Scouring and Bleaching on One Bath for Tussah Silk

Jie Lin, Yanghua Lu, Sheng, Lu, Dehong Cheng*

Eastern Liaoning University, Dandong, Liaoning, China

chengdehongldxy@qq.com

Keywords: One bath process, Tussah silk, Whiteness, Degumming rate, Salt, Hydrogen peroxide

Abstract. In this paper the one bath process of scouring and bleaching was applied to degum and

bleach tussah silk. In this process degumming and bleaching of tussah silk was achieved only through

one step. The effects of salt, decolorizer, treat time and temperature on whiteness, degumming rate

and break strength were investigated. The optimal degumming and bleaching condition was that the

concentration of Na2SiO3 salt was 10 o.w.f. %, concentration of hydrogen peroxide was 10 o.w.f %,

the scouring and bleaching time was 40 min and temperature was 95 °C. Under the optimal scouring

and bleaching condition the whiteness of tussah silk was 82, degumming rate was 11.5% and the

breaking strength was 370 N.

Introduction

Tussah silk is a kind of proteins fiber including fibroin, sericin and natural pigments and so on. The

disadvantages of the untreated Tussah silk such as crude guise, hard handle and yellowish brown

result in the poor performances in wettability, gas permeability and heat retention property [1, 2]

. In

order to enhance performances of Tussah silk the wild and natural Tussah silk is degummed and

bleached before subsequent process. Some process technologies have been applied to treat the tussah

silk to reduce sericin and enhance whiteness [3-5]

. In conventional technologies the degumming and

bleach processes are independent and degumming of Tussah silk was carried out before bleaching,

which results in the increment of energy consumption and cost of production.

In this paper, the pre-treatment technology of tussah silk was investigated. The one bath process

of scouring and bleaching was applied to degum and bleach tussah silk. In this process degumming

and bleaching of tussah silk was achieved only through one step. The effects of salt, decolorizer, treat

time and temperature on whiteness, degumming rate and break strength were investigated. The

obtained results indicated that one bath process of scouring and bleaching could enhance

performances of Tussah silk.

Experimental process

One Bath Process for Scouring and Bleaching of Tussah Silk. An amount of tussah silk were

firstly immersed in the solution with 10 g/L sodium carbonate (Na2CO3) at 40 °C under bath ratio for

1:30 condition. After 30 min the an amount of 35% hydrogen peroxide (H2O2), refining agent FS-303

were added to the treat solution, and then the temperature of solution was heated to 95 °C for 40 min.

Tussah silk was washed and then dried in 90°C for 1 h.

Determination of tussah silk. The whiteness of the treatment tussah silk was determined by

ADCI-60 Brightness Meter. The degumming rate was calculated based on the weight of tussah before

and after treatment. The breaking strength of tussah silk was determined by YG (B) 026H-250 tester.

The width of per-treatment tussah silk was 5 cm.

Results and discussion

Effect of concentration of salt and decolorizer on whiteness of tussah silk. The whiteness of

tussah silk under different concentrations of salts such as Sodium Carbonate Na2CO3 and Sodium

Silicate Na2SiO3 were investigated and shown in Fig.1. The obtained result indicated that the

Advanced Materials Research Vols. 821-822 (2013) pp 60-63Online available since 2013/Sep/18 at www.scientific.net© (2013) Trans Tech Publications, Switzerlanddoi:10.4028/www.scientific.net/AMR.821-822.60

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maximum of whiteness was 78 with o.w.f 10% Na2CO3 salt and the maximum of whiteness was 84

for o.w.f 10% Na2SiO3 salt. The whiteness of tussah silk with Na2SiO3 salt was obvious more than

that with Na2CO3 salt. The main reason maybe that Na2SiO3 salt as stabilizer for hydrogen peroxide

could retard the release of hydrogen peroxide; however Na2CO3 salt didn’t affect the release of

hydrogen peroxide and only adjusted the pH value of solution.

Fig.1 Whiteness of tussah silk with different salts under different concentration:a, Na2SiO3 salt; b,

Na2CO3 salt

The effect of concentration of hydrogen peroxide on whiteness of tussah silk was investigated

and shown in Fig. 2. When the concentration of hydrogen peroxide was less than 35 o.w.f. %

whiteness of tussah silk increased with the concentration increment and when the concentration of

hydrogen peroxide was more than 35 o.w.f. % whiteness of tussah silk reduced with concentration

increment. The main reason maybe that tussah silk was excessive bleached when the concentration of

hydrogen peroxide was more than 35 o.w.f. %.

