Design Life-Cycle

Aida Musazay

05 December 2019

DES 40A

Professor Cogdell

Nylon Carpets: Raw Materials 

Carpets have been a key part of household staples and are the products we have been consistently relying on for centuries. Today it is nylon carpets that are the most popular in the residential carpet industry. Carpetmaking first began with natural materials and changed tremendously over time. The comfort and efficiency carpets offer are a key factor in why carpets are so commonly used and correlates with the reason carpet production and materials have changed over time.  There has been a tremendous shift in the materials used for carpets, and now nylon is the most common material used in carpet making. Although I have not focused on a specific brand of nylon carpets, there are two types of nylon used in rug-making which are nylon 6, and nylon 66. Raw materials derived in the earth are necessary to be acquired for the production and formulation of nylon, as well as the distribution stage, maintenance, recyclability and waste management of the nylon carpets. The environmental impact of nylon carpets is important when analyzing and tracking the raw materials used in the production of nylon carpets and system of the products life cycle, especially when considering the recyclability of the product. 

The earth is beginning to be drained out of its raw materials, and we continue to use up all the natural resources. We are now beginning to see how much the earth’s natural resources are decreasing in its availability and increasing in its scarcity. Materials need to be recycled but rather landfills are overflowing with products made of synthetic sources, which contributes to increasing the drainage of the earth’s raw materials. Nylon carpets are made of synthetic materials, chemically formed and bonded, which are long lasting and great for consumers, but can be damaging after consumed if not disposed of or recycled properly, yet even when recycling they pose problems. (Corbin) When making nylon, the primary raw material used is petroleum which leads the way to later creating all the other raw materials used in manufacturing nylon carpets. The nylon carpet face is made of fiber-forming polymers from adipic acid and hexamethylenediamine which are polymers combining with air and nitric acid (Mallonee).

Nylon is a synthetic carpet face made of polyolefins and polypropylene. The use of polypropylene is to decrease staining and is also naturally antistatic, but the downside to this production is that is doesn’t maintain its shape or appearance very long. The fibers are formed through polymerization of polymers that are mixed with polyolefin which create fiber-like threads that are sourced from polyester and polyamide. Polyamide includes the condensation of dibasic acid, hexamethylenediamine, and adipic acid which then are combined to form polycaproamide known as, nylon 6. Polyester polymers can be prepared from many different sources such as, alcohols or halogenated acids. These also help with decreasing the flammability of nylon used to form the carpet face. The materials would all be considered secondary raw materials, as petroleum was the first raw material that is used in developing these raw materials, making them secondary raw materials. (Bunn) Due to the fact that nylon 66 is sourced through petroleum, which is used in the production of both hexamethylenediamine and adipic acid, nylon 66 becomes a limited resource. (Crowley) To combine nylon carpet face into carpet the carpet face must go through a process called tufting. In tufting carpets is a well known and commonly used method. Carpets that are made with backing from woven fabric are used as the base for the tufting to be done, specifically where the fibers for the carpet will be attached. A common practice is to apply a second backing which would help the structure of the tuft and increase the firmness overall. This extra backing creates support and improves the longevity and makes it more resistant to abrasion, more powerful so that it doesn’t wear out and creates a more stable structure. In addition to all the beneficial qualities, the appearance of the carpet is also improved through the secondary backing. The general tuft height for nylon carpets is 0.44 inches or 1.11 centimeters, and the tufting yarn is what the nylon is used for. When the tufting process is complete, the entire carpet is dyed just like broadloom carpets using a dye beck. The final step is to before drying the nylon carpet is adding latex to the backing of the carpet to increase its longevity. (Lup) Although, one factor I could not find sufficient evidence for which raw materials are used to fuel at the nylon production factories. 

