**4. Irradiation in textiles**

Irradiation processes have several commercial applications, in the coating of metals, plastics and glass, in printing, wood finishing, film and plastic cross linking and in the fields of adhesive and electrical insulations. The advantages of this technology are well known energy saving (low-temperature process), low environmental impact, simple, economical and high treatment speed. Despite these advantages, there have been few applications of radiation curing in the textile industry, such as non woven fabric bonding, fabric coating and pigment printing (Ferrero and Monica, 2011). Radiation treatment on fabric and garments can add value in colouration. Modification of the surface fiber can allow more dye uptake; its fixation at low temperature and increase wettability. Cotton knitwear pilling can be eliminated from the surface of the fabric by radiation treatment without affecting the strength of the fiber (Kim *et al.*, 2005).Effect of UV radiation in natural as well as synthetic dyeing using irradiated cotton fabric has given significant results.

#### **4.1 Effect of UV and gamma radiation on the fabric dyed with natural dyes**

There is a remarkable difference in colour strength when different extracts of irradiated and un-irradiated turmeric powder were used to dye the irradiated and un-irradiated fabric (Afifah *et al.*, 2011). The methanol solubilized extract gave more colour strength than aqueous (heat) solubilized and alkali solubilized extract as displayed in Fig. 2. The low colour strength using alkali solubilized extract is due to alkaline degradation of curcumin into products like vaniline, vanilic acid, feruloylmethane, ferulic acid and other fission products, which sorb on the fabric along with colourant and impart dull redder shades(Tonnesen and Karlsen,1985a). While using (heat) aqueous solubilized extract, the colourant being insoluble in water may undergo hydrolytic degradation and the actual colourant concentration becomes low onto the fabric as a result low colour strength is observed (Tonnesen and Karlsen, 1985 b). By using methanol solubilized extract, the actual colourant get significant chance to sorb onto fabric and impart yellow colour with dark shades.

The irradiation of fabric is also another factor which affects the colour strength of the fabric. Previous studies show that UV irradiation adds value to colouration and also increases the dye uptake ability of the cotton fabrics through oxidation of surface fibers of cellulose(Millington , 2000; Javed *et al* ., 2008). The colourants from Methanol solubilized extract reach the vicinities of fibres and upon investigation of colour strength using spectraflash SF 650, dark yellow shade was observed. In the case of un-irradiated fabric, the insoluble impurities get significant chance to sorb on the matrix along with colourant which showed the dull redder shades.

Effect of Radiation on Textile Dyeing 9

**(b)**

**RP/RC RP/NRC RC/NRP NRP/NRC Sample codes**

> Aqueous Alkaline

**100Gy 300Gy 500Gy 700Gy 900Gy**

**100Gy 300Gy 500Gy 700Gy 900Gy**

Fig. 3. Effect of gamma radiation on the colour strength of the cotton dyed with

(a) ethanolic (b) aqueous extracts obtained form irradiated and un-irradiated Eucalyptus powder. NRP-un-irradiated powder, RP – irradiated powder, RC- irradiated cotton fabric,

**Colour strength (%)**

**(a)**

NRC-un-irradiated cotton fabric

**RP/RC RP/NRC RC/NRP NRP/NRC Sample codes**

0

URP/RC

RP/URC

**Sample Codes**

The colour strength changes significantly in aqueous than in alkaline media. The fabrics dyed in aqueous extract of turmeric powder were darker yellow in shades than that of

Fig. 4. Effect of gamma radiation on the colour strength of the cotton dyed with extracts obtained form irradiated and un-irradiated turmeric powder using aqueous and alkaline media (Where URP-un-irradiated powder, RP – irradiated powder, RC- irradiated cotton

RP/RC

URP/URC

20

40

60

80

**Colour Strength (%)**

fabric, URC-un-irradiated cotton fabric )

100

120

140

160

**Colour strength (%)**

Fig. 2. Effect of UV radiation on the colour strength of the irradiated and un-irradiated cotton dyed with heat solubilized, alkali solubilized and methanol solubilized extract of irradiated and un-irradiated turmeric powder (Where URP-un-irradiated powder, RP – irradiated powder, RC- irradiated cotton fabric, URC-un-irradiated cotton fabric )

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 reactive, and they will combine with the material in their vicinity. Upon irradiation the cross linking changes the crystal structure of the cellulose, which can add value in colouration process and causes photo modification of surface fibers. The irradiated modified fabrics can allow: more dye or pigment to become fixed, producing deeper shades, more rapid fixation of dyes at low temperature and increases wet ability of hydrophobic fibers to improve depth of shade in printing and dyeing (Millington, 2000).

