**1. Introduction**

Polymer and textiles have a vast number of advantages and attractiveness as a material. However, despite these advantageous, polymers have limitations. In general, special surface properties with regard to chemical composition, hydrophilicity, roughness, crystallinity, conductivity, lubricity, and cross-linking density are required for successful application of polymers in such wide fields as adhesion, membrane filtration, coatings, friction and wear, composites, microelectronic devices, thin-film technology and biomaterials, and so on. Un‐ fortunately, polymers very often do not possess the surface properties needed for these ap‐ plications. In fact, polymeric fibers that are mechanically strong, chemically stable, and easy to process usually will have inert surfaces both chemically and biologically. Vice versa, those polymers having active surfaces usually do not possess excellent mechanical proper‐ ties which are critical for their successful application.

Due to this dilemma, surface modification of the polymeric fibers without changing the bulk properties has been a classical research topic for many years, and is still extensive studies as new applications of polymeric materials emerge, especially in the fields of biotechnology, bi‐ oengineering, and most recently in nanotechnology.

Modification is used to designate a deliberate change in composition or structure leading to an improvement in different type of fiber properties.

The challenge is, however, that there does not exist an ideal modification that eliminates all the negative properties and preserves all the positive properties of the fibers. This is why there are a great number of different single-purpose modifications. [1]

© 2013 Shahidi et al.; licensee InTech. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2013 Shahidi et al.; licensee InTech. This is a paper distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

In spite of the great number of existing modification methods no consistent classification is available as yet. Some authors divide the methods into two groups depending on whether they involve changes in fiber composition (chemical modification) or changes in fiber struc‐ ture (physical modification).

ence enhances the durability of textile materials against washing, ultraviolet radiation, fric‐ tion, abrasion, tension and fading. Textile fibers typically undergo a variety of pretreatments before dyeing and printing is feasible. Nonetheless, these treatments still create undesirable process conditions which can result in increased waste production, unpleasant working conditions and higher energy consumption. Therefore reducing pollution in textile production is becoming of utmost importance for manufacturers worldwide. In coming years, the textile industry must implement sustainable technologies and develop environ‐

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35

Plasma is by far the most common form of matter. Plasma in the stars and in the tenuous space between them makes up over 99% of the visible universe and perhaps most of that

The coupling of electromagnetic power into a process gas volume generates the plasma me‐ dium comprising a dynamic mix of ions, electrons, neutrons, photons, free radicals, metastable excited species and molecular and polymeric fragments, the system overall being at room temperature. This allows the surface functionalisation of fibres and textiles without af‐ fecting their bulk properties. These species move under electromagnetic fields, diffusion gradients, etc. on the textile substrates placed in or passed through the plasma. This enables a variety of generic surface processes including surface activation by bond breaking to cre‐ ate reactive sites, grafting of chemical moieties and functional groups, material volatilisation and removal (etching), dissociation of surface contaminants/layers (cleaning/ scouring) and deposition of conformal coatings. In all these processes a highly surface specific region of the material is given new, desirable properties without negatively affecting the bulk proper‐

Plasmas are acknowledged to be uniquely effective surface engineering tools due to:

**•** Their non-equilibrium nature, offering new material and new research areas.

**•** Their unparalleled physical, chemical and thermal range, allowing the tailoring of surface

mentally safer methods for textiles processing to remain competitive. [4, 5]

**1.1. Physical methods for modification of textile fabrics**

*1.1.1. Plasma types and applications*

which is not visible.

ties of the constituent fibres.

**Plasma reactors**

Low-frequency (LF, 50–450 kHz)

Radio-frequency (RF, 13.56 or 27.12 MHz) Microwave (MW, 915 MHz or 2.45 GHz)

properties to extraordinary precision.