Nylon carpets are mostly produced and manufactured outside of the United States in countries such as China and India, or Europe which therefore makes the raw materials used for distribution and transportation typically more difficult to trace. The world's production rate of both types of nylons, 6 and 66, are produced ninety-five percent more than the number of polyamides produced overall. Of all synthetic fibers, nylon is the most common synthetic fiber produced, with more that eighty percent of all synthetic fibers produced world-wide being of nylon. Of the two nylons, it was nylon 66 that was synthetically formed first in 1940 by W.H. Carothers, which is nylon made of hexamethylene diamine and adipic acid. Now, nylon by Du Post has continuously been on the market since it first started yet the difference is that now it is produced at an industrial scale, in extremely larger quantities at a much faster rate as well. Due to different patents in the United States that restrict production and involve raw material considerations, nylon 6 is mostly produced out of the United States in Germany, and nylon 66 is produced in the United States. (Bellusssi) To conclude my research of the raw materials used in the distribution and transportation of raw materials for nylon carpets, I was not able to find proper evidence through sources providing what materials are used but one can generally assume that petroleum fuel would be used for ground transportation, airplanes and ocean freight.

Raw materials which are beneficial during and post-consumer use is that there are heat resistant properties in the fibers that make up the nylon, which makes the carpets more long-lasting and safer. (Green) The materials used to produce nylon can also be reused after consumption if it is recycled properly. The extent to how much can be done with it post consumption all depends on the use of the nylon carpet during consumption, how much can be recycled and how the waste from the carpet is managed and possibly reused afterward. The reusability of nylon carpets is an important factor when analyzing the importance of how environmentally friendly they are by recycling postconsumer carpets, analyzing methods of recycling carpets and the relationship between the reusability and recyclability of carpets are all important contributing factors.  Raw materials used to produce nylon carpets are reused afterward if recycled, but it depends on what is done with the nylon carpet after consumption. As important as carpets are for our households, whether they can be recycled is just as important because of its effect on the environment which is determined by the carpet recycling process system, recycling of postconsumer carpets, recycling of nylon from carpet waste, and recycling in general which saves a lot but also still results in a lot of waste. Managing the waste produced from nylon carpets is tremendously important because otherwise all the efforts made to make nylon carpets environmentally friendly would be a complete waste. Nylon waste management can be monitored through extracting nylon fibers and making the nylon carpets environmentally friendly just as they were made synthetically easy to produce. There is method for recycling carpet that forms to new reusable components from the waste of the carpet. The method is done through a system of separating and packaging fibrous and backing material from the carpet to be recycled and used for other products. The process is done by cutting the carpet into small pieces of two by two or four by four inches and is done so by sending it through a shredding machine. Then the machine sends the pieces separately through a machine that sweeps the pieces and evenly delivers them to an elutriator. There an air delivery technique is used for sending off the fibrous pieces and backing pieces to be separated and ready to be used in a recycled project. (Sharer) One issues with recycling nylon carpets is that nylon itself is a very complex structure, making it hard to recycle and when placed in a landfill it is not biodegradable. Therefore it would make most sense to reuse nylon so that it is processed and put to use as much a possible due to the fact that it is not biodegradable. (Mihut) The challenge of recycling nylon carpet and the carpet not being biodegradable has forming a huge issue that has yet to be properly addressed. Due to the issue of not being able to properly recycle the nylon carpet large amounts of carpet are ultimately sent to landfills, and this also poses an issue for landfills as the carpets are not biodegradable. Another issue with recycling is that after breaking down the components it may get difficult to use later for other products. To resolve this issue, a new system that would separate the materials but not destroy the components would be the ideal solution for recycling nylon carpets and keeping them out of landfills. (Robinson) 

Nylon carpets have an environmental impact staring from when the materials used to create it are created to after its been consumed and where it ultimately ends up. The raw material acquisition for nylon production, and the different stages of nylon to when it is finally in a carpet form all correlate with the distribution stage, maintenance, recyclability and waste management of nylon carpets in general. The environmental impact of nylon carpets is important when analyzing and tracking the raw materials used in the production of nylon carpets and system of the products life cycle, because of the lasting effects it has on the environment as there still is not a complete solution as to what can be done with nylon carpets after consumption. 

