Cellulose

, Volume 17, Issue 2, pp 417–426

Chemical and physical analysis of cotton fabrics plasma-treated with a low pressure DC glow discharge

Authors

  • S. Inbakumar
    • Department of PhysicsKongunadu Arts and Science College
    • Research Unit Plasma Technology (RUPT), Department of Applied Physics, Faculty of EngineeringGhent University
  • N. De Geyter
    • Research Unit Plasma Technology (RUPT), Department of Applied Physics, Faculty of EngineeringGhent University
  • T. Desmet
    • Polymer Chemistry and Biomaterials Research Group, Department of Organic Chemistry, Faculty of SciencesGhent University
  • A. Anukaliani
    • Department of PhysicsKongunadu Arts and Science College
  • P. Dubruel
    • Polymer Chemistry and Biomaterials Research Group, Department of Organic Chemistry, Faculty of SciencesGhent University
  • C. Leys
    • Research Unit Plasma Technology (RUPT), Department of Applied Physics, Faculty of EngineeringGhent University
Article

DOI: 10.1007/s10570-009-9369-y

Cite this article as:
Inbakumar, S., Morent, R., De Geyter, N. et al. Cellulose (2010) 17: 417. doi:10.1007/s10570-009-9369-y

Abstract

This paper focuses on the modification of cotton fabrics using a low pressure DC glow discharge obtained in air. The influence of different operating parameters such as treatment time, discharge power and operating pressure on the chemical and physical properties of the cotton fabrics is studied in detail. Surface analysis and characterization of the plasma-treated cotton fabrics is performed using vertical wicking experiments, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and weight loss measurements. The cotton fabrics show a significant increase in wicking behaviour; an effect which increases with increasing treatment time, increasing discharge power and increasing pressure. Results also show that low pressure DC glow treatment leads to surface erosion of the cellulose fibres, accompanied by an incorporation of oxygen-containing groups (C–O, C=O, O–C–O and O–C=O) on the cotton fibres. The DC glow treatment has thus the potential to influence not only the chemical but also the physical properties of cotton fabrics and this without the use of water or chemicals.

Keywords

Glow dischargeCottonWickingX-ray photoelectron spectroscopyProcess parameters

Introduction

Cotton is the most important textile fibre in the world despite the inroads made into its market by synthetic fibres (Johansson 2007). Cotton is mainly composed of cellulose with some non-cellulosic components including proteins, waxes, pectic substances, organic acids, sugars,… (Karahan and Özdogan 2008). Cellulose has traditionally been modified through reactions of the various hydroxyl groups, leading to esterification and etherification. In the last decades, non-thermal (or cold) plasmas are gaining popularity as a cellulose modification technique since this technique varies significantly from the traditional esterification and etherification routes (Johansson 2007). A non-thermal plasma contains activated species, such as electrons, ions, radicals, photons, … which are able to abstract hydrogen from either carbon or oxygen atoms present on the cotton surface. In this way, cellulose can be oxidized, reduced and/or substituted in new, unique ways (Johansson 2007).

In the last decades, the application of cold plasmas to modify the surface properties of textile materials is experiencing rapid growth (Chen et al. 2008; De Geyter et al. 2006; Morent et al. 2008; Samanta et al. 2009). Non-thermal plasmas are able to alter the physico-chemical properties of a polymer surface: the main effects of interaction between active plasma species and polymeric surfaces is breaking polymer molecular chains, inducing new functional groups and altering morphological properties (Caiazzo et al. 1996; Keil et al. 1998; Toufik et al. 2002). Some of the possible effects include improved hydrophilic properties (De Geyter et al. 2006; Pandiyaraj and Selvarajan 2008; Vesel et al. 2008), an improved adhesion to coatings and to polymer matrices (Liston 1989; Liston et al. 1993; Dumitrascu and Borcia 2006; Zhang et al. 2009), an improved dye ability (Jocic et al. 2005; Ren et al. 2008), induced hydrophobic properties (Hodak et al. 2008; Leroux et al. 2008), …. Apart from creating interesting textile properties, plasma processing is a rapid and environmentally friendly technique producing virtually no waste (Verschuren et al. 2007; Yip et al. 2002). Moreover, plasma treatment only changes the uppermost layers of a material surface without interfering with the bulk properties (Poll et al. 2001).