**•** Their low temperature, thus avoiding sample destruction.

Different types of power supply to generate the plasma are:

**•** Their dry, environmentally friendly nature. [5, 6]

Surface modification of polymers has become an important research area in the plastic in‐ dustry. Because polymers are inert materials and usually have a low surface energy, they often do not possess the surface properties needed to meet the demands of various applica‐ tions. Advances in surface treatment have been made to rather chemical and physical prop‐ erties of polymer surfaces without affecting bulk properties. Technologies such as surface modifications, which convert inexpensive materials into valuable finished goods, will be‐ come even more important in the future as material cost becomes a significant factor in de‐ termining the success of an industry. [2]

There are a few factors to consider when modifying a surface:


This review is focused on the application of recent methods for the modification of textiles using physical methods (corona discharge, plasma, laser, electron beam and neutron irradia‐ tions, Ion beam), chemical methods (ozone-gas treatment, surface grafting, enzymatic modi‐ fication, sol-gel technique, micro-encapsulation method and treatment with different reagents). Nowadays, surface functionalization of synthetic fibers for various applications is considered as one of the best methods for modern textile finishing processes especially for improving the dyeability of fabrics. [3] Combination of physical technologies and nano-sci‐ ence enhances the durability of textile materials against washing, ultraviolet radiation, fric‐ tion, abrasion, tension and fading. Textile fibers typically undergo a variety of pretreatments before dyeing and printing is feasible. Nonetheless, these treatments still create undesirable process conditions which can result in increased waste production, unpleasant working conditions and higher energy consumption. Therefore reducing pollution in textile production is becoming of utmost importance for manufacturers worldwide. In coming years, the textile industry must implement sustainable technologies and develop environ‐ mentally safer methods for textiles processing to remain competitive. [4, 5]

### **1.1. Physical methods for modification of textile fabrics**

## *1.1.1. Plasma types and applications*

In spite of the great number of existing modification methods no consistent classification is available as yet. Some authors divide the methods into two groups depending on whether they involve changes in fiber composition (chemical modification) or changes in fiber struc‐

Surface modification of polymers has become an important research area in the plastic in‐ dustry. Because polymers are inert materials and usually have a low surface energy, they often do not possess the surface properties needed to meet the demands of various applica‐ tions. Advances in surface treatment have been made to rather chemical and physical prop‐ erties of polymer surfaces without affecting bulk properties. Technologies such as surface modifications, which convert inexpensive materials into valuable finished goods, will be‐ come even more important in the future as material cost becomes a significant factor in de‐

**1.** Thickness of the surface is crucial. Thin surface modifications are desirable, otherwise mechanical and functional properties of the material will be altered. This is more so

**2.** Sufficient atomic or molecular mobility must exist for surface changes to occur in rea‐ sonable periods of time. The driving force for the surface changes is the minimization of

**3.** Stability of the altered surface is essential, achieved by preventing any reversible reac‐ tion. This can be done by cross-linking and/or incorporating bulky groups to prevent

**4.** In some cases a transparent scaffold is desired, especially in optical sensors or ophthal‐ mology; after surface treatment they should remain transparent. Any cloudiness intro‐

**5.** Uniformity, reproducibility, stability, process control, speed, and reasonable cost should be considered in the overall process of surface modification. The ability to ach‐ ieve uniform surface treatment of complex shapes and geometries can be essential for

**6.** Precise control over functional groups. This is a challenging yet difficult scope. Many functional groups might bond to the surface such as hydroxyl, ether, carbonyl, carbox‐

This review is focused on the application of recent methods for the modification of textiles using physical methods (corona discharge, plasma, laser, electron beam and neutron irradia‐ tions, Ion beam), chemical methods (ozone-gas treatment, surface grafting, enzymatic modi‐ fication, sol-gel technique, micro-encapsulation method and treatment with different reagents). Nowadays, surface functionalization of synthetic fibers for various applications is considered as one of the best methods for modern textile finishing processes especially for improving the dyeability of fabrics. [3] Combination of physical technologies and nano-sci‐

yl, and carbonate groups, instead of one desired functional group.

when dealing with nanofibers as there is less bulk material present.

ture (physical modification).

