Jane Go
DES 40A
Research Assignment: embodied energy
Professor Cogdell
March 13, 2013
Polyester’s Embodied Energy
Although first created in the early- to mid-20th century, polyester fabric became most popular throughout the 1970s. John Travolta’s white leisure suit, seen in Saturday Night Fever, is perhaps the most famous example of polyester in fashion history. This textile proved to be useful not only in fashion, but also in durability and low-maintenance for consumers. To better understand polyester, I examined the extensive processes and tools used to create the fibers, and in succession, the woven fabric. With a concentration on embodied energy, I realized that the energy involved with the production of the raw materials is essential to my understanding of the life cycle of polyester. Like other man made materials, the embodied energy of polyester encompasses many power sources, machinery, and manufacturing processes, which includes the production of raw resources, most importantly petroleum. Based on extensive research and investigation, I will discuss and analyze the energy and processes required to produce, transport, care for, and recycle polyester fabric, as well as its raw materials.
Because polyester is petroleum-based, I want to focus on the formation, extraction, and refining of petroleum before tackling the production of synthetic fibers. Petroleum, also crude oil, began forming about 90-150 million years ago, in the Cretaceous and Jurassic periods. Zooplankton, algae, and other organic material that was deposited on the ocean floors contained molecules consisting of energy-rich carbon-hydrogen (—CH; known as hydrocarbons) bonds, which make up polymer chains. Due to natural geologic processes of the earth, the organic material was buried by sediment, pressurized by overburden, and heated. At depths of about 7,500 feet, the organic molecules were decomposed, forming liquid petroleum.[1]
After petroleum was formed, it was extracted for use. Energy is required to locate and explore different regions (land and sea) of the earth for sources of petroleum. The energy required comes from the acquisition of seismic data, which enables geologists to create interpretative maps of the area that exists several miles below the earth’s surface. A chapter from Environmental Science: In Context briefly describes the use of seismic data:
The data are generated by sending a series of pulsed energy waves into the subsurface and recoding the reflections as the energy bounces off the different rock interfaces and passes through the various rock material and fluids trapped within the natural porosity of the rock. The process requires the use of specialized vehicles on land, in the air, and at sea that consume fuel. The generation of energy waves requires energy consumption.[2]
Although it is not mentioned in the chapter, I only assume that the “specialized vehicles” are fueled by natural gas, which in essence is petroleum. Once located, large drill rigs are transported to the drilling site, and petroleum wells are created. The drill rigs are composed of a hydraulically-driven Kelly spinner, a mud mixer, a platform, and a derrick. The raw fluid that’s extracted from the wells must be separated between its liquids and gases before it can be transported to refineries. In order to reduce environmental damage, all treatment processes of the oil and impurities must follow environmental guidelines and site regulations. Incineration of gases, for example, is only necessary when a large volume of gas is found in the wells. When I investigated incineration in Green Energy, I was impressed to find that wastes can be “recycled” as power sources.[3] For example, steam and gas can be used to drive gas turbines to generate electricity onsite at petroleum refineries. Furthermore, pyrolysis, or more commonly “cracking,” of crude oil yields carbon monoxide , hydrogen, and methane, which can be used in exothermic reactions to produce usable energy.[4]
Once petroleum is extracted and treated, it can be transported to refineries by trucks, ships, tankers, and/or pipelines. Transportation requires the extensive use of engines to generate power to drive oil pumps and other included machinery.[5] Because my research did not yield a vast amount of information on the trucks and ships used in petroleum transport—other than the use of diesel fuel—I will describe energy pipelines. Because of the broad range of fluids petroleum can take (from light oils to thick tars), pipelines aid tremendously in transportation. Petroleum can be transported in either gaseous or liquefied forms. The form that’s ideal for polyester production is liquefied petroleum gas (LPG).[6] Pipelines can either be short or several miles long, with a diameter of a meter. The machinery that provides the energy used in pushing products through pipelines is pumping stations, which require venting of gases and removal and disposal of impure fluids to maintain safe operation. Pipelines, according to Green Energy, “are transport systems for energy, and effectively redistribute carbon and other emissions into the environment.”[7]
Once it reaches a processing facility, LPG is refined. Petrochemical products are derived from a distillation system—composed of steam and hydrocarbon feedstock (from LPG)—that’s driven by heat from direct fuel consumption. These fuels and systems comprise 86% of the total primary energy in refining, while electricity accounts for only 4% of the total energy consumption.[8] “Cracking” produces petrochemical products. Once cracked, the products are removed from the system at their respective boiling points, and then they can be used for specific uses.[9] These products include aliphatic molecules—those with hydrocarbons—which are the building blocks of petroleum, and they store a substantial amount of chemical energy. Of the many petrochemical products derived, ethylene, a monomer, is the starting point for the production of polyester. Once the distillation system reaches about 1400-1600º F, ethylene is removed.[10] The data I found for the embodied energy of producing ethylene gave four total figures, all in Btu/lb (British thermal unit per pound; 1Btu=1055 joules): specific energy, average specific energy, total energy use, and estimated chemical industry use. Although all data include fuel, electricity, heat and combustion of feedstock, energy losses and exports, I’m providing the estimated chemical industry use because I think it’s more encompassing of both the industry and environment. I’ve provided Figure 1 to show the different calculations for the embodied energy of polyester manufacture, and also a chart to show energy in petroleum refining. For the manufacture of ethylene, the total energy embodied is 837.8×1012 Btu/lb. This includes heating the system to extreme temperatures, as well as cooling the products after cracking.[11]
