Property Evaluation of Sound-Absorbent Nonwoven Fabrics Made of

Polypropylene Nonwoven Selvages

Jia-Horng Lin1,2, b, Chen-Hung Huang3, c, Ying-Huei Shih1, Yu-Chun Chuang1,

Ching-Wen Lin4 and Ching-Wen Lou5,a

1Laboratory of Fiber Application and Manufacturing, Department of Fiber and Composite Materials,

Feng Chia University, Taichung City 407, Taiwan, R.O.C.

2School of Chinese Medicine, China Medical University, Taichung 40402, Taiwan, R.O.C.

3Department of Aerospace and Systems Engineering, Feng Chia University, Taichung City 407,

Taiwan, R.O.C.

4Department of Fashion Design, Asia University, Taichung 41354, Taiwan, R.O.C.

5Institute of Biomedical Engineering and Material Science, Central Taiwan University of Science

and Technology, Taichung 406, Taiwan, R.O.C.

acwlou@ctust.edu.tw,bjhlin@fcu.edu.tw, cchhuang@fcu.edu.tw

Keywords: recycle, polypropylene (PP), sound absorption, selvages, nonwoven fabrics.

Abstract. The rapid development of textile industry at the beginning of the Industrial Revolution

results in the invention of synthetic fibers. As synthetic fibers cannot be decomposed naturally,

significant textile waste is thus created. Selvages, which make up the majority of our total garbage

output, have a low value and thus are usually sold cheaply or outsourced as textile waste. This study

aims to recycle and reclaim the nonwoven selvages which are discarded by the textile industry. The

recycled polypropylene (PP) selvages, serving as a packing material, and 6 denier PP staple fibers

are made into the recycled PP nonwoven fabrics. The resulting nonwoven fabrics are subsequently

tested in terms of maximum tensile breaking strength, tearing strength, surface observation,

thickness measurement and sound absorption coefficient.

Introduction

Since the Industrial Revolution, noise constantly influences people’s living environment. To

many people, noise is a sound that is undesired or unpleasant; however, the judgment depends on

individual concepts influenced environmentally and mentally. The real noise is a sound which

exceeds the volume level that the country law bans, or results in bad effect to the human mind

approved by science. Noise debilitates people, influencing their concentration and working

efficiency [1]. Noise pollution is one reason to cause public safety, and when exposing to a high

level of noise for a long time, people may suffer from auditory fatigue [2]. To avoid the harm

caused by noise, Parkinson et al. (2002) explored the sound absorption of the composites made of

elastic, porous material and impervious membranes [3]. With an increasing emphasis on

environmental protection, Hong et al. (2007) created a novel sound-absorbent composite with

recycled rubber pellets [4]. The majority of sound-absorbent materials are inflammable; to cope

with this shortcoming, Ogawa et al. (2009) thus created sheet of flame retardant porous material,

molded article thereof and flame retardant sound-insulating material for car. It is hard to evade the

low-frequency noise, which damages the human body more greatly than high-frequency noise does.

Yang (2010) invented a sound-insulating car mat with an upper water-repellent layer of foamed

polymer and a lower sound-absorbent layer of needle-punching cotton. From 2011 to 2012, Lin et al.

have utilized nonwoven in Sound-Absorbent products [5-11]. Environment has been polluted and

Advanced Materials Research Vol. 627 (2013) pp 855-858Online available since 2012/Dec/27 at www.scientific.net© (2013) Trans Tech Publications, Switzerlanddoi:10.4028/www.scientific.net/AMR.627.855

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destroyed since the Industrial Revolution; in addition, the invention and great uses of polymers also

cause a significant garbage output. What is worse, garbage is often taken care by burning it,

resulting in the green house effect. According to the fourth report of the Intergovenmental Panel on

Climate Change (IPCC), green house effect is primarily caused by human activities [12]. The rapid

development of textile industry brings severe environmental protection problems. Selvages, making

up a majority of the textile waste, are outsourced at a cheap price or for free. It is statistically stated

that millions of tons of selvages are buried [2]. In addition, PP fibers have a low cost and a low

density [13] and are largely used in nonwoven fabrics [14]. Therefore, in this study, PP nonwoven

selvages are used as packing material to reduce the use of PP staple fibers and to form the recycled

PP nonwoven fabrics.

Experimental

Material

PP nonwoven selvages are provided by Kang Na Hsiung Co., Ltd., Taiwan, ROC. The 6 denier

(D) PP staple fibers (Lcy Chemical Corp., Taiwan, ROC.) have a length of 50 mm and a melting

point of 160-177 °C.