Fig. 2 Effect of concentration of hydrogen peroxide on whiteness of tussah silk

Effect of concentration of salt and decolorizer on whiteness of tussah silk. The degumming rate

of tussah silk under different concentrations of salts were investigated and shown in Fig. 3.The

obtained result indicated that degumming rate firstly increased and then reduced. When the

concentration of salt was 10 o.w.f. % the degumming rate of tussah silk was 11.8 for Na2SiO3 salt and

6.4 for Na2CO3 salt. Integrally considering with whiteness the optimal concentration of Na2SiO3 salt

was 10 o.w.f % with best whiteness and degumming rate.

a

b

70

74

78

82

86

90

0 5 10 15 20 25 30

Concentration owf %

Wh

iten

ess a

b

70

74

78

82

86

90

0 5 10 15 20 25 30

Concentration owf %

Wh

iten

ess

70

74

78

82

86

90

20 30 40 50 60

H2O2 concentration owf %

Wh

iten

eess

Advanced Materials Research Vols. 821-822 61

Fig. 3. Degumming rate of tussah silk under different salt concentrations: a, Na2SiO3 salt; b, Na2CO3

salt

Fig. 4. Degumming rate of tussah silk under different concentration of H2O2

In one bath technology hydrogen peroxide as decolorizer was applied to increase whiteness of

tussah silk. The effect of hydrogen peroxide on degumming rate of tussah silk also was investigated

and shown in Fig. 4. the results illustrated that the degumming rate of tussah silk was 10.4 % when

the concentration of hydrogen peroxide was 10 o.w.f. % and the degumming rate did not vary even

though the concentration increment of hydrogen peroxide.

Effect of concentration of salt and decolorizer on breaking strength of tussah silk. During

degumming and bleaching process the breaking strength of tussah silk reduced because the structure

of tussah silk was destroyed. The breaking strengths of tussah silk were determined under different

concentrations of salts and decolorizer and shown in Fig. 5. the results indicated that the breaking

strength of tussah silk was slowly reduced with increment of the salt concentration, however the

breaking strength of tussah silk was obviously reduced with increment of hydrogen peroxide

concentration. The main reason was that fiber surface was corroded by hydrogen peroxide and the low

concentration of hydrogen peroxide was favor to the breaking strength of Tussah silk.

Fig 5 The breaking strengths of tussah silk under different concentration: a, Na2SiO3 salt; b, Na2CO3

salt; c, hydrogen peroxide

0

3

6

9

12

15

0 6 12 18 24 30

Concentration % owfD

egree

of

degu

mm

ing

a

b

7

8

9

10

11

12

0 10 20 30

H2O2 concentration owf %

Deg

um

min

g r

ate

%

320

340

360

380

400

0 10 20 30

Concentration owf %

Breakin

g s

trength

N

b

a

c

320

340

360

380

400

0 10 20 30

Concentration owf %

Breakin

g s

trength

N

b

a

c

62 Advances in Textile Engineering and Materials III

Effect of time and temperature on whiteness, degumming rate and breaking strength of silk.

The whiteness, degumming rate and breaking strength under different times were shown in Table 1.

The results indicated that the whiteness and degumming rate were max, and the breaking strength was

354 N when time was 40 min. The whiteness, degumming rate and breaking strength under different

temperatures were shown in Table 2. the whiteness and breaking strength of tussah silk was almost

not chang, however degumming rate of tussah silk obviously increased with the increment of

temperature. Integrally considering the optimal time and temperature conditions were 40 min and 95

°C.

Table 1 Whiteness, degumming rate and breaking strength under different times

Time (min) 25 30 40 50 60

whiteness 80 82 84 82 80

Degumming rate (%) 9.3 10.1 11.5 10.5 10.3

Breaking strength (N) 378 365 354 350 351

Table 2 Whiteness, degumming rate and breaking strength under different times

Temperature (°C) 80 85 90 95 100

whiteness 78 80 82 84 82

Degumming rate (%) 4.5 6.3 9.8 11.5 11.2

Breaking strength (N) 389 382 378 370 361

Conclusions

The optimal degumming and bleaching condition was that the concentration of Na2SiO3 salt was 10

o.w.f. %, concentration of hydrogen peroxide was 10 o.w.f %, the scouring and bleaching time was 40

min and temperature was 95 °C. Under the optimal scouring and bleaching condition the whiteness of

tussah silk was 82, degumming rate was 11.5% and the breaking strength was 370 N.

Acknowledgements

This work was financially supported by Program of Liaoning Excellent Talents in University (No.

LJQ2011138), the Science and Technology Foundation of Liaoning (No. 201202081) and Key

Discipline Project of Liaoning Province Universities (No. 2012310)

References

[1] M. Nakpathom, B. Somboon, N. Narumol: Journal of Microscopy Society of Thailand Vol.23

(2009), p. 142

[2] D.H. Cheng: CIESC Journal Vol. 62 (2011), p. 169

[3] G. Fredddi, R. Mossotti, R. Innocenti: J. Biotech. Vol. 106 (2003), p. 101

[4] V. A. Rinsey Johnny, S. Karpagam Chinnammal: I.J.S.N. Vol. 3 (2012), p.51

[5] D.H. Cheng: Advanced Materials Research Vol. 331 (2011), p. 253

Advanced Materials Research Vols. 821-822 63

Advances in Textile Engineering and Materials III 10.4028/www.scientific.net/AMR.821-822 Scouring and Bleaching on One Bath for Tussah Silk 10.4028/www.scientific.net/AMR.821-822.60

DOI References

[3] G. Fredddi, R. Mossotti, R. Innocenti: J. Biotech. Vol. 106 (2003), p.101.

http://dx.doi.org/10.1016/j.jbiotec.2003.09.006 [5] D.H. Cheng: Advanced Materials Research Vol. 331 (2011), p.253.

http://dx.doi.org/10.4028/www.scientific.net/AMR.331.253