34 Eco-Friendly Textile Dyeing and Finishing

termining the success of an industry. [2]

the interfacial energy.

duced is of real concern.

surface structures from moving.

sensor and biomedical applications.

There are a few factors to consider when modifying a surface:

Plasma is by far the most common form of matter. Plasma in the stars and in the tenuous space between them makes up over 99% of the visible universe and perhaps most of that which is not visible.

The coupling of electromagnetic power into a process gas volume generates the plasma me‐ dium comprising a dynamic mix of ions, electrons, neutrons, photons, free radicals, metastable excited species and molecular and polymeric fragments, the system overall being at room temperature. This allows the surface functionalisation of fibres and textiles without af‐ fecting their bulk properties. These species move under electromagnetic fields, diffusion gradients, etc. on the textile substrates placed in or passed through the plasma. This enables a variety of generic surface processes including surface activation by bond breaking to cre‐ ate reactive sites, grafting of chemical moieties and functional groups, material volatilisation and removal (etching), dissociation of surface contaminants/layers (cleaning/ scouring) and deposition of conformal coatings. In all these processes a highly surface specific region of the material is given new, desirable properties without negatively affecting the bulk proper‐ ties of the constituent fibres.

Plasmas are acknowledged to be uniquely effective surface engineering tools due to:


#### **Plasma reactors**

Different types of power supply to generate the plasma are:

Low-frequency (LF, 50–450 kHz)

Radio-frequency (RF, 13.56 or 27.12 MHz)

Microwave (MW, 915 MHz or 2.45 GHz)

The power required ranges from 10 to 5000 watts, depending on the size of the reactor and the desired treatment.

of the benefits of the vacuum, cold-plasma method, while operating at atmospheric pres‐

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37

Cold plasmas can be used for various treatments such as: plasma polymerisation (gaseous monomers); grafting; deposition of polymers, chemicals and metal particles by suitable se‐

**1.** Surface reactions: Reactions between gas-phase species and surface species and reac‐ tions between surface species produce functional groups and cross-links, respectively, at the surface. Examples of these reactions include plasma treatment by argon, ammo‐ nia, carbon monoxide, carbon dioxide, fluorine, hydrogen, nitrogen dioxide, oxygen,

**2.** Plasma polymerization: The formation of a thin film on the surface of polymer via poly‐ merization of an organic monomer such as CH4, C2 H6, C2 F4, or C3 F6 in plasma. It in‐ volves reactions between gas-species, reactions between gas-phase species and surface

**3.** Etching: Materials are removed from a polymer surface by physical etching and chemi‐ cal reactions at the surface to form volatile products. Oxygen plasma and oxygen and fluorine-containing plasmas are frequently used for the etching of polymers. [6, 7]

Plasma treatment play very important role for improving the dyeing properties of textile

Polypropylene (PP) non-woven fabrics have been activated by an atmospheric-pressure plasma treatment using surface dielectric barrier discharge in N2 and ambient air. Subse‐ quently, the plasma activated samples were grafted using catalyst-free water solution of acrylic acid. Surface properties of the activated and polyacrylic acid post-plasma grafted non-woven were characterized by scanning electron microscopy, Fourier transform infra‐ red spectroscopy, electron spin resonance spectroscopy, surface energy and dyeability

The plasma activation in nitrogen plasma gas was more efficient than in air. Post-plasma surface grafting lead to a stable and homogeneous grafting of pAA onto PP non-woven fabrics, which made PP fabrics easily coloured by conventional water-soluble acid dye. Supposedly, peroxy radicals formed at a short ambient air exposure of the plasma activat‐ ed fabrics were responsible for initiating the grafting process. Regarding the surface per‐ oxy radicals generation, the nitrogen plasma gas was superior to ambient air and

*1.1.1.1. Surface modification of polypropylene non-woven fabrics by atmospheric-pressure plasma*

The grafted non-woven exhibit improved water transport and dyeing properties.

lection of gas and process parameters; plasma liquid deposition in vaporised form.

