**1.2. Chemical modification of fabrics**

Chemical treatment has been used in industry to treat large objects that would be diffi‐ cult to treat by other commonly used industrial technique such as flame and coronadischarge treatments. Chemical etchants are used to convert smooth hydrophobic polymer surfaces to rough hydrophilic surfaces by dissolution of amorphous regions and surface oxidation. Chromic acid is the most widely used etchant for polyolefins and other polymers. [2]

(Figure 5). The reaction thus resulted in a bifunctional polyester surface. The ratio of amine and carboxylic acid groups differed with unhydrolyzed and hydrolyzed starting materials

Surface Modification Methods for Improving the Dyeability of Textile Fabrics

http://dx.doi.org/10.5772/53911

45

The sol-gel process is an excellent tool to obtain ordered hybrid organic-inorganic nanocom‐ posites. The method involves the mixing of precursors in an aqueous or alcoholic medium. Precursors are molecules, which contain a central metal or semimetal atom, to which reac‐ tive alkoxy groups and/or organic groups are bonded. These reactive groups are subjected to an acidic or alkaline catalyzed hydrolysis and condensation reaction, thus forming a sol and subsequently a gel. Aging or drying step enables the production of powders, xerogels, aerogels, fibers, or coatings [18]. The latter procedure renders possible surface modification

The sol-gel technology was also applied to influence the dyeing properties. Luo et al. [19] succeeded in improving the wash fastness of cotton materials that had been dyed with di‐ rect dyes using GPTMS and TEOS. Mahltig incorporated dyes into a silica matrix [20-22]. Du investigated the fixation properties and mechanism of direct dyes on silk, nylon 6 and cot‐ ton applying various organotrialkoxysilanes. They found that the most suitable precursors for silk and nylon 6 are amide- and vinyl-containing sols [14]. Yin also managed to enhance

Schramm and his coworker investigated the impact of alkoxysilanes (TEOS, GPTMS, APTES, and TESP-SA) on the dyeing process of cotton substrates, which were dyed with 4 % owf C.I. Reactive Red 141 and 4 % owf C.I. Reactive Black 5. (Figure 6) For this purpose cotton samples were pre-treated with the alkoxysilanes and subsequently dyed. The results show that TESP-SA are lowering the L\* values significantly, whereas TEOS, GPTMS, and

the fastness properties of cotton material that had been dyed with direct dyes [22].

(Figure 5). Strength loss was somewhat greater than with alkaline hydrolysis. [17]

**Figure 5.** Hydrolysis and aminolysis of polyester

*1.2.2. Sol gel pre modification of fabrics*

of textiles, thus imparting novel properties to the material.

*1.2.2.1. Dyeing Treatment of Sol-gel Pre-treated Cotton Fabrics*

Alkaline, acidic and solvents hydrolysis is another method to improve various physical and chemical properties of synthetic fibers. The alkaline hydrolysis of PET fibers is usually car‐ ried out with an aqueous alkaline solution, such as sodium hydroxide. In the alkaline hy‐ drolysis process, PET undergoes a nucleophilic substitution. Chain scission of PET occurs, resulting in a considerable weight loss and the formation of hydroxyl and carboxylate end groups, which improves the handling, moisture absorption and dyeability of the fabric with enhanced softness.

There are different kinds of auxiliaries that are used to modify the surface properties of tex‐ tile fabrics. Some of new chemical and their applications in textile industry are described bellow:

#### *1.2.1. Aminolysis*

Several studies have assessed the effects of amine interaction with polyester. Early studies assessed the aminolysis of polyester as a means of examining fiber structure without regard to maintaining the integrity of the polymer.

