Effect of Moisture Regain of Cotton Roving on Spun Yarn Quality

Yanming ZHANG 1, a, Qiming ZHAO 1, b and Zhengxue WU 1, c 1School of Textile and Garment, Wuyi University, Jiangmen City, Guangdong, P. R. China

azhym@wyu.edu.cn, bzhqm@wyu.cn, cwuzhengxue2009@163.com

Keywords: Cotton roving, Moisture regain, Relative humidity, Spun yarn

Abstract. Different moisture regain of cotton roving was obtained by changing the relative humidity

of constant temperature and humidity chamber. Then the cotton roving with different moisture regain

was used for producing spun yarn on sample spinning frame. The hairiness value, evenness, breaking

strength and elongation of the above spun yarns were tested. And the influence of moisture regain of

cotton roving on the quality of spun yarn was discussed. The results show that, there is an exponential

relationship between moisture regains of cotton roving and relative environmental humidity, and

when the value of the moisture regain of cotton roving is about 7% ~7.3%, the spun yarn quality is the

best.

Introduction

During the spinning process, there are many different requirements for fiber properties in each

working procedure. But the temperature and humidity are the direct factors effecting on physical and

mechanical properties of fibers, such as strength, elongation, conductivity, softness, moisture regain,

friction coefficients, etc. When the relative enviremental humidity changes, the cotton fiber will be

moisture pick-up or liberation, thus its moisture regain will rise or fall [1-3]. It is called equilibrium

moisture regain when materials moisture pick-up and liberation reach the balance in certain

atmospheric conditions. In the actual spinning process, the relative environmental humidity of spun

yarn workshop is generally higher than roving workshop, so the roving will be in a state of moisture

liberation in spinning. It is very useful to maintain suitable temperature and humidity in workshop

environment which can ensure smooth running of textile manufacture and improve the textile

products quality [4].

The effect of relative environmental humidity on the moisture liberation regain of cotton roving

was discussed at first in this article. Then the roving with different moisture regain would be obtained

by changing the relative humidity. At last, the effect of moisture regain of cotton roving on spun yarn

quality was discussed.

Experimental

Material - 629.3 tex cotton roving

Equipment

- Y802N eight-basket constant temperature oven;

- JA5003A electronic balance;

- YG751B constant temperature and humidity chamber;

- AS511A sample ring spinning frame;

- Mode1616T dehumidifier;

- Heating and air conditioner;

- 272-type dry and wet bulb thermometer.

Yarn Spinning Technology. AS511A sample ring spinning frame which can produce spun yarn

with raw materials of cotton, wool, synthetic or blended fiber was used in the experiment. Following

variables of this machine were selected:

Advanced Materials Research Vol. 627 (2013) pp 279-282Online available since 2012/Dec/27 at www.scientific.net© (2013) Trans Tech Publications, Switzerlanddoi:10.4028/www.scientific.net/AMR.627.279

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- Teeth number of gear = AZ :30; BZ :26; CZ :38; and DZ :45

- Draft ratio = former zone:9.71; central zone: 1.152; and back zone: 3.66.

Thus the general draft ratio is

26 4539.893 39.893 40.94

30 38

B D

A C

Z ZE

Z Z= × × = × × =

Experimental Procedures

The Effect of Relative Humidity on Equilibrium Moisture Liberation Regain of Cotton

Roving. The roving segments each was 10m long cut out from one roving bobbin were put into the

constant temperature and humidity chamber which temperature was set to 20 ˚C and its humidity was

set to 90%, 80%, 70%, 60% and 50% in progression. The moisture liberation regain of cotton roving

segments can be obtained by weighing those samples. The specific experimental procedures were as

follows:

- Five cotton roving segment samples each was 10m long were put into eight-basket constant

temperature oven which temperature was set to 105 ˚C. Then the samples were dried and

weighted separately.

- The temperature of constant temperature and humidity chamber was set to 20 ˚C, and the

humidity was set to 90%.

- Five cotton roving segment samples known dry-weight were put into the constant temperature

and humidity chamber to balance. After eight hours, the wet-weight of samples was weighted

and the moisture regain was calculated.

- The temperature of the constant temperature and humidity chamber was set to 80%, 70%, 60%

and 50% in progression, and repeat the step given above to get the moisture regain of five

cotton roving segment samples in each of the above humidity.

Effect of Moisture Regain of Cotton Roving on Spun Yarn Quality. The cotton roving with the

corresponding equilibrium moisture regain was obtained according to the effect of the relative

humidity on equilibrium moisture liberation regain of cotton roving. Specific experimental steps were

as follows:

- The environmental temperature of the spinning laboratory was controlled at 20 ˚C and the

relative humidity was controlled at 75% using air conditioners and dehumidifiers.

- The temperature of constant temperature and humidity chamber was set to 20 ˚C, and the

humidity was set to 75%.

- One cotton roving bobbin was put into the constant temperature and humidity chamber to

balance for 8 hours.

- The roving reaching equilibrium state was taken out from the constant temperature and

humidity chamber and sealed with a plastic bag. And then it was used for spinning in the ring

spinning frame.