Now that we have ethylene, we can produce the raw materials needed for polyester fibers. First is ethylene oxide, which is a derivative of ethylene. To get ethylene oxide, we directly oxidize ethylene by heating ethylene and air to 500-550º F.[12] Heating, cooling, and distilling to produce ethylene oxide uses about 220.7×1012 Btu/lb.[13] The next step is to combine ethylene oxide and water (pure and recycled from previous systems) in a hydration reactor with or without a catalyst. Lower temperatures (120-210º F) and less atmospheric pressure can be used in the reactor in the presence of a catalyst, which saves energy by speeding the reaction. In the end, ethylene glycol is produced, while steam and water from the reaction is recycled.[14] This process consumes about 137.0×1012 Btu/lb. The products and derivatives of ethylene manufacture are given in Figure 2, and the inputs and outputs of manufacture are listed in Figure 3.
Now, polyester is well on its way. Just as the manufacture of raw materials is very energy-intensive, the majority of the embodied energy of polyester is in production of the textile. This is because the processes use large quantities of heat and steam, which are powered by fossil fuels.[15] There are two commonly used methods for producing polyester, both taking place inside a large metal autoclave: batch and continuous. Both methods yield the same final product through the same reactions of esterification and polymerization—notice the names (“poly” and “ester”). Two main acids are used in the production of polyester: dimethyl terephthalate (DMT) and terephthalic acid (TPA). Both are organic compounds produced from air oxidation of p-xylene, a monomer that’s cracked from petroleum refining, like with ethylene. Both DMT and TPA are stored in molten form and transported in tanks from refineries.[16] In batch polymerization, DMT reacts with ethylene glycol in esterification to form a monomer alcohol, which then polymerizes with TPA. The continuous method, on the other hand, involves polymerization between TPA and ethylene glycol, so DMT is not necessary. Both methods involve heating either DMT or TPA with ethylene glycol to about 536º F for 30 minutes at atmospheric pressure, and then the reactants spend 10 hours under vacuum.[17] No matter which process is used, polyethylene terephthalate (PET) is the end product.[18] PET is the most commercially used form of polyester, and from what I’ve researched, the terms “polyester” and “PET” are used interchangeably. Fresh PET should have the consistency and color of honey. When this viscosity is reached, PET is extruded from the autoclave, dried by a cooling process and cut into chips. This drying process only occurs during the batch method; it is skipped in continuous polymerization. The PET chips are re-melted to continue production, or they can be transported to other textile mills. Textile manufacturers usually cut out the drying step when possible, since electricity and steam energy can be saved without it. The United Nations Industrial Development Organization (UNIDO) states that reducing/accelerating the processing time is fundamental to energy conservation.[19]
Whether or not drying is used, the next step is spinning PET fibers. Three different methods of spinning can be used: dry, wet, or melt. Dry spinning involves solidifying the fibers by exposing them to hot air. Wet spinning submerges the fibers in a coagulating solution bath (usually alcohol), which hardens the PET. The fibers processed in melt spinning simply harden upon contact with the air (not heated), while dry and wet spinning use more energy.[20] Melt spinning begins when high pressure is used to extrude the molten PET through tiny holes of a spinneret or jet. The number of holes determines which kind of fiber the PET will become: filament or staple. Filament is created through a spinneret with fewer holes, so the fibers are thicker and more easily stretched than staple fibers. Filament is elongated and drawn with heated draw rollers, which gives the fiber high strength, tenacity, and resilience. Polyester yarn is created when the filaments are twisted. The yarn is then wound around large bobbins or onto flat-wound packages, ready to be woven into fabric. [21] Preparing staple is more energy-intensive, since the fibers are thinner than filament.[22] Staple also requires more steps which involve: cooling the extruded bundles of fibers, drawing with heated rollers, compression (crimping), heat setting at 212-302º F, and cutting the dried fibers.[23]
The new fibers are finished after they are woven or knitted. According to the Industrial Energy Use Data Book the finishing process accounts for 19.1 to 24% of the total energy used in production, while spinning accounts for 6.35%.[24] UNIDO provides several diagrams that each show the energy used in every step of industrial textile production and finishing.[25]Polyester fibers are made and weaved with machinery that uses steam and electricity. The dyeing process also uses steam and electricity, with the addition of gas energy during the drying stages before the final setting of the fabric.[26] From what I’ve observed, the reason why the finishing process contributes the most energy use in production is that finishing consists of more steps than the other processes. The same kinds of energy are used—steam, gas, and electricity—so an increase in the number of steps increases the embodied energy. In Figure 4 I’ve compared a diagram of the weaving process to a diagram of finishing and dyeing in order to present a visual difference in energy use. Although finishing uses more energy, fiber production emits significant levels of CO2, as compared to organic textiles. O Ecotextiles indicates that 9.52 kilograms (kg) of CO2 is emitted per ton of spun polyester fiber. Crop cultivation and fiber production of organic cotton emits only 2.35 kg.[27]In addition, I have given a chart of The Nordic Fashion Industry’s summary on polyester’s environmental impact on the industrial level in Figure 5.