The degradation effects on polyester of a monofunctional amine versus alkaline hydrolysis have been studied. These studies, which again involved high levels of fiber degradation, demonstrated that alkaline hydrolysis has a more substantial effect on fiber weight without extensive strength loss. In contrast, aminolysis had less effect on fiber weight but decreased fiber strength, indicative of a reaction within the polymer structure rather than simply at the surface. It was later demonstrated that bifunctional amine compounds could be reacted with the polymer with minimal loss in strength while generating amine groups at the fiber sur‐ face. The early stages of the reaction were largely confined to the fiber surface and the re‐ sulting fiber had modified wetting properties and improved adhesion with the matrix when used in composites. A recent paper has re-examined the interaction of untreated and alkali hydrolyzed polyester with a range of aliphatic diamines. 1,6-Hexanediamine, 2-methylpen‐ tamethylene diamine, 1,2- diaminocyclohexane, tetraethylenepentamine, and ethylene dia‐ mine were applied to untreated polyester. Ethylene diamine was also applied for a range of solution concentrations in toluene. The treatment generated amine groups on the fiber sur‐ face and was revealed by staining with anionic dyes under conditions in which the amine group was protonated. Unexpectedly, the reaction resulted in the simultaneous formation of carboxylic acid groups in a manner similar to alkaline hydrolysis, revealed by staining with Methylene Blue

(Figure 5). The reaction thus resulted in a bifunctional polyester surface. The ratio of amine and carboxylic acid groups differed with unhydrolyzed and hydrolyzed starting materials (Figure 5). Strength loss was somewhat greater than with alkaline hydrolysis. [17]

**Figure 5.** Hydrolysis and aminolysis of polyester

**1.2. Chemical modification of fabrics**

44 Eco-Friendly Textile Dyeing and Finishing

and other polymers. [2]

enhanced softness.

*1.2.1. Aminolysis*

Methylene Blue

to maintaining the integrity of the polymer.

bellow:

Chemical treatment has been used in industry to treat large objects that would be diffi‐ cult to treat by other commonly used industrial technique such as flame and coronadischarge treatments. Chemical etchants are used to convert smooth hydrophobic polymer surfaces to rough hydrophilic surfaces by dissolution of amorphous regions and surface oxidation. Chromic acid is the most widely used etchant for polyolefins

Alkaline, acidic and solvents hydrolysis is another method to improve various physical and chemical properties of synthetic fibers. The alkaline hydrolysis of PET fibers is usually car‐ ried out with an aqueous alkaline solution, such as sodium hydroxide. In the alkaline hy‐ drolysis process, PET undergoes a nucleophilic substitution. Chain scission of PET occurs, resulting in a considerable weight loss and the formation of hydroxyl and carboxylate end groups, which improves the handling, moisture absorption and dyeability of the fabric with

There are different kinds of auxiliaries that are used to modify the surface properties of tex‐ tile fabrics. Some of new chemical and their applications in textile industry are described

Several studies have assessed the effects of amine interaction with polyester. Early studies assessed the aminolysis of polyester as a means of examining fiber structure without regard

The degradation effects on polyester of a monofunctional amine versus alkaline hydrolysis have been studied. These studies, which again involved high levels of fiber degradation, demonstrated that alkaline hydrolysis has a more substantial effect on fiber weight without extensive strength loss. In contrast, aminolysis had less effect on fiber weight but decreased fiber strength, indicative of a reaction within the polymer structure rather than simply at the surface. It was later demonstrated that bifunctional amine compounds could be reacted with the polymer with minimal loss in strength while generating amine groups at the fiber sur‐ face. The early stages of the reaction were largely confined to the fiber surface and the re‐ sulting fiber had modified wetting properties and improved adhesion with the matrix when used in composites. A recent paper has re-examined the interaction of untreated and alkali hydrolyzed polyester with a range of aliphatic diamines. 1,6-Hexanediamine, 2-methylpen‐ tamethylene diamine, 1,2- diaminocyclohexane, tetraethylenepentamine, and ethylene dia‐ mine were applied to untreated polyester. Ethylene diamine was also applied for a range of solution concentrations in toluene. The treatment generated amine groups on the fiber sur‐ face and was revealed by staining with anionic dyes under conditions in which the amine group was protonated. Unexpectedly, the reaction resulted in the simultaneous formation of carboxylic acid groups in a manner similar to alkaline hydrolysis, revealed by staining with

### *1.2.2. Sol gel pre modification of fabrics*

The sol-gel process is an excellent tool to obtain ordered hybrid organic-inorganic nanocom‐ posites. The method involves the mixing of precursors in an aqueous or alcoholic medium. Precursors are molecules, which contain a central metal or semimetal atom, to which reac‐ tive alkoxy groups and/or organic groups are bonded. These reactive groups are subjected to an acidic or alkaline catalyzed hydrolysis and condensation reaction, thus forming a sol and subsequently a gel. Aging or drying step enables the production of powders, xerogels, aerogels, fibers, or coatings [18]. The latter procedure renders possible surface modification of textiles, thus imparting novel properties to the material.