Procedure

PP nonwoven selvages are smashed and then blended with 6D PP staple fibers with blending

ratios of 0:100, 5:95, 10:90, 15:85 and 20:80, and then undergo carding, lining, lapping, and

needle-punching, forming the recycled PP composite nonwoven fabrics. The resulting nonwoven

fabrics are evaluated for absorption coefficient, maximum tensile breaking strength, and tearing

tests as specified in ASTM E1050-10, ASTM D5035-11, and ASTM D5035-11, respectively. Then,

the thickness and surface of the fabrics is measured and observed.

Results and Discussion

Maximum Tensile Breaking Strength of the Recycled PP Nonwoven Fabrics as Related to

Various Blending Ratios Figures 1 (a) and (b) show that tensile breaking strength along the cross machine direction (CD)

and machine direction (MD) slightly decreases when the content of PP nonwoven selvages

increases. This decrease occurs because PP nonwoven selvages have short fibers which create neps

that entangle themselves within the fibers of web, when they pass through the cylinder and Doffer,

resulting in an uneven fibrous distribution. Selvages also hamper the cohesion between PP fibers,

making the stress not effectively transmitted when the nonwoven fabrics are imposed a force.

Tensile breaking strength along the CD is greater than that along the MD, this is because fibers are

arranged along the CD during the carding process. It can be surmised that the virgin PP staple fibers

can be substituted with the selvages, without influencing the tensile breaking strength of the

resulting nonwoven fabrics.

Figure 1. Tensile breaking strength along the (a)CD(b) MD of the recycled PP nonwoven fabrics as

related to various blending ratios.

a b

856 Advances in Textile Engineering and Materials

Tearing Strength of the Recycled PP Nonwoven Fabrics as Related to Various Blending Ratios

Figure 2 shows a significant decrease in tearing strength along the CD and MD of the recycled

PP nonwoven fabrics, due to the neps that selvages create when undergoing the carding and lining

process. The neps will entangle themselves with the fibers in the web, resulting in an uneven fibrous

distribution. Selvages also obstruct the cohesion between PP fibers, making the stress not

effectively transmitted when the nonwoven fabrics are imposed a force.

Figure 2. Tearing strength along the MD and CD of the recycled PP nonwoven fabrics as related to

various blending ratios.

Sound Absorption Coefficient of the Recycled PP Nonwoven Fabrics as Related to Various

Blending Ratios

Figure 3 shows that the sound absorption coefficient of the recycled PP nonwoven fabrics is

low, regardless of the blending ratios. This is due to the high porosity of the recycled PP nonwoven

fabric; the internal abrasion of the fabrics is not good, resulting in a low sound absorption (internal

abrasion refers to when sound waves enter the porous material and encounter the walls of the pores,

becoming weaker in strength and turning into heat which later dissipates). The content of recycled

PP nonwoven selvages does not significantly influence the sound absorption, the variation of which

is only 0.001 in nonwoven fabrics of 20 wt% and 0 wt%. Therefore, it can be concluded that

recycled PP nonwoven selvages can take the place of the virgin PP staples fibers, helping to further

recycle and reclaim textile waste.

Figure 3. Sound absorption coefficient of the recycled PP nonwoven fabrics as related to various

blending ratios.

Surface Observation and Thickness Measurement

According to Figure 4 (b), there are neps between the fibers in recycled selvages, and thus

influencing the mechanical properties of the resulting nonwoven fabrics. However, Table 1 shows

that the size of neps is not big, and does not influence the thickness of the nonwoven fabrics.

Table 1. Thickness measurement of the nonwoven fabrics.

Thickness (mm) Standard Deviation

Polypropylene nonwoven

Fabrics

2.1 0.11

Nonwoven fabrics with 20wt%

polypropylene selvages

2.3 0.13

Advanced Materials Research Vol. 627 857

Figure 4. Surface observation of a) polypropylene nonwoven fabric, and b) nonwoven fabrics with

20wt% polypropylene selvages (scale bar=1 mm).

Conclusion

This study uses recycled PP nonwoven selvages and virgin PP staples fibers to make the

recycled PP nonwoven fabrics. When the content of the selvages is 20 wt%, the maximum tensile

breaking strength is lower than that of the pure PP nonwoven fabrics by 10.3 % along the CD and

19.7% along the MD, respectively. The tearing strength of the resulting nonwoven fabrics decreases

41.6% along the CD and 69.6 % along the MD. The sound absorption of the resulting nonwoven

fabrics decreases by 0.02 (11.3%) and its coefficient decreases by 0.02 when the content of selvages

is 20 wt%, indicating an insignificant influence of the selvage content on the sound absorption.

Acknowledgements

This work would especially like to thank National Science Council of the Republic of China,

Taiwan, for financially supporting this research under Contract NSC 99-2621-M-035-001.

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Advances in Textile Engineering and Materials 10.4028/www.scientific.net/AMR.627 Property Evaluation of Sound-Absorbent Nonwoven Fabrics Made of Polypropylene Nonwoven

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