See discussions, stats, and author profiles for this publication at: https://www.researchgate.

net/publication/269223569

Bleaching of Black Pigmented Karakul Wool Fibers Using Copper Sulfate as

Catalyst

Article in Fibers and Polymers · November 2014

DOI: 10.1007/s12221-014-2297-y

CITATIONS READS

6 1,943

4 authors:

Meghdad Kamali moghaddam Somayeh Safi

University of Bonab Isfahan University of Technology
26 PUBLICATIONS 340 CITATIONS 24 PUBLICATIONS 369 CITATIONS

SEE PROFILE SEE PROFILE

Sayed Majid Mortazavi Maedeh Zamani

Isfahan University of Technology Stanford University
27 PUBLICATIONS 580 CITATIONS 17 PUBLICATIONS 1,557 CITATIONS

SEE PROFILE SEE PROFILE

Some of the authors of this publication are also working on these related projects:

This study is related to my graduate thesis View project

The manufacturing of a natural fiber kit for oil pollution absorption from the sea level View project

All content following this page was uploaded by Meghdad Kamali moghaddam on 12 December 2014.

The user has requested enhancement of the downloaded file.

Fibers and Polymers 2014, Vol.15, No.11, 2297-2306 DOI 10.1007/s12221-014-2297-y

Bleaching of Black Pigmented Karakul Wool Fibers Using Copper

Sulfate as Catalyst
Sayed Majid Mortazavi, Somayeh Safi*, Meghdad Kamali Moghadam, and Maede Zamani
Textile Engineering Department, Isfahan University of Technology, Isfahan 84156-83111, Iran
(Received August 7, 2013; Revised May 10, 2014; Accepted June 8, 2014)

Abstract: The best chance for an efficient bleaching of highly pigmented wool with minimum fiber damage is provided by
the use of metal catalysts in mordanting step preceding peroxide bleaching. This study evaluates the catalytic effect of copper
sulfate (CuSO ) in the bleaching process of pigmented wool fibers under the used condition. The effects of CuSO and
4 4

Na P O (as a stabilizer) concentration, bleaching time and rinsing time after mordanting on yellowness index, optical and
4 2 7

mechanical properties were investigated and the optimum conditions for each step was reported. The results showed that an
excellent depigmentation with minimum fiber damage is provided by using 1 %w/v CuSO and subsequent rinsing for
4

60 min, as well as bleaching with 60 ml/l H O and 7 %w/v Na P O for 15 min. The optical properties of fibers were
2 2 4 2 7

improved after bleaching under optimum conditions compared with raw samples. The color indices revealed that the black
wool fibers have turned into a pale light brown shade. The morphology and structure of wool fibers, before and after
bleaching, were characterized by using optical microscopy, scanning electron microscopy (SEM), and EDAX test method.
Keywords: Copper sulfate, Depigmentation, Bleaching, Pigmented wool, Karakul wool

Introduction recent research on the electrical properties of eumelanin has

indicated that it may consist of more basic oligomers adhering
The native color of wool fibers is closely related to the to one another by some other mechanism. Thus, the precise
character of the environment in which sheep live. In nature, nature of eumelanin’s molecular structure is once again the
wool fibers are usually found in various shades of white, object of study [5,6]. The generally accepted chemical
yellow, and in some case brown or black, due to the natural structures of eumelanin and pheomelanin pigments are
pigment, melanin [1,2]. presented in Figure 1 [5-7].
Melanins are biological polymeric pigments formed from For light pastel shade textile articles, it is essential to use
the sequential oxidation of tyrosine and located inside the white material, and this can be obtained by the depigmentation
cortex of wool fiber. Melanin produced in follicular melanocytes of colored fibers [1,8,9]. Bleaching is a potential solution to
is the major basis for pigmentation of hair and wool in ‘lighten’ the color so that bright colored textile articles can
mammals [3]. There are two types of melanin: eumelanin is be produced from brown/black wool fibers. An efficient
found in wool (or hair and skin), and colors wool gray, pigment bleaching with minimum fiber damage is provided
black, yellow, and brown; pheomelanin imparts a pink to red by the use of metal catalysts in mordanting step preceding
hue and, thus, is found in particularly large quantities in red peroxide bleaching. A comparison of different metal salts
wool [3,4]. Eumelanin polymers have long been thought to that were candidates for bleaching catalysts showed that
comprise numerous cross-linked 5,6-dihydroxyindole and only iron (II), iron (III), and copper (II) ions had a significant
5,6-dihydroxyindole-2-carboxylic acid polymers. However, catalytic effect under the conditions used [2]. Because the
electron density of native melanin is higher than that of
keratin, the metal cations are preferably absorbed by the
melanin. After mordanting, the excess un-complexed metal
ions are thoroughly rinsed from the wool. In the second
stage, metal cations bound to the melanin catalytically
decompose hydrogen peroxide (H2O2) to produce highly
aggressive hydroxyl free radicals. This selectively attack and
bleach the melanin, while un-pigmented regions experience
a normal peroxide bleach [1,10,11]. The basic principles of
this process are illustrated in Figure 2.
A review of the literature reveals that many studies on
pigmented fiber bleaching are concerned with improving the
Figure 1. Chemical structure of pheomelanin (A) and eumelanin whiteness and mechanical properties of bleached fibers
(B). [2,8,11-17]. The method of depigmentation commonly used
in industrial practice consists of a mordanting bath containing
*Corresponding author: s.safi@tx.iut.ac.ir iron (II) ions which precedes a bleaching process using