The sol-gel technology was also applied to influence the dyeing properties. Luo et al. [19] succeeded in improving the wash fastness of cotton materials that had been dyed with di‐ rect dyes using GPTMS and TEOS. Mahltig incorporated dyes into a silica matrix [20-22]. Du investigated the fixation properties and mechanism of direct dyes on silk, nylon 6 and cot‐ ton applying various organotrialkoxysilanes. They found that the most suitable precursors for silk and nylon 6 are amide- and vinyl-containing sols [14]. Yin also managed to enhance the fastness properties of cotton material that had been dyed with direct dyes [22].

### *1.2.2.1. Dyeing Treatment of Sol-gel Pre-treated Cotton Fabrics*

Schramm and his coworker investigated the impact of alkoxysilanes (TEOS, GPTMS, APTES, and TESP-SA) on the dyeing process of cotton substrates, which were dyed with 4 % owf C.I. Reactive Red 141 and 4 % owf C.I. Reactive Black 5. (Figure 6) For this purpose cotton samples were pre-treated with the alkoxysilanes and subsequently dyed. The results show that TESP-SA are lowering the L\* values significantly, whereas TEOS, GPTMS, and APTES give rise to a moderate change of L\*. The after-treatment of dyed cotton fabrics with alkoxysilane causes almost no effect with respect to the colorimetric data. The direct incor‐ poration of the alkoxysilanes into the dyeing bath resulted in a reduction of the color prop‐ erties, when APTES or TESP-SA was employed. The crease-proof finishing treatment caused an increase in the a\* value of red-dyed samples. [23]

Moreover, the vividness after copper salt or diazotization finishing usually fades away, so that the application scope of direct dyes have been seriously limited in textile industry. A novel dyeing solution containing silica and direct dyes has been prepared by the sol–gel process. During this process, EtOH, tetraethoxysilane (TEOS), H2O and 3-glycidoxypropyl‐ trimethoxysilane (GPTMS) were added in turn. The molar ratio of TEOS:H2O:EtOH was

The concentration of NaCl added into the dyeing solution was 10 g/L. The dyed fabrics were

hanced by more than 10%, the rubbing fastness and the washing change fastness are im‐ proved by one grade and the washing staining fastness is improved by half a grade. Not only is the K/S value enhanced from 9.3 to 11.5, but also the wet rubbing fastness and the washing change fastness are increased half a grade. Using a video microscope, a smoother fiber surface is observed. The calculated sol–gel weight gain is 4.6%. As a nonpolluting proc‐ ess, the sol–gel technology shortens the dyeing process and brings a better fixation property,

The dyeability of synthetic fibers depends on their physical and chemical structure. Dyeing process consist of three steps including the diffusion of dye through the aqueous dye bath on to the fiber, the adsorption of dye into the outer layer of the fiber and the diffusion of dye from the adsorbed surface into the fiber interior. It was shown by researchers that functional groups of PET and water molecules play a great role in this process. The terminal carboxylic and hydroxyl groups in PET chains interact with water molecules. This makes a swelled fi‐ ber resulting to increase the attraction of disperse dye by these functional groups of fiber.

