DES 040 A: Energy and Materials, Design
Instructor: Christina Cogdell
Date: December 6th, 2018
Wastes and Emissions: Polyurethane Skateboard Wheels
Imagine riding down on the first developed skateboard. Imagine riding down the asphalt in the early 1960s where the wheels on the board are made of a clay compound. Riding that road would be very bumpy wouldn't it?1 In this day Skateboard wheels are mostly made out of urethane compounds that allows the structure for better stability and traction 1. Like most manufactured goods, polyurethane wheels to go through a process where they are manufactured, sold to skateboard companies, and either repurposed or thrown out. In its life cycle though there are certainly going to be wastes and emissions being released. These emissions are most prominent in the remanufacturing of the polyurethane compound as well as the extraction of the natural compound. So even though the wastes in polyurethane wheels can be positive because its structure is chemically alternated for it to be durable for long periods of time, it can also be negative due to the emissions released when extracted and manufactured.
The commence of the polyurethane skateboard wheels starts with the extraction of crude oil. Crude oil as we know it is extracted using wells and fracking that allow the raw petroleum or “crude oil” to travel up. This process is highly toxic though when it comes to the emissions released. As noted in Sofia Plagakis article, “Oil and Gas Production a Major Source of Greenhouse Gas Emissions, EPA Data Reveals”, Plagakis explains that the extraction and production of gas and oil are the second largest in the world to release greenhouse gasses. She claims, “The oil and natural gas sector emitted 225 million metric tons of carbon dioxide equivalent that year, making it the second-largest major industry sector producing greenhouse gas pollution.”2. This process of gas release is due to the number of gasses trapped within the rock and sediment being drilled. Depending on which way the crude oil is being extracted through gasses can be extracted along to be used for other purposes, like the propane industry, as explained by the Department of Chemistry, University of York, UK3. The chemical compounds that are formed in the Polyurethane structure are all extracted from the fracking process. As explained on Europur.org, Polyurethane is produced by reacting polyols and diisocyanates, which come from the crude oil 4.
Once the Polyurethane is processed chemically it can be shipped to different companies depending on how they want they want it. It is important to acknowledge though how the polyurethane is being shipped as it too can be a factor to the wastes and emissions produced. As stated before companies that manufacture the wheels themselves were private and were inaccessible, but it can be presumed that the wheels were transported by shipment trucks if in the same place. In the time for change webpage, it is explained that “modern lorry and trucks” produce 60 to 150 g” of carbon dioxide 5. This amount is dispensed for every metric ton. If done continually, which it is can be a very negative effect on the environment.
Polyurethane is in many things other than wheels, and are most prominent in insulation material for appliances like fridges. Different catalysts or additives are added to the polyurethane in order to create different effects and uses 6. In the case of the wheels, the additive that is most commonly used is butyrate 430-A-ORO-43-MS. This chemical compound allows for “good frictional characteristics, tear, and tensile strength, and, partly by virtue of its resilience, being relatively quiet”. As explained in the patent, the combination of these chemical compounds allows faster production time due to the time it takes to dry as well as reducing material costs 7. Throughout the molding process, there seems to be little to no waste of materials. The casts used throughout the process also seem to exhibit little waste. This information is not as valid though because of the lack of knowledge in this area. As exhibited in the “ How Its Made - 1405 Skateboard Wheels” very little information regarding the waste and emissions 8. Different companies were also contacted throughout the research process but because they were private companies, we were unable to receive further information concerning the wastes and emissions throughout the production process. From the acquired information though it can be inferred that while the wheels are in use little waste will be emitted. This is due to the compounds creating “strength” and “resilience”.
Even though there was a lack of information in manufacturing, when it came to the end of the wheel life cycle, information was more accessible. Polyurethane is considered a type of plastic, and as is known plastics are some of the slowest biodegradables. As examined before in the manufacturing process the compound created by polyurethane and butyrate creates a strong and resistant product. This is necessary when it comes to using as the consumer would want their wheels to last for large amounts of time when commuting on them. When it comes to disposing of the wheels it can have a rather negative effect. This is negative because in a landfill this takes longer to degrade leaving more waste. There is research though that has found that the polyurethane can degrade much quicker. In Gary T. Howard’s “Bio-degradation of polyurethane: a review” Dr. Howard explains that scientists have found ways to weaken the structure of polyurethane to increase bio-degradation. He explains “By changing and varying the polyhydroxy and polyfunctional nitrogen compounds, different PUs can be synthesized” 7. This is important as it can help reduce excess waste. Recently though due to changing regulations, there has been an alteration in just dumping used polyurethane in the landfill. Recycling has become an important factor in its life cycle.