2297
2298 Fibers and Polymers 2014, Vol.15, No.11 Sayed Majid Mortazavi et al.

Figure 2. Principles of pigmented fiber bleaching; (a) pigmented fiber, (b) mordanted fiber, (c) mordanted/rinsed fiber, and (d) bleached fiber.

H2O2. However, as far as the author is aware, there is not a The hydrogen peroxide (H2O2) used was a 30 % (w/w)
comprehensive study on copper (II) ions as a mordant agent aqueous solution. The non-ionic detergent (Ultravon GP,
in the bleaching process of pigmented wool. Ciba) and Na2CO3 (Merck Co., Germany) was used for
The use of copper ion as a bleaching catalyst was developed scouring process of wool fiber. Copper sulfate (CuSO4) in
some advantages compared with the iron mordanting method reagent grade was purchased from Merck Co. Tetra sodium
[2]: pyrophosphate (Na4P2O7) was obtained from Aldrich Chemicals
i. No reducing agents during mordanting are needed. Company. All other chemicals used were supplied by Merck
ii. Air need not be excluded, and therefore there is no Co., Germany.
limitation in the choice of bleaching machinery.
iii. Un-pigmented wool is not discolored. Pigment Bleaching of Wool Fibers
iv. Treatment times are much shorter. Scouring Process
This study evaluates the catalytic effect of copper sulfate Samples of karakul wool fiber were scoured in three steps
(CuSO4) in the bleaching process of pigmented wool fibers before using for the bleaching process experience. Firstly,
under the used condition. Investigation is concerning the raw wool fibers were rinsed with warm water, and then
effects of copper sulfate and tetra sodium pyrophosphate treated in a bath containing 0.1 %w/v Na2CO3 and 0.3 %w/v
(Na4P2O7; as a stabilizer) concentration, bleaching and non-ionic detergent (Ultravon GP, Ciba) at 40 oC for 15 min.
rinsing time after mordanting on yellowness degree, surface Finally, these fibers were rinsed with cold water.
morphology, optical and mechanical properties. Moreover, Depigmentation Process
the optimum conditions for each step is reported. The depigmentation process consisted of mordanting step
followed by a bleaching step and was carried out at the
Experimental experimental conditions (shown in Table 2).
The sample was depigmented (mordanting, rinsing,
Materials bleaching, and rinsing) at a fiber liquor ratio of 1:40. Different
Naturally pigmented black karakul wool fiber (60±22 µm concentrations of Na4P2O7 (2.5-10 %w/v) (as a stabilizer in
fineness and 80-170 mm length) was used. The properties of bleaching bath) and CuSO4 (0.4-1.2 %w/v) were tested. The
this fiber are summarized in Table 1. H2O2 concentration of 60 ml/l was used. Also, the effect of
bleaching and rinsing time after mordanting treatment were
Table 1. Yellowness index (Y.I.), CIE Lab indices, and strength of studied. After the bleaching step, each sample was rinsed with
pigmented wool fiber pure water, centrifuged and dried at room temperature.
CIELab Strength
Fiber Y.I Evaluation of Bleaching Effects
*
L a *
b *
(cN)
Color Measurement
Karakul wool 16.268 1.119 0.267 22.66 6.98
Bleached product quality can be defined by its whiteness

Table 2. Experimental conditions of depigmentation process for different fiber samples