Perhaps the most difficult part of my research was transportation and distribution of polyester fabric from manufacturers to retail companies and the public. From what I found was that industries today use automated systems and computers to distribute their products. The use of machinery was first used to support the growing market for textiles, and as technology became more advanced, human labor decreased:
Muratech Textile Machinery developed an automatic transportation system for synthetic fibers. This system can automate every aspect of a synthetic textile plant, from package transportation to package inspection. These automation systems enhance quality and production control, improve working environments and save labor.[28]
The automation systems enable speedy production during spinning and weaving, as well as computerized distribution to apparel and retail companies. E-commerce is used between manufacturers and companies. An electronic database contains digital images of sample yardage, along with detailed product descriptions online. Since the materials are purchased through quick response programs (websites), the time between placement of retail orders and delivery of goods is shortened.[29]I assume that the computers and machinery run on electrical power, and the trucks that deliver the products are fueled by natural gas. The transportation of polyester only uses about 3 mega joules (MJ) of energy, while production uses 11 MJ. Surprisingly, this was found to be less than the transportation energy of cotton, which is 7 MJ. [30] I believe this has something to do with the fact that polyester is a more lightweight fabric. [31]
Once polyester products leave the factories and stores, consumer care is the next contributor to polyester’s embodied energy. The hydrocarbons I mentioned in petroleum formation and refining is the key to polyester’s success in maintenance. Hydrocarbons are hydrophobic molecules, meaning they resist water, which makes polyester slick and waterproof. The strength, resilience, and tenacity of the fibers that was formed during spinning also make polyester difficult to crease and tear. In addition, the fabric is resistant to damage from weather, mildew, and moths.[32] Polyester doesn’t require to be washed as often as natural fabrics, but when it is washed, it’s reasonably low-maintenance. The energy required to wash polyester is the standard amount used to turn the washing drum of the machine. This energy also includes heating the water to a temperature of 40º C (104º F). Polyester can be line dried and doesn’t need to be ironed, so no further energy is required in fabric care.[33]
Although a person can probably keep polyester garments his/her entire life, I will discuss polyester disassembly and disposal. I can only do so briefly because of lack of research regarding disassembly. Garments made of pure polyester fabrics sewn to pure natural fabrics enable easy disassembly. The only energy required involves a sharp tool ripping the seams and threads between the natural and the synthetic fabrics, and then separate disposal. A 2010 study on sustainable design for textile disassembly refers to natural fabrics as “biological nutrients” and synthetics as “technical nutrients.”[34] Biological nutrients can collectively be composted once separated from technical nutrients, and technical nutrients must be separated from everything except identical nutrients before they can be disposed or recycled. For instance, wool and cotton can be composted together, but polyester and acrylic cannot be recycled together. Polyester blends, unfortunately, cannot be separated easily in disassembly; more energy is needed to separate out the contaminants and clean the polymers than it takes to produce new polyester.[35]
Recycled post consumer polyester is more often made from PET plastic bottles rather than old fabrics, since polyester disassembly is a complicated and expensive process.[36] There is also some controversy about whether recycling polyester textiles is energy efficient or not. For the most part, using PET bottles to make fabrics reduces landfill waste, pollution, and production energy. In fiber production, recycled PET (rPET) uses 33 to 53% less energy than it takes to make virgin PET (vPET), and rPET also emits 54.6% fewer CO2 levels.[37] The production of rPET fibers is the same as that of vPET, except for a few additional steps: collected PET bottles are sorted by hand, melted down, and formed into chips (like in batch polymerization). The chips are sent to yarn spinning mills, melted down, and often mixed with vPET before being spun into yarn.[38] Often times de-polymerization and re-polymerization of recycled polyester produces better quality fibers than simply melting it down.[39] The benefits of rPET are less energy use and less plastic in landfills. Recycling polyester can also increase energy use, however, as in the re-dyeing process. According to Phil Patterson, rPET fibers have a problem of inconsistency of dye uptake. This produces uneven color shades in the new batches of fibers and results in high levels of re-dye. The dye color inconsistency usually results in base color inconsistency of the rPET chips, which vary from white to creamy yellow.[40] Color inconsistency is a problem that calls for the use of more dye and chemicals than is used in vPET dyeing, longer processes, and more energy. Even though re-dyeing poses flaws to the recycling process of polyester, people are always working towards more efficient ways of doing things.