At the beginning of the life cycle analysis, it was explained that polyurethane is extracted from crude oils, this is not the only way that polyurethane wheels can be made though. In Khalid Mahmood Zia, Haq Nawaz Bhatti, and Ijaz Ahmad Bhatti article, “Methods for polyurethane and polyurethane composites, recycling and recovery: A review” there are examples of the types of manufacturing processes that are used in recycling this material. In the article, it is explained that the methods of recycling polyurethane are mechanical recycling, chemical processing, thermochemical processing, and energy recovery. It is explained that mechanical engineering involves regrinding the existing polyurethane to a powder form to be reused. Chemical processing as explained uses chemicals to repurpose the product. The article does explain though that these forms of repurposing old polyurethane are, “Nevertheless, they remain of considerable interest for their long-term potential” 9. After going through every type of recycling method the article comes to a conclusion. It states that even though many forms of recycling have been developed, “but still requires more development in order to tolerate more contamination” 9. This contamination is demonstrated thermal processing which “poses the risk of formation of nitrogen oxides (NOx, N2O), ammonia, pyridines, and other hazardous or toxic nitrogen compounds as a result of the high nitrogen content of the material” 10. This statement is found in an article published by the Helinski University of Technology. The article also explains that the polyurethane that is being sent to landfills isn’t even happening in the countries where that polyurethane is being produced. It states, “These shipments may soon suffer from competition from Latin America and Asia and it is questionable whether an additional 70000 tons of scrapped PU foam from ELVs can be disposed of by exporting them to outside the US as well”7. Even though the polyurethane can be recycled it is also important to recognize that it isn’t as sustainable as we expect it to be.
Polyurethane wheels are a great product when riding due to its resilience to wear and tear. The chemical compounds produced by the additives make a product that will last forever. When focusing on the waste of this specific product there is very little waste occurring. There seems to be an issue when it comes to the emissions be released though. Like other raw materials extracted there will be an environmental conflict. As noted the fracking process of the crude oils has a major impact, as well as the transportation involved. Although the research was restricted, due to companies being private, we were still able to find or closely assume some of the emissions released during production. Through this process, we also became aware that the fight for a sustainable and ecological way of repurposing old polyurethane hasn’t really been found. Although recycling is being used to repurpose instead of allowing the material to decay, there are still negative emissions being released in this process. It can be concluded that even though the product of polyurethane skateboard wheels are a strong product due to their structure, their life cycle allows emissions to released, making it ecologically and sustainably unreliable.
1. Skateboard Design: Making Skateboard Wheels | Exploratorium. (n.d.). Retrieved from
2. "Oil and Gas Production a Major Source of Greenhouse Gas Emissions, EPA Data Reveals | Center for Effective Government." Center for Effective Government | Because Government Matters, www.foreffectivegov.org/oil-and-gas-production-major-source-of-greenhouse-gas-emissions-epa-data-reveals.
3. Lichtarowicz, Marek. "Extracting Crude Oil and Natural Gas." The Essential Chemical Industry (online), www.essentialchemicalindustry.org/processes/extracting-oil-and-natural-gas-fracking.html.
4. Lichtarowicz, Marek. "Extracting Crude Oil and Natural Gas." The Essential Chemical Industry (online), www.essentialchemicalindustry.org/processes/extracting-oil-and-natural-gas-fracking.html.
5. "CO2 Emissions for Shipping of Goods Time for Change." timeforchange.org/co2-emissions-shipping-goods.
6.“Composition and Production of Polyurethane.” Polyurethanes in Composition and Production
of Polyurethane, ISOPA, polyurethanes.org/en/what-is-it/composition-production.
7. Lichtarowicz, Marek. "Extracting Crude Oil and Natural Gas." The Essential Chemical Industry (online), www.essentialchemicalindustry.org/processes/extracting-oil-and-natural-gas-fracking.html.
8. "How Its Made - 1405 Skateboard Wheels." YouTube, How Its Made, 12 Apr. 2018, www.youtube.com/watch?v=U64j80P-Vl0. Accessed 3 Dec. 2018.
9. Lichtarowicz, Marek. "Extracting Crude Oil and Natural Gas." The Essential Chemical Industry (online), www.essentialchemicalindustry.org/processes/extracting-oil-and-natural-gas-fracking.html.
10. Zevenhoven, Ron. "TREATMENT AND DISPOSAL OF POLYURETHANE WASTES: OPTIONS FOR RECOVERY AND RECYCLING." Åbo Akademi | Startsida, users.abo.fi/rzevenho/tkk-eny-19.pdf. Accessed 2 Dec. 2018.