Mordanting Rinsing Bleaching Rinsing
CuSO : 0.4-1.2 %w/v
4
Cold water Na P O : 2.5-10 %w/v
4 2 7
Pure water
o
L.R.: 1:40 Neutralization with NH OH4
H O 30 %: 60 ml/l
2 2
Temperature: 50 C
pH (HCO H): 3.5
2
pH: 11 L.R.: 1:40 Time: 5 min
o o
Temperature: 80 C Temperature: 45 C pH: 8.5
o
Time: 15 min Time: 15-75 min Temperature: 50 C
Time: 15-180 min
Bleaching Karakul Wool Using Copper Sulfate as Catalyst Fibers and Polymers 2014, Vol.15, No.11 2299

or yellowness. Yellowness index (Y.I) measurements were The wool fibers (1 g) were first dried in an oven at 110 oC
performed on a Datacolor Texflash, a reflectance spectro- for 1 h. After cooling for 10 min, the sample was weighed
photometer. The color of bleached pigmented wool fibers again and dipped in 100 ml of sodium hydroxide solution
was calculated on the basis of CIELAB color value. L* is the (0.1 N) at 65 oC for 1 h. Subsequently, the wool fibers were
position on the axis dark/light (0 for black and 100 for filtered and rinsed six times with distilled water. Then, the
white), a* is the position on the axis red (+a*)/ green (−a*), sample was neutralized with acetic acid (1 %) and rinsed
and b* is the position on the axis yellow (+b*)/ blue (−b*). again with distilled water for several. Finally, the fibers were
Mechanical Properties of Fibers dried at 110 oC for 1 h, cooled and re-weighed [18].
The tensile properties of wool fibers, before and after Weight Loss
bleaching treatment, was determined by Zwick universal The weight loss percentage (wi) of bleached fibers was
testing machine (Model 1446-60, Germany) according to determined using following equation [11]:
ASTM D3822-01 (at an elongation rate of 20 mm/min and a wpre – wafter
length of 25 mm). For mechanical properties, 300 measures - × 100
wi = ------------------------ (2)
wpre
were realized for each sample.
Alkaline Solubility where wpre is the mass of fibers before treated (at 20±2 oC
The extent of fiber damage caused by bleaching was and 65±2 RH) and wafter is the mass of fiber after bleaching
determined by the alkaline solubility test. Alkaline solubility treatment.
is the weight loss of wool yarns after treatment with alkali
solution and was determined using the following equation: Surface Characterization
The surface morphology of wool fibers, before and after
Alkaline solubility % = bleaching, was observed using optical microscopy (Nikon,
CSM, Japan) and scanning electron microscopy (SEM;
(-----------------------------------------------------------------------------------
Initial weight – Secondary weight )-
× 100 (1) model VEGA-TESCAN-LMU). Moreover, elemental analysis
Initial weight
was conducted with EDAX spectra. A sputter coater was

Figure 3. Effect of copper sulfate concentration on; (a) yellowness index, (b) weight loss, (c) strength, and (d) alkaline solubility of bleached
wool fibers (treated with 60 ml/l H O and 7 %w/v Na P O for 30 min).
2 2 4 2 7
2300 Fibers and Polymers 2014, Vol.15, No.11 Sayed Majid Mortazavi et al.

used to pre-coat conductive gold onto the surface before

measuring the micro structures.

Results and Discussion

Effect of Mordant Concentration

In this work, copper sulfate (CuSO4) is used as a mordant
and its catalytic effect under the used conditions was
investigated. To determine the effect of mordant concentration
on bleaching of black pigmented wool fibers, a series of
trials were performed using five different CuSO4 concentrations
(0.4, 0.6, 0.8, 1.0, and 1.2 %w/v). The yellowness index,
weight loss percentage, strength, and alkaline solubility
results of bleached wool fibers for different mordant
concentrations are shown in Figure 3. The results of tensile
test of 300 fiber specimen are illustrated in graph with error
bar.
When the results of the bleaching trials are compared * *