The proportion of crystalline and amorphous regions of polymer is another factor influencing the dyeability. Researchers are concerned with the development and implementation of new techniques in order to fulfill improvement in dyeability of various polymers. Blending of poly‐ meric fibers with nanoclays as inexpensive materials is still claimed as cost effective method to enhance dyeability. Up to now, only two research articles are focused on dyeing properties of polypropylene- and polyamide 6- layered clay incorporated nanocomposites prepared by melt compounding. Toshniwal et al. suggested that polypropylene fibers could be made dyeable

The previous study on dyeability of PET/clay nanocomposites stated the following type of

**•** Hydrogen bonding between OH groups of modified clays and the NH2 and CO groups of

**•** Electrostatic bonding between the negatively charged oxygen atom of carbonyl groups in disperse dye molecule and positively charged nitrogen atom of quaternary ammonium

**•** Direct π interactions and van der Waals forces between methyl and ethyl groups of modi‐ fied clays on one hand and methoxy group and benzene rings of disperse dye molecule

with disperse dyes by addition of nanoclay particles in polymer matrix [25].

interactions between the disperse dye and clay surfaces:

disperse dye molecules.

salt in modified clays.

on the other hand.

C for 5 min. With this process, the results indicate that the K/S value is en‐

Surface Modification Methods for Improving the Dyeability of Textile Fabrics

C for 40 min.

47

http://dx.doi.org/10.5772/53911

1:5:8 and the concentration of GPTMS was 0.05 mol/L. Fabric was dyed at 90o

meeting the needs of energy-saving and pollution-free processes.

*1.2.3. Application of nanoparticles for surface modification of fibers*

baked at 150o

**Figure 6.** Chemical formula of the substances of interest.

#### *1.2.2.2. An evaluation of the dyeing behavior of sol–gel silica doped with direct dyes*

Direct dyes are important dyes used on cellulose fiber directly. They can be applied in the same dyeing bath with other dyes. Moreover, the price is much lower than that of other dyes. However, several problems often occur in dyed fabric with direct dyes, such as lower washing and rubbing fastnesses. Some direct dyes perform rather poorly with respect to washing and rubbing fastnesses. They are mainly caused by the water-soluble groups, sul‐ phonic and/ or carboxyl groups. Without an appropriate treatment, direct dyes bleed a little with each washing, lose their color on fabric and endanger other clothes washed in the same bath. At present, copper salt fixing reagent and cationic fixing reagent are widely used in textile industry to improve the fastness by cross-linking reactions between metal ion or formaldehyde and other molecules. But metal ions in fixing reagent such as cupric cation (Cu2+) will aggravate the difficulty of waste processing. Also some reagents and intermedi‐ ates used in diazotization or crosslinking reactions such as formaldehyde, nitroaniline seri‐ ously affect the human health and the environment.

Moreover, the vividness after copper salt or diazotization finishing usually fades away, so that the application scope of direct dyes have been seriously limited in textile industry. A novel dyeing solution containing silica and direct dyes has been prepared by the sol–gel process. During this process, EtOH, tetraethoxysilane (TEOS), H2O and 3-glycidoxypropyl‐ trimethoxysilane (GPTMS) were added in turn. The molar ratio of TEOS:H2O:EtOH was 1:5:8 and the concentration of GPTMS was 0.05 mol/L. Fabric was dyed at 90o C for 40 min. The concentration of NaCl added into the dyeing solution was 10 g/L. The dyed fabrics were baked at 150o C for 5 min. With this process, the results indicate that the K/S value is en‐ hanced by more than 10%, the rubbing fastness and the washing change fastness are im‐ proved by one grade and the washing staining fastness is improved by half a grade. Not only is the K/S value enhanced from 9.3 to 11.5, but also the wet rubbing fastness and the washing change fastness are increased half a grade. Using a video microscope, a smoother fiber surface is observed. The calculated sol–gel weight gain is 4.6%. As a nonpolluting proc‐ ess, the sol–gel technology shortens the dyeing process and brings a better fixation property, meeting the needs of energy-saving and pollution-free processes.

### *1.2.3. Application of nanoparticles for surface modification of fibers*

APTES give rise to a moderate change of L\*. The after-treatment of dyed cotton fabrics with alkoxysilane causes almost no effect with respect to the colorimetric data. The direct incor‐ poration of the alkoxysilanes into the dyeing bath resulted in a reduction of the color prop‐ erties, when APTES or TESP-SA was employed. The crease-proof finishing treatment caused

an increase in the a\* value of red-dyed samples. [23]

46 Eco-Friendly Textile Dyeing and Finishing

**Figure 6.** Chemical formula of the substances of interest.

ously affect the human health and the environment.