In general, reactions of gas plasmas with polymers can be classified as follows:

species, and reactions between surface species.

fabrics. Some of these improvements are discussed as follow.

*activation followed by acrylic acid grafting*

sure. [5]

and water.

measurements.

provided better grafting. [7-9]

#### **Low-pressure plasmas**

Low-pressure plasmas are a highly mature technology developed for the microelectronics industry. However, the requirements of microelectronics fabrication are not, in detail, com‐ patible with textile processing, and many companies have developed technology of low pressure reactors to achieve an effective and economically viable batch functionalisation of fibrous products and flexible web materials.

A vacuum vessel is pumped down to a pressure in the range of 10-2 to 10-3 mbar with the use of high vacuum pumps. The gas which is then introduced in the vessel is ionised with the help of a high frequency generator.

The advantage of the low-pressure plasma method is that it is a well controlled and repro‐ ducible technique.

#### **Atmospheric pressure plasmas**

The most common forms of atmospheric pressure plasmas are described below.

#### **Corona treatment**

Corona discharge is characterised by bright filaments extending from a sharp, high-voltage electrode towards the substrate. Corona treatment is the longest established and most wide‐ ly used plasma process; it has the advantage of operating at atmospheric pressure, the re‐ agent gas usually being the ambient air. Corona systems do have, in principle, the manufacturing requirements of the textile industry (width, speed), but the type of plasma produced cannot achieve the desired spectrum of surface functionalisations in textiles and nonwovens. In particular, corona systems have an effect only in loose fibres and cannot pen‐ etrate deeply into yarn or woven fabric so that their effects on textiles are limited and shortlived. Essentially, the corona plasma type is too weak. Corona systems also rely upon very small interelectrode spacing (1 mm) and accurate web positioning, which are incompatible with 'thick' materials and rapid, uniform treatment.

#### **Dielectric barrier discharge (silent discharge)**

The dielectric barrier discharge is a broad class of plasma source that has an insulating (die‐ lectric) cover over one or both of the electrodes and operates with high voltage power rang‐ ing from low frequency AC to 100 kHz. This results in non-thermal plasma and a multitude of random, numerous arcs form between the electrodes. However, these microdischarges are nonuniform and have potential to cause uneven treatment.

#### **Glow discharge**

Glow discharge is characterised as a uniform, homogeneous and stable discharge usually generated in helium or argon (and some in nitrogen). This is done, for example, by applying radio frequency voltage across two parallel-plate electrodes. Atmospheric Pressure Glow Discharge (APGD) offers an alternative homogeneous cold-plasma source, which has many of the benefits of the vacuum, cold-plasma method, while operating at atmospheric pres‐ sure. [5]

Cold plasmas can be used for various treatments such as: plasma polymerisation (gaseous monomers); grafting; deposition of polymers, chemicals and metal particles by suitable se‐ lection of gas and process parameters; plasma liquid deposition in vaporised form.

In general, reactions of gas plasmas with polymers can be classified as follows:

The power required ranges from 10 to 5000 watts, depending on the size of the reactor and

Low-pressure plasmas are a highly mature technology developed for the microelectronics industry. However, the requirements of microelectronics fabrication are not, in detail, com‐ patible with textile processing, and many companies have developed technology of low pressure reactors to achieve an effective and economically viable batch functionalisation of

A vacuum vessel is pumped down to a pressure in the range of 10-2 to 10-3 mbar with the use of high vacuum pumps. The gas which is then introduced in the vessel is ionised with the

The advantage of the low-pressure plasma method is that it is a well controlled and repro‐