[1] Corbin, Thomas F., Otto M. Ilg, and Robert N. Armstrong. "Process for manufacturing substantially 100% nylon 6 carpet." 

[2] Mallonee, William C. "Process of making fiber for carpet face yarn." 

[3] Bunn, Howard. "Cost and availability of raw materials." 

[4] Crowley, Katie, et al. "Life Cycle Analysis of Interface's Bentley Prince Street Carpet vs Traditional Carpets." 

[5] Lup, Jung Shee. "Lubricated polypropylene polyethylene self-bonded nonwoven carpet backing." 

[6] Bellussi, Giuseppe, and Carlo Perego. "Industrial catalytic aspects of the synthesis of monomers for nylon production." 

[7] Green, James R. "Blend of cotton, nylon and heat-resistant fibers." 

[8] Sharer, Paul C. "Method of recycling carpet forming components from waste carpet." 

[9] Mihut, Corina, et al. "Recycling of nylon from carpet waste." 

[10] Robinson, Forrest L., and Willis R. Campbell. "Method of extracting nylon fiber from a comminuter." 

Bibliography

Bellussi, Giuseppe, and Carlo Perego. "Industrial catalytic aspects of the synthesis of monomers for nylon production." Cattech 4.1 (2000): 4-16.

Bunn, Howard. "Cost and availability of raw materials." Industrial & Engineering Chemistry 44.9 (1952): 2128-2133.

Corbin, Thomas F., Otto M. Ilg, and Robert N. Armstrong. "Process for manufacturing substantially 100% nylon 6 carpet." U.S. Patent No. 5,370,757. 6 Dec. 1994.

Crowley, Katie, et al. "Life Cycle Analysis of Interface's Bentley Prince Street Carpet vs Traditional Carpets." (2010).

Green, James R. "Blend of cotton, nylon and heat-resistant fibers." U.S. Patent No. 4,920,000. 24 Apr. 1990.

Lup, Jung Shee. "Lubricated polypropylene polyethylene self-bonded nonwoven carpet backing." U.S. Patent No. 3,322,607. 30 May 1967.

Mallonee, William C. "Process of making fiber for carpet face yarn." U.S. Patent No. 5,811,040. 22 Sep. 1998.

Mihut, Corina, et al. "Recycling of nylon from carpet waste." Polymer Engineering & Science 41.9 (2001): 1457-1470.

Robinson, Forrest L., and Willis R. Campbell. "Method of extracting nylon fiber from a comminuter." U.S. Patent No. 6,398,138. 4 Jun. 2002.  

Sharer, Paul C. "Method of recycling carpet forming components from waste carpet." U.S. Patent No. 5,518,188. 21 May 1996.

Johan Martinez

DES 40A

November 20, 2019

The Energy of Nylon Carpet; is it worth it?

A majority of people wonder how much energy is used to produce a generic nylon carpet? As well as using the nylon material in a multitude of ways and not just carpet? Yes, it is possible. Surprisingly enough, I did not know it at first. However, this is not a part of the essay; I am just going to focus on the life-cycle of the nylon carpet. Especially how it is embodied energy in the process, from beginning to end, of the systems that produce, distribute, disassemble, and recycle. Have people ever wondered how much energy is used to produce both the nylon material and the carpet, or if it is even good for our environment, as well? Nylon is a general term for synthetic materials or polymer fabric that are processed into different shapes and textures to various uses. Nylon is a plastic with super-long, heavy molecules built up of short, continuously reduplicating sections of atoms. The polymers can be assimilated with various substances to achieve different variations in properties. Energy can be excessive when it comes to being used, all in all, when it is in use for producing nylon carpet and all the other, smaller materials that are used to make the nylon beforehand, and how horrible it is for our environment. With this thorough explanation in the paper, the life cycle map for the energy section will be apparent. The most important points of this essay will be about the beginning to end, the production, how it is bad for the environment, distribution process, how it is disassembled and recycled. 