Plasma modification of cotton fibres and textiles has been extensively studied in numerous scientific papers (Karahan and Özdogan 2008; Pandiyaraj and Selvarajan 2008; Samanta et al. 2009; Sun and Stylios 2004; Ward and Benerito 1982), however, there is a lack of literature describing the effects of different process parameters such as discharge power, operating pressure, exposure time,… on the chemical and physical properties of cotton textiles. Therefore, in the present work, the effect of different operating parameters on cotton plasma modification will be studied in detail. Plasma treatment will be performed on cotton woven fabrics using a low pressure glow discharge operated in air in order to improve their hydrophilicity. This improved water wetting is essential for effective processing (dyeing and finishing) and maintenance (cleaning) of cotton assemblies involving aqueous media, because it facilitates the transport of active reagents between and into the fibres (Topalovic et al. 2007). An evaluation of the hydrophilic behaviour will be performed using wicking rate experiments. The untreated and plasma-treated cotton fabrics will also be characterized using X-ray photoelectron spectroscopy (XPS) in order to correlate the hydrophilic properties with the chemical composition of the cotton surfaces. To gather information on the plasma-induced physical changes, weight loss measurements and scanning electron microscopy (SEM) experiments will be carried out. The above-mentioned experiments will be performed for selected plasma exposure times, operating pressures and discharge powers in order to study the influence of these plasma parameters on the hydrophilic behaviour of cotton fabrics.

Materials and methods

Materials

Commercially available woven grey cotton (warp count = 29, weft count = 23), supplied by the South Indian Textile Research Association (Coimbatore – India) is used in this study. Before plasma treatment, the grey cotton samples were scoured by treating them in a 2% aqueous NaOH (Nice Chemicals – India) solution for 2 h at 95 °C followed by washing in distilled water and drying in air. This pre-treatment is used to remove waxes, pectins and other impurities from the fabric surface (Chung et al. 2004).

Non-thermal plasma treatment

The plasma system used in this paper is schematically shown in Fig. 1 and consists of a cylindrical plasma chamber (length 0.5 m, diameter 0.25 m), a vacuum pumping system (VS-114D, Hindhivac – India) and a DC power supply (Devi Electric Corporation – India). Inside the vacuum chamber, plasma is generated between two copper electrodes with a diameter of 8 cm and a thickness of 1 mm. One electrode is permanently fixed, the other one is variable in height and the distance between both electrodes is set at 3 cm. Before putting the fabric sample into the system, the chamber is first cleaned with distilled water and afterwards with acetone. After this cleaning step, a cotton fabric sample is fixed in a sample holder and inserted into the plasma chamber by using an adjustable rod. For all experiments performed in this paper, the cotton fabric is placed parallel with the electrodes at 1 cm from the cathode. This distance was found to be adequate to avoid thermal alteration of the fabric during plasma processing. The plasma chamber is firmly closed after introduction of the cotton fabric and the vacuum pumping system consisting of a rotary vacuum pump and a diffusion pump is switched on. The pressure inside the plasma chamber is measured using a pirani gauge P (A6STM-D – Hindhivac – India) and during plasma processing, the desired pressure (0.03–0.07 kPa) is maintained by using a needle valve. After reaching the preset pressure in the plasma chamber, the DC power supply is switched on applying the desired voltage (250–400 V) between both electrodes. In order to calculate the discharge power, the discharge current is measured using an ammeter A (OSAW – India) connected between the lower electrode and the DC power supply. The typical operating parameters for the cotton plasma treatments performed in this work are shown in Table 1.
https://static-content.springer.com/image/art%3A10.1007%2Fs10570-009-9369-y/MediaObjects/10570_2009_9369_Fig1_HTML.gif
Fig. 1

Schematic diagram of plasma system (1—anode; 2—cathode; 3—cotton sample; 4—sample holder; 5—plasma chamber; 6—pumping equipment; 7—needle valve; A—ammeter; P—Pirani gauge)

Table 1

Typical plasma operating parameters

Discharge potential (V)

250–400 V

Discharge current (I)

7–19 mA

Pressure (P)

0.03–0.07 kPa

Exposure time (t)

1–10 min

Electrode separation (d)