The influence of gamma radiation on the colour strength values of the fabric dyed with natural dyes extracted from eucalyptus bark has been shown in Fig. 3. High colour strengths and dark brown shades of the fabric dyed in ethanolic extract were obtained as compared to aqueous extracts. The low colour strength and un-evenness in shade in aqueous extract is due to presence of insoluble impurities that might come on the fabric along with colourant.(Vankar *et al.*, 2000) The results shown in Fig. 3. demonstrate that irradiated fabric dyed using alcoholic extract gave more colour strength than un-irradiated fabric. Previous studies showed that gamma irradiation causes dislocation and fragmentation of fabric fibers (Foldvary *et al.*, 2003) however, only soluble colourant free from impurities get maximum chances to sorb on the fabric. But un-irradiated fabric contained less dye and yielded greener shade.

Colour Strength (%)

URP/URC

of shade in printing and dyeing (Millington, 2000).

greener shade.

URP/RC

RP/URC

Sample Codes

un-irradiated cotton dyed with heat solubilized, alkali solubilized and methanol

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 reactive, and they will combine with the material in their vicinity. Upon irradiation the cross linking changes the crystal structure of the cellulose, which can add value in colouration process and causes photo modification of surface fibers. The irradiated modified fabrics can allow: more dye or pigment to become fixed, producing deeper shades, more rapid fixation of dyes at low temperature and increases wet ability of hydrophobic fibers to improve depth

The influence of gamma radiation on the colour strength values of the fabric dyed with natural dyes extracted from eucalyptus bark has been shown in Fig. 3. High colour strengths and dark brown shades of the fabric dyed in ethanolic extract were obtained as compared to aqueous extracts. The low colour strength and un-evenness in shade in aqueous extract is due to presence of insoluble impurities that might come on the fabric along with colourant.(Vankar *et al.*, 2000) The results shown in Fig. 3. demonstrate that irradiated fabric dyed using alcoholic extract gave more colour strength than un-irradiated fabric. Previous studies showed that gamma irradiation causes dislocation and fragmentation of fabric fibers (Foldvary *et al.*, 2003) however, only soluble colourant free from impurities get maximum chances to sorb on the fabric. But un-irradiated fabric contained less dye and yielded

Fig. 2. Effect of UV radiation on the colour strength of the irradiated and

solubilized extract of irradiated and un-irradiated turmeric powder (Where URP-un-irradiated powder, RP – irradiated powder, RC- irradiated cotton fabric, URC-un-irradiated cotton fabric )

RP/RC

Heat Solubilized

Alkali Solubilized

Methanol solubilized

Fig. 3. Effect of gamma radiation on the colour strength of the cotton dyed with (a) ethanolic (b) aqueous extracts obtained form irradiated and un-irradiated Eucalyptus powder. NRP-un-irradiated powder, RP – irradiated powder, RC- irradiated cotton fabric, NRC-un-irradiated cotton fabric

Fig. 4. Effect of gamma radiation on the colour strength of the cotton dyed with extracts obtained form irradiated and un-irradiated turmeric powder using aqueous and alkaline media (Where URP-un-irradiated powder, RP – irradiated powder, RC- irradiated cotton fabric, URC-un-irradiated cotton fabric )

The colour strength changes significantly in aqueous than in alkaline media. The fabrics dyed in aqueous extract of turmeric powder were darker yellow in shades than that of

Effect of Radiation on Textile Dyeing 11

Reactive Disperse

> Reactive Disperse Mixed

 0 mint 30 mint 60 mint 90 mint **Irradiation Time**

Fig. 6. Effect of UV irradiation time on the colour strength of the irradiated cotton fabric

Reactive Disperse Mixed

**C olor S trength (% )**

(a) (b)

The un-irradiated and irradiated cotton fabric for the period of 30, 60 and 90 min was dyed, the results of fabrics have been shown in Figure 7. (a,b) shows that irradiated fabric and irradiated dyes for 90 min has maximum affinity for dye to attach on it. Oxidation of cellulose upon UV radiation significantly increases the dye uptake in the substrate due to the interstices available in the case of irradiated fabric surface (Michael and EL-Zaher, 2005).

