dyed using sucrose as a reducing agent under the same conditions as followed in hydros and same amount of sucrose as hydros show in the table 3.7 Table 3.7 : Treatment conditions for dyeing with sucrose: liquor used concentration ratio Testing All the Control and Treated samples were conditioned at Standard Temperature as per IS: 6359- Characterization of Products: The Control and Treated fabric samples were characterized for various physical properties as mentioned below Determination of Geometrical properties: Fabric Set was determined as per IS: 1963-1969 and an average of 5 measurements is reported Determination of Yarn Linear Density: IS: 3442-1986 was referred to measure the Yarn Linear density and at least average of 5 replications is considered for the result Determination of Fabric GSM: Fabric GSM was determined and the value reported is an average of measurements 1964-1970) Determination of Fabric Thickness: Fabric Thickness was measured using Shirley Thickness gauge 7702-1975). [...]
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