3 cm

Gas

Atmospheric air

Wicking rate experiments

For surfaces with a closed structure, for example polymer foils, the surface energy can be derived from the measurement of the static contact angle of small droplets of distilled water or other liquids (like pure glycerin) on the treated surface (Temmerman et al. 2005). However, for surfaces with a more open structure, like non-woven and woven fabrics, contact angle measurements are difficult due to the roughness and porous structure of the fabrics. Therefore, in this work, the hydrophilic behaviour of the untreated and plasma-treated cotton samples will be determined by performing wicking rate measurements based on the standard DIN 53 923 (EDANA 10.1-72). A cotton fabric strip (2 cm × 7 cm) is suspended vertically with the lower end dipped in a water-dye liquor (1 ml Royal Blue (Industrial Research Corporation – India) dissolved in 100 ml distilled water) and as a result, a spontaneous wicking occurs due to capillary forces (Harnett and Mehta 1984; Wong et al. 2001; Ferrero 2003). The blue coloration of the dye solution on the cotton fabric clearly indicated the capillary rise height and a ruler (in millimetres) assembled along the cotton strip enables the height measurements. Height readings were made at time intervals of 30 s in the first 3 min and at time intervals of 60 s for longer wicking times. Since natural materials are very variable by nature, the capillary rise results shown in this work are the average of 10 independent measurements performed on cotton samples treated under the same conditions. Moreover, also the standard deviation on these average values will be reported in the following sections.

XPS measurements

XPS analysis is used to determine the chemical composition of the untreated and plasma-modified cotton samples in order to correlate the hydrophilic behaviour of the samples with the chemical composition of their surfaces. XPS measurements are carried out on a S-Probe monochromatized XPS spectrometer of Surface Science Instruments (VG), using monochromatic Al Kα-radiation (hν = 1486.6 eV). The angle between the photoelectron emission direction and the plane of the sample is kept constant at 45°. The pressure in the analyzing chamber is maintained at 1 × 10−9 Pa or lower during analysis and the size of the analyzed area is 250 μm × 1,000 μm. The high-resolution spectra are collected in the constant analyzer energy mode and the value of 285.0 eV of the C1s core level is used for calibration of the energy scale. Curve fitting of the C1s peak is performed using CasaXPS software.

Weight loss experiments and SEM measurements

Upon exposure to plasma, some degradation reactions could potentially be initiated on the cotton surfaces due to ion and electron bombardment (Inagaki et al. 2004). As a result, weight loss of the cotton fabrics and morphological changes of the fibre surfaces can occur. In order to examine the etching effect of the low pressure glow discharge on the cotton fabrics, weight loss experiments and SEM measurements are performed. To obtain the weight loss percentage of the plasma-treated cotton fabrics, the weight of the samples is measured before and immediately after plasma exposure using a Shimadzu AUY220 analytic balance. The weight loss percentage is then calculated according to the following equation:
$$ W_{\text{loss}} (\% ) = 100\,{\frac{{W_{\text{ut}} - W_{\text{pt}} }}{{W_{\text{ut}} }}} $$
where Wut and Wpt are the weight of the untreated and plasma-treated samples respectively. The weight measurements are repeated 10 times for each plasma-treated sample in order to obtain an average weight loss percentage.

In order to visualize the plasma-induced morphological changes on the fibre surfaces, SEM measurements are performed using a Quanta 200F scanning electron microscope (FEI – Japan). Prior to SEM investigation, the cotton samples were coated with a thin layer of gold since non-conducting specimens (such as polymers) will charge under electron bombardment.

Results and discussion

Wicking rate results

Effect of exposure time

In a first series of experiments, the operating parameters pressure and discharge power are kept constant at 0.03 kPa and 4.2 W respectively, while the exposure time is varied between 1 and 10 min. Figure 2 shows the evolution of the average wicking height as a function of wicking time for cotton fabrics which were plasma-treated at different exposure times. The wicking height of the untreated cotton fabric remains the same (i.e. zero) as a function of the wicking time due to its poor wetting nature and is therefore not presented in Fig. 2. This bad wicking behaviour of the scoured untreated cotton fabrics can be explained by the significant amount of non-cellulosic components present on the scoured cellulose fibres, as will be explained in detail in “XPS results”. Figure 2 clearly shows that initially the wicking height increases fast with increasing wicking time for all plasma-treated samples before levelling off at a certain wicking time. For the upward wicking, it is obvious that if the distance travelled by the liquid becomes high enough, there will be a noticeable effect of gravity on the flow rate, leading to a reduction of wicking height increase. As seen in Fig. 2, increasing the plasma exposure time leads to a higher wicking rate. This observation suggests that with increasing treatment time, the cellulose fibres may become more hydrophilic since wettability is a perquisite for wicking: a liquid that does not wet fibres cannot wick into a fabric. Moreover, due to plasma etching effects, the effective pore size present in the plasma-treated cotton fabrics may increase and adversely reduce the capillary pressure, thus increasing the wicking ability (Sun and Stylios 2004; Wong et al. 2001). Both of these aspects will be further explored by performing weight loss, SEM and XPS measurements in order to determine the chemical and physical properties of the plasma-treated cellulose fibres.
https://static-content.springer.com/image/art%3A10.1007%2Fs10570-009-9369-y/MediaObjects/10570_2009_9369_Fig2_HTML.gif
Fig. 2