Fig. 7. Effect of UV irradiation time on the colour strength of the irradiated cotton fabric dyed with un-irradiated multifunctional triazine (a) and irradiated reactive and dianix

 0 mint 30 mint 60 mint 90 mint **Irradiation Time**

The above Fig. 6. shows that the fabric irradiated for 90 min. has maximum affinity for dye substrate to attach. The fabric irradiated for 30 and 60 minutes show even shades having good colour strength. This improvement might be due to the oxidation of cellulose in to carboxylic acid group upon exposure of cellulose to UV radiation which interacts more

dyed with un-irradiated reactive and disperse dye

towards the dye material to form covalent bond.

 0 mint 30 mint 60 mint 90 mint **Irradiation Time**

disperse and mixed dye (b)

**Color Strength (%)**

**C o lo r S tren g th (% )**

fabrics dyed in alkaline extract. The low colour strength was due to alkaline degradation of curcumin into water-soluble products like vaniline, vanilic acid, feruloylmethane, ferulic acid and other fission products, which gave dull redder shades (Tonessen and Karlsen, 1985a). Tonessen and Karlsen reported that below pH 7, curcumin existed in yellow colour and is insoluble in water (Tonessen and Karlsen, 1985b). Due to insolubility, the colourant might have tendency to get absorbed completely on the fabric without passing through the medium and shows darker yellow shades. Hence irradiated fabrics dyed in aqueous media gave more colour strength than un-irradiated fabrics due to oxidative degradation of cellulose fibres. Treatment of fabric by high-energy radiation causes either dislocation and fragmentation or slight loss in mass of fabric (Foldvary *et al.*, 2003; Takacs *et al.*, 2000). However, only colourants get maximum chance to sorb on fabric than insoluble impurities. So more colour strength is obtained in case of irradiated fabric dyed using aqueous extract of irradiated turmeric powder. Thus it is found that if irradiated fabric dyed with aqueous extract of irradiated turmeric powder, maximum colour strength and darker yellow shade was obtained.

#### **4.2 Effect of UV and gamma radiation on the fabric dyed with synthetic dyes**

UV irradiation effects the colour strength values and shades of fabric dyed with synthetic dyes. Using suitable dye and fabric, the process of irradiation can produce large variation in shades.

Fig. 5. Effect of UV irradiation time on the colour strength of the irradiated cotton fabric dyed with irradiated stilbene based reactive dye

The data displayed in Fig 5. shows that irradiated fabric for 120 min. gave maximum colour strength as compared to un-irradiated fabric. The fabric irradiated for 120 min. showed even shade with better colour strength. The reason might be the oxidation of cellulose upon exposure to UV radiation. Michael and EL-Zaher in 2005 reported that the UV treatment of cellulose fibre created spaces between fibres which imbibed more dye and as a result the interaction between dye and cellulose fabric becomes more significant. The dye molecules rush rapidly onto the fabric and as a result darker shades were obtained (Tayyba, 2010).

fabrics dyed in alkaline extract. The low colour strength was due to alkaline degradation of curcumin into water-soluble products like vaniline, vanilic acid, feruloylmethane, ferulic acid and other fission products, which gave dull redder shades (Tonessen and Karlsen, 1985a). Tonessen and Karlsen reported that below pH 7, curcumin existed in yellow colour and is insoluble in water (Tonessen and Karlsen, 1985b). Due to insolubility, the colourant might have tendency to get absorbed completely on the fabric without passing through the medium and shows darker yellow shades. Hence irradiated fabrics dyed in aqueous media gave more colour strength than un-irradiated fabrics due to oxidative degradation of cellulose fibres. Treatment of fabric by high-energy radiation causes either dislocation and fragmentation or slight loss in mass of fabric (Foldvary *et al.*, 2003; Takacs *et al.*, 2000). However, only colourants get maximum chance to sorb on fabric than insoluble impurities. So more colour strength is obtained in case of irradiated fabric dyed using aqueous extract of irradiated turmeric powder. Thus it is found that if irradiated fabric dyed with aqueous extract of irradiated turmeric powder, maximum colour strength and darker yellow shade