    Before going into the process of the production of the nylon carpet, it is best believed to talk about the history of the synthetic fabric before going into further detail, to get a better understanding, let us begin talking about the nylon material's process first. Nylon was first developed in the early 1920's by a company called: DuPont corporation. Furthermore, it was initially supposed to go by the name "no-run," according to Sewport, "What Is Nylon Fabric: Properties, How It's Made and Where."  Since it can resist droplets of liquids running on the fabric material, however, it was soon discovered it could not resist liquid runs long term, and so the name was changed to "Nuron." Then the name later changed again to nylon but switched the I to y. The nylon material's usage dates back during war times in the United States. However, cotton was the primary usage, which is more than 80% of textile applications.

By the year 1945, only 25% of the synthetic fabric, nylon, is constituted of textile applications. Once the war was over, many manufacturers sought new ways to use this method of creating fabric. Considering there is a shortage of organic materials like silk and cotton, so this is a perfect opportunity for them to take this revolutionary method. When the war was entirely over, there was a severe shortage of cotton and silk. Thus, bringing in the nylon material and changing its purpose. They started using the nylon material in women's garments, stockings, and dresses. After that, the production of the nylon material quickly picked up and is a part of everyday products such as items like clothing and carpets in the 21st century. Over the years, it has dropped in popularity since the material itself is not biodegradable because it uses petroleum oil. At the same time, when it was dropping popularity, it was gaining popularity with industrial production and scientific research purposes. 

The process of making nylon fabric is by extracting diamine acid from crude oil. Then diamine acid is forced into a reaction with adipic acid to produce a polymer, known as nylon salt. This crystallization form is heated with a molten substance. Next, the material is extruded through a metal spinneret and added to a bobbin. Afterward, the fabric is stretched to increase its elasticity as well as strength. Finally, the fabric is ready to be woven together with other materials to make products and dyed to a preferred color, (Nylon Copolymer and Nylon Blends and Films Made Therefrom.) and (Jonella, and Nirmala.).

Considering they used crude oil as their number one constituent, as I mentioned before, it hurts the environment. It is not biodegradable and crude oil was discovered in petroleum; petroleum is harvested in fossil fuels and or cracking. Which we all know harms our environment, according to Jonella, and Nirmala.. Throughout this entire process from gathering petroleum, then extracting it to get crude oil to the process of making the synthetic fabric and mixing it to making the products, uses it up quite a lot of energy. Side note, I could not find further information on how much energy is used precisely in this entire process of just getting to the point of nylon woven into the fabric. All I was getting is information about which companies make the best carpet or online stores to buy carpets from. After doing more research, I found a link from the same source I used: Sewport, "What Is Nylon Fabric: Properties, How It's Made and Where." They mentioned that a great deal of energy is required to make nylon fabric, including several:

waste materials, which are produced during the manufacturing process. Large quantities of water are used to cool down the nylon fabric fibers, and this water often carries pollutants into the hydrosphere surrounding manufacturing locations. In the production of adipic acid, which is the second constituent part of most types of nylon fabric, nitrous oxide is released into the atmosphere, and this was considered to be 300 times worse for the environment than CO2.

 They did not go into specific detail on how much energy is used precisely, but it does give useful information about how terrible it is for our environment, which I will go further detail. 

The beginning of the production of the nylon to the end of its production is a long process and has excessive usage of energy. Let us see how bad the production for nylon carpet is for our environment, as mentioned before, when creating most types of nylon since there are around ten different types of nylon. Most types of nylon fabric creates nitrous oxide in its production. Which goes into the atmosphere, and it is considered to be 300 times worse for the environment than carbon dioxide. Not only that, but considering the nylon carpet is wholly made out of synthetic material, it is not biodegradable ("Nylon vs. Polyester Carpet – Compare and Contrast.). I am mentioning this again because nylon carpet is not entirely sustainable; I will go further detail as to why it is not entirely sustainable. Now back to why it is not biodegradable is because the nylon carpet, the fabric of itself, will remain in our environment for a century (Sewport).