*1.2.2.2. An evaluation of the dyeing behavior of sol–gel silica doped with direct dyes*

Direct dyes are important dyes used on cellulose fiber directly. They can be applied in the same dyeing bath with other dyes. Moreover, the price is much lower than that of other dyes. However, several problems often occur in dyed fabric with direct dyes, such as lower washing and rubbing fastnesses. Some direct dyes perform rather poorly with respect to washing and rubbing fastnesses. They are mainly caused by the water-soluble groups, sul‐ phonic and/ or carboxyl groups. Without an appropriate treatment, direct dyes bleed a little with each washing, lose their color on fabric and endanger other clothes washed in the same bath. At present, copper salt fixing reagent and cationic fixing reagent are widely used in textile industry to improve the fastness by cross-linking reactions between metal ion or formaldehyde and other molecules. But metal ions in fixing reagent such as cupric cation (Cu2+) will aggravate the difficulty of waste processing. Also some reagents and intermedi‐ ates used in diazotization or crosslinking reactions such as formaldehyde, nitroaniline seri‐

The dyeability of synthetic fibers depends on their physical and chemical structure. Dyeing process consist of three steps including the diffusion of dye through the aqueous dye bath on to the fiber, the adsorption of dye into the outer layer of the fiber and the diffusion of dye from the adsorbed surface into the fiber interior. It was shown by researchers that functional groups of PET and water molecules play a great role in this process. The terminal carboxylic and hydroxyl groups in PET chains interact with water molecules. This makes a swelled fi‐ ber resulting to increase the attraction of disperse dye by these functional groups of fiber.

The proportion of crystalline and amorphous regions of polymer is another factor influencing the dyeability. Researchers are concerned with the development and implementation of new techniques in order to fulfill improvement in dyeability of various polymers. Blending of poly‐ meric fibers with nanoclays as inexpensive materials is still claimed as cost effective method to enhance dyeability. Up to now, only two research articles are focused on dyeing properties of polypropylene- and polyamide 6- layered clay incorporated nanocomposites prepared by melt compounding. Toshniwal et al. suggested that polypropylene fibers could be made dyeable with disperse dyes by addition of nanoclay particles in polymer matrix [25].

The previous study on dyeability of PET/clay nanocomposites stated the following type of interactions between the disperse dye and clay surfaces:


## *1.2.4. Application of cyclodextrins in textile dyeing*

Cyclodextrins can be considered as a new class of auxiliary substances for the textile indus‐ try. Cyclodextrins can be used for textile application because of their natural origin and their biodegradability. Cyclodextrins play on important role in textile scientific research area and should play a significant role in the textile industry as well to remove or substitute various auxiliaries or to prepare textile materials containing molecular capsules which can immobi‐ lize perfumes, trap unpleasant smells, antimicrobial reagents and flame retardants. As cyclo‐ dextrins can incorporate different dyes into their cavity, they should be able to act as retarders in a dyeing process. Various auxiliary products are used in wet finishing process‐ es, especially in dyeing and washing. One of the dyeing auxiliary products are leveling agent. Leveling agents help to achieve uniform dyeing by slowing down the dye exhaustion or by dispersing the dye taken by the fibre in a uniform way. They can be classified into two groups: agents having affinity to the dye and agents having affinity to the fibre. Agents hav‐ ing affinity to the dyes slow down the dyeing process by forming complexs with the dyes. The complex compound moves slower compared to the dye itself; at higher temperature the dye is released and it can be fixed to the fibre. Application of cyclodextrins as leveling agents having affinity to dyestuffs has been investigated in research work about dyeing of cellulose fibres with direct dyes by exhaust method where β-cyclodextrin was tested as a dye complexing agent. cyclodextrins as a dye retardant in the dyeing of PAN fibres with cat‐ ionic dyes was studied; further it was reported that some azo disperse dyes formed inclu‐ sion complexes with cyclodextrins. [26]

