**5. Plasma technology**

Faraday proposed to classify the matter in four states: solid, liquid, gas and radiant. Re‐ searches on the last form of matter started with the studies of Heinrich Geissler (1814-1879): the new discovered phenomena, different from anything previously observed, persuaded the scientists that they were facing with matter in a different state. Crookes took again the term "radiant matter" coined by Faraday to connect the radiant matter with residual mole‐ cules of gas in a low-pressure tube. Sufficient additional energy, supplied to gases by an electric field, creates plasma [62]. The plasma is referred to as the fourth state of matter (in addition to solid, liquid, gaseous) [63].

**Figure 8.** States of matter [64]

lowness index, and weight loss. The beneficial effects of this treatment on dyeability, color parameters, light fastness characteristics, and the change in color difference after exposure of the treated dyed samples to artificial daylight for about 150 hours were investigated. The results indicated that the improvement in wetting processes may have been due to surface modifications; this meant that an increase in the amorphousity of the treated samples, the oxidation of the cystine linkage on the surface of the fabrics, and the formation of free-radi‐

*Sargunamani and Selvakumar (2007)* investigated the effects of process parameters (pick-up value, pH and time) in the ozone treatment of raw and degummed tassar silk fabrics on their properties such as yellowness index, breaking strength, breaking elongation, weight, amino group content. Decrease in yellowness index, breaking strength, breaking elongation,

*Perincek et.al (2008)* investigated a novel bleaching technique for Angora rabbit fiber. For this purpose, a detailed investigation on the role of the fiber moisture, pH, and treatment time during ozonation was carried out. Also, the effect of ozonation on the dyeing properties of Angora rabbit fibers was researched. Consequently, it was found that ozonation improved

*Atav and Yurdakul (2010)* investigated the use of ozonation to achieve dyeability of the angora fibers at lower temperatures without causing any decrease in dye uptake by modifying the fiber surfaces. The study was carried out with known concentration of ozone, involving process parameters such as wet pick-up (WP), pH, and treatment time. The effect of fiber ozonation was assessed in terms of color, and test samples were also evaluated using scanning electron microscopy (SEM). The optimum conditions of ozona‐ tion process were determined as WP 60%, pH 7 and 40 min. According to the experi‐ mental results it can be concluded that, ozonated angora fibers can be dyed at 90°C with acid and reactive dye classes without causing any decrease in color yield [61]. In an oth‐ er study on ozonation process carried out by *Atav and Yurdakul (2011)* the optimum con‐ ditions for mohair fiber were determined as WP 60%, pH 7 and 30 min. Dyeing kinetics also studied and it was demonstrated that the rate constant and the standard affinity of

Faraday proposed to classify the matter in four states: solid, liquid, gas and radiant. Re‐ searches on the last form of matter started with the studies of Heinrich Geissler (1814-1879): the new discovered phenomena, different from anything previously observed, persuaded the scientists that they were facing with matter in a different state. Crookes took again the term "radiant matter" coined by Faraday to connect the radiant matter with residual mole‐ cules of gas in a low-pressure tube. Sufficient additional energy, supplied to gases by an electric field, creates plasma [62]. The plasma is referred to as the fourth state of matter (in

and weight as well an increase in amino group content was observed [58].

the degree of whiteness and dyeability of Angora rabbit fiber [57].

cal species encouraged dye uptake [60].

116 Eco-Friendly Textile Dyeing and Finishing

ozonated sample increased [54].

addition to solid, liquid, gaseous) [63].

**5. Plasma technology**

The plasma is an ionized gas with equal density of positive and negative charges which ex‐ ist over an extremely wide range of temperature and pressure [65]. As shown in Fig. 9, the plasma atmosphere consists of free electrons, radicals, ions, UV-radiation and a lot of differ‐ ent excited particles in dependence of the used gas [66].

**Figure 9.** The principle of the plasma treatment [66]

There are different methodologies to induce the ionization of plasma gas for textile treat‐ ment [65]:

ma, that is, low-temperature plasma (LTP) treatment is the most commonly used physical method for a surface specific fiber modification, as it affects the surface both physically and chemically [72]. The advantage of such plasma treatments is that the modification turns out to be restricted in the uppermost layers of the substrate, thus not affecting the overall desira‐

The Use of New Technologies in Dyeing of Proteinous Fibers

http://dx.doi.org/10.5772/53912

119

The plasma gas particles etch on the fabric surface in nano scale so as to modify the func‐ tional properties of the fabric. Unlike conventional wet processes, which penetrate deeply into fibers, plasma only reacts with the fabric surface and does not affect the internal struc‐ ture of the fibers. Plasma technology modifies the chemical structure as well as the topogra‐ phy of the textile material surface. In conclusion, plasma can modify the surface properties of textile materials, deposit chemical materials (plasma polymerization) to add functionality, or remove substances (plasma etching) from the textile materials [65]. Essentially, four main