Furthermore, it is considered to be a waste for some nylon carpets, since not all of it can be recycled because not all waste management can recycle most nylon carpets. This point brings up my next statement is that most of the nylon carpet can be recycled, especially the nylon fabric material. This point may sound counterintuitive; it may not, I may have misinterpreted it, but to be frank, yes, some nylon carpet can be recycled while others cannot depending on which type of nylon material is used into creating the carpet.  Adding on to why it is terrible for the environment is because it is inimical, according to two sources, "Nylon vs. Polyester Carpet – Compare and Contrast" and Sewport, "What Is Nylon Fabric: Properties, How It is Made and Where." Both sources state the nylon carpet damage on the environment can not alleviate the manufacturing process. One method to make the situation better is by knowing how to safely dispose of the waste from the carpet by burning it and recycling it. Which only depends on what type of nylon, synthetic carpet is made out of and as well as where it was produced.  Even so, some nylon carpets may quiet contain evidence results of virulent components while they are assembled into garments and exchanged to consumers.

Conversely, the usage of energy when producing the nylon carpet, let us talk about the distribution process for the nylon carpets. I could not find any helpful information to help further my point about the excess usage of energy in the scheme — however, one of my sources from Jonella and Nirmala as well as both sources I have mentioned earlier, Sewport for example, as a matter of fact, the United States does develop nylon carpet, but it is significantly low compared to other countries. Like China, Pakistan, Brazil, and India are the ones that create more of the nylon carpet supply. So, I can only assume that we import a lot of synthetic carpets from them. They are making it the most substantial energy consumption and process to bring the carpets to a local consumer store. 

In addition, together with the information I previously mentioned, if the nylon carpet can be recycled/thrown away. I would like to a few statements from "Nylon Carpet Recycling," they state that: "Large amounts of post‐consumer carpet are discarded every year. Most of this waste is currently landfilled, while a small percentage is incinerated. The face carpet fibers, consisting primarily of nylon 6 and nylon 6,6, represent the majority component in the carpet waste." Also, they mention that they are looking and creating different and environmentally friendly methods to dispose of the nylon carpet fabric. Other than just incinerating it and if they do not need to extract the fabric to reuse it. 

In brief, the focus of this paper is going to on the life-cycle of the nylon carpet. Especially how it is embodied energy in the process, from beginning to end, of the systems that produce, distribute, disassemble, and recycle. The research itself was a bit difficult to gather because I could not find enough to support a couple of my points for the distribution process and the exact number of energy is used for every step of the process of nylon carpet. Energy can be excessive when it comes to being used, all in all, when it is in use for producing nylon carpet and all the other, smaller materials that are used to make the nylon beforehand, and how horrible it is for our environment. The most important points of this essay will be about the beginning to end, the production, how it is bad for the environment, distribution process, how it is disassembled and recycled. After all this research about the nylon carpet, I best believe this synthetic carpet is not the best, and not environmentally friendly; not worth it.

Work Cited

Abdalah, G. , Ramkumar, S. S. , & Simonton, J. (1999). An investigation of environmentally friendly chemicals in textile processes to reduce water, air, and odor emissions. Texas Food and Fibers Commission Annual Project Report. Retrieved September 12, 2004, from Texas Tech University Web site, http://www.tffc.state.tx.us/TECHTXRL/PROGRESS/1998-1999/environ.html 

Jonella, and Nirmala. “What Is Nylon? From Stockings To Ropes; A Versatile Fibre.” Contrado Blog, 22 Oct. 2019, www.contrado.co.uk/blog/what-is-nylon/.

Kelly, John. “How to Choose the Right Carpet Fiber.” HowStuffWorks, HowStuffWorks, 20 Oct. 2010, home.howstuffworks.com/home-improvement/home-diy/flooring/choose-right-carpet-fiber1.htm.

Mihut, Corina, et al. “Review: Recycling of Nylon from Carpet Waste.” Wiley Online Library, John Wiley & Sons, Ltd, 7 Apr. 2004, onlinelibrary.wiley.com/doi/pdf/10.1002/pen.10845.