Corona discharge is characterised by bright filaments extending from a sharp, high-voltage electrode towards the substrate. Corona treatment is the longest established and most wide‐ ly used plasma process; it has the advantage of operating at atmospheric pressure, the re‐ agent gas usually being the ambient air. Corona systems do have, in principle, the manufacturing requirements of the textile industry (width, speed), but the type of plasma produced cannot achieve the desired spectrum of surface functionalisations in textiles and nonwovens. In particular, corona systems have an effect only in loose fibres and cannot pen‐ etrate deeply into yarn or woven fabric so that their effects on textiles are limited and shortlived. Essentially, the corona plasma type is too weak. Corona systems also rely upon very small interelectrode spacing (1 mm) and accurate web positioning, which are incompatible

The dielectric barrier discharge is a broad class of plasma source that has an insulating (die‐ lectric) cover over one or both of the electrodes and operates with high voltage power rang‐ ing from low frequency AC to 100 kHz. This results in non-thermal plasma and a multitude of random, numerous arcs form between the electrodes. However, these microdischarges

Glow discharge is characterised as a uniform, homogeneous and stable discharge usually generated in helium or argon (and some in nitrogen). This is done, for example, by applying radio frequency voltage across two parallel-plate electrodes. Atmospheric Pressure Glow Discharge (APGD) offers an alternative homogeneous cold-plasma source, which has many

The most common forms of atmospheric pressure plasmas are described below.

the desired treatment. **Low-pressure plasmas**

36 Eco-Friendly Textile Dyeing and Finishing

ducible technique.

**Corona treatment**

**Glow discharge**

fibrous products and flexible web materials.

with 'thick' materials and rapid, uniform treatment.

are nonuniform and have potential to cause uneven treatment.

**Dielectric barrier discharge (silent discharge)**

help of a high frequency generator.

**Atmospheric pressure plasmas**


Plasma treatment play very important role for improving the dyeing properties of textile fabrics. Some of these improvements are discussed as follow.

## *1.1.1.1. Surface modification of polypropylene non-woven fabrics by atmospheric-pressure plasma activation followed by acrylic acid grafting*

Polypropylene (PP) non-woven fabrics have been activated by an atmospheric-pressure plasma treatment using surface dielectric barrier discharge in N2 and ambient air. Subse‐ quently, the plasma activated samples were grafted using catalyst-free water solution of acrylic acid. Surface properties of the activated and polyacrylic acid post-plasma grafted non-woven were characterized by scanning electron microscopy, Fourier transform infra‐ red spectroscopy, electron spin resonance spectroscopy, surface energy and dyeability measurements.

The grafted non-woven exhibit improved water transport and dyeing properties.

The plasma activation in nitrogen plasma gas was more efficient than in air. Post-plasma surface grafting lead to a stable and homogeneous grafting of pAA onto PP non-woven fabrics, which made PP fabrics easily coloured by conventional water-soluble acid dye. Supposedly, peroxy radicals formed at a short ambient air exposure of the plasma activat‐ ed fabrics were responsible for initiating the grafting process. Regarding the surface per‐ oxy radicals generation, the nitrogen plasma gas was superior to ambient air and provided better grafting. [7-9]

## *1.1.1.2. One-bath one-dye class dyeing of pes/cotton blends after corona and chitosan treatment*

blue metal-complex dyes, and dyeing behaviour were studied by means of on-line VIS spec‐ trophotometry. Finally, dyed samples were colourimetricaly evaluated and colour differen‐ ces were calculated. The results provided evidence that the overall carbon content was decreased while oxygen and nitrogen atoms were increased when using ionized air for fab‐ ric modification. It has also been noted that the amount of positive-charged functional groups in various pH ranges are higher for Corona-treated wool fabric in comparison with

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39

**Figure 1.** Effects of plasma and cationising processes in the surface functionalization of the cellulose constituting the

The surface performances of untreated and Corona-treated wool fabrics were studied both morphologically and chemically. Corona treatment is confirmed as inducing chemical and physical changes on the surface such as oxidizing/removing external fatty-acid monolayer, enlarging positively charged functional groups, creating new dyesites, and therefore, im‐