I have thoroughly examined each step of the life cycle of polyester, from extraction of its non-renewable base to the formation of recycled fibers. Now that I better understand polyester and have investigated its embodied energy, I realize that synthetic textiles have major pros and cons. Nearly all my sources indicate that polyester is the most popularly used synthetic fabric, mainly due to its durability. Many of these sources have also established that it’s one of the worst products in terms of energy use and environmental impact. In the middle of my research I asked myself, “Why is polyester so popular if it’s so harmful?” After examining many books and articles, I came to the conclusion that polyester has different qualities that balance each other: a vast amount of energy is used to produce it, but it lasts a life time. The production and recycling of polyester is also moving towards better energy efficiency. People favor “going green” and finding ways to accelerate production while reducing wastes. The next time I buy clothes, or any kind of textile, I’ll check the labels for the now familiar polyester. If I see it and decide to purchase the garment, I’ll know about the disassembly and recycling stages that lie ahead of polyester, and make sure that it gets there.
Figures
Figure 1 (from "The Ethylene Chain")
Figure 2 (from "The Ethylene Chain")
Figure 3 (from "The Ethylene Chain")
Figure 4 (from UNIDO, “Handy Manual on Textile Industry)
Figure 5 (from Nordic Fashion Industry, “Synthetics in Production”
Bibliography
Energetics, Inc. and E3M, Inc. “Energy Use, Loss and Opportunity Analysis: U.S. Manufacturing and Mining.” U.S. Department of Energy. Last modified December 2004. https://www1.eere.energy.gov/manufacturing/intensiveprocesses/pdfs/energy_use_loss_opportunities_analysis.pdf.
Frumkin, Howard, Jeremy Hess, and Stephen Vindigni. “Energy and Public Health.” Public Heath Reports, 124. (Jan-Feb 2009): 5-19. Accessed February 15, 2013. PubMed Central (PMC).
Gam, Hae Jin, Huantian Cao, Jaclyn Bennett, Caroline Helmkamp, and Cheryl Farr. “Application of Design for Disassembly in Men’s Jacket: A Study on Sustainable Apparel Design.” International Journal of Clothing Science and Technology 23. Issue 2/3(2011): 86. Accessed March 9, 2013. Emerald Insight.
Lerner, Brenda Wilmoth and K. Lee Lerner. Environmental Science: In Context. Farmington Hills: Gale, Cengage Learning, 2009. 272-278.
Marlow-Ferguson, Rebecca. Encyclopedia of American Industries. 3rd edition. Farmington Hills: Gale Group, 2001.
Mulvaney, Dustin and Paul Robbins. Green Energy: an A-Z guide. Thousand Oaks: SAGE Publications, Inc., 2011.
Nordic Fashion Industry. “Synthetics in Production.” NICE. Last modified 2009. http://www.nicefashion.org/en/professional-guide/production/synthetics.html.
Patterson, Phil. “Reduce, Re-use, Re-dye?” Ecotextile News, no. 17, 20-21. August/September 2008.
“Polyester.” Encyclopedia of Textiles. 3rd edition. Edited by the editors of American Fabrics and Fashions Magazine. 29-32. Englewood Cliffs: Prentice-Hall, Inc., 1980.
SIDS Initial Assessment Report for SIAM 11. “Dimethyl Terephthalate.” United States: UNEP Publications, 2001.
SIDS Initial Assessment Report for SIAM 12. “Terephthalic Acid.” Paris: UNEP Publications, 2001.