(Figure 3), it is clear that bleached wool mordanted with Figure 5. Effect of copper sulfate concentration (%w/v) on a -b
higher CuSO4 concentration has a lower yellowness index, of bleached wool fibers.
so that the minimum yellowness index (55.85) was obtained
in the mordant concentration of 1.2 %w/v. In fact, the obvious that the alkali solubility increased with copper
increasing of Cu (II) concentration caused more decomposition concentration.
of H2O2 and led to an increase in the reaction of the According to the results obtained from Figure 3, an
oxidative agent with wool fibers. However, this caused the excellent depigmentation with minimum fiber damage is
breaking of chemical bonds in fiber structure and reduction provided by using CuSO4 concentration equal to 1 %w/v.
in fiber strength. This is reflected in weight loss percentage, The effect of the CuSO4 concentration on optical properties
tensile strength, and alkaline solubility results of bleached of the samples is shown in Figure 4. The curves show an
wool fibers (Figure 3(b)-(d)). The results show that the increase and decrease of the lightness (L*) and redness (a*)
tensile strength decreased (from 4.68 to 4.44 cN) and the of bleached fibers, respectively, with raising the CuSO4
weight loss, increased (from 14 to 20 %) with CuSO4 concentration, so that the maximum value of L* was obtained at
concentration, respectively. The Figure 3(d) shows that the 1.2 %w/v CuSO4. The reason for this observation could be
alkali solubility of treated fibers was higher than 78 %, explained by the fact that copper can catalytically degrade
whereas this parameter was 8.98 % for untreated wool. It is H2O2 and cause better bleaching to produce larger L* and
smaller a* value. The L*, a*, and b* values also increased in
comparison with the raw sample.
As shown in Figure 5, all bleached mordanted samples
were in red-yellow quadrant of CIELab color space. The
color indices revealed that the black wool fibers have turned
into a pale light brown shade after bleaching process.

Effect of Tetra Sodium Pyrophosphate Concentration

Tetra sodium pyrophosphate (Na4P2O7) acts as a stabilizer
in bleaching bath and enhances the stability of the bleaching
samples and inhibits the breakdown of perhydroxy ion
radicals. To investigate the effect of Na4P2O7 concentration
on the bleaching efficiency of the black wool fibers, six
different Na4P2O7 concentrations (2.5, 4.0, 5.5, 7.0, 8.5, and
10 %w/v) was used. The yellowness index, weight loss
percentage, alkaline solubility and strength results of bleached
wool fibers for different Na4P2O7 concentrations are shown
Figure 4. Effect of copper sulfate concentration on optical in Figure 6.
properties of bleached wool fibers for 30 min with 60 ml/l H O
2 2
The curves show minimum yellowness index (50.15) was
and 7 %w/v Na P O .
4 2 7
obtained at 5.5 %w/v Na4P2O7. As shown in Figure 6, the
Bleaching Karakul Wool Using Copper Sulfate as Catalyst Fibers and Polymers 2014, Vol.15, No.11 2301

Figure 6. Effect of tetra sodium pyrophosphate concentration on; (a) yellowness index, (b) weight loss percentage, (c) strength, and (d)
alkaline solubility of wool fibers (mordanted with 1 %w/v CuSO and bleached with 60 ml/l H O for 30 min).
4 2 2

Na4P2O7 concentration is 7 %w/v in testing conditions.

The optical properties of bleached fibers presented in
Figure 7, also revealed that a slight increase and decrease of
lightness and a*-b* of wool fibers, respectively, at 5.5 %w/v
Na4P2O7. However, the maximum whiteness degree which
can be obtained by H2O2 bleaching is not considered optimal
unless provided a slightly lower damage incurred by wool
fibers.

Effect of Bleaching Time

To study the effect of different bleaching times on the
bleaching efficiency of karakul wool fibers, seven different
bleaching times (15, 30, 45, 60, 90, 120, and 180 min) were
applied. The yellowness index, weight loss percentage,
alkaline solubility and strength results of bleached wool
Figure 7. Effect of tetra sodium pyrophosphate concentration on
fibers for different bleaching times are shown in Figure 8.
optical properties of bleached wool fibers (mordanted with 1 %w/v It can be seen from the figure that a minimum yellowness
CuSO and bleached with 60 ml/l H O ).
4 2 2
index (44.65) was obtained at bleaching time equal to
120 min. However, the use of high bleaching times should
be avoided because they reduce the fiber strength [8,11,19].
increasing of Na4P2O7 concentration from 5.5 to 7 %w/v The curves (Figure 8) show an increase and decrease
provides maximum strength (4.62 cN) with minimum weight evolution of weight loss percentage and strength of bleached
loss (16 %) and alkaline solubility (79.12 %). So, the optimum wool fibers, respectively, according to the bleaching time.
2302 Fibers and Polymers 2014, Vol.15, No.11 Sayed Majid Mortazavi et al.

