How sustainable are recycled plastics?

We’ve always been intrigued by environmentally friendly ideas, but are we all so caught up with the ideas that we sometimes disregard some of their drawbacks? Recently, my dad, who works in the garment industry, talked about his visit to the recycled fabric factory, where plastics are recycled to make a type of fabric called PET fabric. I was instantly fascinated by it and I wanted to learn more, so I began my little research. I found out that the concept of recycled plastics to make fabrics is not new, so I decided that I wanted to know to what extent this process of recycled plastics are really sustainable. I began by looking at the nature of PET.

PET stands for Polyethylene terephthalate, a type of strong and transparent polyester primarily used for plastic bottles and jars (Napcor, 2013). This is one of the most manufactured polymers in the world (Derry, Clark, Ellis, Jeffrey, & Jordan, 2009). PET consists of ethylene glycol, extracted from petroleum, and terephtalic acid. Both are linked together to form a polymer chain (PET Resin Association, 2012). As can be seen from the image shown below, PET has a large molecular structure, thus the name “polyethylene” to describe the many ethylene parts. The large structure also contributes to the fact that PET is a strong material. Strands of PET are cut into little balls and are melted so it can be molded into different types of products. This type of structure is known to be “chemically inert”, meaning that they do not readily react with other chemicals. (How Stuff Works, 2007). This makes plastics like PET unable to decompose, in other words, not biodegradable, posing a threat to our environment.

Today, many PET fabrics are made from recycled plastic bottles. This is a very good way of recycling plastic, rather than stacking more of them in the landfill. The plastics are re-melted and made into clothing fibers that are later used to manufacture PET garments. From this perspective, recycling PET can be very energy efficient. Because ethylene is extracted from petroleum, recycling PET will reduce dependence on the scarce raw material. The material is heat and electricity resistant, making PET great insulators. All of this is great, but what if these do not end up getting recycled? What if no one wanted your PET garments, and you had no choice but to toss these clothes out?

Another disadvantage of PET manufacturing is its inevitable toxic emissions detrimental to the environment. Although recycling polymers is environmentally friendly, ironically its production releases carcinogens like CFCs that deplete the ozone layer (Derry, Clark, Ellis, Jeffrey, & Jordan, 2009). Can we now say that recycling plastics is sustainable in the long run?

Scientists have been working towards biopolymers and biodegradable plastics to reduce these environmental issues. Cellulose, starches, and soy protein polyesters from plants and bacteria can be used to make biodegradable plastics. Perhaps this can one day reduce the amount poured into those filthy and toxic landfills. Although it is still expensive to produce bio plastics, research and development has been advancing, and hopefully it can serve as a more economical and sustainable alternative to the current plastics we use.

Works Cited:

Derry, L., Clark, F., Ellis, J., Jeffrey, F., & Jordan, C. (2009). Chemistry for use with the IB Diploma Programme Options: Standard and Higher Level. Melbourne, Victoria: Pearson Heinemann.

Freudenrich (2007), How Plastics Work. How Stuff Works. Retrieved from http://science.howstuffworks.com/plastic.htm

PET Resin Association (2012), An Introduction to PET, PET Resin Association. Retrieved from http://petresin.org/news_introtoPET.asp

Napcor (2013), PET Sustainability. National Association for PET Container Resources. Retrieved from http://www.napcor.com/PET/sustainability.html

Polyethylene_terephthalate [image]. (2007). Retrieved from https://upload.wikimedia.org/wikipedia/commons/f/ff/Polyethylene_terephthalate.svg

One thought on “How sustainable are recycled plastics?

  1. Environmentally friendly products have always been something I enjoy talking about with my family, which was why I was especially drawn to Vrishti’s post on PEP and recyclable plastic. In her post, Vrishti addressed PEP’s recyclable properties but also its emissions of carcinogens during production, and she concluded her post with insights into biodegradable plastics as a more sustainable alternative to petroleum-based plastics. Biodegradable plastics: would this be the cure-all to the oil crisis? Intrigued, I looked into the manufacturing of bioplastics and learned that, although most are biodegradable, there has been much environmental concern regarding their processing.