**4.2 Effect of UV and gamma radiation on the fabric dyed with synthetic dyes** 

UV irradiation effects the colour strength values and shades of fabric dyed with synthetic dyes. Using suitable dye and fabric, the process of irradiation can produce large variation in

> 0 min 30 min 60 min 90 min 120 min 150 min **Irradiation time**

Fig. 5. Effect of UV irradiation time on the colour strength of the irradiated cotton fabric

The data displayed in Fig 5. shows that irradiated fabric for 120 min. gave maximum colour strength as compared to un-irradiated fabric. The fabric irradiated for 120 min. showed even shade with better colour strength. The reason might be the oxidation of cellulose upon exposure to UV radiation. Michael and EL-Zaher in 2005 reported that the UV treatment of cellulose fibre created spaces between fibres which imbibed more dye and as a result the interaction between dye and cellulose fabric becomes more significant. The dye molecules rush rapidly onto the fabric and as a result darker shades were

was obtained.

**Color Strength (%)**

obtained (Tayyba, 2010).

dyed with irradiated stilbene based reactive dye

shades.

Fig. 6. Effect of UV irradiation time on the colour strength of the irradiated cotton fabric dyed with un-irradiated reactive and disperse dye

The above Fig. 6. shows that the fabric irradiated for 90 min. has maximum affinity for dye substrate to attach. The fabric irradiated for 30 and 60 minutes show even shades having good colour strength. This improvement might be due to the oxidation of cellulose in to carboxylic acid group upon exposure of cellulose to UV radiation which interacts more towards the dye material to form covalent bond.

Fig. 7. Effect of UV irradiation time on the colour strength of the irradiated cotton fabric dyed with un-irradiated multifunctional triazine (a) and irradiated reactive and dianix disperse and mixed dye (b)

The un-irradiated and irradiated cotton fabric for the period of 30, 60 and 90 min was dyed, the results of fabrics have been shown in Figure 7. (a,b) shows that irradiated fabric and irradiated dyes for 90 min has maximum affinity for dye to attach on it. Oxidation of cellulose upon UV radiation significantly increases the dye uptake in the substrate due to the interstices available in the case of irradiated fabric surface (Michael and EL-Zaher, 2005).

Effect of Radiation on Textile Dyeing 13

RP/RC RP/NRC NRP/NRC

> 0.50% 1.00%

100 200 300 400 500 **Doses(Gy)**

cotton fabric dyed with Irradiated and un- irradiated reactive blue dye powder

Fig. 9. Effect of gamma irradiation on the colour strength of the irradiated and un-irradiated

The result displayed in Fig. 10. reveal that colour strength values decrease with increase in absorbed doses. The more colour strength is because of photo modified surface of cellulose which may have more affinity for dye substrate (Mughal *et al.*, 2007). The results show that the dyeing performed using 200Gy dose gives maximum colour strength with darker shades. At sufficient higher dose insoluble impurities along with dye molecule become fixed and causes uneven shades, while below optimum dose, surface of cellulose do not stimulate much to interact significantly with dye material. Thus dyeing performed using cotton fabric irradiated to an absorbed dose of 200Gy gave better colour strength

> 100 Gy 200 GY 300 Gy 400 Gy 500 Gy **Absorbed doses**

Fig. 10. Effect of gamma irradiation on the colour strength of irradiated cotton fabric dyed

0

20

40

60

80

**Colour strength(%)**

(Toheed Asghar, 2009).

**Colour strength (%)**

with Irradiated reactive black dye powder

100

120

140

The dye molecules rush rapidly on to the fabric and as a result darker shades were obtained (Sajida Parveen, 2009, Afifah Kausar, 2009; Afifah *et al.*, 2011). Previous study carried out by K.R. Millington suggested that photo modification of surface fiber may attain more dye or pigment to become fixed producing deeper shades. UV radiation causes more rapid fixation of dyes increases wettability of hydrophobic fibers to improve depth and shade in printing. For knitted wool and cotton fabrics, the problem of pilling can be eliminated.