In similar research work, Jocic and his coworkers assessed the interactions that could occur during dyeing of the chitosan treated wool fibres, by measuring the absorbance values of the solutions containing dye and chitosan. It has been shown that there is a 1:1 stoichiometry between protonated amino groups and sulfonate acid groups on the dye ions in low concen‐ trated chitosan solutions. This interaction forms an insoluble chitosan/dye product. With the excess of chitosan in the solution, the dye can be distributed between the different chitosan molecules and the soluble chitosan/dye products remain in the solution. It is suggested that the mechanism of the interaction involves the possibility of adsorbed dye molecules to be desorbed and redistributed between other components present in the system, depending on system parameters (pH, temperature and electrolyte presence). This fact is important in ex‐ planation of dyeing behaviour of chitosan treated wool and enables the assessment of the

Surface Modification Methods for Improving the Dyeability of Textile Fabrics

http://dx.doi.org/10.5772/53911

49

Also Kitkulnumchai et al, showed that, the KIO4 oxidation of cellulose fabrics created more aldehydic groups on the fabric surface and the following reductive ammination with chito‐ san afforded stable C–N bonds between cellulose and chitosan chains. The attachment of chitosan to the fabric considerably improved dye uptake of mono chlorotriazine and vinyl

The enhanced dyeability of the modified fabric is likely resulted from the reduction of the coulombic repulsion between the fabric surface and the anionic dye molecules in the pres‐ ence of the positively charged chitosan on the surface. The oxidation step can cause some drop in the fabric strength. This oxidation reductive amination with chitosan is thus a con‐ venient method for modifying the surface activity of cellulose fabrics whereas the fabric

In another research, Cotton fabrics have been successfully dyed by green tea extract upon chitosan mordanting, and UV protection property of the chitosan mordanted green tea dyed

**1.** Chitosan mordanting can effectively increase the ΔE and the K/S, that is, the dyeing effi‐ ciency of green tea dyeing onto cotton fabrics. As chitosan concentration increased, the

**2.** Chitosan mordanting can effectively increase the UV protection property of both UV-A and UV-B of green tea dyed cotton fabrics. Chitosan mordanted undyed cotton and chi‐ tosan unmordanted dyed cotton did not show an increase in UV protection property. Therefore, it can be assumed that chitosan increased the uptake of active moiety, cate‐ chin, in green tea, which would be responsible for the UV protection and subsequently increased UV protection property of the chitosan mordanted green tea dyed fabric. **3.** As chitosan mordanting concentration increased, UV protection property increased in

Around 7% UV protection increase from control was observed upon chitosan mordanting, which is similar value of the green tea dyed cellulose fabric using a specific metal mordant.

ΔE and the K/S of cotton fabrics by green tea extract increased gradually.

sulfone reactive dyes resulting in greater dye exhaustion and the color yield (K/S).

mechanism of dyeing of accordingly modified textile fibres [29].

The following conclusions have been made from this study;

strength is not of the great priority.[30]

cotton was increased.

both UV-A and UV-B.

#### *1.2.5. Chitosan applications in textile dyeing*

Nowadays, the surface modification of textile fibres is considered as the best route to obtain modern textile treatments.

Among various available biopolymers, the polysaccharide chitosan (CHT) is highly recom‐ mendable, since it shows unique chemical and biological properties and its solubility in acidic solutions makes it easily available for industrial purposes. The polysaccharide-based cationic biopolymer chitosan is poly(1,4)-2-amino-2-deoxy-b-D-glucan, usually obtained by deacetylation of chitin that is widely present in the nature as a component of some fungi, exoskeleton of insects and marine invertebrates (crabs and shrimp). The chemistry of chito‐ san is similar to that of cellulose, but it reflects also the fact that the 2-hydroxyl group of the cellulose has been replaced with a primary aliphatic amino group. Among many other uses, it has been recently shown that chitosan improves the dye coverage of immature fibres in cotton dyeing and that it could be successfully used as a thickener and binder in pigment printing of cotton.