“Nylon and Polyester Carpet Fibers in Construction.” Building With Chemistry, buildingwithchemistry.org/chemistry-in-bc/carpet-fibers/.

“Nylon Carpet Cleaning & Maintenance.” Nylon Carpet Cleaning & Maintenance | Unique Carpets, Ltd., www.uniquecarpetsltd.com/nylon-maintenance.

“Nylon Carpet Recycling.” Energy.gov, www.energy.gov/eere/amo/nylon-carpet-recycling.

“Nylon - The Science of Synthetic Textiles.” Explain That Stuff, 31 Jan. 2019, www.explainthatstuff.com/nylon.html.

Sewport. “What Is Nylon Fabric: Properties, How Its Made and Where.” Sewport, Sewport, sewport.com/fabrics-directory/nylon-fabric.

Sharon. “Nylon vs Polyester Carpet – Compare and Contrast.” Home Flooring Pros, www.homeflooringpros.com/blog-guides/nylon-vs-polyester-carpet.

Simmons, Cheryl. “Discover the Pros and Cons of Nylon Carpet Fiber.” The Spruce, The Spruce, 20 Oct. 2019, www.thespruce.com/carpet-fibers-101-nylon-2908796.

“US4647483A - Nylon Copolymer and Nylon Blends and Films Made Therefrom.” Google Patents, Google, patents.google.com/patent/US4647483A/en.

Xier Che

DES 40A

Professor Cogdell

                                          Waste Emissions of Nylon Carpet

Nylon carpet is a textile floor covering made of an upper layer of nylon pile                           

and has a backing attached to it. Nylon is one of the most common materials for the carpet construction since 20th century due to it has outstanding wear-resistance and the pattern can be printed easily. It is also popular for its durability and stain-resistance. 45% of carpet in the world comes from the United States’ carpet industry. The carpet industry generates a large amount of wastes every year, and they create serious environmental impact, which makes studying the emitted wastes and improving the recycling process of them becomes crucial. Throughout the paper, I focus on examining the wastes and emissions generated in each stage of nylon carpet’s whole life cycle, through transportation activities of raw materials to final carpet disposal and recycling.

          To begin with, I first examine waste and emissions associated with raw materials acquisition of Nylon.  The raw material production stage uses up 68% of energy and generates 71.49% of the carbon emissions. It is saying that this stage spends the most energy and generates the most carbon emissions. The nylon carpet production process is twisting, warping, tufting, blending, coating and finishing. “Since the demand of nylon carpet is 807.35 M m2 in the year 2017, the nylon carpet production needs 2462.43 M kg of PVC, 750.84 M kg of latex, 650.56 M kg of caprolactam, 104.96 M kg of polypropylene, and 54.90 M kg of fiberglass. Thus, the raw material production of nylon carpet requires 157.65 B MJ (17.57 MJ/FU) of energy and produces 30.78 B kg CO2-e (3.43 kg CO2-e/FU) of emissions. Caprolactam and PVC are two materials that contribute about 90% of the total energy consumption and the total carbon emissions at the raw material production stage of a nylon carpet” (Haehun, Vittaldas, 1237). 