Figure 8. Effect of bleaching time on; (a) yellowness index, (b) weight loss percentage, (c) strength, and (d) alkaline solubility of bleached
wool fibers (mordanted with 1 %w/v CuSO , bleached with 60 ml/l H O and 7 %w/v Na P O ).
4 2 2 4 2 7

damage arising from H2O2 attack on amino acids in the

keratin fiber due to the longer treatment in bleaching bath.
Maximum strength value (4.66 cN) and minimum weight
loss (14 %) and alkaline solubility (80.64 %) were observed
at bleaching time equal to 15 min. Moreover, after 15 min,
the yellowness index of beached fiber (46.2) is reasonable
and hence bleaching time equal to 15 min was considered as
the optimum condition.
The effect of bleaching time on optical properties of the
samples is shown in Figure 9. As bleaching time increased,
the lightness value (L*) increased and a*, and b*slightly
reduced in the samples. This could be related to the removal
of pigments from wool fibers. The a* and b* values also
increased in comparison with the raw sample.

Effect of Rinsing Time after Mordanting Process

Rinsing following the mordanting step proved to be
Figure 9. Effect of bleaching time on optical properties of
critical with regard to fiber damage [2,11]. In this experiment,
bleached wool fiber at optimum conditions. five different rinsing times (15, 30, 45, 60, and 75 min) after
the mordanting step was tested. The curves in Figure 10
demonstrate the influence of the rinsing process on the
The alkaline solubility of these fibers also increased with properties of treated wool. It can be seen from the figure that
bleaching time. These are probably explained in term of a minimum yellowness index (26.6) was obtained at rinsing
Bleaching Karakul Wool Using Copper Sulfate as Catalyst Fibers and Polymers 2014, Vol.15, No.11 2303

Figure 10. Effect of rinsing time after mordanting on; (a) yellowness index, (b) weight loss percentage, (c) strength, and (d) alkaline
solubility of bleached wool fiber at optimum conditions.

of copper during mordanting, and its retention after rinsing,

may cause severe damage to the fiber. Rinsing following the
mordanting is important to reduce the fiber damage. During
rinsing, the copper ion not bound to the melanin pigments
will be removed from the keratin fiber matrix. Existence of
non-melanin bound copper in the fiber causes over bleaching
and reduces the fiber strength. If absorbed copper is
completely removed from the fiber keratin, the attack of
radicals will be localized exclusively at the melanin pigment,
while the fiber keratin undergoes only a simple peroxide
bleaching [2,10]. Although the maximum strength value
(4.53), minimum weight loss (18 %), and alkaline solubility
(81.02 %) were obtained at rinsing time of 75 min, considering
the yellowness index results, rinsing time of 60 min was
selected as an optimum condition.
The optical properties of bleached wool fiber were
presented in Figure 11. As the rinsing time (after mordanting)
Figure 11. Effect of rinsing time on optical properties of bleached increased, the lightness value (L*) decreased and a* and
wool fiber at optimum conditions. b*nearly remained unchanged in the samples. However, a
slight improvement in the L* was observed at rinsing time
time equal to 60 min. However, the bleached fiber’s strength equal to 60 min. The L* and b* values also increased in
is significantly increased in all cases, particularly at the long comparison with the raw sample, but a* has not changed
rinsing time. significantly. Smaller lightness of bleached fibers after
In mordant bleaching, adsorption of an excessive amount increasing of rinsing time could be related to the removal of
2304 Fibers and Polymers 2014, Vol.15, No.11 Sayed Majid Mortazavi et al.

Figure 12. Optical microscopic image of the wool fiber before (a) and after (b) of bleaching process.

Figure 13. SEM images of the wool fibers with two magnifications: raw pigmented wool (a: 250× and d: 1000×), mordanted fiber (b: 250×
and e: 1000×), and bleached fiber (c: 250× and f: 100×).

some copper ions from melanin, in addition to fiber keratin. fibers are shown in Figure 13. The raw pigmented wool has
some unknown material deposited on the cuticle surface
Microscopic Observations (Figure 13(a)). As shown in Figure 13(b), the surface of the
Figure 12 shows the longitudinal section of unbleached mordanted wool fibers was covered with copper particles.
and bleached karakul wool fibers. It is clearly obvious that However, the bleached fibers (Figure 13(c)) have a much
the black karakul wool fibers are white after the bleaching smoother surface than the mordanted one, so it appears
process. It is seen that the epicuticle remain unchanged after lustrous. In the latter case, the scale structure remained
the bleaching and the bleaching process do not modify the almost intact without noticeable damage.
surface of wool fibers. The EDAX spectra obtained for the surface of samples
The SEM images of the surface morphology of wool shown in Figure 13, where indicated the characteristic peaks
Bleaching Karakul Wool Using Copper Sulfate as Catalyst Fibers and Polymers 2014, Vol.15, No.11 2305