Fig. 8. Effect of UV irradiation time on the colour strength of the irradiated cotton fabric dyed with un-irradiated and irradiated 5 % (a) and 1% (b) Reactive Blue dye

The result shown in Fig. 8. (a & b) indicate that colour strength values of 5% solution of dye powder are more as compared to colour strength values obtained in case of 1 % solution. The optimized time for irradiating cotton fabric is 30 minutes as shown in Fig. 8. (a & b).At this time, oxidation of cellulose generates carboxylic acid group which helps in significant interaction of dye with oxidized a surface and show darker shades. Irradiation for less time does not activate the surface to interact with dye molecules to such an extent. While irradiation for long time may either facilitate insoluble impurities to rush onto modified fabric due to availability of wide interstices /gaps among the fibers which may cause dull and uneven shades having low colour strength (Saddique, 2008).

*Gamma radiation* shows a promising influence in textile dyeing since irradiated fabric dyed with synthetic dye gave a prominent difference The result shown in Fig. 9. indicate that colour strength values change remarkably using irradiated fabric which results in darker colour strength and more bluer shades than that of un-irradiated fabrics. This low colour strength is due the stuffing of insoluble impurities present in the dye solution on to the fabric.

Results given in Fig. 9. show that the dyeing performed using irradiated fabric treated with 300Gy absorbed dose gave maximum colour strength with darker bluer shades. At higher doses, low colour strength is obtained, which may be due to the degradation or dislocation of crystal moieties on cellulosic material (Foldvary *et al.* 2003; Takacs *et al.*2000). While at low dose, fabric surface does not activate enough to fix dye onto it and does not able to make firm interaction with dye material.

The dye molecules rush rapidly on to the fabric and as a result darker shades were obtained (Sajida Parveen, 2009, Afifah Kausar, 2009; Afifah *et al.*, 2011). Previous study carried out by K.R. Millington suggested that photo modification of surface fiber may attain more dye or pigment to become fixed producing deeper shades. UV radiation causes more rapid fixation of dyes increases wettability of hydrophobic fibers to improve depth and shade in printing.

**C oluo r Stren g th (% )**

Fig. 8. Effect of UV irradiation time on the colour strength of the irradiated cotton fabric

The result shown in Fig. 8. (a & b) indicate that colour strength values of 5% solution of dye powder are more as compared to colour strength values obtained in case of 1 % solution. The optimized time for irradiating cotton fabric is 30 minutes as shown in Fig. 8. (a & b).At this time, oxidation of cellulose generates carboxylic acid group which helps in significant interaction of dye with oxidized a surface and show darker shades. Irradiation for less time does not activate the surface to interact with dye molecules to such an extent. While irradiation for long time may either facilitate insoluble impurities to rush onto modified fabric due to availability of wide interstices /gaps among the fibers which may cause dull and uneven shades having low colour strength (Saddique,

*Gamma radiation* shows a promising influence in textile dyeing since irradiated fabric dyed with synthetic dye gave a prominent difference The result shown in Fig. 9. indicate that colour strength values change remarkably using irradiated fabric which results in darker colour strength and more bluer shades than that of un-irradiated fabrics. This low colour strength is due the stuffing of insoluble impurities present in the dye solution on to the

Results given in Fig. 9. show that the dyeing performed using irradiated fabric treated with 300Gy absorbed dose gave maximum colour strength with darker bluer shades. At higher doses, low colour strength is obtained, which may be due to the degradation or dislocation of crystal moieties on cellulosic material (Foldvary *et al.* 2003; Takacs *et al.*2000). While at low dose, fabric surface does not activate enough to fix dye onto it and does not able to make

dyed with un-irradiated and irradiated 5 % (a) and 1% (b) Reactive Blue dye

20 30 40 50 60 **Irradiation Time (min)**

RP/RC RP/NRC NRP/RC NRP/NRC

For knitted wool and cotton fabrics, the problem of pilling can be eliminated.

RP/RC RP/NRC NRP/RC NRP/NRC

**Colour Strength (%**

2008).

fabric.

firm interaction with dye material.