“Synthetic Fabric vs. Natural Fabric.” Just a Zipper. Polartec. Posted October 14, 2008. http://justazipper.files.wordpress.com/2008/10/synthetic-fabric-vs-natural-fabric.pdf.
“The Ethylene Chain.” U.S. DOE Energy Efficiency and Renewable Energy. Accessed February 15, 2013. http://www1.eere.energy.gov/manufacturing/resources/chemicals/pdfs/profile_chap2.pdf.
United Nations Industrial Development Organization. “Handy Manual on Textile Industry.” Energy Conservation Center of Japan. Accessed February 23, 2010. http://www.unido.org/fileadmin/import/userfiles/puffk/textile.pdf.
Weber, Don and Harvey S. Leff. “Chapter 11: Textiles.” In Industrial Energy Use Data Book. Edited by Lisa Carroll, 11-5. Oak Ridge: Oak Ridge Associated Universities, 1980.
Van Drusen, Leigh Anne and Patty Grossman. “Beyond Natural Fibers.” O Ecotextiles. Posted July, 11, 2012. http://oecotextiles.wordpress.com/category/fibers/synthetic/recycled-polyester-synthetic/.
Van Drusen, Leigh Anne and Patty Grossman. “Estimating the Carbon Footprint of a Fabric.” O Ecotextiles. Posted January 19, 2011. http://oecotextiles.wordpress.com/2011/01/19/estimating-the-carbon-footprint-of-a-fabric/.
Van Drusen, Leigh Anne and Patty Grossman. “Man-made Synthetic Fibers.” O Ecotextiles. Posted July 7, 2010. http://oecotextiles.wordpress.com/tag/melt-spinning/.
Van Drusen, Leigh Anne and Patty Grossman. “Polyester-to recycle or not to recycle?” O Ecotextiles. Posted January 12, 2011. http://oecotextiles.wordpress.com/category/fibers/synthetic/recycled-polyester-synthetic/.
Van Drusen, Leigh Anne and Patty Grossman. “Why is Recycled Polyester Considered a Sustainable Textile?” O Ecotextiles. Posted July 14, 2009. http://oecotextiles.wordpress.com/2009/07/14/why-is-recycled-polyester-considered-a-sustainable-textile/.
[1] Frumkin, Howard, Jeremy Hess, and Stephen Vindigni, “Energy and Public Health,” Public Heath Reports 124, (Jan-Feb 2009): 6, accessed February 15, 2013, PubMed Central (PMC).
[2] Lerner, Brenda Wilmoth and K. Lee Lerner, ed., Environmental Science: In Context (Farmington Hills: Gale, Cengage Learning), 272.
[3] Mulvaney, Dustin and Paul Robbins, ed., Green Energy: an A-Z guide, (Thousand Oaks: SAGE Publications, Inc.), 439-441.
[4] Ibid.
[5] Lerner and Lerner, ed., Environmental Science: In Context, 275.
[6] Energetics, Inc. and E3M, Inc., “Energy Use, Loss and Opportunity Analysis: U.S. Manufacturing and Mining,” U.S. Department of Energy, last modified December 2004, https://www1.eere.energy.gov/manufacturing/intensiveprocesses/pdfs/energy_use_loss_opportunities_analysis.pdf, 29.
[7] Mulvaney and Robbins, Green Energy: an A-Z guide, 353-354.
[8] Energetics, Inc. and E3M, Inc., “Energy Use, Loss and Opportunity Analysis,” 30.
[9] Mulvaney and Robbins, Green Energy: an A-Z guide, 179.
[10] “The Ethylene Chain,” U.S. DOE Energy Efficiency and Renewable Energy, accessed February 15, 2013, http://www1.eere.energy.gov/manufacturing/resources/chemicals/pdfs/profile_chap2.pdf, 54-55.
[11] Ibid, 70.
[12] Ibid, 64.
[13] Ibid, 75.
[14] Ibid, 66.
[15] Van Drusen, Leigh Anne and Patty Grossman, “Estimating the Carbon Footprint of a Fabric,” O Ecotextiles, posted January 19, 2011, http://oecotextiles.wordpress.com/2011/01/19/estimating-the-carbon-footprint-of-a-fabric/.
[16] SIDS Initial Assessment Report for SIAM 11, ”Dimethyl Terephthalate,” United States: UNEP Publications, 11; SIDS Initial Assessment Report for SIAM 12, “Terephthalic Acid,” Paris: UNEP Publications, 9.
[17] Van Drusen and Grossman, “Man-made Synthetic Fibers,” O Ecotextiles, posted July 7, 2010, http://oecotextiles.wordpress.com/tag/melt-spinning/.