Corona treatment applied in the pre-treatment stages of wool production can lead to an op‐ timization of different dyeing procedures, implying lower dyeing temperatures and shorter dyeing time, achieving the same or even better colour exhaustion in comparison to conven‐ tional pre-treated wool fabric. For these reasons, the energy consumption can be reduced,

Ionization radiation such as high-energy electrons, X-rays, and gamma-rays can displace electrons from atoms and molecules, producing ions. It differs from other types of radiation such as infrared, visible, and UV in that it is highly energetic and delivers to the irradiated material a large amount of energy, much greater than that associated with chemical bonds. Common industrial ionization radiation sources are high-energy electrons (0.1-10 MeV) and

the untreated sample.

cotton fibre

proving the exhaustion rate during dyeing.

thus also enhancing environmental protection. [12]

*1.1.2. Surfaces modification with ionization radiation*

cobalt-60 sources, and gamma radiation.

The feasibility of one-bath one-dye class dyeing of PES/cotton blend with direct (Direct Red 80) or reactive (Reactive Red 3) dye after pre-treatment with corona discharge (CD) and chitosan has been investigated by Ristic and his coworkers. It has been confirmed that corona discharge treatment enhances hydrophilicity of cotton and PES fibers due to surface modification of the material and formation of C-O, C=O, and COOH groups. In‐ creased hydrophilicity of PES and cotton induced only slightly increased color intensity (K/S) with both dyes investigated. Nevertheless, subsequent treatment with biopolymer chitosan noticeably enhanced the color intensity obtained, especially with PES fiber. The dyeability improved proportionally with the concentration of chitosan treatment solutions. However, the highest values of color intensity were obtained for the PES/cotton fabric subjected to the combined CD and chitosan treatment, suggesting that CD pre-treatment enhances efficiency of chitosan application.

Satisfactory values of dye fastness and fixation degree of reactive dye were obtained. [10]

#### *1.1.1.3. Surface and bulk cotton fibre modifications: plasma and cationization. influence on dyeing with reactive dye*

In similar research work, the single or combined effects of corona air plasma and cationising with an epihalohydrin have been evaluated on the surface and dyeing properties of open‐ work twill cotton fabrics. Dyeing was performed with a hetero-bis functional reactive dye. Wetting properties of cotton fabrics were improved with a very short corona plasma treat‐ ment and a double side-effect was observed on the dyed fabric by contact angle analysis, be‐ cause of the low penetration of the plasma on the fabric. Exhaustion of the dye and colour intensity of the cotton fabrics were increased due to the plasma treatment. This is well ex‐ plained by the functionalisation of the surface with oxygenated moieties, without any signif‐ icant alteration in surface topography of the fibres. Cationising of the cotton fabrics using an epihalohydrin as cationising agent increases the exhaustion of the dyestuff as high as 90%, and produces a dramatic improvement (80% increase) in the colour intensity (K/Scorr) on both sides of the fabrics. The improvement in colour intensity of the cationised cotton fabrics can be explained taking into account that the hydrolised reactive dye has high anionic char‐ acter which can be bound to the cationic amine of the cationic agent on the cotton fabrics. It has been observed that plasma treatment previous to cationising increases the impregnation of the fabrics. [11]All theses possible effects are schematically represented in Figure 1.

