Property Evaluation of Sound-Absorbent Nonwoven Fabrics Made of
Polypropylene Nonwoven Selvages
Jia-Horng Lin
1,2, b, Chen-Hung Huang
3, c, Ying-Huei Shih
1,
Yu-Chun Chuang
1,
Ching-Wen Lin
4and Ching-Wen Lou
5,a1Laboratory 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. a[email protected],b[email protected], c[email protected]
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
a b
and 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.
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
a b
Nonwoven fabrics with 20wt% polypropylene selvages
2.3 0.13
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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