**•** The cleaning effect: It means the removal of impurities or substrate material from the ex‐ posed surface [73]. It is mostly combined with changes in the wettability and the surface

**•** Increase of microroughness: This affects, for example, an anti-pilling finishing of wool.

**•** Generation of radicals: Presence of free radicals induces secondary reactions like crosslinking. Furthermore, graft polymerization can be carried out as well as reaction with

**•** Plasma polymerization: In plasma polymerization, a monomer is introduced directly into the plasma and the polymerization occurs in the plasma itself [73]. It enables the deposi‐

When a surface is exposed to plasma a mutual interaction between the gas and the substrate takes place. The surface of the substrate is bombarded with ions, electrons, radicals, neutrals and UV radiation from the plasma while volatile components from the surface contaminate the plasma and become a part of it. Whatever may be the final outcome on the surface, the basic effect that causes modification is based on the *radical formation* (attachment of function‐ al group and deposition/polymerization) and *etching* phenomena. Fig. 10 illustrates the

Low temperature plasma treatment of wool has emerged as one of the environmental friendly surface modification method for wool substrate. The efficiency of the low tempera‐

ture plasma treatment is governed by several operational parameters like;

tion of solid polymeric materials with desired properties onto the substrates [66].

effects can be obtained depending on the treatment conditions;

texture. This leads for example to an increase in dye-uptake.

oxygen to generate hydrophilic surfaces [66].

mechanism of plasma modification [74].

**•** Nature of the gas used

**•** Duration of treatment

**•** System pressure

**•** Discharge power

ble bulk properties [62].


Practically, one generates the plasma by applying an electrical field over two electrodes with a gas in between. This can be carried out at atmospheric pressure or in a closed vessel under reduced pressure. In both cases, the properties of the plasma will be determined by the gas‐ ses used to generate the plasma, as well as by the applied electrical power and the electrodes (material, geometry, size, etc.). The pressure of the gas will have a large influence on the plasma properties but also on the type of equipment needed to generate the plasma [69].

The plasmas can be classified as being of the low pressure and atmospheric type. Both plas‐ mas can be used for the surface cleaning, surface activation, surface etching, cross linking, chain scission, oxidation, grafting, and depositing of materials, and generally similar effects are obtained; however, atmospheric plasma has many advantages when compared with vac‐ uum plasma [70]. *Low pressure plasmas* are typically in the pressure range of 0.01 kPa. A vac‐ uum chamber and the necessary vacuum pumps are required, which means that the investment cost for such a piece of equipment can be high. These plasmas are characterized by their good uniformity over a large volume. *Atmospheric plasmas* operate at standard at‐ mospheric pressure (~ 100 kPa). Open systems using the surrounding air exist. The range of processes is not as wide as for low pressure plasmas. On the other hand, these systems are easily integrated in existing finishing lines, a major advantage from industrial view point. Of course, for an inline process to be feasible, the plasma treatment has to be done at suffi‐ ciently high line speeds, which is not evident for textile materials [69].

Due to increasing requirements on the finishing of textile fabrics, increasing use of technical textiles with synthetic fibers, as well as the market and society demand for textiles that have been processed by environmentally sound methods, new innovative production techniques are demanded [66]. Plasma technology is an important alternative to wet treatments, be‐ cause there is no water usage, treatment is carried out in gas phase, short treatment time is enough, it does not cause industrial waste, and it provides energy saving [71]. In Cold plas‐ ma, that is, low-temperature plasma (LTP) treatment is the most commonly used physical method for a surface specific fiber modification, as it affects the surface both physically and chemically [72]. The advantage of such plasma treatments is that the modification turns out to be restricted in the uppermost layers of the substrate, thus not affecting the overall desira‐ ble bulk properties [62].

The plasma gas particles etch on the fabric surface in nano scale so as to modify the func‐ tional properties of the fabric. Unlike conventional wet processes, which penetrate deeply into fibers, plasma only reacts with the fabric surface and does not affect the internal struc‐ ture of the fibers. Plasma technology modifies the chemical structure as well as the topogra‐ phy of the textile material surface. In conclusion, plasma can modify the surface properties of textile materials, deposit chemical materials (plasma polymerization) to add functionality, or remove substances (plasma etching) from the textile materials [65]. Essentially, four main effects can be obtained depending on the treatment conditions;


When a surface is exposed to plasma a mutual interaction between the gas and the substrate takes place. The surface of the substrate is bombarded with ions, electrons, radicals, neutrals and UV radiation from the plasma while volatile components from the surface contaminate the plasma and become a part of it. Whatever may be the final outcome on the surface, the basic effect that causes modification is based on the *radical formation* (attachment of function‐ al group and deposition/polymerization) and *etching* phenomena. Fig. 10 illustrates the mechanism of plasma modification [74].