          Next is the waste and emissions associated with manufacturing and processing. There are three production process of the manufacturing of nylon carpet: caprolactam production, nylon fiber production, and nylon carpet production. “During the production of 0.09 m2 nylon functional units (FU) using nylon fibers (0.81 kg / m2), 0.07363 kg of caprolactam and 0.0729 kg of nylon yarn are required. During nylon yarn production, the original mass of caprolactam was reduced by 1% through the extrusion process (Li, 2007). Similarly, referring to BEES (Lippiatt, 2007), in order to produce 0.0729 kg of nylon fiber, the production process of nylon yarn fiber requires 0.13122 MJ of electricity, 0.01458 MJ of natural gas, and 0.05103 MJ of fuel oil, while producing 0.02928 of carbon produced from energy use Kg of CO2 equivalent emitted. In addition, the production process of nylon carpet requires 0.162 MJ of electricity, 0.738 MJ of natural gas, 0.00612 kg of glass fiber, 0.0837 kg of latex and 0.0117 kg of polypropylene, and the carbon emissions generated by the energy use generated during the production process are 0.03527 Kg of carbon dioxide processed 0.09 square meters of nylon carpet. After delivery from the raw material manufacturer, the raw material caprolactam is extruded to produce nylon yarn nylon 6 fiber. Next, the nylon yarn is tufted into a carpet of a specific density, pattern and style, and woven into cotton. After the tufting process, the tufted carpet is adhered to the backing. The tufted carpet is then steamed, mixed, coated, dried and finished. The carpet enters the coating phase, where the latex coating is applied to the underside of the carpet and then dried during the drying process. Finally, complete nylon carpets are available to customers. According to Lee's research on nylon carpets (2007), the general manufacturing process of nylon carpets. Based on the proportion of energy in the life cycle assessment of chemical processes (Li, 2007), Table 5 lists the energy used in the production of nylon carpets and the carbon emissions of each process. Carbon emission density is the density of each process that is obtained by multiplying energy by the energy's carbon emission density. For example, the extrusion process requires three sources of energy-1.8 MJ of electricity, 0.2 MJ of natural gas, and 0.7 MJ of fuel oil-to process one kilogram of caprolactam and produce 0.40168 kilograms of CO2-e, which is each carbon produced by three energy sources Sum of emissions. In its carbon emission estimation, the carbon emission densities used in this study are electricity 0.19528 kg CO2-e / MJ, natural gas 0.00493 kg CO2-e / MJ, and fuel oil 0.07027 kg CO2-e / MJ (EPA, 2017)” (Haehun, Vittaldas, 1237). The manufacturing process consumes a lot of water and produced large amount of wastewater and pollutes the environment seriously(Haehun, Vittaldas, 1239).

       In addition, the waste and emissions associated with distribution and transportation cannot be ignored. Carpet recycling transportation includes carbon density of carpet recycling transportation, carbon emission of carpet recycling transportation, yarn transportation and raw material transportation made a number of waste emission of the whole transportation process that we cannot ignored: .021568 B kg CO2-e carbon emission in total.

       Furthermore, I study the waste and emissions generated during the use stage. The use stage includes process of installation, maintenance and cleaning. This stage consumes 24.36% of energy and generates 25.37% of the carbon emissions. It is saying that this stage uses up the second most energy and generates the second most carbon emissions. After the finished nylon carpet is distributed to the distribution facility, it will be installed and used by customers. For the carpet installation and use phase of nylon carpets, the same carbon emissions are generated. In the installation phase, nylon carpets require 2.21 B MJ (0.2466 MJ / FU), which accounts for 0.97% of the total energy consumption of nylon carpets during the life cycle, and also produces 0.43199 B kg CO2-e (0.04816 kg CO2-e / FU), which accounts for nylon carpet 1.00% of total life-cycle carbon emissions. On the other hand, during the 11-year service life of nylon carpets (Bowyer et al., 2009), the use phase of nylon carpets consumes 55.77 B MJ (6.22 MJ / FU), accounting for 24.36% of the total energy consumption. During the entire life cycle, the total amount of carbon dioxide produced was 10.92 B kg of CO2-e (1.22 kg of CO2-e / FU), accounting for 25.37% of the total carbon emissions throughout the life cycle.

