Investigation of Volatile Organic Compounds from the Manufacturing Process of Recycled PET Fibers Using TGA-DTA/MS Technique

Abstract:

Recycling is promising to dispose the wasted Poly (ethylene terephthalate) (PET) fibers currently. However, high temperature and oxygen in the recycling process may accelerate the degradation of PET and residual dyes, resulting in the volatile organic compounds (VOCs) emissions, which will do serious harm to the environment and human health. Exploring the source of VOCs is significant to remove VOCs and keep products safety. This study was carried out to investigate the influence of high temperature on the release of four VOCs (formaldehyde (CH₂O), acetaldehyde (C₂H₄O), benzene (C₆H₆) and toluene (C₇H₈)) during the recycling process of PET fibers, utilizing thermogravimetric analysis and differential thermal analysis coupled with mass spectrometric (TGA-DTA/MS). The atmospheres and heating conditions of esterification, polycondensation and melt spinning were simulated by TGA with various atmospheres and programmed heating processes (heating from 50 °C to 240 °C in Ar, 280 °C in Ar and 280 °C in air, respectively, and then maintaining for 30min). Bis (2-hydroxyethyl) terephthalate (BHET) (esterification product) and virgin PET (VPET) were used to explore the thermal degradation of PET. White PET popcorn, black PET popcorn and dyes were used to explore the effect of dyes on the release of VOCs. The results indicated that: (1) Aldehydes including formaldehyde and acetaldehyde are generated during the manufacturing process of PET, mainly due to its thermal oxidation;(2) Aromatic compounds including benzene and toluene are originated from the disperse dyes. So the degree of dye removing has a great influence on the production safety; (3) Thermal oxidation causes more VOCs than nonoxidative thermal degradation. So in the stages of melt spinning and slightly alcoholysis, usually in O₂ containing atmosphere, devolatilization should be developed further.

• Periodical: Materials Science Forum (Volume 944)
• Pages: 1221-1225
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.944.1221
• Online since: January 2019
• Authors: Ji Yue Hu, Ye Chen*, Shan Shan Liu, Fu You Ke, Ling Ling Gao, Chao Sheng Wang, Hua Ping Wang
• Keywords: Dyes, MS, Recycled PET Fibers, TGA, VOCs

References

[1] M. Frounchi. Studies on degradation of PET in mechanical recycling, J. Macromol. Symp. 1999, 144(1) 465-469.

DOI: 10.1002/masy.19991440142

[2] C. C. Lin. Recycling technology of poly(ethylene terephthalate) materials, J. Macromol. Symp, 2015. 135(1) 129-135.

DOI: 10.1002/masy.19981350115

[3] M. Ghaemy, K. Mossaddegh. Depolymerisation of poly(ethylene terephthalate) fibre wastes using ethylene glyco, J. Polym. Degrad. Stabil. 2005, 90(3) 570-576.

DOI: 10.1016/j.polymdegradstab.2005.03.011

[4] M. E. Tawfik, S. B. Eskander. Chemical recycling of poly(ethylene terephthalate) waste using ethanolamine. Sorting of the end products, J. Polym. Degrad. Stabil. 2010, 95(2) 187-194.

DOI: 10.1016/j.polymdegradstab.2009.11.026

[5] S. Zhang, X. Song, D. Zhang and Y. G. Tian. Kinetics of the hydrolytic depolymerization of poly(ethylene terephthalate) under microwave irradiation, J. Polym. J. 2011, 43(10) 811-815.

DOI: 10.1038/pj.2011.73

[6] B. Heinssaron, Clodoaldo. Chain extension of poly (ethylene terephthalate) by reactive extrusion with secondary stabilizer[J]. Mater. Res. 2012, 15(3) 467-472.

DOI: 10.1590/s1516-14392012005000058

[7] F. Awaja, F. Daver, E. Kosior. Recycled poly(ethylene terephthalate) chain extension by a reactive extrusion process, J. Polym. Eng. Sci. 2004, 44(8) 1579–1587.

DOI: 10.1002/pen.20155

[8] M. Bounekhel, I. C. Mcneill. Thermal degradation studies of terephthalate polyesters: 2. Poly(ether-esters), J. Polym. Degrad. Stabil. 1995, 49(3) 347-352.

DOI: 10.1016/0141-3910(95)00097-6

[9] F. Samperi, C. Puglisi, R. Alicata and G. Montaudo. Thermal degradation of poly(ethylene terephthalate) at the processing temperature, J. Polym. Degrad. Stabil. 2004, 83(1) 3-10.

DOI: 10.1016/s0141-3910(03)00166-6

[10] F. A. Pitten, J. Bremer and A. Kramer. Air contamination with volatile organic compounds (VOCs) and health complaints, J. Deut. Med. Wochenschr. 2000, (18) 545-550.

[11] J. E. Lerner, T. Kohajda, M. E. Aguilar, L. A. Massolo, E. Y. Sanchez, A. A. Porta, P. Opitz, G. Wichmann, O. Herbarth and A. Mueller. Improvement of health risk factors after reduction of VOC concentrations in industrial and urban areas, J. Environ. Sci. Pollut. R. 2014, 21(16) 9676-9688.

DOI: 10.1007/s11356-014-2904-x

[12] J. D. Badia, A. Martinez-Felipe, L. Santonja-Blasco and A. Ribes-Greus. Thermal and thermo-oxidative stability of reprocessed poly(ethylene terephthalate), J. J. Anal. Appl. Pyrol. 2013, 99(3) 191-202.

DOI: 10.1016/j.jaap.2012.09.003