Low temperature plasma treatment of wool has emerged as one of the environmental friendly surface modification method for wool substrate. The efficiency of the low tempera‐ ture plasma treatment is governed by several operational parameters like;


There are different methodologies to induce the ionization of plasma gas for textile treat‐

**•** Glow Discharge: It is the oldest type of plasma; it is produced at reduced pressure and assures the highest possible uniformity and flexibility of any plasma treatment [67]. The methodology applies direct electric current, low frequency over a pair of electrodes [65]. Alternatively, a vacuum glow discharge can be made by using microwave (GHz) power

**•** Corona Discharge: It is formed at atmospheric pressure by applying a low frequency or pulsed high voltage over an electrode pair [65]. Typically, both electrodes have a large difference in size. The corona consists of a series of small lightning-type discharges. High local energy levels and problems related to the homogeneity of the classical corona treat‐

**•** Dielectric-Barrier Discharge: DBD is produced by applying a pulsed voltage over an elec‐ trode pair of which at least one is covered by a dielectric material [65]. Although light‐ ning-type discharges are created, a major advantage over corona discharges is the

Practically, one generates the plasma by applying an electrical field over two electrodes with a gas in between. This can be carried out at atmospheric pressure or in a closed vessel under reduced pressure. In both cases, the properties of the plasma will be determined by the gas‐ ses used to generate the plasma, as well as by the applied electrical power and the electrodes (material, geometry, size, etc.). The pressure of the gas will have a large influence on the plasma properties but also on the type of equipment needed to generate the plasma [69].

The plasmas can be classified as being of the low pressure and atmospheric type. Both plas‐ mas can be used for the surface cleaning, surface activation, surface etching, cross linking, chain scission, oxidation, grafting, and depositing of materials, and generally similar effects are obtained; however, atmospheric plasma has many advantages when compared with vac‐ uum plasma [70]. *Low pressure plasmas* are typically in the pressure range of 0.01 kPa. A vac‐ uum chamber and the necessary vacuum pumps are required, which means that the investment cost for such a piece of equipment can be high. These plasmas are characterized by their good uniformity over a large volume. *Atmospheric plasmas* operate at standard at‐ mospheric pressure (~ 100 kPa). Open systems using the surrounding air exist. The range of processes is not as wide as for low pressure plasmas. On the other hand, these systems are easily integrated in existing finishing lines, a major advantage from industrial view point. Of course, for an inline process to be feasible, the plasma treatment has to be done at suffi‐

Due to increasing requirements on the finishing of textile fabrics, increasing use of technical textiles with synthetic fibers, as well as the market and society demand for textiles that have been processed by environmentally sound methods, new innovative production techniques are demanded [66]. Plasma technology is an important alternative to wet treatments, be‐ cause there is no water usage, treatment is carried out in gas phase, short treatment time is enough, it does not cause industrial waste, and it provides energy saving [71]. In Cold plas‐

ciently high line speeds, which is not evident for textile materials [69].

ment of textiles make it problematic in many cases [68].

improved textile treatment uniformity [68].

ment [65]:

supply [68].

118 Eco-Friendly Textile Dyeing and Finishing


Plasma treatment can impart anti-felting effect, degreasing, improved dyestuff absorption and increased wetting properties to wool fibers [68]. These effects of the plasma process are attributed to several changes in the wool surface, such as;

depth of shade are increased. In literature there are many studies related to the effect of plasma treatment on dyeability of proteinous fibers. Some of them are summarized below.

The Use of New Technologies in Dyeing of Proteinous Fibers

http://dx.doi.org/10.5772/53912

121

*Wakida et al. (1993)* treated the merino wool top with low-temperature plasmas of helium/ argon and acetone/argon under atmospheric pressure for 30 seconds and then dyed with two leveling acid dyes, and two milling acid dyes. Dyeing rate and final dye uptake in‐ creased with the atmospheric low-temperature plasma treatments. In particular, helium/ argon plasma was found to be much more effective than acetone/argon plasma at improving

*Yoon et al. (1996)* treated the wool fabrics with low temperature oxygen plasma and exam‐ ined their mechanical and dyeing properties. Plasma pretreatment caused an increase in strength. Furthermore, it was observed that when wool was dyed with a leveling acid dye, equilibrium dye uptake did not change, but the dyeing rate increased with a milling acid

*Jing (1996)* investigated the surface modification of silk fabric by plasma graft copolymeriza‐ tion with acrylamide and acrylic acid. The dependence of graft degree was examined on the conditions of plasma grafting. The relationships were discussed between graft degree and factors such as crease recovery, dyeability, colour fastness and mechanical properties. It was shown that the dyeability and color fastness have been improved for samples grafted with

*Wakida et al. (1996)* treated wool fibers with oxygen low-temperature plasma and then dyed with acid and basic dyes. Despite the increase of electronegativity of the fiber surface caused by the plasma treatment, the rate of dyeing of wool was increased with both dyes [80].