Also Gupta et al showed that, chitosan treated cotton has better dyeability with direct and reactive dyes and treatment with modified chitosan makes it possible to dye cotton in bright shades with cationic dyes having high wash fastness. Treated samples showed good antimi‐ crobial activity against Escherichia coli and Staphylococcus aureus at 0.1% concentration as well as improved wrinkle recovery. [28]

In similar research work, Jocic and his coworkers assessed the interactions that could occur during dyeing of the chitosan treated wool fibres, by measuring the absorbance values of the solutions containing dye and chitosan. It has been shown that there is a 1:1 stoichiometry between protonated amino groups and sulfonate acid groups on the dye ions in low concen‐ trated chitosan solutions. This interaction forms an insoluble chitosan/dye product. With the excess of chitosan in the solution, the dye can be distributed between the different chitosan molecules and the soluble chitosan/dye products remain in the solution. It is suggested that the mechanism of the interaction involves the possibility of adsorbed dye molecules to be desorbed and redistributed between other components present in the system, depending on system parameters (pH, temperature and electrolyte presence). This fact is important in ex‐ planation of dyeing behaviour of chitosan treated wool and enables the assessment of the mechanism of dyeing of accordingly modified textile fibres [29].

Also Kitkulnumchai et al, showed that, the KIO4 oxidation of cellulose fabrics created more aldehydic groups on the fabric surface and the following reductive ammination with chito‐ san afforded stable C–N bonds between cellulose and chitosan chains. The attachment of chitosan to the fabric considerably improved dye uptake of mono chlorotriazine and vinyl sulfone reactive dyes resulting in greater dye exhaustion and the color yield (K/S).

The enhanced dyeability of the modified fabric is likely resulted from the reduction of the coulombic repulsion between the fabric surface and the anionic dye molecules in the pres‐ ence of the positively charged chitosan on the surface. The oxidation step can cause some drop in the fabric strength. This oxidation reductive amination with chitosan is thus a con‐ venient method for modifying the surface activity of cellulose fabrics whereas the fabric strength is not of the great priority.[30]

In another research, Cotton fabrics have been successfully dyed by green tea extract upon chitosan mordanting, and UV protection property of the chitosan mordanted green tea dyed cotton was increased.

The following conclusions have been made from this study;

*1.2.4. Application of cyclodextrins in textile dyeing*

48 Eco-Friendly Textile Dyeing and Finishing

sion complexes with cyclodextrins. [26]

*1.2.5. Chitosan applications in textile dyeing*

well as improved wrinkle recovery. [28]

modern textile treatments.

printing of cotton.

Cyclodextrins can be considered as a new class of auxiliary substances for the textile indus‐ try. Cyclodextrins can be used for textile application because of their natural origin and their biodegradability. Cyclodextrins play on important role in textile scientific research area and should play a significant role in the textile industry as well to remove or substitute various auxiliaries or to prepare textile materials containing molecular capsules which can immobi‐ lize perfumes, trap unpleasant smells, antimicrobial reagents and flame retardants. As cyclo‐ dextrins can incorporate different dyes into their cavity, they should be able to act as retarders in a dyeing process. Various auxiliary products are used in wet finishing process‐ es, especially in dyeing and washing. One of the dyeing auxiliary products are leveling agent. Leveling agents help to achieve uniform dyeing by slowing down the dye exhaustion or by dispersing the dye taken by the fibre in a uniform way. They can be classified into two groups: agents having affinity to the dye and agents having affinity to the fibre. Agents hav‐ ing affinity to the dyes slow down the dyeing process by forming complexs with the dyes. The complex compound moves slower compared to the dye itself; at higher temperature the dye is released and it can be fixed to the fibre. Application of cyclodextrins as leveling agents having affinity to dyestuffs has been investigated in research work about dyeing of cellulose fibres with direct dyes by exhaust method where β-cyclodextrin was tested as a dye complexing agent. cyclodextrins as a dye retardant in the dyeing of PAN fibres with cat‐ ionic dyes was studied; further it was reported that some azo disperse dyes formed inclu‐