Average wicking height as a function of wicking time for cotton fabrics plasma-treated at different exposure times (pressure = 0.03 kPa, discharge power = 4.2 W)

Effect of discharge power

To study the influence of discharge power, a series of experiments are performed at constant operating pressure (0.03 kPa) and constant plasma exposure time (6 min). To easily visualize the effect of discharge power on cotton wettability, it is preferred to present the average wicking height after 5 min of wicking (H5min) as a function of discharge power instead of presenting the wicking height as a function of wicking time for various discharge powers. Figure 3 shows the evolution of H5min as a function of discharge power. Based on this figure, one can assume that increasing the discharge power leads to an enhanced wicking behavior of the cellulose fibres. This can be explained by the fact that increasing the discharge power results in an increase of the amount of reactive plasma species. The presence of more plasma species can lead to an increased fibre wettability and/or an increased wicking ability due to a more intense bombardment of active plasma species.
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Fig. 3

Average wicking height after 5 min of wicking (H5min) as a function of discharge power (pressure = 0.03 kPa, treatment time = 6 min)

Effect of operating pressure

In a final series of experiments, the influence of pressure on the hydrophilicity of the plasma-treated cotton fabrics is studied in detail in the pressure range 0.03–0.07 kPa. The pressure variation is limited to this small range to ensure the stability of the DC glow discharge and the discharge power and the plasma exposure time are kept constant at 4.2 W and 6 min, respectively. Figure 4 shows the evolution of the average wicking height after 5 min of wicking (H5min) as a function of operating pressure. As observed in Fig. 4, increasing the plasma pressure in the range 0.03–0.07 kPa leads to an increase in cotton wicking ability. It is known that while the electron energy (and hence the average energy of the reactive plasma particles) decreases with increasing pressure, its density increases (Shi and Clouet 1992). The observed wicking behavior is probably a result of these two antagonist effects, however, since wicking proceeds faster at higher pressures, it is likely that the density increase dominates the energy decrease.
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Fig. 4

Average wicking height after 5 min of wicking (H5min) as a function of operating pressure (discharge power = 4.2 W, treatment time = 6 min)

XPS results

XPS measurements are carried out to evaluate the chemical composition of the untreated and plasma-treated cotton fabrics. At first, low-resolution XPS survey scans are performed to determine the percentages of elements present at the cotton surfaces before and after plasma treatment. As expected for cellulose fibres, the main elements detected are carbon and oxygen, since hydrogen cannot be detected using XPS. Using area sensitivity factors, the oxygen-to-carbon (O/C) atomic ratios were calculated for the untreated fabric and fabrics plasma-treated at different treatment times as shown in Table 2. The O/C atomic ratio of the untreated cellulose fabric is 0.30, while the value expected for pure cellulose is 0.83. This observation indicates that the surface of the untreated cotton fabric does not consist of pure cellulose. The low O/C ratio is due to a considerable amount of carbon atoms without oxygen neighbours, which should not be present in pure cellulose. However, it is well known (Topalovic et al. 2007; Chung et al. 2004; Karahan and Özdogan 2008) that laminar layers of waxes, proteins and pectin cover the natural cotton fibres and since these layers mainly consist of unoxidized carbon atoms, one can conclude that waxes, proteins,… are still present on the cellulose fibres, even after NaOH pre-treatment. This result is in agreement with the results of Mitchell et al. (2005), who also observed the presence of non-cellulosic components on scoured cotton fibres.
Table 2

O/C ratio of untreated and plasma-treated cellulose fabrics (pressure = 0.03 kPa, discharge power = 4.2 W)

Treatment time (min)

O/C ratio (%)