    Interestingly, bioplastics have existed for decades. The first one, polyhydroxybutyrate (PHB), was discovered in 1926 by French researcher Maurice Lemoigne (bioplastic, 2012). However, his discovery was largely overlooked because petroleum was inexpensive and abundant at the time. It wasn’t until the 1970s when interests in petroleum alternatives were renewed. But even with an increase in their uses, why haven’t bioplastics replaced petroleum-based plastics? Curious, I researched more.

    As Vrishti says in her post, plastics are carbon polymers (Freudenrich, 2007). Bioplastics can be derived from soybean, corn, beets, and potatoes (Bioplastics, 2012) and be made via two strategies: microbial fermentation and genetic engineering. Through fermentation, bacteria are able to mass-produce biopolymers, which can be extracted and processed into bioplastics; through genetic engineering, the bacterial genes that code for bacterial plastics can be transferred into plants for plants to produce the biopolymers (Freudenrich, 2007). To better understand how bacterial plastics work, I have decided examine the bioplastic polylactic acid (PLA), which is 100% biobased and has been known as “one of the most environmentally friendly bioplastic available (Why PLA). Through fermentation, bacteria are able to produce lactic acid, which undergo condensation reactions. The water molecules produced from this reaction prevents, however, the growing chain of lactic acid from staying together, so small chains known as polylactic acid oligomers are produced and processed into lactide molecules, which then act as monomers for the polymerization of PLA (Washam, 2010), as seen in the figure below (I don’t know how to insert a picture on here, but it’s from this site https://www.acs.org/content/dam/acsorg/education/resources/highschool/chemmatters/archive/bioplastics-cm-apr-2010.pdf.

    So what exactly makes bioplastics so desirable? Such bioplastics can be degraded by microorganism or by water (bioplastic, 2014), which, in contrast to the inert petroleum-based plastics, is highly desirable. Furthermore, such degradation products are also natural metabolites, which can be used for medical purposes, such as control-release drug packaging and absorbable surgical stitching (bioplastic, 2014). Another advantage of bioplastics is that, as opposed to petroleum-based plastics, they are produced from renewable sources such as bacteria and plant.

    As my research confirmed my belief that bioplastics are indeed environmentally friendly, I have also however become aware of environmental dilemma surrounding bioplastics. The very fact that they are biodegradable has been an issue, because there are different types of biodegradability – those via oxygen and those via UV radiation (Grabianowski, 2012), meaning that some can degrade under the sun. Furthermore, the decomposing process often takes years and releases toxic chemicals (Grabianowski, 2012). While some bioplastics have been produced to degrade when composted (Grabianowski, 2012), often times they are not able to undergo the required industrial composting process because most go to the landfill instead, where they will decompose slowly in the oxygen-free landfill environment and ultimately release methane, which is a “greenhouse gas 20 times more potent than carbon dioxide” (Washam, 2010). Thus, there is a need for better labeling for compostable bioplastics to be at the right place for proper processing. Coupled with the abovementioned controversies, bioplastic production and development has also been hindered by its cost, which is “higher than for petroleum-based plastics” (Bioplastics, 2012), making it less competitive than its rival plastic.

    Although bioplastics, with their environmental dilemma, have not at this time proved themselves to be the solution of a greener petroleum-based plastic alternative, I feel confident and hope that, with our current research and development in biodegradable products, bioplastics will eventually become a very desirable product, both environmentally and economically speaking. After all, with global issues such as ozone depletion gaining increasing attention, a better and greener alternative is what we need, and bioplastics is one promising solution.

    “Bioplastics.” Biotechnology: Changing Life Through Science. Detroit: U*X*L, 2012.Science in Context. Web. 27 Feb. 2014.

    “bioplastic.” Britannica School. Encyclopædia Britannica, Inc., 2014. Web. 28 Feb. 2014. .

    Freudenrich, Ph.D., Craig. “How Plastics Work” 14 December 2007. HowStuffWorks.com. 27 February 2014.

    Grabianowski, Ed. “What is the future of bioplastics?” 16 April 2012. HowStuffWorks.com. 27 February 2014.

    Washam, Cynthia. “Plastics Go Green.” ChemMatters. April 2010. American Chemical Society Web. 27 Feb. 2014.

    “Why PLA?.” Corbion Purac. N.p., n.d. Web. 27 Feb. 2014. .

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