 **)**

> 20 30 40 50 60 **Irradiation Time (min)**

Fig. 9. Effect of gamma irradiation on the colour strength of the irradiated and un-irradiated cotton fabric dyed with Irradiated and un- irradiated reactive blue dye powder

The result displayed in Fig. 10. reveal that colour strength values decrease with increase in absorbed doses. The more colour strength is because of photo modified surface of cellulose which may have more affinity for dye substrate (Mughal *et al.*, 2007). The results show that the dyeing performed using 200Gy dose gives maximum colour strength with darker shades. At sufficient higher dose insoluble impurities along with dye molecule become fixed and causes uneven shades, while below optimum dose, surface of cellulose do not stimulate much to interact significantly with dye material. Thus dyeing performed using cotton fabric irradiated to an absorbed dose of 200Gy gave better colour strength (Toheed Asghar, 2009).

Fig. 10. Effect of gamma irradiation on the colour strength of irradiated cotton fabric dyed with Irradiated reactive black dye powder

Effect of Radiation on Textile Dyeing 15

Abdul Fattah, S., E. El-Khatib, A.Z.K Antouch and I.El-Zawawi. 2010. Finishing of wool

Afifah Kausar. 2009. Effect of UV irradiation time on the colour strength of the irradiated

Afifah,K., I.A.Bhatti, S.Adeel and E.Osman. 2011. Influence of UV radiations on the

Deo, H.T and B.K. Desai., 1999. Dyeing of cotton and jute with tea as natural dye. Journal

Ellison, M.S. 2003. "Piezoelectricity in Natural and Synthetic Silks". Spring Symposium,

Ferreo, F. and M. Periolatto. 2011. UV curing for surface modification of textile fabric. J.

Ferrero. F and Monica. P. 2011. Ultraviolet Curing for Surface Modification of Textile

Foldvary, C.M., E. Takacs and L. Wojnarovits. 2003. Effect of high energy radiation and

Gulrajani, M. L. 1992. Introduction to dyes. Indian institute of technology, New Delhi: 1-2. Hunger, K.2003. Industrial Dyes: Chemistry, Properties, Application. Wiley –Vch-Verley

Javed, I., Bhatti, I.A., Adeel, S., 2008.Effect of UV radiation on dyeing of cotton fabric with extracts of henna leaves. Indian Journal of fiber and textile research, 33,157-162. Jun, Z., and Chen, G.Q., 2006. The study of the Structures of Silk Fibers Grafted with

Jun, L., Y. Min and H. Hongfei. 2001. Solvent effect on grafting polymerization of NIPAAM

Kim, T.K., M.K. Kim and Y.A. Son. 2005. Degradation of the diazo by the sulfur-containing

Kiran. M. 2009. Effect of UV radiation on dyeing of cotton and polyester fabric.

Michael, M.N., and El-Zaher, N.A. 2005. Investigation into the effect of UV/ozone treatment on the dyeing properties of natural dyes on natural fabrics. Colourage. 52:83-88. Millington K.R. 1998 (c): U.S.A. Patent. Application of UV surface treated in textile industry.

Millington, K.R. 1997.Wool and Wool blend fabric treated: US Patent Document: 5,595,572:1-8. Millington, K.R. 1998(a): Use of UV Radiation to reduce pilling of knitted wool and cotton.

amino acids of wool fibers. Dyes and Pigment, 78: 67-127.

fabric with metal ion and silver nano particles to acquire antimicrobial and UV

cotton fabric dyed with irradiated multifunctional triazine reactive and dianix

extraction and dyeing of cotton fabric with *Curcuma longa* L. Indian J. Fibre and

Advanced Flexible materials and structure: Engineering with fibers. June 30- July 2,

alkali treatment on the properties of cellulose. J.Radiation Physics and Chemistry.

Hexaflurobutyl Methacrylate, International Forum of textile and Engineering for

on cotton cellulose via-pre irradiation method. Rdiation Physics and Chemistry.55:

Red Tech 98 North Americas: UNEB Conference Proceeding Chicago ILLINOIS

**7. References** 

properties. R.J.T.A. 14(1):53-64.

Textile Research (In Press)

Loughborough, England

Fabrics. 11: 0-1

67: 505–508

625-628.

America.

disperse and mixed dye. M.Phil. Thesis. 45-48

Society Dyers and Colourists.115:224-227.

Nano science and Nanotechnology/11(xx):

GmbH kGA, Weinheim, Germany

Doctoral candidates, China.

M.Phil.Thesis. 27:30

J.Textile Research 68(6): 413-421.