[18] “Polyester,” Encyclopedia of Textiles, 3rd edition, (Englewood Cliffs: Prentice-Hall, Inc.), 29.
[19] United Nations Industrial Development Organization, “Handy Manual on Textile Industry,” Energy Conservation Center of Japan, accessed February 23, 2010, http://www.unido.org/fileadmin/import/userfiles/puffk/textile.pdf, 29.
[20] Van Drusen and Grossman, “Man-made Synthetic Fiber,” melt spinning is powered by steam and electricity.
[21] Ibid.
[22] Nordic Fashion Industry, “Synthetics in Production,” NICE, last modified 2009, http://www.nicefashion.org/en/professional-guide/production/synthetics.html.
[23] “Polyester,” Encyclopedia of Textiles, 31.
[24] Weber, Don and Harvey S. Leff, “Chapter 11: Textiles,” in Industrial Energy Use Data Book, ed. Lisa Carroll (Oak Ridge: Oak Ridge Associated Universities), 11-5.
[25] UNIDO, “Handy Manual on Textile Industry,” 3-11.
[26] Ibid, 11.
[27] Van Drusen and Grossman, “Estimating the Carbon Footprint of a Fabric.”
[28] Marlow-Ferguson, Rebecca, ed., Encyclopedia of American Industries, (Farmington Hills: Gale Group), 913.
[29] Ibid, 163.
[30] “Synthetic Fabric vs. Natural Fabric,” Just a Zipper, Polartec, posted October 14, 2008, http://justazipper.files.wordpress.com/2008/10/synthetic-fabric-vs-natural-fabric.pdf.
[31] “Polyester,” Encyclopedia of Textiles, 32.
[32] Ibid.
[33] Nordic Fashion Industry, “Synthetics in Production.”
[34] Gam, Hae Jin, Huantian Cao, Jaclyn Bennett, Caroline Helmkamp, and Cheryl Farr, “Application of design for disassembly in men’s jacket: a study on sustainable apparel design,” International Journal of Clothing Science and Technology 23, issue 2/3(2011): 86, accessed March 9, 2013, Emerald Insight.
[35] Van Drusen and Grossman, “Polyester-to recycle or not to recycle?” O Ecotextiles, posted January 12, 2011, http://oecotextiles.wordpress.com/category/fibers/synthetic/recycled-polyester-synthetic/.
[36] Ibid.
[37] Van Drusen and Grossman, “Why is Recycled Polyester Considered a Sustainable Textile?” O Ecotextiles, posted July 14, 2009, http://oecotextiles.wordpress.com/2009/07/14/why-is-recycled-polyester-considered-a-sustainable-textile/.
[38] Van Drusen and Grossman, “Beyond Natural Fibers,” O Ecotextiles, posted July, 11, 2012, http://oecotextiles.wordpress.com/category/fibers/synthetic/recycled-polyester-synthetic/.
[39] Patterson, Phil, “Reduce, Re-use, Re-dye?” Ecotextile News, no. 17, (August/September 2008): 21.
[40] Ibid
Trina Do
Wastes and Emissions
Polyester is one of the most common fibers used today. Through its many advantages, polyester is popular for its wrinkle and wear/tear resistance, water proof and drying speed. It is used to manufacture clothing, home furnishing, durable fabric used for outdoors, PET (plastic bottles), ropes, hoses, and other various products. Although the use of synthetic polyester has become a universal fiber for many products, the process to manufacture the fiber has been known to create many toxic wastes and emissions. The toxic chemicals can harm our skin, air, and land. By researching through articles, journals, and books; the production of synthetic polyester can reveal the hazardous waste and emissions that cause pollution and harm to our environment and society.
For this paper, I used Google to find most of my sources. I also used Springer Link and the UC Davis Library journals. First I attempted to search for books at the library through the catalog, but I found it difficult to find a book on Polyester. So, I tried Polymers, but the sources I found did not have the information I was looking for. When I tried searching through online databases, it helped a lot more because I could be more specific on the types of articles and journals that I wanted to find. I was able to search Polyester, Polyester Waste, Textile Waste, Polyester Resins, and Polyester Hazards. These keywords lead me to many journals and articles that gave me a lot of helpful facts and information. However, I did run into some trouble when I wanted to know specifically, which machines emitted the waste that was causing the hazards. But, I was still able to generalize the types of wastes that came from Polyester production.