#### *1.1.1.4. The impact of corona modified fibres' chemical changes on wool dyeing*

Corona/plasma treatment is an environmentally friendly process applied to wool fabrics. The main contribution of the present work was to study the impact of Corona on dyeability of wool fibers. First, the different chemical aspects of a woven wool fabric's surface were de‐ termined using two different analytical skills (XPS and polyelectrolyte titration).The results show that, low-temperature plasma treatment has ability to change wool fibre morphology which could have an impact on sorption properties. fabrics were dyed with blue acid and blue metal-complex dyes, and dyeing behaviour were studied by means of on-line VIS spec‐ trophotometry. Finally, dyed samples were colourimetricaly evaluated and colour differen‐ ces were calculated. The results provided evidence that the overall carbon content was decreased while oxygen and nitrogen atoms were increased when using ionized air for fab‐ ric modification. It has also been noted that the amount of positive-charged functional groups in various pH ranges are higher for Corona-treated wool fabric in comparison with the untreated sample.

**Figure 1.** Effects of plasma and cationising processes in the surface functionalization of the cellulose constituting the cotton fibre

The surface performances of untreated and Corona-treated wool fabrics were studied both morphologically and chemically. Corona treatment is confirmed as inducing chemical and physical changes on the surface such as oxidizing/removing external fatty-acid monolayer, enlarging positively charged functional groups, creating new dyesites, and therefore, im‐ proving the exhaustion rate during dyeing.

Corona treatment applied in the pre-treatment stages of wool production can lead to an op‐ timization of different dyeing procedures, implying lower dyeing temperatures and shorter dyeing time, achieving the same or even better colour exhaustion in comparison to conven‐ tional pre-treated wool fabric. For these reasons, the energy consumption can be reduced, thus also enhancing environmental protection. [12]

#### *1.1.2. Surfaces modification with ionization radiation*

*1.1.1.2. One-bath one-dye class dyeing of pes/cotton blends after corona and chitosan treatment*

enhances efficiency of chitosan application.

38 Eco-Friendly Textile Dyeing and Finishing

*with reactive dye*

The feasibility of one-bath one-dye class dyeing of PES/cotton blend with direct (Direct Red 80) or reactive (Reactive Red 3) dye after pre-treatment with corona discharge (CD) and chitosan has been investigated by Ristic and his coworkers. It has been confirmed that corona discharge treatment enhances hydrophilicity of cotton and PES fibers due to surface modification of the material and formation of C-O, C=O, and COOH groups. In‐ creased hydrophilicity of PES and cotton induced only slightly increased color intensity (K/S) with both dyes investigated. Nevertheless, subsequent treatment with biopolymer chitosan noticeably enhanced the color intensity obtained, especially with PES fiber. The dyeability improved proportionally with the concentration of chitosan treatment solutions. However, the highest values of color intensity were obtained for the PES/cotton fabric subjected to the combined CD and chitosan treatment, suggesting that CD pre-treatment

Satisfactory values of dye fastness and fixation degree of reactive dye were obtained. [10]

*1.1.1.3. Surface and bulk cotton fibre modifications: plasma and cationization. influence on dyeing*

*1.1.1.4. The impact of corona modified fibres' chemical changes on wool dyeing*

In similar research work, the single or combined effects of corona air plasma and cationising with an epihalohydrin have been evaluated on the surface and dyeing properties of open‐ work twill cotton fabrics. Dyeing was performed with a hetero-bis functional reactive dye. Wetting properties of cotton fabrics were improved with a very short corona plasma treat‐ ment and a double side-effect was observed on the dyed fabric by contact angle analysis, be‐ cause of the low penetration of the plasma on the fabric. Exhaustion of the dye and colour intensity of the cotton fabrics were increased due to the plasma treatment. This is well ex‐ plained by the functionalisation of the surface with oxygenated moieties, without any signif‐ icant alteration in surface topography of the fibres. Cationising of the cotton fabrics using an epihalohydrin as cationising agent increases the exhaustion of the dyestuff as high as 90%, and produces a dramatic improvement (80% increase) in the colour intensity (K/Scorr) on both sides of the fabrics. The improvement in colour intensity of the cationised cotton fabrics can be explained taking into account that the hydrolised reactive dye has high anionic char‐ acter which can be bound to the cationic amine of the cationic agent on the cotton fabrics. It has been observed that plasma treatment previous to cationising increases the impregnation of the fabrics. [11]All theses possible effects are schematically represented in Figure 1.