     During the nylon carpet recycling process, large amount of wastes is produced. The recycling process of nylon carpet is collecting waste nylon 6 carpet and put them in shredder, after air separation, adding catalyst in extruder; then vacuum pump; finally put wastes in condenser and produce caprolactam. During the shredding process, there is 0.01137 kg CO2/unit carbon produced. Negligible amount of carbon is produced is separation. 0.01726 kg CO2/unit carbon is produced in extrusion process, 0.02296 kg CO2/unit carbon produced in condenser and 0.01133 kg CO2/unit carbon generates during vacuuming (Haehun, Vittaldas, 1239). “According to the study of Subbiah (2008), 0.09571 kg of caprolactam is recovered from one kg of post-costumer nylon carpet (0.00698 kg/FU). Thus, the recycling of a FU of nylon carpet saves 0.81945 MJ of energy and 0.16005 kg CO2-e in the raw material production stage. In line with the demand of the year of 2017, it is possible to reduce 7348.08 M MJ of energy consumption and 1435.19 M kg of carbon emission equivalent production by using recycled caprolactam from nylon carpet recycling. In other words, the use of recycled raw material has the potential of reducing 3.21% of the total energy consumption and 3.33% of carbon emissions in 2017. On the other hand, as an alternative of a recycling stage, to the combustion process uses 3.68 B MJ (0.41043 MJ/FU) and produces 0.71936 B kg CO2-e (0.08019 kg CO2-e/FU)” (Haehun, Vittaldas, 1238). “Evergreen Nylon Recycling, that has resulted in the development of a patented chemical process to convert nylon 6 carpet into caprolactam. This process is essentially a depolymerization process whereby nylon carpet is fed into a reactor and exposed to patented temperature, pressure, and steam conditions. The process separates the nylon from its coproducts, which includes about 20% other polymers and 80% calcium carbonate. The recycled caprolactam is being marketed under the brand name Infinity and is described as an “infinitely renewable nylon resin” (Honeywell Inter- national, 2000). It consists mainly (80%) of postconsumer carpet but will also contain postindustrial manufacturing waste. The program hopes to recover an estimated 100 million pounds of caprolactam from approximately 200 million pounds of discarded nylon 6 carpet every year. This would divert about 20% of the nation’s used nylon 6 carpet from landfills” (United States Paten, 3). The use of waste fibers as reinforcement in polymer composites is another part of recycling process. “Kotliar et al. have explored the use of carpet face yarn and textiles as reinforcement for a composite or laminate. Because of the fine diameter of the fibers involved, a low viscosity prepolymer in a water base was used to insure complete coverage of fibers. Adhesives were selected to result in a high-modulus and creep resistant material with good weathering characteristics” (Wang, 77). As I mentioned before, the carpet industry “discharges a significant wastewater, high in volume and in most pollution parameters. Due to increasing water scarcity and costs, there is a need for water re-use. Re-use of wastewater requires the installation of drains above the dyehouse floor for ease access and possible segregation of effluent streams. Low contaminated and colorless wastewater from pre-treatment like washing and blending can often be re- used directly in rinsing and washing processes” (Wang, 83). Biological treatment, chemical precipitation, ozonation, activated carbon absorption and evaporation and membrane technology are methods used in wastewater treatment of nylon carpet industry.

       For the end-of-life stage, “there are generally two methods for reclaiming nylon 6 waste. The first one is to reprocess the waste nylon 6. For example, via extrusion to form useful articles. This concept is demonstrated in U.S. Pat. No. 4,143,001 to Raab et al. The second method involves chemical regeneration through depolymerization. Processes for depolymerizing Solid polyamide waste are known. For example, U.S. Pat. No. 2,343,174 to Edison et al. shows general hydrolytic degradation using steam. U.S. Pat. No. 3,988,406 to Nakamura et al. shows the recycling of polyamide waste by heat depolymerization. Among the polyamides depolymerized for re-use of the monomer is nylon 6. For example, U.S. Pat. No. 4,107,160 to Dicoi et al. describes reclamation of solid nylon6wasteaccumulatedduringtheendprocessingof45 nylon 6, low molecular weight oligomers and residual monomer from the polycondensation of caprolactam” (free patterns online).

         As my research illustrates, the carpet industry generates a large amount of wastes every year, and they create serious environmental impact, which makes studying the emitted wastes and improving the recycling process of them becomes crucial.  By examining the wastes and emissions generated in each stage of nylon carpet’s whole life cycle, through transportation activities of raw materials to final carpet disposal and recycling, I think it is worth researching more recycle and re-use technology of carpet waste.

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