*Wakida et al. (1998)* treated wool fabrics with oxygen, carbon tetrafluoride, and ammonia low temperature plasmas and then dyed with several natural dyes. The dyeing rate of the plas‐ ma-treated wool increased considerably with cochineal, Chinese cork tree, and madder, but not with gromwell. Furthermore, plasma-treated wool fabrics dyed with cochineal and Chi‐

*Kan et al. (1998)* investigated the induced surface properties of wool fabrics created by the sputtering of low-temperature plasma treatment, such as surface luster, wettability, surface electrostatic and dyeability. After the low-temperature plasma treatment, the treated wool fabric specimens exhibited better hydrophilicity and surface electrostatic properties at room temperature, together with improved dyeing rate. The occurrence of some grooves on the fiber specimens was determined by scanning electron microscope and it was stated that

*Kan et al. (1998)* treated the wool fiber with low-temperature plasma (LTP) using different non-polymerising gases and dyed with chrome dye. The rate of dyeing, the time of half-dye‐ ing (t1/2), the final dye uptake, the chromium exhaustion and the chromium fixation were studied. The results showed that LTP treatments can alter the dyeing properties to various degrees. The nature of the LTP gases plays an important role in affecting the behavior of

nese cork tree have increased brightness compared with untreated wool [81].

these grooves might possibly provide a pathway for a faster dyeing rate [82].

dyeing properties [77].

dye [78].

acrylic acid [79].

chrome dyeing [83].


**Figure 10.** Mechanism of plasma-substrate interaction [74]

Plasma treatments modify the fatty acid monolayer present in the outermost part of the wool fiber, generating new hydrophilic groups as a result of the hydrocarbon chain oxida‐ tion and reducing the fatty acid chain length. The oxidation process also promotes the for‐ mation of Bunte salt and cysteic acid residues on the polypeptide chain. Particularly when oxidizing gasses are used, plasma induces cystine oxidation in the A-layer of the exocuticle, converting it into cysteic acid and thus reducing the number of crosslinkages in the fiber surface [72]. As the surface is oxidized, the hydrophobic character is changed to become in‐ creasingly hydrophilic [76]. The etching of the hydrophobic epicuticle and increase in sur‐ face area also contributes towards the improvement in the ability of the fibers to wet more easily [74].

Plasma treatment of wool fibers causes improvement in dyeability of wool fibers due to the changes occurred on fiber surface. For this reason dyeing kinetics, dye uptake and hence depth of shade are increased. In literature there are many studies related to the effect of plasma treatment on dyeability of proteinous fibers. Some of them are summarized below.

Plasma treatment can impart anti-felting effect, degreasing, improved dyestuff absorption and increased wetting properties to wool fibers [68]. These effects of the plasma process are

**•** partial removal of covalently bonded fatty acids belonging to the outermost surface of the

Plasma treatments modify the fatty acid monolayer present in the outermost part of the wool fiber, generating new hydrophilic groups as a result of the hydrocarbon chain oxida‐ tion and reducing the fatty acid chain length. The oxidation process also promotes the for‐ mation of Bunte salt and cysteic acid residues on the polypeptide chain. Particularly when oxidizing gasses are used, plasma induces cystine oxidation in the A-layer of the exocuticle, converting it into cysteic acid and thus reducing the number of crosslinkages in the fiber surface [72]. As the surface is oxidized, the hydrophobic character is changed to become in‐ creasingly hydrophilic [76]. The etching of the hydrophobic epicuticle and increase in sur‐ face area also contributes towards the improvement in the ability of the fibers to wet more

Plasma treatment of wool fibers causes improvement in dyeability of wool fibers due to the changes occurred on fiber surface. For this reason dyeing kinetics, dye uptake and hence

attributed to several changes in the wool surface, such as;

**Figure 10.** Mechanism of plasma-substrate interaction [74]

fiber, and

easily [74].

**•** the etching effect [75].

120 Eco-Friendly Textile Dyeing and Finishing

**•** the formation of new hydrophilic groups (sulphonate and carboxylate),

*Wakida et al. (1993)* treated the merino wool top with low-temperature plasmas of helium/ argon and acetone/argon under atmospheric pressure for 30 seconds and then dyed with two leveling acid dyes, and two milling acid dyes. Dyeing rate and final dye uptake in‐ creased with the atmospheric low-temperature plasma treatments. In particular, helium/ argon plasma was found to be much more effective than acetone/argon plasma at improving dyeing properties [77].

*Yoon et al. (1996)* treated the wool fabrics with low temperature oxygen plasma and exam‐ ined their mechanical and dyeing properties. Plasma pretreatment caused an increase in strength. Furthermore, it was observed that when wool was dyed with a leveling acid dye, equilibrium dye uptake did not change, but the dyeing rate increased with a milling acid dye [78].