0

0.30

2

0.38

4

0.40

6

0.42

8

0.43

10

0.46

Table 2 also shows that with increasing plasma exposure time, the O/C atomic ratio gradually increases from 0.30 for an untreated sample to 0.46 for a sample plasma-treated for 10 min. This increase suggests that new oxygen-containing groups are formed on the cellulose fabrics after plasma treatment in air. Since these oxygen groups have a polar character, one can conclude that plasma treatment increases the hydrophilicity of the cellulose fabrics, which can contribute to the increased wicking behaviour observed in “Effect of exposure time”. It is also important to mention that the plasma modification does not lead to a significant increase in N/C atomic ratio. Therefore, no nitrogen-containing functional groups are introduced on the cotton surfaces during plasma treatment despite the abundance of nitrogen present in the air plasma. These results underlie the extreme reactivity of oxygen species present in the air plasma compared to the nitrogen species.

To obtain more detailed information, high-resolution scans are performed on the C1s region for all samples listed in Table 2 in order to determine the types and relative amounts of the different carbon–oxygen bonds present on the surface. A detailed analysis of the O1s peak is not performed, since it is generally less useful. Figure 5 shows the C1s spectra of the untreated cellulose fabric (a) and of the cellulose fabric plasma-treated for 10 min (b). Both C1s peaks can be decomposed into four components: a component C1 at 285.0 eV due to C–C and C–H bonds, a component C2 at 286.5 ± 0.1 eV due to C–O bonds, a component C3 at 288.0 ± 0.1 eV due to C=O or O–C–O bonds and finally a component C4 at 289.0 ± 0.1 eV due to O–C=O bonds (Briggs 1990). Based on these high resolution C1s peaks, the percentage of each chemical group present on the cellulose fibres can be calculated and the obtained results are presented in Table 3. It can be derived from Table 3 that with increasing plasma treatment time, the concentration of C–C and C–H groups decreases, while the concentration of oxygenated carbon groups (C–O, C=O, O–C–O and O–C=O) increases. The higher amount of these polar oxygen-containing groups yields a more polar and more wettable cotton fibre surface, which in turn contributes to an increased wicking ability, as observed in “Effect of exposure time”.
https://static-content.springer.com/image/art%3A10.1007%2Fs10570-009-9369-y/MediaObjects/10570_2009_9369_Fig5_HTML.gif
Fig. 5

C1 s peak of a untreated cotton fabric and b cotton fabric plasma-treated for 10 min (operating pressure = 0.03 kPa, discharge power = 4.2 W)

Table 3

Percentage of the different chemical groups present on the untreated and plasma-treated cotton fabrics (pressure = 0.03 kPa, discharge power = 4.2 W)

Treatment time (min)

C–C/C–H (%)

C–O (%)

C = O/O–C–O (%)

O–C=O (%)

0

72.8

18.3

7.3

1.6

2

65.4

21.2

10.1

3.3

4

63.6

21.4

11.1

3.9

6

62.2

21.9

11.7

4.2

8

60.6

23.0

12.0

4.4

10

59.5

23.2

12.2

5.1

Weight loss and SEM results

From the previous section, it can be concluded that cellulose fibres become more hydrophilic after plasma treatment due to the incorporation of oxygen-containing functional groups. However, an increased wettability is not the only effect that can be responsible for the strongly increased wicking ability of the samples after plasma treatment. As stated previously at the end of “Effect of exposure time”, also physical modifications caused by plasma etching could contribute to the increased wicking ability. Therefore, in this section, the physical modifications of the cellulose fabrics are studied in detail using SEM and weight loss measurements.