The raw materials used to make polyester are Polyethylene Terephthalate, resin, and fiberglass. What are used to fuel the production of polyester are water, coal, and air. The chemical reactions that start the production of synthetic polyester are called polymerization. (Bruna Messina, The Health Risks of Toxic Fibers and Fabrics) Polyester fiber is made from synthetic polymers that are made from esters of dihydric alcohol and terpthalic acid. Each stage of production releases waste such as carbon dioxide, acid gases such as hydrogen chloride, and unstable organic compounds. Through the manufacturing of Polyester, it has caused a great concern from the waste and emissions that result in the process of creating this synthetic fiber. When polyester is manufactured in factories/plants through an energy-intensive process, the production requires high levels of heat, various chemicals, and dyes. In the different stages of manufacturing coal, air, water, and petroleum are used.
Polyester resins have become a health hazard to us. Usually during production, resins are not strong if used alone; it is combined with filler or fiberglass to form the polymer that we use for products. When produced together, it can then create the toxic hazard that is harmful when in contact to the skin, eyes, nose throats trachea, and cause some side effects to the person handling it. Disposal of the extra waste is important, and if left alone with the improper car, can cause more serious risks. Many cases have causes irritation to the skin and respiratory issues, so caution is important when near the hardened resins. (L. B. Bourne and J.M. Milner, Polyester Resin Hazards)
During production of Polyester fiber, a certain amount of waste is generated. Polymerizations, drying, melt spinning, drawing the fiber, and winding are involved in the process of productions; mainly requiring a lot of energy from water and coal in order to heat/dry the compounds to create the synthetic fiber. When heated, the emissions of the chemicals are released into the air. Many of the waste emissions are hazardous and can harm us, or our environment with toxins. Also, emissions of nitrous oxide are also present. Nitrous oxide is a gas that entraps heat 310 times more efficiently than carbon dioxide, which increases the pollution in the air. All the toxins can affect our air, water, fauna, and animals in those habitats. (Sonali Bhawsar, Toxic Fibers and Fabrics) The chemicals that don’t remain on the fiber are emitted into the water and eventually dumped into streams or rivers, harming the environment.
While researching, I found it difficult to find the specific wastes and emission that come from polyester production. Many articles stated water, air, and pollutant waste, but not the specific machines that caused them. What I found most useful were the sources that spoke generally about textile production, rather than just specific Polyester production. The textiles all use similar techniques in manufacturing and the types of wastes that come from creating fibers, so I was able to find more information when searching in a general topic. Even though I wasn’t able to find specifics on polyester production machines, I could still connect it back to the wastes resulting from the production.
Synthetic Polyesters are separated into two forms, Water soluble, and water insoluble. Water soluble polymers do not litter the environment, but they enter streams, and it can lead to landfills, where it pollutes the ground or surface waters. The toxins in the land or water can neither be or incinerated or recycled. Water insoluble polymers litter the environment and end up as landfill which is non-biodegradable, but some can be recycled. (Breakdown of Plastics and Polymers by Microorganisms, 153, 161)
Textile water waste is common in the production of fibers, which is a mixture of many different chemical compounds. As stated by Environmental Consideration (Environmental Considerations, pg. 489) waste waters originate from pretreatment, dyeing, printing, or finishing. Pretreatment includes washing, desizing, bleaching, or boiling off. When the synthetic fiber is pretreated, the chemicals wash off into the water. Dyeing requires different compounds and toxins in order for the fiber to stain with color, but some parts do not remain on the fabric, causing it to run off into the water. Printing with ink also has the same effect. Finishing includes any removal of waste on the fibers before sending it off for further production.
Dyeing the fiber also plays important factor in waste emissions. The dyes already contain a number of chemicals and compound in order for it to change the fibers into the color that we want to produce. The ratio of liquid decreases the level of exhaustion of the dye. So, when the amount of liquid dye increases, so does the waste that results from it, because the decreased level of exhaustion causes the dye to not absorb as much into the fiber. The liquid level also affects the amount of chemicals consumed during the process. (Environmental Considerations, pg. 524)
The high level of water and energy can also be caused by poorly handled techniques, such as overfilling and spillage during production. Any changes or repeated stages in production, leads to more chemicals, use of materials, and an increase in energy. The residual padding in the pipes and pumps also has to be discarded when a new dye color is being replaced. When it is discarded, it creates a higher amount of pollution. Because polyester is non-biodegradable, these chemicals remain in our environment and create solid waste, which is hard to manage.