*Jing (1996)* investigated the surface modification of silk fabric by plasma graft copolymeriza‐ tion with acrylamide and acrylic acid. The dependence of graft degree was examined on the conditions of plasma grafting. The relationships were discussed between graft degree and factors such as crease recovery, dyeability, colour fastness and mechanical properties. It was shown that the dyeability and color fastness have been improved for samples grafted with acrylic acid [79].

*Wakida et al. (1996)* treated wool fibers with oxygen low-temperature plasma and then dyed with acid and basic dyes. Despite the increase of electronegativity of the fiber surface caused by the plasma treatment, the rate of dyeing of wool was increased with both dyes [80].

*Wakida et al. (1998)* treated wool fabrics with oxygen, carbon tetrafluoride, and ammonia low temperature plasmas and then dyed with several natural dyes. The dyeing rate of the plas‐ ma-treated wool increased considerably with cochineal, Chinese cork tree, and madder, but not with gromwell. Furthermore, plasma-treated wool fabrics dyed with cochineal and Chi‐ nese cork tree have increased brightness compared with untreated wool [81].

*Kan et al. (1998)* investigated the induced surface properties of wool fabrics created by the sputtering of low-temperature plasma treatment, such as surface luster, wettability, surface electrostatic and dyeability. After the low-temperature plasma treatment, the treated wool fabric specimens exhibited better hydrophilicity and surface electrostatic properties at room temperature, together with improved dyeing rate. The occurrence of some grooves on the fiber specimens was determined by scanning electron microscope and it was stated that these grooves might possibly provide a pathway for a faster dyeing rate [82].

*Kan et al. (1998)* treated the wool fiber with low-temperature plasma (LTP) using different non-polymerising gases and dyed with chrome dye. The rate of dyeing, the time of half-dye‐ ing (t1/2), the final dye uptake, the chromium exhaustion and the chromium fixation were studied. The results showed that LTP treatments can alter the dyeing properties to various degrees. The nature of the LTP gases plays an important role in affecting the behavior of chrome dyeing [83].

*Kan et al. (1999),* have studied the influence of the nature of gas (oxygen, nitrogen, and a 25% hydrogen/75% nitrogen gas mixture) in plasma treatments on the fiber-to-fiber fric‐ tion, feltability, fabric shrinkage, surface structure, dyeability, alkali solubility, and sur‐ face chemical composition properties of wool substrates. After the low temperature plasma (LTP) treatment, those properties of the LTP-treated substrates changed, and the changes depended on the nature of the plasma gas used [84]. *Kan et al. (1999),* have also searched the surface characteristics of wool fibers treated with LTP with different gases, namely, oxygen, nitrogen and gas mixture (25% hydrogen / 75% nitrogen). Investigations showed that chemical composition of wool fiber surface varied differently with the dif‐ ferent plasma gas used. The surface chemical composition of the different LTP-treated wool fibers was evaluated with different characterization methods, namely FTIR-ATR, XPS and saturated adsorption value [85].

properties of wool changed remarkably after oxygen plasma treatment. There were no sig‐ nificantly observed differences between plasma treated and un-treated fabrics after scouring

The Use of New Technologies in Dyeing of Proteinous Fibers

http://dx.doi.org/10.5772/53912

123

*Masukuni and Norihiro (2006),* studied the dyeing properties of Argon (Ar)-plasma treated wool using the six classes of dyestuffs, i.e., acid, acid metal complex, acid mordant, reactive, basic and disperse dyes. Ar-plasma treatment greatly improved the color yield and level‐ ness, together with the decrease of tippy dyeing. A condition in the plasma treatment en‐ hanced not only the color yield but also the anti-felting performance. The relationship between the improvement of dyeing properties by the plasma treatment and the chemical structure of the dyes was also examined. In the case of the acid dyes, the effect of plasma treatment on color yield was more significant for the milling type dyes with large molecular weight than the leveling type dye with low molecular weight. Furthermore, the hot water

*Kan and Yuen (2006)* treated the wool fibers with oxygen plasma and then dyed these fibers with acid, chrome and reactive dye. For acid dyeing, the dyeing rate of the LTP-treated wool fiber was greatly increased, but the final dye uptake equilibrium did not show any signifi‐ cant change. For the chrome dyeing, the dyeing rate of the LTP-treated wool fiber was also increased, but the final dye uptake equilibrium was only increased to a small extent. For the reactive dyeing, the dyeing rate of the LTP-treated wool fiber was greatly increased, and the

*El-Zawahry et al. (2007)* investigated the impact of plasma-treatment parameters on the sur‐ face morphology, physical-chemical, and dyeing properties of wool using anionic dyes. The LTP-treatment resulted in a dramatic improvement in fabric hydrophilicity and wettability, the removal of fiber surface material, and creation of new active sites along with improved initial dyeing rate. The nature of the plasma gas governed the final uptake percentage of the used acid dyes according to the following descending order: nitrogen plasma > nitrogen/ oxygen (50/50) plasma > oxygen plasma > argon plasma ≥ control. Prolonging the exposure

time up to 20 minutes resulted in a gradual improvement in the extent of uptake [92].