In order to visualize the plasma-induced morphological changes on the fibre surfaces, SEM measurements are performed. Figure 6 shows (a) a SEM image of the untreated cotton fibre, (b) a SEM image of a plasma-treated cotton fibre with an exposure time equal to 4 min and (c) a SEM image of a plasma-treated cotton fibre with an exposure time equal to 10 min. The untreated cotton fabric consists of cellulose fibres with a relatively smooth surface, however, some grooves and cracks are already present. After plasma treatment, the surface of the cellulose fibres seems to become rougher with a significant amount of tiny grooves and cracks, as illustrated in Fig. 6b, c. Based on these SEM images, one may conclude that the applied plasma treatment etches the surface of the cotton fabrics. It should be however highlighted that it is extremely difficult to make a sound and justified conclusion based on SEM images alone. The SEM images provided in Fig. 6 show single fibres on local places of the cotton fabric: other fibres in the untreated cotton fabric seem to be as rough as the ones provided in Fig. 6c, while fibres in the plasma-treated fabrics are as smooth as the ones shown for the untreated cellulose fabric. To confirm the etching behavior of the discharge used in this paper, weight loss measurements are performed. Table 4 shows the average weight loss percentage for various plasma-treated samples together with the calculated standard deviations. Table 4 clearly shows that the weight loss percentage increases with increasing treatment time up to approximately 4.5% at a treatment time of 10 min. As a result, one can conclude with certainty that the discharge used in this paper etches the surface of the cotton fabrics. It is however very difficult to know if the plasma removes the non-cellulosic components from the cellulose fibres or if the plasma etches the cellulose fibres themselves. Most likely, a combination of both effects will take place during plasma treatment.
https://static-content.springer.com/image/art%3A10.1007%2Fs10570-009-9369-y/MediaObjects/10570_2009_9369_Fig6_HTML.jpg
Fig. 6

SEM images of a untreated cotton fabric, b cotton fabric plasma-treated for 4 min and c cotton fabric plasma-treated for 10 min (discharge power = 4.2 W, operating pressure = 0.03 kPa)

Table 4

Average weight loss (%) of 10 cotton fabrics plasma-treated with different operating parameters

Treatment time (min)

Pressure (kPa)

Discharge power (W)

Average weight loss (%)

Standard deviation (%)

1

0.03

4.2

1.68

0.08

2

0.03

4.2

2.11

0.05

3

0.03

4.2

2.70

0.10

4

0.03

4.2

3.00

0.07

5

0.03

4.2

3.34

0.06

6

0.03

4.2

3.64

0.11

7

0.03

4.2

4.20

0.05

8

0.03

4.2

4.39

0.03

9

0.03

4.2

4.48

0.04

10

0.03

4.2

4.56

0.03

6

0.04

4.2

4.00

0.11

6

0.05

4.2

4.35

0.03

6

0.06

4.2

4.43

0.33

6

0.07

4.2

4.64

0.34

6

0.03

2.1

2.91

0.05

6

0.03

2.6

3.43

0.05

6

0.03

5.6

4.08

0.07

6

0.03

7.6

4.35

0.06

This etching effect may be due to electron and ion bombardment in addition to the contribution of oxidative reactions with activated oxygen atoms to degradation reactions (Inagaki et al. 2004). Table 4 also shows that the weight loss percentage increases with increasing discharge power and increasing operating pressure. This can be explained by the fact that more plasma species can interact with the fabric surface at higher discharge power and higher operating pressure. Taking into account the above mentioned results, one can conclude that the low pressure DC glow discharge causes both chemical and physical modifications to the cellulose fibres, which both attribute to the increased wicking behaviour after plasma treatment.

Conclusion

The primary aim of this study was to investigate the effects of a low pressure DC glow discharge on the chemical and physical properties of cotton fabrics. The influence of different operating parameters, such as treatment time, discharge power and operating pressure on the plasma modification were studied in detail using vertical wicking experiments. Results have clearly shown that plasma treatment leads to a significant increase in cotton wicking ability; an effect which increases with increasing treatment time, increasing discharge power and increasing operating pressure. XPS measurements have demonstrated that this enhanced wicking ability can be attributed to an enhanced wettability of the cotton fibres since plasma treatment introduces polar oxygen-containing groups such as C–O, C=O, O–C–O and O–C=O groups on the cotton fibres. However, in this paper, it is also shown that not only chemical modifications but also physical modifications contribute to the enhanced wicking ability of plasma-treated cotton fabrics. Based on SEM and weight loss measurements, it was shown that the low pressure DC glow discharge etches the surface of the cotton fabrics, an effect which also increases with increasing treatment time, increasing discharge power and increasing operating pressure.

As a concluding remark, one can state that plasma treatment can be used as an effective method for cotton pre-treatment with the advantage of low application temperature, without the necessity of any chemical substance, without any water consumption and without imposing any alteration to the interior part of the cellulose fibres.

Acknowledgments

S. Inbakumar would like to thank the Director of the Collegiate Education, Chennai – 600 006, Tamilnadu for providing a scholarship for a research study.

Copyright information

© Springer Science+Business Media B.V. 2009