The amount of energy to produce the Synthetic Polyester is very high. In order to generate the temperature and the water, coal and oil creates a lot of waste and uses large amounts of chemicals and emissions. The process of creating the fiber takes many steps and the amount of embodied energy is what creates the waste in our environment. Embodied energy is all the energy consumption phases from production to transportation. Waste from production includes, solid waste, water waste, and pollution. Embodied energy from transportation usually results in carbon dioxide emissions from trucks, airplanes, etc. (F. P. Torgal and S. Jalali, 36-37)
Solid waste is the amounts of polyester products that are dumped into our environment, either in landfills or incinerators. (Environmental Considerations, pg. 493) Only about 10% of the polyester products are actually recycled, while the rest are discarded as solid waste. Because of the structure of polyester, it makes it difficult for the breakdown of the cell walls. It was difficult the find ways of degradation because research is still being done. This is because we haven’t found an efficient way to biodegrade plastic, so solid waste is still a concern.
As said by Sonali Bhawsar (Toxic Fibers and Fabrics), along with the toxins released in the air and water, some chemicals cannot be completely taken out during production, and are absorbed into the fiber, which can go into our skin when wearing the synthetic polyester. Monomers are used in the production of the Polyester, and are responsible for acute skin rashes, redness, itching, dermatitis, when wearing it for a long time. The chemicals that are carried into the fibers transfer onto out skin, which is why it causes irritation. The longer we are exposed to the chemicals of polyester the worse the affect it is, although we don’t always feel the harmful effects. It can also cause long term conditions and diseases such as skin cancer and other types of cancer, chronic and severe respiratory infections.
After production of the polyester, the fibers are used for various products, but an issue with them is that polyester is non-biodegradable. And, because it would be expensive to properly degrade the fiber, a lot of the waste builds up in our environment if there is improper disposal. But, Polyester is recyclable. So most of the time the product is melted back into a state that can be used for other purposes to decrease the amount of waste.
When polyester is manufactured into clothing, the waste also continues in our homes. Recent studies have revealed that when washing polyester sheds tiny fibers into wash water, which eventually leads to the ocean. When the polyester fibers are in the ocean, it attracts oily pollutants which become harmful because it creates chemicals in the seawater, which affects our animals and the food web. Synthetic Polyester is basically a plastic material synthesized from crude oil and natural gas. We normally don’t think too much of polyester as a huge concern because plastic bottles and harmful littering of waste is normally seen as pollutants of the water, but when exposed to heat, those plastic materials eventually breakdown to the micro plastics that are the basics of polyester material. Once in the ocean, it also makes it very difficult to clean, and even when recycled, still creates the harmful affect to our environment. (Sarah Mosko, Microplastics)
Synthetic Polyester goes through a life cycle which I discovered uses a lot of energy and waste, which has become a concern to our environment. From raw materials, to embodied energy, and waste and emissions; I was able to find how synthetic polyester is produced, what they use to make it, and how much affect the waste has on our environment and ourselves. The two types of synthetic polyester, water soluble and water insoluble have created issues in our water and land. From production, the use of chemicals, coal, water, resins and crude oil; it has emitted waste and has contaminated our society. The hazards are a huge concern because the structure of synthetic polyester is non-biodegradable and a small percentage is only recycled. I was able to identify the types of waste through my research, and was able to find out how certain procedures in production have led to water waste, and solid waste. Many of the chemicals and toxins have made its way after manufacturing, into our land, air and water. When synthetic polyester is made into clothing, it has become a risk to ourselves when we wear the fibers for a long period of time. During production, some of the toxins could not be washed off all the way, so it is absorbed into the fiber. When worn, the polyester creates irritation to skin, and can also emit the toxins into our bodies. From research, it is said that it can cause respiratory issues when in contact with resins, and could be an additional cause to types of cancers. In conclusion, through the life cycle of synthetic polyester, I was able to reveal the cause and effects of production, transportation, and emitted waste; which has caused many health and environmental concerns due to the huge amounts of energy and toxins being used.
Sources:
{C}1) F. P. Torgal and S. Jalali. Eco-efficient Construction and Building Materials, Chapter 3, Springer-Verlag London Limited 2011
{C}2) Enviromental Consideration for Textile Processes and Chemicals, Volume 7
3) Messina, Bruna. The Health Risks of Toxic Fibers and Fabrics, Fashionbi Magazine, 2012
4) Bhawsar, Sonali. Toxic Fiber and Fabric, Biotech Articles, 2011
5) Moskow, Sarah. Micro plastics: Avoid polyester fabrics to help prevent ocean pollution, Surf Voice.org, 2011
6) R. Gautam, A.S. Bassi, and E.K. Yanful. A Review of Biodegradation of Synthetic Plastic and Foam, Human Press Inc, 2006
7) Kawai, Fusako. Breakdown of Plastic and Polymers by Microorganisms, Advances in Biochemical Engineering/ Biotechnology, Vol. 52 Managing Editor: A. Fiechter 9 Springer-Verlag Berlin Heidelberg 1995