*Demir et al. (2008),* were treated the knitted wool fabrics with atmospheric argon plasma, en‐ zyme (protease), chitosan and a combination of these processes. The treated fabrics were evaluated in terms of their dyeability, color fastness and shrinkage properties, as well as bursting strength. The surface morphology was characterized by SEM images. In order to show the changes in wool surface after plasma treatment, XPS analysis was done. According to the experimental results it was stated that atmospheric plasma has an etching effect and

*Chvalinova and Wiener (2008)* investigated the effects of atmospheric pressure plasma treat‐ ment on dyeability of wool fabric. Untreated and plasma treated wool materials were dyed with acid dye in weak acid solution (pH 6). Experiments showed invasion of surface layer of cuticle by plasma and it was observed that the plasma treated wool fabric for 100 seconds,

and rubbing fastness were improved by Ar-plasma treatment [90].

final dye uptake equilibrium was also increased significantly [91].

increases the functionality of a wool surface [93].

absorbed double more dye than untreated wool fabric [94].

and dyeing [89].

*Iriyama et al. (2002)* treated the silk fabrics with O2, N2, and H2 plasmas for deep dyeing and good color fastness to rubbing. C.I. Reactive Black 5 was used as a dye, and color was evalu‐ ated by total K/S. All plasma-treated silk fabrics showed weight loss, especially by O2 plas‐ ma. Total K/S of dyed silk fabrics treated at 60 Pa of all plasmas was improved greatly. Total K/S increased with increasing plasma treatment time, weight loss of the fabrics in the treat‐ ment, and dye concentration in dyeing. They gained greater total K/S even dyed in 6% of dye concentration compared with untreated one dyed in 10%. Color fastness to wet rubbing of silk fabrics was not improved by plasma treatment. However, most of them were still within the level for commercial use [86].

*Sun and Stylios (2004),* have investigated the effects of LTP on pre-treatment and dyeing processes of cotton and wool. The contact angles, wicking properties, scourability, and dyea‐ bility of fabrics were affected by low-temperature plasma treatments. After treatment, the dye uptake rate of plasma treated wool has been shown to increase. It has been shown that O2 plasma treatment increases the wetability of wool fabric and also the disulphide linkages in the exocuticle oxidize to form sulphonate groups which also enhances the wetability [87].

*Binias et al. (2004)* have investigated the effect of low temperature plasma on some proper‐ ties (surface characteristic, water absorption capacity, capillarity, dyeability) of wool fibers. Selected properties of wool textiles were changed by the influence of low-temperature plas‐ ma on the fiber's surface layers, acting only on a very small thickness. The level of changes was limited by parameters of the low-temperature plasma. Lowering of the dyeing tempera‐ ture was achieved [88].

*Jocic et al. (2005),* have investigated the influence of low-temperature plasma and biopolymer chitosan treatments on wool dyeability. Wool knitted fabrics were treated and characterized by whiteness and shrink-resistance measurements. Surface modification was assessed by contact-angle measurements of human hair fibers. It was stated that after plasma treatment the whiteness degree and hydrophility of fibers increased and fiber dyeability was im‐ proved [71].

*Sun and Stylios (2005),* have determined the mechanical and surface properties and handle of wool and cotton fabrics treated with LTP. This investigation showed that the mechanical properties of wool changed remarkably after oxygen plasma treatment. There were no sig‐ nificantly observed differences between plasma treated and un-treated fabrics after scouring and dyeing [89].

*Kan et al. (1999),* have studied the influence of the nature of gas (oxygen, nitrogen, and a 25% hydrogen/75% nitrogen gas mixture) in plasma treatments on the fiber-to-fiber fric‐ tion, feltability, fabric shrinkage, surface structure, dyeability, alkali solubility, and sur‐ face chemical composition properties of wool substrates. After the low temperature plasma (LTP) treatment, those properties of the LTP-treated substrates changed, and the changes depended on the nature of the plasma gas used [84]. *Kan et al. (1999),* have also searched the surface characteristics of wool fibers treated with LTP with different gases, namely, oxygen, nitrogen and gas mixture (25% hydrogen / 75% nitrogen). Investigations showed that chemical composition of wool fiber surface varied differently with the dif‐ ferent plasma gas used. The surface chemical composition of the different LTP-treated wool fibers was evaluated with different characterization methods, namely FTIR-ATR,