Nowadays, the surface modification of textile fibres is considered as the best route to obtain

Among various available biopolymers, the polysaccharide chitosan (CHT) is highly recom‐ mendable, since it shows unique chemical and biological properties and its solubility in acidic solutions makes it easily available for industrial purposes. The polysaccharide-based cationic biopolymer chitosan is poly(1,4)-2-amino-2-deoxy-b-D-glucan, usually obtained by deacetylation of chitin that is widely present in the nature as a component of some fungi, exoskeleton of insects and marine invertebrates (crabs and shrimp). The chemistry of chito‐ san is similar to that of cellulose, but it reflects also the fact that the 2-hydroxyl group of the cellulose has been replaced with a primary aliphatic amino group. Among many other uses, it has been recently shown that chitosan improves the dye coverage of immature fibres in cotton dyeing and that it could be successfully used as a thickener and binder in pigment

Also Gupta et al showed that, chitosan treated cotton has better dyeability with direct and reactive dyes and treatment with modified chitosan makes it possible to dye cotton in bright shades with cationic dyes having high wash fastness. Treated samples showed good antimi‐ crobial activity against Escherichia coli and Staphylococcus aureus at 0.1% concentration as


Around 7% UV protection increase from control was observed upon chitosan mordanting, which is similar value of the green tea dyed cellulose fabric using a specific metal mordant. Therefore, it can be concluded that green tea dyeing can be used in developing UV protec‐ tive cotton textiles, and the chitosan mordanting process would be necessary in green tea dyeing of cotton to increase not only the dyeing efficiency but also the UV protection prop‐ erty of cotton fabrics. [31]

[8] L'. ˇCern´akov´a, D. Kov´aˇcik, A. Zahoranov´a M. ˇCern´ak, and M. Maz´ur, Surface Modification of Polypropylene Non-Woven Fabrics by Atmospheric-Pressure Plasma Activation Followed by Acrylic Acid Grafting Plasma Chemistry and Plasma Proc‐

Surface Modification Methods for Improving the Dyeability of Textile Fabrics

http://dx.doi.org/10.5772/53911

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[9] Nebojša Risti , Petar Jovan i , Cristina Canal, and Dragan Joci, One-bath One-dye Class Dyeing of PES/Cotton Blends after Corona and Chitosan Treatment , Fibers

[10] Alejandro Patin˜o Cristina Canal Cristina Rodrı´guez Gabriel Caballero Antonio Navarro Jose´ Ma Canal, Surface and bulk cotton fibre modifications: plasma and cat‐ ionization. Influence on dyeing with reactive dye Cellulose (2011) 18:1073–1083

[11] Darinka Fakin, Alenka Ojstrsˇek, Sonja Cˇ elan Benkovicˇ The impact of corona modi‐ fied fibres' chemical changes on wool dyeing, journal of materials processing tech‐

[12] Javed, I., Bhatti, I.A., Adeel, S., 2008.Effect of UV radiation on dyeing of cotton fabric with extracts of henna leaves. Indian Journal of fiber and textile research, 33,157-162.

[13] Eun-Min Kim and Jinho Jang , Surface Modification of Meta-aramid Films by UV/

[14] Hongje Kim and Jin-Seok Bae, Modification of Polypropylene Fibers by Electron Beam Irradiation. I.Evaluation of Dyeing Properties Using Cationic Dyes Fibers and

[15] Joanne Yip Kwong Chan Kwan Moon Sin Kai Shui Lau, UV Excimer laser modifica‐ tion on polyamide materials: effect on the dyeing properties, Mat Res Innovat (2002)

[16] Martin Bide, Matthew Phaneuf, Philip Brown, Geraldine McGonigle, and Frank Lo‐ Gerfo, MODIFICATION OF POLYESTER FOR MEDICAL USES, Modified Fibers

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[23] Yunjie Yin , Chaoxia Wang , Chunying Wang, An evaluation of the dyeing behavior of sol–gel silica doped with direct dyes , J Sol-Gel Sci Technol (2008) 48:308–314

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