#### **4.3 Effect of UV and gamma radiation on wool and silk and polyester**

Studies on wool keratin have been previously performed in order to evaluate the effect of UV radiation. Chemical changes induced by short term UV radiation are confined to fibers at surface where as it is unable to penetrate into the fabric. The colour changes i.e. green followed by yellow in wool keratin due to UV radiation have been observed also (Millington, 2000).There are several processes to reduce the pilling yet no process can guarantee the zero pilling in wear. But Millington reported that it is only UV radiation which can reduce the pilling through siro flash technology followed by oxidation with hydrogen peroxide in germicidal UV Tubes. After using such techniques and then dyeing with UV irradiated wool fabric, the characterization of wool fabric meets standard marks by ISO. Thus the continuous UV reduction of the fabric followed by batch oxidation is of great commercial value. (Millington, 1998a; Millington, 1998b; Millington, 1997).

When wool fabric is exposed to UV radiation, it exhibits some physical and chemical changes on its surface. This interaction not only modifies the fabric of wool but also improve the shades particularly grey and black. It also helps in even dyeing, deeper shades, chlorine free printing and improve the photo bleaching of wool (Millington, 1998c). Now a days, UV curing technology is being used for the modification of wool surface that helps in finishing as well as deepening the shades of wool when dyed using reactive dyes. By using UV curing technology, there are no risks involved to any loss of fabrics fibers in weight as well as in its physical appearance. This technology also do not cause any hazardous use of chemicals, smoothness of surface, unpilling as well as deep hues (Ferrero and Periolatto, 2011; Abdul Fattah *et al.*, 2010).

#### **5. Conclusion**

Radiation processes has several commercial applications starting from curing of fabrics, finishing, improvement of shades and characterization of dyed fabrics. The advantage of this technology are well known such as improvement in shades , enhanciong colour fastness , colour stregnth , low cost effective and reduction of the concentration of the dye. All these results have been seen from our above experiments. Radiation curing of silk, wool and cotton fabric to reduce pilling , their finishing and mercerization processes has also been improved. Thus both UV and gamma radiation has improved the textile sttuff according to standards of ISO , EPA and FAO.

The use of eco-friendly technnology giving eco–label products under the influence of high energy radiations that may give new orientation for other dyes such as vat, reactrive azo and other brands. Similarly improvement of fibers of wool , silk , nylonn , Polyester cotton (P.C). etc., for dyeing to get good shades, even and lavelled dyeing, accepatable fastness properties yet are underway.So the dyers and colourists should try such techniques inorder to get better results and alternating methods for any risks related to human health.

#### **6. Acknowledgement**

The authors are thankful to Dr. H. F. Mansour, Dr. Eman Osman, Dr. Nagia Ali and Dr. Khaled El Negar from Natioanal Textile Research Centre, Cairo Egypt, Dr. M. Zuber, Professor of Applied Chemistry, GC Univeristy Faisalaabd Pakistan for valuable discussion during this work. We are grateful to Abher Rashid, T. Bechtold and Peter Hauser for their technical help.

#### **7. References**

14 Textile Dyeing

Studies on wool keratin have been previously performed in order to evaluate the effect of UV radiation. Chemical changes induced by short term UV radiation are confined to fibers at surface where as it is unable to penetrate into the fabric. The colour changes i.e. green followed by yellow in wool keratin due to UV radiation have been observed also (Millington, 2000).There are several processes to reduce the pilling yet no process can guarantee the zero pilling in wear. But Millington reported that it is only UV radiation which can reduce the pilling through siro flash technology followed by oxidation with hydrogen peroxide in germicidal UV Tubes. After using such techniques and then dyeing with UV irradiated wool fabric, the characterization of wool fabric meets standard marks by ISO. Thus the continuous UV reduction of the fabric followed by batch oxidation is of great

When wool fabric is exposed to UV radiation, it exhibits some physical and chemical changes on its surface. This interaction not only modifies the fabric of wool but also improve the shades particularly grey and black. It also helps in even dyeing, deeper shades, chlorine free printing and improve the photo bleaching of wool (Millington, 1998c). Now a days, UV curing technology is being used for the modification of wool surface that helps in finishing as well as deepening the shades of wool when dyed using reactive dyes. By using UV curing technology, there are no risks involved to any loss of fabrics fibers in weight as well as in its physical appearance. This technology also do not cause any hazardous use of chemicals, smoothness of surface, unpilling as well as deep hues (Ferrero and Periolatto, 2011; Abdul