*Iriyama et al. (2002)* treated the silk fabrics with O2, N2, and H2 plasmas for deep dyeing and good color fastness to rubbing. C.I. Reactive Black 5 was used as a dye, and color was evalu‐ ated by total K/S. All plasma-treated silk fabrics showed weight loss, especially by O2 plas‐ ma. Total K/S of dyed silk fabrics treated at 60 Pa of all plasmas was improved greatly. Total K/S increased with increasing plasma treatment time, weight loss of the fabrics in the treat‐ ment, and dye concentration in dyeing. They gained greater total K/S even dyed in 6% of dye concentration compared with untreated one dyed in 10%. Color fastness to wet rubbing of silk fabrics was not improved by plasma treatment. However, most of them were still

*Sun and Stylios (2004),* have investigated the effects of LTP on pre-treatment and dyeing processes of cotton and wool. The contact angles, wicking properties, scourability, and dyea‐ bility of fabrics were affected by low-temperature plasma treatments. After treatment, the dye uptake rate of plasma treated wool has been shown to increase. It has been shown that O2 plasma treatment increases the wetability of wool fabric and also the disulphide linkages in the exocuticle oxidize to form sulphonate groups which also enhances the wetability [87].

*Binias et al. (2004)* have investigated the effect of low temperature plasma on some proper‐ ties (surface characteristic, water absorption capacity, capillarity, dyeability) of wool fibers. Selected properties of wool textiles were changed by the influence of low-temperature plas‐ ma on the fiber's surface layers, acting only on a very small thickness. The level of changes was limited by parameters of the low-temperature plasma. Lowering of the dyeing tempera‐

*Jocic et al. (2005),* have investigated the influence of low-temperature plasma and biopolymer chitosan treatments on wool dyeability. Wool knitted fabrics were treated and characterized by whiteness and shrink-resistance measurements. Surface modification was assessed by contact-angle measurements of human hair fibers. It was stated that after plasma treatment the whiteness degree and hydrophility of fibers increased and fiber dyeability was im‐

*Sun and Stylios (2005),* have determined the mechanical and surface properties and handle of wool and cotton fabrics treated with LTP. This investigation showed that the mechanical

XPS and saturated adsorption value [85].

122 Eco-Friendly Textile Dyeing and Finishing

within the level for commercial use [86].

ture was achieved [88].

proved [71].

*Masukuni and Norihiro (2006),* studied the dyeing properties of Argon (Ar)-plasma treated wool using the six classes of dyestuffs, i.e., acid, acid metal complex, acid mordant, reactive, basic and disperse dyes. Ar-plasma treatment greatly improved the color yield and level‐ ness, together with the decrease of tippy dyeing. A condition in the plasma treatment en‐ hanced not only the color yield but also the anti-felting performance. The relationship between the improvement of dyeing properties by the plasma treatment and the chemical structure of the dyes was also examined. In the case of the acid dyes, the effect of plasma treatment on color yield was more significant for the milling type dyes with large molecular weight than the leveling type dye with low molecular weight. Furthermore, the hot water and rubbing fastness were improved by Ar-plasma treatment [90].

*Kan and Yuen (2006)* treated the wool fibers with oxygen plasma and then dyed these fibers with acid, chrome and reactive dye. For acid dyeing, the dyeing rate of the LTP-treated wool fiber was greatly increased, but the final dye uptake equilibrium did not show any signifi‐ cant change. For the chrome dyeing, the dyeing rate of the LTP-treated wool fiber was also increased, but the final dye uptake equilibrium was only increased to a small extent. For the reactive dyeing, the dyeing rate of the LTP-treated wool fiber was greatly increased, and the final dye uptake equilibrium was also increased significantly [91].

*El-Zawahry et al. (2007)* investigated the impact of plasma-treatment parameters on the sur‐ face morphology, physical-chemical, and dyeing properties of wool using anionic dyes. The LTP-treatment resulted in a dramatic improvement in fabric hydrophilicity and wettability, the removal of fiber surface material, and creation of new active sites along with improved initial dyeing rate. The nature of the plasma gas governed the final uptake percentage of the used acid dyes according to the following descending order: nitrogen plasma > nitrogen/ oxygen (50/50) plasma > oxygen plasma > argon plasma ≥ control. Prolonging the exposure time up to 20 minutes resulted in a gradual improvement in the extent of uptake [92].

*Demir et al. (2008),* were treated the knitted wool fabrics with atmospheric argon plasma, en‐ zyme (protease), chitosan and a combination of these processes. The treated fabrics were evaluated in terms of their dyeability, color fastness and shrinkage properties, as well as bursting strength. The surface morphology was characterized by SEM images. In order to show the changes in wool surface after plasma treatment, XPS analysis was done. According to the experimental results it was stated that atmospheric plasma has an etching effect and increases the functionality of a wool surface [93].