- Then the relative humidity of the spinning laboratory and constant temperature and humidity

chamber was set to 69%, 63%, 57% and 51% respectively, repeating the two steps given above.

Test Indicator - Hairiness value. Yarn hairiness of equal or longer than 3mm was measured on YG172A yarn

hairiness tester. The yarn speed was 30 m/min, and 10 samples each was 10m long were tested.

- Evenness. Yarn evenness CV value was measured on YG136 evenness tester at a speed of 200

m/min, and the test time was 1 min.

- Breaking strength and elongation. Yarn breaking strength and elongation were measured on

XL-2 yarn strength tester, at a clamp speed of 500 mm/min, gauge length of 500 mm. And thirty

samples were tested in each case.

280 Advances in Textile Engineering and Materials

Results and Discussion

Effect of Environmental Humidity on Equilibrium Moisture Regain of Cotton Roving. The

equilibrium moisture liberation regain of cotton roving under different relative environmental

humidity was shown in Table 1.

Table 1 Equilibrium moisture regain of cotton roving under different relative humidity

Relative humidity (%) 90 80 70 60 50

Equilibrium moisture liberation regain (%) 10.17 8.76 7.66 6.63 5.88

The moisture pick-up and moisture liberation of fibers is an exponential increase process [5].

Based on the data in Table 1, the moisture liberation regression curve and equation of cotton roving

was obtained using Excel, see Fig. 1.

Fig. 1 Regression curves of moisture liberation

According to the regression equation and correlation coefficient R calculated, the process of

moisture liberation of cotton roving was highly in line with the rule of exponential increase.

Effect of Roving Moisture Regain on the Quality of Spun Yarn. Based on the regression

equation of moisture liberation of cotton roving given in Fig. 1, the equilibrium moisture liberation

regain of cotton roving on a roving bobbin under the relative environmental humidity selected

separately was obtained, as shown in Table 2.

Table 2 Roving equilibrium moisture regain under relative humidity selected

Relative humidity (%) 75 69 63 57 51

Moisture regain (%) 8.2 7.5 7.0 6.4 5.9

The hairiness value, evenness, breaking strength and elongation of spun yarn samples produced

with cotton roving under the above five equilibrium moisture regain were measured, and the results

were shown in Table 3.

Table 3 Spun yarn quality

Moisture regain (%) 5.9 6.4 7.0 7.5 8.2

Hairiness value above 3 mm (root/m) 6.5 6.1 5.7 5.4 6.5

Evenness CV (%) 16.0 15.1 13.6 13.9 15.0

Breaking strength (cN) 558.7 577.6 600.5 579.8 575.4

Breaking elongation rate (%) 7.6 7.9 7.8 8.0 7.9

The discipline of hairiness value, evenness, breaking strength and elongation of spun yarn changed

with the moisture regain of cotton roving were shown in Fig. 2 ~ Fig. 5 respectively.

As can be seen in Fig. 2 ~ Fig. 5, along with the increase of the roving moisture regain, yarn

hairiness value and evenness decreased first and then increased, but yarn breaking strength and

elongation increased first and then decreased. Considering the various indicators, the formed yarn

quality was better when the roving moisture regain was about 7% ~ 7.3%.

Advanced Materials Research Vol. 627 281

When the roving moisture regain was lower, it would generate the static electricity and cause the

increase of yarn hairiness. When the roving moisture regain was appropriate, fibers were soft and

easy to be twisted into yarn body, and meanwhile the static electricity would be reduced, which

helped to improve the yarn quality. But when the value of roving moisture regains was too high, it

would cause the adhesion between fibers and rubber roller, thus disordered the fibers in the yarn, and

thereby damaged the formed yarn quality.

Conclusions

- With the increase of relative environmental humidity, the moisture regain of cotton roving

increased.

- Whatever the values of moisture regain of cotton roving was higher or lower, the quality of

spun yarn was always poor. When the moisture regain of cotton roving was about 7% ~ 7.3%,

the formed yarn quality was better.

References

[1] Zhongzhi MA, “Influence of temperature and humidity of workshop on cotton spinning

technology and yarn quality” in China Yarn Quality and New Product Development Technology

Forum, Qingdao, China, May 22-25, 2006, p. 591-595 (In Chinese)

[2] Xiaofei DONG, Cotton Textile Technology Vol. 35 (2007), p. 33 (In Chinese)

[3] Micheae Wallace: Cotton Incorporated Vol. 2 (2002), p. 1

[4] Yasu ZHOU, Changde GAN, Jingde ZHAO: Textile Mill Air Conditioning (Third Edition)

(China Textile & Apparel Press, 2009), p.5-6 (In Chinese)

[5] Mu YAO: Textile Material (Third Edition) (China Textile & Apparel Press, 2009), p.43-47 (In

Chinese)

Fig. 3 Effect of the roving moisture regain

on evenness value of spun yarn

Fig. 5 Effect of the roving moisture regain

on breaking elongation rate of spun yarn

Fig. 4 Effect of the roving moisture regain

on breaking strength of spun yarn

Fig. 2 Effect of the roving moisture regain

on hairiness value of spun yarn

282 Advances in Textile Engineering and Materials

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