Corona/plasma treatment is an environmentally friendly process applied to wool fabrics. The main contribution of the present work was to study the impact of Corona on dyeability of wool fibers. First, the different chemical aspects of a woven wool fabric's surface were de‐ termined using two different analytical skills (XPS and polyelectrolyte titration).The results show that, low-temperature plasma treatment has ability to change wool fibre morphology which could have an impact on sorption properties. fabrics were dyed with blue acid and

Ionization radiation such as high-energy electrons, X-rays, and gamma-rays can displace electrons from atoms and molecules, producing ions. It differs from other types of radiation such as infrared, visible, and UV in that it is highly energetic and delivers to the irradiated material a large amount of energy, much greater than that associated with chemical bonds. Common industrial ionization radiation sources are high-energy electrons (0.1-10 MeV) and cobalt-60 sources, and gamma radiation.

Electron beams from 0.1 to several mega electron volts are used for high doses and high speeds in various industrial processes, with penetration up to several millimeters for poly‐ meric materials.

*1.1.2.3. Modification of polypropylene fibers by electron beam irradiation. i. evaluation of dyeing*

The dyeing properties of hydrophobic polypropylene fibers using cationic dyes were inves‐ tigated to improve dyeability by electron beam irradiation and sulfonic acid incorporation. The best dyeing result was obtained when polypropylene fibers incorporated by sulfonic acid group after electron beam irradiation were dyed with cationic dyes at alkaline condi‐ tions and 30~75 kGy irradiation ranges. In order to improve the dyeing properties of elec‐ tronic beam irradiated polypropylene, sulfonic acid group which has good reactivity was introduced on the fiber. To incorporate sulfonic acid with the electronic beam irradiated (70.5 kGy) polypropylene fiber, the fibers were added and reacted to the solution of 1,4-di‐

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41

In order to make hydrophobic polypropylene fibers dyeable, it was shown that functional group such as carboxylate was formed on fiber substrates by electronic beam irradiation.

Concerning the pH and amount of absorbed electronic beam irradiation, the color strength increased as pH increased in alkaline conditions, and also increased as the absorbed dose increased to 30~75 kGy. As a result, it was confirmed that the pH of the dyebath and the amount and the range of the absorbed irradiation could be important variables for color

In the case of polypropylene fibers incorporated by sulfonic acid group to improve dyeabili‐ ty, the introduction of sulfonic acid group was confirmed by ESCA analysis and it was judged that such introduction has some advantages in color strength over only electronic beam irradiated fibers. Finally, the wash fastness of dyed fabrics using cationic dyes showed satisfactory ratings of 4~5 on both electronic beam irradiated fibers and sulfonic acid incor‐

*properties using cationic dyes*

oxane and ClSO3H at 70 o

C (Figure 2).

**Figure 2.** Introduction of sulfone groups on electron beam irradiated PP.

strength but it seemed difficult to get deeper colors.

porated fibers. [15]

Surface modification by UV and IR lasers is useful in some specific applications. One key advantage of laser treatment is that the area to be treated can be very small and localized. Depending on the level of power chosen, ablation or chemical and physical changes can oc‐ cur. Various chemical changes occur on photon-irradiated polymer surfaces. When PTFE was irradiated with ArF laser at high fluencies, defluorination and surface oxidation occur‐ red. For polypropylene, formation of oxygen functional groups such as C-O and C=O groups was detected after UV laser irradiation in air and water, and in ozon. The treated surfaces were shown to have improved bond ability with an epoxy adhesive. The surface of poly(vinyl chloride) becomes electrically conductive after successive UV irradiation in chlor‐ ine and nitrogen and argon laser irradiation in air. These types of surface modification are very useful for increasing the dyeability of polymeric textile fabrics. [2] Some of irradiation dyeability modification is discussed below.