*Chvalinova and Wiener (2008)* investigated the effects of atmospheric pressure plasma treat‐ ment on dyeability of wool fabric. Untreated and plasma treated wool materials were dyed with acid dye in weak acid solution (pH 6). Experiments showed invasion of surface layer of cuticle by plasma and it was observed that the plasma treated wool fabric for 100 seconds, absorbed double more dye than untreated wool fabric [94].

*Naebe et al. (2010)* treated the wool fabric with atmospheric-pressure plasma with helium gas for 30 seconds. X-ray photoelectron spectroscopy and time-of-flight secondary ion mass spectrometry confirmed removal of the covalently-bound fatty acid layer (F-layer) from the surface of the wool fibers, resulting in exposure of the underlying, hydrophilic protein material. Dye uptake experiments were carried out at 50°C to evaluate the effects of plasma on the rate of dye uptake by the fiber surface, as well as give an indication of the adsorption characteristics in the early stages of a typical dyeing cycle. The dyes used were typical, sulfonated wool dyes with a range of hydrophobic characteristics, as deter‐ mined by their partitioning behavior between water and n-butanol. No significant effects of plasma on the rate of dye adsorption were observed with relatively hydrophobic dyes. In contrast, the relatively hydrophilic dyes were adsorbed more rapidly (and uniformly) by the plasma-treated fabric [95].

*Demir (2010)* treated the mohair fibers by air and argon plasma for modifying their some properties such as hydrophilicity, grease content, fiber to fiber friction, shrinkage, dyeing, and color fastness. The results showed that the atmospheric plasma has an etching effect and increases the functionality of a fiber surface. The hydrophilicity, dyeability, fiber friction coefficient, and shrinkage properties of mohair fibers were improved by atmospheric plas‐ ma treatment [96].

**Figure 11.** Gamma ray radiation [99]

ated with a dose of 108

Studies on the interaction of high energy radiation with polymers have attracted the atten‐ tion of many researchers. This is due to the fact that high-energy radiation can induce both chain scission and/or crosslinking [100]. The efficiency of these two types of reactions de‐ pends mainly on polymer structure and irradiation atmosphere. However, dose rate, types of radiation source and temperature during irradiation can influence the reaction rates [101]. For some applications radiation degradation can be controlled and devoted to achieve a spe‐ cific property [100]. Degradation, in broad terms, usually involves chemical modification of the polymer by its environment; modification that is often (but not always) detrimental to the performance of the polymeric material. Although the chemical change of a polymer is frequently destructive, for some applications degradation can be controlled and encouraged to achieve a specific property. In this regard, different vinyl monomers have been grafted onto gamma irradiated wool fabric to improve some favorable properties such as dyeability, and moisture regain. These studies have been based on the formation of stable peroxides on wool, upon irradiation, which are thermally decomposed to initiate polymerization [102].

The Use of New Technologies in Dyeing of Proteinous Fibers

http://dx.doi.org/10.5772/53912

125

Gamma rays are ionizing radiations that interact with the material by colliding with the electrons in the shells of atoms. They lose their energy slowly in material being able to travel through significant distances before stopping. The free radicals formed are extremely reac‐ tive, and they will combine with the material in their vicinity. The irradiated modified fab‐ rics can allow: more dye or pigment to be fixed, producing deeper shades and more rapid fixation of dyes at low temperature [32]. In literature it is stated that two kinds of effects might occur in parallel in wool during the irradiation. The first effect as manifests as an evi‐ dent decrease in dye accessibility at lower doses may not be altogether independent of crosslinking. On the other hand, the remarkable increase in the uptake at higher doses seems to be associated with strong structural damage of fibers. It is interesting to note that the increase in accessibility to dyes of the highly irradiated fibers is so great that the bilateral structure is hardly visualized by the partial staining. Thus the cross-sections of fibers irradi‐

tion which does not give rise to the staining of unirradiated fibers [103]. In literature there

roentgens are stained uniformly in dark tone even under the condi‐

*Atav and Yurdakul (2011)* investigated the use of plasma treatment for the modification of fi‐ ber surfaces to achieve dyeing of mohair fibers at lower temperatures without decreasing dye uptake. The study was carried out by using different gases under various powers and times. The effect was assessed in terms of color. Test samples were also evaluated using scanning electron microscopy (SEM). The optimum conditions of plasma treatment for im‐ proving mohair fiber dyeability, is treatments carried out by using Ar gas at 140 W for 60''. According to the experimental results it can be concluded that plasma treated mohair fibers can be dyed at lower temperatures (90°C) shorter times (1 h instead of 1.5 h) with reactive dyes without decreasing color yield. Dyeing kinetics was also searched in the study and it was demonstrated that the rate constant and the standard affinity of plasma treated sample was increased [97].