Figure 14. EDAX spectra of the wool fibers; (a) raw pigmented wool, (b) mordanted fiber, and (c) bleached fiber.

for different element in the functional layer of wool fibers yellowness degree, optical and mechanical properties.
(Figure 14). As expected, by mordanting of karakul wool The results showed that an excellent depigmentation with
fibers, more copper particles have been deposited on the minimum fiber damage is provided by using CuSO4 concen-
surface of the fibers (Figure 14(b)). The EDAX analyses tration equal to 1 %w/v. In mordant bleaching, adsorption of
revealed that the surface of wool fibers contained significant an excessive amount of copper during mordanting, and its
concentrations of C, O, N, and much less S or Ca. retention after rinsing, may cause severe damage to the fiber.
Therefore, rinsing following the mordanting is important to
Conclusion reduce the fiber damage. In this study, the rinsing time equal
to 60 min was selected as an optimum condition. Optimum
In this study, the catalytic effects of copper sulfate in the results for bleaching conditions were obtained when bleaching
bleaching process of pigmented karakul wool fibers were time was 15 min, H2O2 concentration was 60 ml/l, and using
evaluated under the used condition. Investigation is concerning the 7 %w/v Na4P2O7 in bleaching bath.
the effects of CuSO4 and Na4P2O7 (as a stabilizer) con- The advantages of using Cu (II) mordant (compare to iron
centration, bleaching and rinsing time after mordanting on (II) ions) are no need the use of any reducing agent in
2306 Fibers and Polymers 2014, Vol.15, No.11 Sayed Majid Mortazavi et al.

mordanting bath and lower limitations for the selected Press, San Diego, USA, 1992.
bleaching machine, due to the lack of sensitivity of copper 6. S. Ito, Pigment Cell Res., 16, 230 (2003).
mordant to oxygen of air during the bleaching process. 7. D. Nezirevic, K. Arstrand, and B. Kagedal, J. Chromatogr.
In all samples, L*, a*, and b* increased after bleaching in A, 1163, 70 (2007).
comparing to raw samples; however, increasing copper 8. T. Harizi, S. Dhouib, S. Msahli, and F. Sakli, ISRN Textiles,
sulfate concentration and bleaching time led to increasing L* 2013, 1 (2013).
while decreasing the values of a* and b*. As the rinsing time 9. R. Treigiene, Mater. Sci., 16, 341 (2010).
(after mordanting) increased, the lightness value (L*) 10. D. M. Lewis and J. A. Rippon Eds., “The Coloration of
decreased and the values of a* and b*remained unchanged. Wool and Other Keratin Fibres”, John Wiley & Sons,
The color indices revealed that the black wool fibers have 2013.
turned into a pale light brown shade. 11. X. Liu, C. Hurren, and X. Wang, Fiber. Polym., 4, 124
The microscopic images (SEM and optical) of fibers (2003).
showed that the bleaching process led to an increase in fiber 12. D. C. Teasdale and A. Bereck, Text. Res. J., 51, 541 (1981).
whiteness and did not cause an apparent change in the 13. M. Arifoglu and W. N. Marmer, Text. Res. J., 60, 549
surface morphology of karakul wool fibers. (1990).
14. W. Chen, D. Chen, and X. Wang, Text. Res. J., 71, 441
References (2001).
15. H. Wang, X. Liu, and X. Wang, Fiber. Polym., 6, 263
1. P. A. Duffield and D. M. Lewis, Rev. Prog. Color., 15, 38 (2005).
(1985). 16. M. Montazer, M. Zargaran, and A. Rahimi, Text. Res. J., 79
2. A. Bereck, Rev. Prog. Color., 24, 17 (1994). (2009 ).
3. L. Yehaugn, E. Plahten, D. I. Gew, and S. W. Omholtwz, J. 17. T. J. Kang and K. Oh, “Proc. of AATCC”, 1995.
Theor. Biol., 215, 449 (2002). 18. B. Ahmadi, Ed., “Chemistry of Textiles”, Arak Industries
4. N. A. Barnico and M. S. C. Birbeck in “The Biology of Co., Tehran, Iran, 1986.
Hair Growth” (W. Montagna and R. A. Ellis Eds.), pp.239- 19. D. Yilmazer and M. Kanik, J. Eng. Fiber. Fabric., 4, 45
252, Academic Press, New York, USA, 1958. (2009).
5. G. Prota, Ed., “Melanins and Melanogenesis”, Academic

View publication stats