Radiation processes has several commercial applications starting from curing of fabrics, finishing, improvement of shades and characterization of dyed fabrics. The advantage of this technology are well known such as improvement in shades , enhanciong colour fastness , colour stregnth , low cost effective and reduction of the concentration of the dye. All these results have been seen from our above experiments. Radiation curing of silk, wool and cotton fabric to reduce pilling , their finishing and mercerization processes has also been improved. Thus both UV and gamma radiation has improved the textile sttuff according to

The use of eco-friendly technnology giving eco–label products under the influence of high energy radiations that may give new orientation for other dyes such as vat, reactrive azo and other brands. Similarly improvement of fibers of wool , silk , nylonn , Polyester cotton (P.C). etc., for dyeing to get good shades, even and lavelled dyeing, accepatable fastness properties yet are underway.So the dyers and colourists should try such techniques inorder to get better results and alternating methods for any risks related to human

The authors are thankful to Dr. H. F. Mansour, Dr. Eman Osman, Dr. Nagia Ali and Dr. Khaled El Negar from Natioanal Textile Research Centre, Cairo Egypt, Dr. M. Zuber, Professor of Applied Chemistry, GC Univeristy Faisalaabd Pakistan for valuable discussion during this work. We are grateful to Abher Rashid, T. Bechtold and

**4.3 Effect of UV and gamma radiation on wool and silk and polyester** 

commercial value. (Millington, 1998a; Millington, 1998b; Millington, 1997).

Fattah *et al.*, 2010).

**5. Conclusion** 

health.

standards of ISO , EPA and FAO.

**6. Acknowledgement** 

Peter Hauser for their technical help.


**2** 

*Australia* 

+ 2Na2SO3 + 2H2O

**Dyeing Wool with Metal-free Dyes –** 

**Application of Vat Dyes to Wool** 

John A. Rippon, Jackie Y. Cai and Shaun M. Smith

*CSIRO Materials Science and Engineering,* 

**The Use of Sodium Borohydride for the** 

O-

S

O-

Na<sup>+</sup> Na<sup>+</sup>

Vat dyestuffs are pigments that must be pre-treated with a reducing agent, such as sodium hydrosulphite, to make them water-soluble immediately before they are used for dyeing (Latham, 1995; Trotman, 1984). The reduction step converts the pigment form into a leuco compound. This owes its name to the Greek word for colourless, because many vat dyes are very pale in colour when in the reduced state, due to the lower level of conjugation of double bonds. A schematic of this reaction for the dyestuff Vat Red 1 is shown in Figure 1.

Na2S2O4

Vat Red 1 Leuco Compound

4NaOH <sup>S</sup>

Fig. 1. Structure of Vat Red 1 and formation of the sodium salt of the leuco compound.

In strongly alkaline conditions, the leuco forms of vat dyestuffs are anionic and soluble in water. They can be exhausted onto cotton from long liquors under alkaline conditions in the presence of an electrolyte, such as sodium chloride or sodium sulphate (Latham, 1995; Trotman, 1984). After adsorption by the substrate, the leuco form of the dye is oxidised back to the insoluble coloured pigment inside the fibre. This can be done by exposure to air, or with an oxidising agent such as hydrogen peroxide. Wool is usually dyed with anionic dyestuffs from acidic dyebaths, where the amphoteric wool fibres are positively charged as a result of protonation of amino and carboxyl groups. Under alkaline conditions, however, fewer amino groups are protonated and, depending on the pH, the net charge on the fibres may be neutral or even negative. The effect of this is that conventional acid, premetallised and reactive wool dyes have a lower substantivity for wool under alkaline conditions than under acidic conditions. In contrast to this behaviour, however, even under strongly alkaline conditions, the anionic leuco form of a vat dyestuff has a relatively high substantivity for wool (Bird, 1947; Hug, 1948; Luttringhaus, Flint & Arcus, 1950; Weber, 1951) and wool/cotton blends (Lemin & Collins, 1959). This results in high levels of dyebath

**1. Introduction** 

S

S

exhaustion at pH values as high as pH 9 and above.

O

O

